Next Article in Journal
Biopolymer-Assisted Hydrothermal Synthesis of Manganese Cobalt Spinel Oxide (MnCo2O4) Using Cellulose and Chitosan for Enhanced Catalytic Performance
Previous Article in Journal
Environmental Degradation of Footbed Materials Under Different Conditions
Previous Article in Special Issue
Optimisation of Clutch Disc Friction Material Using a Multi-Layer Perceptron Artificial Neural Network
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Polymers
Volume 17
Issue 23
10.3390/polym17233135
polymers-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Advances in Membranes Based on PLA and Derivatives for Oil–Water Separation

by
Weijun Liang
1,
Akshay Verma
2,
Olga Martin
1,
Gaurav Sharma
2,* and
Alberto García-Peñas
1,*
1
Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IAAB, Universidad Carlos III de Madrid, Avda. de la Universidad, 30, 28911 Madrid, Spain
2
International Research Centre of Nanotechnology for Himalayan Sustainability (IRCNHS), Shoolini University, Solan 173229, HP, India
*
Authors to whom correspondence should be addressed.
Polymers 2025, 17(23), 3135; https://doi.org/10.3390/polym17233135
Submission received: 17 October 2025 / Revised: 18 November 2025 / Accepted: 22 November 2025 / Published: 25 November 2025
(This article belongs to the Special Issue Emerging Trends in Polymer Engineering: Polymer Connect-2024)
Browse Figures
Versions Notes

Abstract

The continuously growing amount of oily wastewater from industrial, domestic, and natural sources poses a major threat to water sustainability, and thus efficient oil–water separation techniques are of utmost relevance. Membrane separation has been a popular approach due to ease of handling, high performance, and versatility. Among all the membrane materials, polylactic acid (PLA) and its derivatives have been of interest as green materials because of their renewability, biocompatibility, and biodegradability. PLA possesses special merits, including low density, high permeability, and high thermal stability. Despite its advantages, PLA also has some demerits, such as brittleness, low tensile strength, and poor heat resistance. These limitations are addressed by PLA-based membranes that are generally reinforced using fillers, surface modification, and structure optimization methods. This review provides a comprehensive overview of recent developments of PLA and its derivatives for oil–water separation, with an emphasis on membrane design, fabrication methods, and porosity enhancement strategies. Some significant fabrication processes like Thermally Induced Phase Separation (TIPS), Nonsolvent-Induced Phase Separation (NIPS), and Freeze Solidification Phase Separation (FSPS) are elaborately addressed. In addition, the review emphasizes methods to improve porosity, mechanical strength, and fouling resistance while maintaining biodegradability. By reviewing recent progress and remaining challenges, this review outlines the future potential of PLA membranes and aims to inspire more research on green, efficient oil–water separation.

1. Introduction

Water is the fundamental basis that nurtures and sustains all life on this planet. Although it is a fundamental human need, access to clean and safe drinking water has become a key issue at the global level. Rapid industrialization, agricultural growth, and technological development spurred by population increase have drained and polluted existing freshwater resources substantially [1]. Among the numerous pollutants involved in this crisis, oil-based pollutants are of special interest. From the Industrial Revolution, the rapid growth of science, technology, and socio-economic industries has led to large-scale oil production to satisfy energy and material needs. While oil is an essential non-renewable source of energy and raw material for modern society, its extraction and use have led to serious environmental challenges. Large amounts of oily industrial waste and regular marine oil spills contaminate water bodies annually, causing serious environmental harm. Consequently, oil-based pollutants now constitute one of the primary causes of water pollution globally [2]. Industries such as textile, petrochemical, mining, and metal processing produce large amounts of oily wastewater. The pollutants usually come in various forms, including emulsified oil (<20 µm), dispersed oil (15–145 µm), and free oil (>145 µm) [3,4,5,6]. Oil spills during production and transportation also have a detrimental effect on aquatic ecosystems and cause the loss of precious natural resources. Thus, there is a need to develop energy-efficient oil–water separation technologies to treat industrial effluents and conserve water resources [7]. Several techniques have been devised for oil–water separation, which can be broadly classified into physical, chemical, and biological methods. All the methods have their advantages and limitations. Of these, membrane filtration has proven to be a successful method for oil–water separation, as it allows for the processing of high volumes of oily wastewater without the need for chemical additives. Additionally, membrane-based systems offer a more efficient and easier method than conventional separation systems [8,9]. Membrane separation processes are scalable, chemical-free, and phase-change-free, making them efficient processes ideal for portable oil–gas systems and offshore use [10]. Yet, in many cases, their operation can be limited by low water permeability and surface fouling, and they require frequent chemical cleaning and high energy input. Hence, it is highly desirable to develop highly permeable membranes with low-pressure-driven effective oil–water separation.
Recent developments in high-performance porous membrane materials have greatly broadened their applications, increasing the need for membranes with better functionality and efficiency [11]. Traditionally, most membranes are fabricated from petroleum-based polymers like PVDF [12], PP [13], PSF [14], and PES [15]. However, these materials pose environmental issues because they are not easily degradable. Although they offer several benefits, oil-based membranes are confronted with economic challenges, including high production costs and negative environmental effects, which limit their widespread industrial application. Consequently, researchers are increasingly focusing on developing renewable and environmentally friendly alternative materials [16].
Conversely, polylactic acid (PLA), a biodegradable thermoplastic polyester derived from renewable plant-based lactic acid, offers a green alternative for membrane fabrication. It offers various advantages, including low density, high surface area, good thermal insulation, high permeability, and intrinsic biodegradability and biocompatibility. It has the disadvantage of low tensile strength, brittleness, and poor resistance to heat [11]. It belongs to the aliphatic polyester class and is typically produced from hydroxy acids [17]. PLA was first synthesized in 1932 by the thermal decomposition of lactic acid under vacuum, producing a material with a relatively low molecular weight. PLA has become an extremely popular polymer due to its non-toxicity and its broad range of applications across numerous industries [18]. Additionally, it is affordable and possesses attractive properties that make it suitable for various industrial applications. Despite these merits, PLA possesses innate limitations such as brittleness and the requirement for alterations to improve its functional and structural performance [16]. In overcoming these deficits, PLA is usually blended with additives and reinforcements like natural fibers, inorganic nanoparticles, and other polymers. These modifications result in PLA-based composites that show remarkably improved mechanical strength, thermal stability, and barrier properties while preserving their biodegradability [19].
PLA membranes can be compared with other polymeric membranes used for oil–water separation, considering that these other membranes have not yet been commercialized. In this context, PLA membranes demonstrate promising results in terms of biodegradability, reducing secondary pollution commonly observed with PVDF and other polymeric membranes. They also exhibit high oil rejection efficiency, reported in some cases to reach up to 99.4%, along with high water flux and strong fouling resistance [20,21,22,23,24,25,26,27]. The use of other membranes, such as those composed of cellulose-based aerogels or graphene-based aerogels, is attracting the attention of numerous scientists due to their high porosity, high efficiency, versatility, good mechanical properties, and durability, among other advantages [28,29].
So far, several reviews have addressed different areas of polylactic acid (PLA)-derived materials, such as their preparation, drug delivery, and preparation of porous PLA membranes [11,30]. Other studies have discussed two-dimensional nanomaterial (2D-NM)-based polymeric composites for oil–water separation and methods to boost their efficiency [7]. Despite the increasing literature, there remains an inadequate number of reviews on recent developments in PLA and its derivatives for oil–water separation. The review begins with a discussion on oil–water separation membranes, followed by a summary of polymeric membrane technologies. It then delves into the production of membranes from PLA and its derivatives, emphasizing key aspects such as fiber formation techniques, surface modification methods, and approaches for enhancing porosity. The most significant preparation methods covered are Thermally Induced Phase Separation (TIPS), Nonsolvent-Induced Phase Separation (NIPS), and Freeze Solidification Phase Separation (FSPS), all of which are vital to achieving customizable membrane properties that ensure optimum oil–water separation performance. Overall, this review intends to fill the present gap by providing a comprehensive critical evaluation of recent developments in PLA-based membranes and derivatives, highlighting their potential, challenges, and future directions for developing efficient and sustainable oil–water separation technologies.

2. Membranes for Oil–Water Separation

The oil–water mixture is a common problem, not only in various mechanical and industrial processes but also in oil production and extraction, oil spills, and even domestic activities such as washing cars or equipment. As a result of these activities, between 470,000 and 8.4 million tons of oil enter the oceans each year through spills and chronic pollution, according to the Safe Drinking Water Foundation. These last two sources significantly contribute to these numbers, as numerous oil spill incidents are reported annually, along with chronic pollution from industrial wastewater, urban runoff, pipeline leaks, bilge water from ships, and atmospheric deposition of fossil fuels (Figure 1).
These mixtures form a suspension that is difficult to separate once it enters soil or natural water sources. Therefore, prevention or separation methods are necessary to avoid irreparable damage. Primarily, separating oil–water suspensions is beneficial for environmental conservation, recovering valuable resources, and improving engine efficiency. For example, irreparable damage can occur when oil–water suspensions come into contact with soil or water bodies, affecting or destroying local flora and fauna. Furthermore, recycling technology can also reclaim new raw materials for the tire and fuel industry from the oil, and the water, if recycled, can be utilized again in secondary applications like cooling or cleaning. Finally, not allowing water to touch the engine can increase its longevity, improve its performance, and prevent issues like corrosion. For this purpose, some components of the traditional processes of oil–water separation are centrifugation, flotation, settling tanks, depth filters, magnetic skimmers for oils, and magnetic separation, among others. However, these processes also have some limitations, such as process complexity, low efficiency, high energy consumption, or inefficiency in the post-treatment process. Some of the primary issues with techniques like physical precipitation, chemical flotation, and mechanical centrifugation are that they have limited practicality, and they are very expensive and rather inefficient [31]. The same goes for techniques like electrochemistry, flocculation, and gravity sedimentation in that they are also subject to secondary pollution, particularly when working with heavy oil [32].
The application of adsorption technologies has yielded extensive outcomes, especially with adsorbents from aerogels, sponges, or foams that can achieve adsorption capacities of up to 68 g/g. Many of these adsorbents are hydrophobic, showing excellent performance in oil–water separation. However, some systems, such as foams, present certain shortcomings, including low tensile strength, poor oil resistance, and the need for secondary treatment to recover the oil [32].
The use of membranes for separating oil and water holds great potential due to their high separation efficiency and relatively low cost compared to other systems [33]. Membranes also offer additional advantages, such as simple operation, low cost, and energy conservation, which contribute to environmental protection [34]. Moreover, their growing popularity in oil–water separation is also due to other functionalities such as superhydrophilicity, superoleophobicity, superhydrophobicity, and superoleophobicity, which can be modulated by the surface free energy and the micro/nano-structure of the materials [31].
Membrane systems offer multiple advantages over other technologies because they do not require thermal generation, a phase change, or active moving parts. They also combine strong anti-fouling capabilities with high separation flux [32,35]. In the past, traditional membranes lacked high selectivity due to interfacial wettability differences between oil and water, resulting in the adsorption of both components and reducing system efficiency. Nevertheless, the problems have been minimized due to better control of tunability in membrane characteristics. This means that membranes can now be specifically designed based on the nature of the oil–water mixture, allowing precise control over superhydrophobic and superoleophilic properties to achieve excellent performance [36].

3. Polymeric Membranes

The various advances in macromolecular chemistry have enabled the formation of membranes with distinct surface affinities and physical characteristics, best suited for oil–water separation according to specific application requirements. Table 1 outlines the materials used in oil–water separation membranes, where the significant contribution of polymers and their blends is notable. Furthermore, the table illustrates some of the benefits of these materials, which are obviously connected to their affinity and separation capacity.
Polymeric materials exhibit an interesting range of properties that can be controlled by their microstructure and composition. In this case, polymers enable control over pore size and surface area during the manufacturing process. Mechanically, polymers can offer excellent properties, including being highly flexible and possessing high durability with resistance to heat, corrosion, and adverse conditions. In most cases, these involve low costs, simplicity in preparation protocols, and high efficiency in oil–water separation processes [22,43].
One of the issues seen in polymeric materials is their limitation regarding hydrophobicity, which results in fouling and thus lowers their usability and efficiency. As a result, the permeation rate is affected, leading to increased energy consumption and a reduced lifespan. To address this, numerous research groups are working on improving surface properties by modifying various polymers and their derivatives [21].
Table 2 lists some of the main polymers used for membranes designed for oil–water separation, along with the most relevant properties that can be achieved based on the requirements dictated by the nature of the mixtures and their conditions.
Polylactic acid (PLA), also known as polylactide, is an environmentally friendly polyester synthesized from lactic acid. It is derived from renewable resources such as starch, corn, and rice through fermentation processes, and can biodegrade after use, releasing CO2 and water [58,62]. Compared to other matrix materials, PLA offers advantageous properties for membrane fabrication, particularly due to its ease of surface modification. When combined with good mechanical strength and processability, PLA emerges as an excellent candidate for oil–water separation membranes, as evidenced by nanofibers exhibiting high lipophilicity and strong oil adsorption capacity [22,68]. Nevertheless, there are some shortcomings associated with its limited thermal stability and lower chemical resistance, which need to be addressed through various approaches.
The importance of PLA in oil–water separation is evident, not only due to new sustainability policies promoted by the European Union, but also from a scientific perspective, where interest in the use of PLA for oil–water separation has increased exponentially since 2018 (Figure 2).

4. Preparation of Membranes Based on PLA and Derivatives

The methods used for preparing membranes for oil–water separation focus on controlling surface characteristics, mechanical properties, and suitability for the intended application. In this context, some of the most common preparation methods for PLA membranes for oil–water separation include electrospinning, phase separation, foaming, aerogel formation, melt blowing, and surface modification of nonwoven membranes.

4.1. Fiber Formation Techniques

One of the most interesting features offered by electrospinning is the ability to obtain a high surface-area-to-volume ratio, porosity, and control over the functionalization of the membranes in terms of hydrophobicity. The increase in surface area is directly related to the membrane’s adsorption capacity [69]. On the other hand, porosity and hydrophilicity are directly associated with water flux. Consequently, electrospinning represents a practical approach for fabricating membranes [70,71]. The use of PLA for membrane preparation via electrospinning, compared to other polymers, offers advantages such as tunable wettability, flexibility, and low cost. Table 3 presents some of the most recent advances in the fabrication of PLA-based membranes and derivatives through electrospinning. It includes data on surface characteristics (fiber diameter, pore size, porosity [%]), hydrophobicity (water contact angle, oil contact angle), separation performance (separation efficiency, static water contact angle under oil, oil uptake [g/g], absorption capacity [g/g], and separation flux). Yang et al. fabricated biodegradable poly(L-lactic acid) (PLLA) nanofiber membranes via electrospinning. PLA particles were dissolved in a DCM/DMF mixed solvent to form the spinning solution, which was electrospun at 25 ± 2 °C and 50 ± 5% humidity. The resulting fibers were collected on a metal drum and dried at 60 °C for 24 h. Parameters such as polymer concentration, solvent ratio, voltage, and collection distance were optimized to control fiber porosity. The optimized porous membrane was finally treated with 90% acetone for 5 min and air-dried to form the final membranes [72]. Another study by Jiang et al. prepared superoleophobic PLA/CDA composite nanofibrous membranes via electrospinning. Initially, PLA was dissolved in a CHL/DMF solvent to form spinning solutions, which were electrospun at 20 kV, a flow rate of 1 mL/h, a distance of 20 cm, and a temperature of 25 ± 3 °C. The solutions were then subjected to heat treatment at 100 °C for 2 h. Cellulose diacetate was then dissolved in acetone, and the heat-treated PLA membranes were immersed in this solution for 30 s, rinsed in deionized water for 1 h, and dried at 60 °C for 3 h to obtain the final PLA/CDA composite membranes [73].
Table 3 enables us to draw important conclusions about the various factors related to oil–water separation. As an example, pristine PLA possesses moderate oil adsorption and hydrophobicity. In such a case, the inclusion of substances like WS2, MoS2, CNTs, and CuMOF tends to be hydrophilic-reducing, characterized by water contact angles greater than 130° and increased oil adsorption. Additionally, the use of silane treatments, such as vinyltrimethoxysilane or aminopropyltrimethoxysilane, further enhances oil adsorption, with values exceeding 60 g/g. Increased surface areas can be attained by increased porosity, roughness, or, in the case of fiber, by decreasing their diameters, which normally leads to enhanced separation efficiency [69]. For instance, Table 3 illustrates fibers with diameters of 200–700 nm, which have higher separation efficiencies compared to larger fibers (>2 μm), which have lower efficiencies but better mechanical properties. The characteristics of fibers generated by electrospinning vary with the polymer solution utilized, as it determines the morphology of the fibers. In this context, viscosity plays a crucial role, affecting both fiber diameter and the degree of polymer chain entanglement.
The increase in the WCA could be attributed to the decreased diameter of fibers, which enhances the surface roughness and promotes the penetration of more air into the gaps between the fibers [76]. The wettability and absorption capacity of the membranes are improved by increasing the water contact angle. At the same time, the membranes showed excellent separation properties when they had an oleophilic feature, which is closely related to higher porosity [79]. It is lower than that of pure PLA nanofibers owing to the presence of POSS particles in the fiber surface and the pores, hence decreasing the porosity [75].
Porosity plays a crucial role and can be estimated using the Cassie–Baxter theory, which relates the differences in water contact angles between the bulk material and the electrospun surface to the presence of air pockets trapped within the structure [70,74]. The modification or functionalization of PLA surfaces with components such as POSS, LDH, carbon dots, and γ-Fe2O3 leads to higher efficiencies by enhancing flux due to changes in superhydrophobic or superoleophilic properties. The preparation of specific composites, such as PLA-γ-Fe2O3 (10 wt.%) combined with glycine, results in high water contact angles (148°), producing hydrophobic surfaces.
It is well known that flux is determined by the composition, porosity, and morphology of the membranes. Flux variations tend to increase significantly in many PLA composites by around 90%, compared to pure PLA, along with an improvement in separation efficiency. For example, the PLA-γ-Fe2O3 40/10/17 composite exhibits a notable n-hexane flux of approximately 57,000 L/m2·h. PLA-based hybrids with MOFs and/or functional nanoparticles (such as WO3, CNTs, CQDs, etc.) can yield excellent wettability and separation efficiency/flux.
The preparation of microfibers by blowing molten PLA is performed through nozzles using hot air. In this process, the fibers produced are coarser than those obtained by electrospinning but offer better industrial scalability. Specifically, electrospinning presents some challenges when working with thermoplastic polymers, which melt blowing can overcome. Additionally, melt blowing provides other advantages, such as high production efficiency and low pollution output [84]. Figure 3 shows the melt-blown system for PLA. The process involves melting the polymer and extruding it through a die with fine nozzles. High-velocity hot air then stretches the molten strands into microfibers, which solidify rapidly and are collected as a nonwoven mat.
Table 4 presents examples of PLA-based membranes prepared by the melt-blown process for oil–water separation. These membranes are scalable to an industrial level, solvent-free, and possess a minimal environmental footprint.
The incorporation of 10 wt.% PBAT raised the water contact angle of the membrane from 122.3° to 133.2° and made the fiber diameter distribution wider. Conversely, with 4 wt.% PBAT, the minimum fiber diameter was 2.3 μm, and the maximum adsorption capacity in oil was 5.18 g/g [62]. Upon increasing the PBE content above 10 wt.%, the melt viscosity of the polymer blend decreases, resulting in increased fluidity and a considerable reduction in fiber diameter. With increasing PBE content from 0% to 20%, the oil absorption capacity of the PLA/PBE micro-nanofiber fabric increases from 4.65 mg/g to 6.22 g/g. As the fiber diameter decreases, the volume-to-surface area ratio reduces, increasing the material’s capillary action and thus its capacity for oil absorption [85].

4.2. Surface Modification Techniques

Several methods have been reported for modifying membrane surfaces for oil–water separation, including interfacial polymerization, plasma treatment, chemical vapor deposition, hydrothermal methods, dope solutions, coating, and heat treatments, among others (Figure 4) [21].
In the case of PLA, plasma treatments have shown interesting results, as PLA membranes can be modified through the introduction of functional groups. These changes promote adhesion, increase surface energy, and provide control over the membrane’s degree of hydrophobicity. Chemical vapor deposition enables PLA surface modification by depositing thin functional layers. On the other hand, surface coatings are applied to PLA membranes to impart additional properties such as photocatalysis and self-cleaning. Nevertheless, interfacial polymerization has not been explored in membranes composed of PLA. Several recent studies have utilized different surface modification techniques. For instance, Sayed et al. fabricated an environmentally friendly and biodegradable PLA@SiO2 nanocomposite membrane for efficient direct contact membrane distillation (DCMD). The SiO2 nanoparticles were derived from rice husk waste through a green synthesis route involving calcination, alkali extraction, and acid precipitation, producing fine white silica powder. A 12.5 wt.% PLA solution was electrospun into a nanofibrous membrane, while SiO2 nanoparticles (2 wt.%) were uniformly coated onto its surface using electrospraying to obtain the PLA@SiO2 membrane. To improve the structural integrity, hydrophobicity, and thermal stability, the membranes underwent post-heat treatments: heat pressing at 140 °C, annealing at 90 °C, and a combined heat press annealing process, each optimized to enhance performance and durability [86]. Another study by Scaffaro et al. developed electrospun PLA membranes and modified their surfaces using plasma treatment to enhance their performance in Streptomyces coelicolor immobilized-cell cultivations for actinorhodin production. The PLA membranes were fabricated via electrospinning and then exposed to air plasma in a radio-frequency reactor (13.56 MHz, 50 W) under controlled pressure conditions (0.5 mbar) for 30 s on each side. This plasma modification effectively altered the surface chemistry and morphology of the PLA membranes, improving their suitability for microbial adhesion and metabolite production [87].
The modification of PLA surfaces in nonwoven membranes depends on the nature of the oil–water mixture. Consequently, the surface properties of the membrane, specifically its wettability, depend on its compositional and microstructural characteristics. Higher hydrophobicity is directly related to lower surface free energy. Surface roughness also plays an important role; for example, a change in wettability can be induced by increasing surface roughness, which alters the topography. This effect is observed after a short preheating treatment in ethylene glycol, which reduces surface crystallinity [88,89]. In general, PLA nonwoven membranes exhibit good porosity and sufficient mechanical properties, enabling their use in numerous applications such as air filtration and medical protection [90,91].
Table 5 shows some of the most promising modified nonwoven membranes based on PLA for oil–water separation. It is observed that the modification of PLA with dopamine leads to hydrophilic membranes, as evidenced by the reduction in the water contact angle. The modified membrane shows a water contact angle of 58.5° compared to 121° for the pure PLA membrane. Similarly, hydrophilicity is enhanced in PLA-PDA-CNC membranes, where water absorption increases from 270% to 1000%. Moreover, the addition of CNCs into these membranes enhances the separation efficiency (99%) as well as the reusability (up to 100 cycles with an efficiency of approximately 98%) [90]. Conversely, incorporation of carbon nanotubes and AC-FAS coatings leads to the development of high water contact angles (approximately 161°). These membranes improve the separation efficiency (99.5%) as well as being reusable in a reasonable manner, with an efficiency of about 98% after 10 cycles. This is due to the phenomenal oil flux [92].
The incorporation of SiO2-based nanoparticles also enhances hydrophobicity, as seen in PLA-PDA-SiO2-PS membranes. Herein, the water contact angle is 152°, which supports huge adsorption capacities for silicone oil (32 g/g) and vegetable oil (30 g/g). These findings can be accounted for by the considerable values of flux, between 9000 and 11,500 L/m2·h, and good reusability [91]. Interesting findings are also seen for TiO2-coated membranes, which attain non-wettability even at elevated temperatures (75 °C) and exposure times of 3 to 7 s. However, the oil adsorption is constant (up to 5–7 g) with efficient reusability, maintaining high performance (10 cycles with 99% efficiency) [93].
Other methods, for example, crosslinking epoxy with PLA nanoparticles, enhance the water contact angle from 119.4° to 152.1° and deliver high separation efficiency (approximately 96%) towards oil–water mixtures. It was also observed that solvent treatments (e.g., dioxane/water) lead to super-hydrophobicity. Specifically, increasing the dioxane content raises the water contact angle from 116° to 153°, enhancing the absorption efficiency for different oils and ensuring high reusability after 10 cycles (97%) [94,95].

4.3. Techniques for Enhancing Porosity

There are multiple techniques to improve the porosity of PLA membranes, but foaming and aerogels are rapidly gaining attention due to their suitability for specific applications. In general, foaming is highly effective for membranes that require high flux and selective permeability. In contrast, aerogels are better suited for developing superhydrophobic properties, which are essential for achieving high oil absorption.
Foaming processes are based on the introduction of gas bubbles into the polymer matrix, leading to a porous structure. For the fabrication of PLA membranes, as with many other membrane types, supercritical CO2 foaming is widely used. In this process, PLA is treated with CO2 under high pressure; when the pressure is subsequently reduced, the polymer expands, forming a uniform porous structure (Figure 5) [96]. This method is considered green (solvent-free), safe, and efficient compared to other techniques.
Table 5. Modified nonwoven membranes based on PLA for oil–water separation.
Table 5. Modified nonwoven membranes based on PLA for oil–water separation.
Membrane/AdditivesModify MethodPore Size Water Contact Angle *
(°)		Separation Efficiency (%)Separation Flux
(L/m2h)		Oil Takes
/Absorption Capacity		ReusefulRef.
PLAImmersed in dopamine aqueous solution/CNCs/Mixture: Hydrophobic > Hydrophilic223 μm121 ~1000Water: 270% [90]
PLA-PDA 58.5 ~3000Water: 778%
PLA-PDA-CNCs128 μm0993710Water: 1000%100 times: 98%
PLAImmersed in dopamine aqueous solution/SiO2 nanoparticles/PS microspheres/Mixture: Hydrophobic > Superhydrophobic 117 [91]
PLA-PDA 23
PLA-PDA-SiO2-PS 152 Hexane: ~9000; Toluene: ~10,500
Silicone Oil: ~11,500
Pump Oil: ~7000
Vegetable Oil: ~8500		Hexane: ~25 g/g; Toluene: ~28 g/g
Silicone Oil: ~32 g/g; Pump Oil: ~23 g/g
Vegetable Oil: ~30 g/g; Soybean Oil: ~33 g/g		10 times:
3–6° change
PLAImmersed in TiO2 suspension: Hydrophobic > Superhydrophobic 97 ESO: ~4 g/g; Peanut Oil: ~2 g/g
Xylene: ~2 g/g		 [93]
PLA-TiO2 (55 °C/7 s) 122 ESO: ~5 g/g; Peanut Oil: ~3.5 g/g
Xylene: ~2.5 g/g
PLA-TiO2 (65 °C/7 s) 126 ESO: ~4.9 g/g; Peanut Oil: ~4.5 g/g
Xylene: ~2.5 g/g
PLA-TiO2 (75 °C/1 s) 121
PLA-TiO2 (75 °C/3 s) No Wetting
PLA-TiO2 (75 °C/7 s) No Wetting ESO: ~4 g/g; Peanut Oil: ~3 g/g
Xylene: ~2.5 g/g		10 times: >99%
PLA-TiO2 (75 °C/16 s) 127
PLAImmersed in dioxane and water solvent: Hydrophobic > Superhydrophobic 116 [94]
PLA–dioxane–water (12 wt.%) ~135
PLA–dioxane–water (16 wt.%) ~141°
PLA–dioxane–water (20 wt.%) 153 N-hexane: 27; Cyclohexane: ~24
Ethanol: 17; CTC: 27		 10 times: >97%
PLA–dioxane–water (22 wt.%) ~140
PLAMWCNTs and AC-FAS sprayed on membrane: Hydrophobic > Superhydrophobic 140 [92]
PLA-MWCNTs (0.05 g) ~142°
PLA-MWCNTs (0.08 g) ~150
PLA-MWCNTs (0.1 g) ~158
PLA-MWCNTs (0.15 g) 16199.5N-hexane: 59,713
Peanut Oil: ~3000
Engineering Oil: ~3000		 10 times: >98.5%
PLA-MWCNTs (0.18 g) ~159
PLA-MWCNTs (0.2 g) ~159
PLA The PLA nanospheres were attached to PLA nonwoven membranes with the help of the chemical crosslinking of epoxy resin (ER)225 μm119.4 [95]
PLA–epoxy 133.2
PLA–epoxy–PLA nanoparticles 140.8
PLA nanoparticles (KH-560 treated) 152.196
* Test Fluid is water.
Polymers 17 03135 g005
Figure 5. PLA foaming process.
Figure 5. PLA foaming process.
Polymers 17 03135 g005
The foaming process enables the production of membranes with controlled and relatively high porosity by adjusting physical parameters such as pressure, temperature, and time. These parameters also allow for the modulation of pore size and volume. Liquid permeability is enhanced because foaming generates interconnected pores, forming a three-dimensional (3D) network structure that significantly improves oil–water separation [97]. However, the presence of interconnected channels can sometimes lead to cell collapse, making it difficult to achieve very high porosity [98].
Table 6 presents some of the most promising foamed membranes for oil–water separation, where hydrophobicity and oleophilicity can be modulated. The highest water contact angles, directly linked to high hydrophobicity, are observed in PLA-GO membranes and PLA membranes treated with water peeling, showing values of 150.6° and 151°, respectively. In this context, PLA-GO membranes achieve a separation efficiency greater than 96%, with an oil adsorption capacity of 19.21 g/g. Even higher capacities are observed in PLA-PBS membranes (20 wt.%), reaching up to 20 g/g. Additionally, PLA membranes incorporating lignin or TPU are more easily produced while still offering competitive performance [99,100,101].
Aerogels used in the preparation of PLA-based membranes enable the achievement of high porosity, large surface areas, and low densities, which enhance adsorption capacity, efficiency, selectivity, and reusability [104]. These aerogels can be prepared via supercritical drying of polymer gels or through freeze-drying. Additionally, reinforcement with silica (SiO2) or nanocellulose further improves mechanical strength. Figure 6 shows the preparation process of PLA aerogel. PLA is dissolved in a good solvent to form a homogeneous solution. After being cast into a membrane, the solution is cooled to a low temperature to undergo physical crosslinking, leading to gelation. The solvent is then removed via freeze-drying under vacuum to produce a PLA gel suitable for oil–water separation (Figure 6).
These aerogels confer outstanding physical properties to the membranes, including high specific surface areas and ultralow thermal conductivities. However, PLA aerogels exhibit low heat resistance, poor mechanical properties, and limited hydrolysis resistance [105]. This includes the hydrolytic degradation of the PLA aerogel, which can negatively impact the efficiency of oil–water separation and significantly reduce the service life of the PLA aerogel [104].
Table 7 presents some of the most interesting aerogels based on PLA for oil–water separation, highlighting several key facts. High-efficiency separation with high flux is reported for PLA-ZIF-8 (1 wt.%), where the separation efficiency is close to 100%, with a high contact angle (145°), and it can be used for different oils such as heptane and carbon tetrachloride. The maximum oil absorption and reusability were reported for the system based on PLLA-PDLA-PEO (50 wt.%), showing clear superhydrophobic behavior (160.7°), high porosity (around 97.9%), and an adsorption capacity of 29.9 g/g in anhydrous ethanol. On the other hand, PLA-ZIF-67 (3 wt.%) membranes present broad oil absorption across various hydrocarbons, such as petroleum ether, CCl4, and heptane. Finally, PLA-H2O + SNFs show extreme hydrophobicity for separation, with an improved porosity close to 95.6%.

4.4. Phase Separation Techniques

Phase separation techniques have been widely investigated in oil–water separation as a highly efficient, energy-saving and eco-friendly technical method. Phase separation can be induced by a variety of factors, including temperature [108], liquid [109], and nonsolvent [110], etc. Under these conditions, the homogeneous mixtures form continuous or discontinuous structures of different phases by nucleation and growth, which can evolve into porous or membrane materials [111]. In the application of PLA in oil–water separation, several strategies have been reported, including thermally induced phase separation (TIPS), nonsolvent-induced phase separation (NIPS) and the freeze solidification phase separation method (FSPS).

4.4.1. Thermally Induced Phase Separation Method (TIPS)

TIPS exploits the thermodynamic instability of PLA solution to separate it into a polymer-rich phase and a polymer-poor phase. During the freezing process, the solvent and polymer undergo liquid–liquid (L-L) separation, reducing the homogeneity of the PLA solution into a polymer-rich phase and a solvent-rich phase. With further temperature decrease, the solvent crystallizes and separates from the polymer-rich phase (solid–liquid separation, S-L) [112]. After solvent removal, a porous membrane is formed, in which the polymer-rich phase forms the porous framework and the polymer-poor phase forms the pore structure. The outstanding advantages of TIPS include a low production cost, simple operation, and an easily tunable porous structure. Table 8 describes the PLA-based films prepared using the TIPS method for oil–water separation. Wang et al. [20] reported that the different amounts of deionized water (0, 2, 3, 4 mL) were added to the PLA/dioxane solution. After phase separation induced by thermal treatment, the addition of 4 mL of deionized water resulted in a micro/nano hybrid honeycomb-like structure, which increased the specific area from 80.34 m2/g to 94.4 m2/g. This improvement resulted in higher hydrophobicity, thereby increasing the oil absorption capacity. Li et al. [112] investigated the effects of varying the content of two PLA enantiomers (PLLA and PDLA) on oil–water separation. Increasing the PDLA fraction promoted stereo complex crystallization and facilitated a change in the pore structure. Consequently, the morphology of membranes became a complex network of submicron or smaller particles, which reduced the pore size. As the pore size decreased, the water contact angle also declined. After being frozen at −20 °C, the pore size decreased from 14.5 μm to 3.3 μm, accompanied by 9% decrease in the water contact angle and an increase in oil absorption capacity of more than 1 g/g. When the membrane is simultaneously grafted with polylactic acid (PLA) and polycaprolactone (PCL), an increase in the proportion of poly(D-lactic acid) (PDLA) leads to higher porosity and enhanced roughness, which collectively contribute to an improved oil absorption capacity [113].

4.4.2. Nonsolvent-Induced Phase Separation Method (NIPS)

NIPS is a widely used technique for preparing porous polymer membranes due to its versatility, simplicity, and adaptability in shaping (Table 9) [114]. In this process, PLA is dissolved in a good solvent to obtain a homogeneous solution, which is subsequently cast into a membrane. The casting membrane is immersed in a nonsolvent bath, where solvent–nonsolvent exchange takes place, leading to a polymer-rich phase and a polymer-lean phase [115]. After drying, these two phases form a skeleton and pores, respectively, forming a continuous matrix [116]. The morphology and properties of the producing membranes are greatly influenced by several parameters, including the temperature of nonsolvent immersion and the concentration and molecular weight of the polymer, as well as the ratio and physicochemical properties of the solvent and nonsolvent system [114].
The method employs N-methyl-2-pyrrolidone (NMP) as the solvent and distilled water as the nonsolvent, where their exchange reaction induces the formation of an asymmetric, finger-like macroporous structure within the PLA membrane. Annealing treatment or the incorporation of polyhedral oligomeric silsesquioxane (POSS) effectively reduces the membrane density. From a microstructural perspective, smaller pore sizes and higher porosity are observed, which significantly improve the membrane’s performance in oil absorption capacity [117].
When n-hexane was added dropwise as a nonsolvent to a 7–17 wt.% PLA/DCM solution, the homogeneous solution underwent phase separation into a white gel. After solvent removal, porous membranes were produced by NIPS. The membrane prepared from 7 wt.% PLA exhibited the highest porosity and oil absorption capacity, approximately 6 g/g. The combination of kapok at 7 wt.% and 13 wt.% increased the oil absorption capacity, indicating that kapok enhances oil absorption. However, the effect of kapok on pore size remains unclear. This improved oil absorption capacity can be attributed to the surface wax of kapok. Subsequently, the wetting process is driven by the interaction between oil and the porous surface, resulting in a rapid initial increase in the oil absorption rate of the kapok. Over time, the oil on the kapok surface migrates and diffuses into the fiber lumen through capillary wicking [119].
Unlike most strategies for enhancing oil absorption capacity by improving membrane hydrophobicity, the addition of amino-SiO2-functionalized multi-walled carbon nanotubes (f-MWCNTs) to PLA results in increased hydrophilicity, as indicated by a decrease in the water contact angle from 91°for the pristine PLA membrane to 72° for the PLA/f-MWCNTs membrane. This effect can be attributed to the inherent hydrophilicity of amino-SiO2, which enhances its ability to attract water molecules more effectively. Simultaneously, the porosity increases from 65% to 82%, significantly improving separation efficiency and separation flux. The super-hydrophilic amino-SiO2 in the MWCNTs-COOH mixed-matrix solution within the membrane promotes the formation of additional nanochannels in the membrane. The presence of these additional nanochannels facilitates efficient water transport through the membrane while effectively hindering oil permeation, thereby improving the overall membrane performance [121].

4.4.3. Freeze Solidification Phase Separation Method (FSPS)

The freeze solidification phase separation method involves rapidly cooling a homogeneous PLA solution to a temperature below the crystallization point of the solvent, where solvent crystallization drives phase separation, leading to the formation of voids and the organization of the polymer into a porous film with large pores, directional pore structure, lamellar structures, or dendritic channels (Table 10) [123,124]. In a composite solvent system, both the choice of solvent ratio and whether the freezing temperature is below the crystallization point of all solvent components significantly affect the pore size and the oil–water separation performance [31].

5. Challenges and Future Perspectives

The commercialization of PLA-based membranes is emerging within the European Union, where several suppliers, such as Nature Plast (France), Total Energies Corbion (Netherlands), and Mi-Plast Ltd. (Belgium), are actively integrating PLA into their product lines and research activities. However, specific PLA membranes designed for oil/water separation have not yet been commercialized. This is primarily due to certain technical and performance limitations, such as mechanical stability, long-term durability under wet conditions, and optimization of surface properties, which still need to be addressed before large-scale market deployment becomes feasible.
Despite polylactic acid (PLA) and its derivatives showing encouraging prospects for oil–water separation, several challenges still restrict their large-scale application and long-term stability. The primary challenge is the inherent brittleness and poor mechanical strength of PLA, which can limit the membrane’s durability and stability under continuous operation. Its inferior heat resistance and poor tolerance towards organic solvents also hinder its application in severe industrial conditions. Another persistent challenge is membrane fouling, which occurs due to the accumulation of oil droplets and organic matter on the membrane surface, leading to reduced permeability and a shorter operational lifespan. Achieving an optimal balance between hydrophilicity, mechanical strength, and biodegradability remains a significant obstacle for researchers.
The production of PLA-based membranes is also subjected to processing constraints, such as the use of organic solvents in the NIPS and TIPS methods, which are not entirely environmentally friendly and hence pose environmental and health problems. Scalability and economy remain significant barriers to commercialization, particularly when advanced modification techniques or composite fillers are employed. Most studies are limited to the laboratory scale, resulting in a lack of knowledge about membrane performance in real, complex wastewater systems.
Hence, efforts should be made in future research toward the engineering of green and energy-conserving fabrication pathways, such as solvent-free processes, melt blending, and additive manufacturing. The addition of natural or biodegradable fillers and the utilization of green surface modification processes could enhance hydrophilicity, toughness, and fouling resistance without compromising the environmental advantages of PLA. The development of innovative or responsive membranes that can adapt to varying wastewater conditions may further enhance separation performance. Moreover, stimuli-responsive and smart PLA membranes capable of responding to pH, temperature, or oil concentration variation could develop new routes for effective and selective separations. Additionally, integrating computational modeling and life cycle assessment can facilitate the rational design and the sustainability evaluation of these advanced materials.
By overcoming these issues through interdisciplinary collaboration among material scientists, chemical engineers, and environmental technologists, PLA-based membranes have the potential to become practical, sustainable, and high-performance solutions for oil–water separation, playing a crucial role in global water purification efforts.

6. Conclusions

Polylactic acid (PLA) and its derivatives have demonstrated significant potential as sustainable oil–water separation membranes, offering a greener alternative to the traditional petroleum-based polymers. Their natural biodegradability, renewability, and biocompatibility make them ideal for the development of environmentally friendly water treatment technologies. Current advancements in fabrication techniques such as TIPS, NIPS, and FSPS have offered better control over pore structure, surface wettability, and mechanical strength, thereby enhancing overall separation performance. However, despite these advances, PLA-based membranes remain prone to brittleness, low thermal stability, and fouling for long operations, which limit their large-scale industrial application and long-term stability. To counteract these issues, research has now begun to focus on incorporating fillers, surface functionalization, and structural optimization to achieve a balance between mechanical strength and biodegradability. In the future, the development of sustainable, solvent-free fabrication pathways and innovative surface modification methodologies will play a crucial role in driving the real-world applications of PLA-based membranes. Integrating computational modeling, life cycle assessment, and pilot-scale studies will further validate their performance and sustainability under real-world conditions. Overall, PLA-based membranes hold excellent promise toward greener, more sustainable oil–water separation technologies. With continuous innovation and interdisciplinary collaboration, these biodegradable membranes have the potential to transform wastewater treatment and make substantial contributions to global environmental protection and resource recovery.

Author Contributions

W.L. and A.V. revised the topic, including reading papers and classification; O.M. revised the manuscript; G.S. and A.G.-P. wrote the review, checked the content, and conceived the original idea. All authors have read and agreed to the published version of the manuscript.

Funding

This work has been supported by the Madrid Government (Comunidad de Madrid, Spain) under the Multiannual Agreement with UC3M (“Fostering Young Doctors Research”, PHOGASUPHY-CM-UC3M).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

No new data were created or analyzed in this study.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
PVDFPolyvinylidene fluoride
LDHLayered double hydroxides
CO2 Carbon dioxide
PPPolypropylene
CNTsCarbon nanotubes
PCLPolycaprolactone
PSFPoly sulfone
CNFCellulose nanofiber
PESPolyether sulfone
WCAWater contact angle
PLAPolylactic acid
PBEPropylene-based elastomer
2D-NM2-Dimensional Nanomaterial
GOGraphene oxide

References

  1. Sen Gupta, R.; Samantaray, P.K.; Bose, S. Going beyond cellulose and chitosan: Synthetic biodegradable membranes for drinking water, wastewater, and oil–water remediation. ACS Omega 2023, 8, 24695–24717. [Google Scholar] [CrossRef]
  2. Li, X.; Jin, X.; Wu, Y.; Zhang, D.; Sun, F.; Ma, H.; Pugazhendhi, A.; Xia, C. A comprehensive review of lignocellulosic biomass derived materials for water/oil separation. Sci. Total Environ. 2023, 876, 162549. [Google Scholar] [CrossRef] [PubMed]
  3. Huang, S.; Ras, R.H.; Tian, X. Antifouling membranes for oily wastewater treatment: Interplay between wetting and membrane fouling. Curr. Opin. Colloid Interface Sci. 2018, 36, 90–109. [Google Scholar] [CrossRef]
  4. Saravanan, A.; Kumar, P.S.; Jeevanantham, S.; Karishma, S.; Tajsabreen, B.; Yaashikaa, P.; Reshma, B. Effective water/wastewater treatment methodologies for toxic pollutants removal: Processes and applications towards sustainable development. Chemosphere 2021, 280, 130595. [Google Scholar] [CrossRef] [PubMed]
  5. Sathya, K.; Nagarajan, K.; Carlin Geor Malar, G.; Rajalakshmi, S.; Raja Lakshmi, P. A comprehensive review on comparison among effluent treatment methods and modern methods of treatment of industrial wastewater effluent from different sources. Appl. Water Sci. 2022, 12, 70. [Google Scholar] [CrossRef]
  6. Zulkefli, N.F.; Alias, N.H.; Jamaluddin, N.S.; Abdullah, N.; Abdul Manaf, S.F.; Othman, N.H.; Marpani, F.; Mat-Shayuti, M.S.; Kusworo, T.D. Recent mitigation strategies on membrane fouling for oily wastewater treatment. Membranes 2021, 12, 26. [Google Scholar] [CrossRef]
  7. Omar, R.A.; Talreja, N.; Ashfaq, M.; Chauhan, D. Two-Dimensional nanomaterial (2D-NMs)-based polymeric composite for Oil–Water separation: Strategies to improve Oil–Water separation. Sustainability 2023, 15, 10988. [Google Scholar] [CrossRef]
  8. Ng, L.Y.; Mohammad, A.W.; Leo, C.P.; Hilal, N. Polymeric membranes incorporated with metal/metal oxide nanoparticles: A comprehensive review. Desalination 2013, 308, 15–33. [Google Scholar] [CrossRef]
  9. Xiang, B.; Sun, Q.; Zhong, Q.; Mu, P.; Li, J. Current research situation and future prospect of superwetting smart oil/water separation materials. J. Mater. Chem. A 2022, 10, 20190–20217. [Google Scholar] [CrossRef]
  10. Sutrisna, P.D.; Kurnia, K.A.; Siagian, U.W.; Ismadji, S.; Wenten, I.G. Membrane fouling and fouling mitigation in oil–water separation: A review. J. Environ. Chem. Eng. 2022, 10, 107532. [Google Scholar] [CrossRef]
  11. Zhao, J.; Liu, X.; Pu, X.; Shen, Z.; Xu, W.; Yang, J. Preparation Method and Application of Porous Poly(lactic acid) Membranes: A Review. Polymers 2024, 16, 1846. [Google Scholar] [CrossRef]
  12. Xiao, Y.; Xiao, F.; Ji, W.; Xia, L.; Li, L.; Chen, M.; Wang, H. Bioinspired Janus membrane of polyacrylonitrile/poly (vinylidene fluoride)@ poly (vinylidene fluoride)-methyltriethoxysilane for oil-water separation. J. Membr. Sci. 2023, 687, 122090. [Google Scholar] [CrossRef]
  13. Huang, Y.; Gancheva, T.; Favis, B.D.; Abidli, A.; Wang, J.; Park, C.B. Hydrophobic porous polypropylene with hierarchical structures for ultrafast and highly selective oil/water separation. ACS Appl. Mater. Interfaces 2021, 13, 16859–16868. [Google Scholar] [CrossRef]
  14. Pagidi, A.; Saranya, R.; Arthanareeswaran, G.; Ismail, A.; Matsuura, T. Enhanced oil–water separation using polysulfone membranes modified with polymeric additives. Desalination 2014, 344, 280–288. [Google Scholar] [CrossRef]
  15. Tavangar, T.; Zokaee Ashtiani, F.; Karimi, M. Morphological and performance evaluation of highly sulfonated polyethersulfone/polyethersulfone membrane for oil/water separation. J. Polym. Res. 2020, 27, 252. [Google Scholar] [CrossRef]
  16. Vatanpour, V.; Dehqan, A.; Paziresh, S.; Zinadini, S.; Zinatizadeh, A.A.; Koyuncu, I. Polylactic acid in the fabrication of separation membranes: A review. Sep. Purif. Technol. 2022, 296, 121433. [Google Scholar] [CrossRef]
  17. Bishai, M.; De, S.; Adhikari, B.; Banerjee, R. A comprehensive study on enhanced characteristics of modified polylactic acid based versatile biopolymer. Eur. Polym. J. 2014, 54, 52–61. [Google Scholar] [CrossRef]
  18. de Albuquerque, T.L.; Júnior, J.E.M.; de Queiroz, L.P.; Ricardo, A.D.S.; Rocha, M.V.P. Polylactic acid production from biotechnological routes: A review. Int. J. Biol. Macromol. 2021, 186, 933–951. [Google Scholar] [CrossRef] [PubMed]
  19. Islam, M.S.; Elahee, G.F.; Fang, Y.; Yu, X.B.; Advincula, R.C.; Cao, C.C. Polylactic acid (PLA)-based multifunctional and biodegradable nanocomposites and their applications. Compos. Part B Eng. 2025, 306, 112842. [Google Scholar] [CrossRef]
  20. Wang, X.L.; Pan, Y.M.; Yuan, H.; Su, M.; Shao, C.G.; Liu, C.T.; Guo, Z.H.; Shen, C.Y.; Liu, X.H. Simple fabrication of superhydrophobic PLA with honeycomb-like structures for high-efficiency oil-water separation. Chin. Chem. Lett. 2020, 31, 365–368. [Google Scholar] [CrossRef]
  21. Mousa, H.M.; Fahmy, H.S.; Ali, G.A.M.; Abdelhamid, H.N.; Ateia, M. Membranes for Oil/Water Separation: A Review. Adv. Mater. Interfaces 2022, 9, 2200557. [Google Scholar] [CrossRef]
  22. Ghadhban, M.Y.; Rashid, K.T.; AbdulRazak, A.A.; Alsalhy, Q.F. Recent progress and future directions of membranes green polymers for oily wastewater treatment. Water Sci. Technol. 2023, 87, 57–82. [Google Scholar] [CrossRef]
  23. Ranakoti, L.; Gangil, B.; Mishra, S.K.; Singh, T.; Sharma, S.; Ilyas, R.A.; El-Khatib, S. Critical Review on Polylactic Acid: Properties, Structure, Processing, Biocomposites, and Nanocomposites. Materials 2022, 15, 4312. [Google Scholar] [CrossRef]
  24. Xing, R.Z.; Huang, R.L.; Qi, W.; Su, R.X.; He, Z.M. Three-dimensionally printed bioinspired superhydrophobic PLA membrane for oil-water separation. AIChE J. 2018, 64, 3700–3708. [Google Scholar] [CrossRef]
  25. Wu, M.M.; Mu, P.; Li, B.F.; Wang, Q.T.; Yang, Y.X.; Li, J. Pine powders-coated PVDF multifunctional membrane for highly efficient switchable oil/water emulsions separation and dyes adsorption. Sep. Purif. Technol. 2020, 248, 117028. [Google Scholar] [CrossRef]
  26. Hudaib, B.; Abu-Zurayk, R.; Eskhan, A.; Esaifan, M. PVDF/Polypyrrole Composite Ultrafiltration Membrane with Enhanced Hydrophilicity, Permeability, and Antifouling Properties for Efficient Crude Oil Wastewater Separation. Polymers 2025, 17, 2566. [Google Scholar] [CrossRef] [PubMed]
  27. Zhang, S.B.; Li, Y.; Yuan, Y.; Jiang, L.; Wu, H.T.; Dong, Y.M. Biomimetic hydrophilic modification of poly (vinylidene fluoride) membrane for efficient oil-in-water emulsions separation. Sep. Purif. Technol. 2024, 329, 125227. [Google Scholar] [CrossRef]
  28. Segneanu, A.E.; Herea, D.D.; Buema, G.; Bradu, I.A.; Cepan, M.; Grozescu, I. Advanced Aerogels for Water Remediation: Unraveling Their Potential in Fats, Oils, and Grease Sorption-A Comprehensive Review. Gels 2025, 11, 268. [Google Scholar] [CrossRef] [PubMed]
  29. Palanisamy, K.; Palanisamy, G.; Im, Y.M.; Thangarasu, S.; Phutela, U.G.; Oh, T.H. Recent Progress in Cellulose-Based Aerogels for Sustainable Oil-Water Separation Technologies. Polymers 2025, 17, 2723. [Google Scholar] [CrossRef]
  30. Sahini, M.G. Polylactic acid (PLA)-based materials: A review on the synthesis and drug delivery applications. Emergent Mater. 2023, 6, 1461–1479. [Google Scholar] [CrossRef]
  31. Zhang, Y.; Sun, T.; Zhang, D.; Sun, S.; Liu, J.; Li, B.; Shi, Z. The Preparation of Superhydrophobic Polylactic Acid Membrane with Adjustable Pore Size by Freeze Solidification Phase Separation Method for Oil-Water Separation. Molecules 2023, 28, 5590. [Google Scholar] [CrossRef]
  32. Yao, X.Y.; Hou, X.B.; Zhang, R.B. Flexible and mechanically robust polyimide foam membranes with adjustable structure for separation and recovery of oil-water emulsions and heavy oils. Polymer 2022, 250, 124889. [Google Scholar] [CrossRef]
  33. Baig, N.; Abdulazeez, I.; Aljundi, I.H. Low-pressure-driven special wettable graphene oxide-based membrane for efficient separation of water-in-oil emulsions. Npj Clean Water 2023, 6, 40. [Google Scholar] [CrossRef]
  34. Xin, Y.P.; Qi, B.; Wu, X.; Yang, C.; Li, B.F. Different types of membrane materials for oil-water separation: Status and challenges. Colloid Interface Sci. 2024, 59, 100772. [Google Scholar] [CrossRef]
  35. Zhai, T.L.; Du, Q.; Xu, S.; Wang, Y.; Zhang, C. Electrospun nanofibrous membrane of porous fluorine-containing triptycene-based polyimides for oil/water separation. RSC Adv. 2017, 7, 22548–22552. [Google Scholar] [CrossRef]
  36. Fang, W.; Liu, L.; Li, T.; Dang, Z.; Qiao, C.; Xu, J.; Wang, Y. Electrospun N-Substituted Polyurethane Membranes with Self-Healing Ability for Self-Cleaning and Oil/Water Separation. Chemistry 2016, 22, 878–883. [Google Scholar] [CrossRef]
  37. Asif, M.B.; Zhang, Z.H. Ceramic membrane technology for water and wastewater treatment: A critical review of performance, full-scale applications, membrane fouling and prospects. Chem. Eng. J. 2021, 418, 129481. [Google Scholar] [CrossRef]
  38. Gupta, S.; Tai, N.H. Carbon materials as oil sorbents: A review on the synthesis and performance. J. Mater. Chem. A 2016, 4, 1550–1565. [Google Scholar] [CrossRef]
  39. Yu, S.; Pang, H.; Huang, S.; Tang, H.; Wang, S.; Qiu, M.; Chen, Z.; Yang, H.; Song, G.; Fu, D.; et al. Recent advances in metal-organic framework membranes for water treatment: A review. Sci. Total Environ. 2021, 800, 149662. [Google Scholar] [CrossRef] [PubMed]
  40. Padaki, M.; Surya Murali, R.; Abdullah, M.S.; Misdan, N.; Moslehyani, A.; Kassim, M.A.; Hilal, N.; Ismail, A.F. Membrane technology enhancement in oil–water separation. A review. Desalination 2015, 357, 197–207. [Google Scholar] [CrossRef]
  41. Li, J.H.; Liu, Q.H.; He, J.M.; Zhao, Y.; Mu, L.H.; Liu, X.F.; Zhang, Y.; Sun, C.L.; Zhang, N.; Qu, M.N. A review of superwetting aerogel-based oil-water separation materials. Mater. Today Sustain. 2024, 26, 100741. [Google Scholar] [CrossRef]
  42. Zhang, Y.; Sam, E.K.; Liu, J.; Lv, X.M. Biomass-Based/Derived Value-Added Porous Absorbents for Oil/Water Separation. Waste Biomass Valoriz. 2023, 14, 3147–3168. [Google Scholar] [CrossRef]
  43. Akoumeh, R.; Idoudi, S.; El-Din, L.A.N.; Rekik, H.; Al-Ejji, M.; Ponnama, D.; Sharma, A.; Shamsabadi, A.A.; Alamgir, K.; Song, K.; et al. Advances in fabrication techniques and performance optimization of polymer membranes for enhanced industrial oil-water separation: A critical review. J. Environ. Chem. Eng. 2024, 12, 114411. [Google Scholar] [CrossRef]
  44. Han, P.; Yu, B.; Chen, Y.; Nie, G.; Wang, K.; Sun, X.; Li, X.; Shao, W.; Liu, F.; He, J. Electrospun Polyacrylonitrile-Fluorinated Polyurethane/Polysulfone Nanofiber Membranes for Oil–Water Separation. ACS Appl. Nano Mater. 2024, 7, 4336–4348. [Google Scholar] [CrossRef]
  45. Kumar, S.; Nandi, B.K.; Guria, C.; Mandal, A. Oil Removal from Produced Water by Ultrafiltration Using Polysulfone Membrane. Braz. J. Chem. Eng. 2017, 34, 583–596. [Google Scholar] [CrossRef]
  46. Dmitrieva, E.S.; Anokhina, T.S.; Novitsky, E.G.; Volkov, V.V.; Borisov, I.L.; Volkov, A.V. Polymeric Membranes for Oil-Water Separation: A Review. Polymers 2022, 14, 980. [Google Scholar] [CrossRef]
  47. Huh, Y.; Yu, S.; Huh, J.; Bang, J. Sustainable Superhydrophobic PVDF-Grafted Cellulose Membrane for Oil/Water Separation. ACS Appl. Polym. Mater. 2022, 4, 8441–8449. [Google Scholar] [CrossRef]
  48. Xie, T.; Zhang, Y.Y.; Zhang, X.; Huang, Y.X. Membrane surface engineering with hyperbranched polylysine for effective oil-water emulsion separation. J. Membr. Sci. 2025, 723, 123935. [Google Scholar] [CrossRef]
  49. Gu, M.H.; Zhang, J.; Wang, X.L.; Tao, H.J.; Ge, L.T. Formation of poly(vinylidene fluoride) (PVDF) membranes via thermally induced phase separation. Desalination 2006, 192, 160–167. [Google Scholar] [CrossRef]
  50. Tian, L.H.; Xing, Y.Q.; Gao, C.M.; Ji, S.F.; Gong, T.M.; Bai, Y.M.; Gan, F.H.; Wu, Z.L. Construction of metal polyphenol network of phytic acid-Graphene oxide PES ultrafiltration membranes achieving high-efficiency separation of oil-water emulsions. J. Environ. Chem. Eng. 2024, 12, 114529. [Google Scholar] [CrossRef]
  51. Cao, J.S.; Cheng, Z.Q.; Kang, L.J.; Zhang, Y.Y.; Zhao, X.D.; Zhao, S.Z.; Gao, B. Novel anti-fouling polyethersulfone/polyamide 66 membrane preparation for air filtration by electrospinning. Mater. Lett. 2017, 192, 12–16. [Google Scholar] [CrossRef]
  52. Cao, J.S.; Cheng, Z.Q.; Kang, L.J.; Chu, M.X.; Wu, D.; Li, M.T.; Xie, S.; Wen, R.C. Novel stellate poly(vinylidene fluoride)/polyethersulfone microsphere-nanofiber electrospun membrane with special wettability for oil/water separation. Mater. Lett. 2017, 207, 190–194. [Google Scholar] [CrossRef]
  53. Huang, J.X.; Tang, J.H.; Zhang, J.; Yang, L.; Zhang, M. Waste mask supported PES membranes for efficient separation of oil/water emulsion. Polym. Eng. Sci. 2024, 64, 3522–3529. [Google Scholar] [CrossRef]
  54. Li, C.; Ren, L.; Zhang, C.; Xu, W.; Liu, X. TiO2 Coated Polypropylene Membrane by Atomic Layer Deposition for Oil–Water Mixture Separation. Adv. Fiber Mater. 2021, 3, 138–146. [Google Scholar] [CrossRef]
  55. Ma, W.J.; Samal, S.K.; Liu, Z.C.; Xiong, R.H.; De Smedt, S.C.; Bhushan, B.; Zhang, Q.L.; Huang, C.B. Dual pH- and ammonia-vapor-responsive electrospun nanofibrous membranes for oil-water separations. J. Membr. Sci. 2017, 537, 128–139. [Google Scholar] [CrossRef]
  56. Yao, X.Y.; Hou, X.B.; Qi, G.C.; Zhang, R.B. Preparation of superhydrophobic polyimide fibrous membranes with controllable surface structure for high efficient oil-water emulsion and heavy oil separation. J. Environ. Chem. Eng. 2022, 10, 107470. [Google Scholar] [CrossRef]
  57. Long, Q.W.; Chen, J.X.; Wang, Z.; Zhang, Z.; Qi, G.X.; Liu, Z.Q. Vein-supported porous membranes with enhanced superhydrophilicity and mechanical strength for oil-water separation. Sep. Purif. Technol. 2021, 254, 117517. [Google Scholar] [CrossRef]
  58. Zhao, H.; He, Y.; Wang, Z.; Zhao, Y.; Sun, L. Mussel-Inspired Fabrication of PDA@PAN Electrospun Nanofibrous Membrane for Oil-in-Water Emulsion Separation. Nanomaterials 2021, 11, 3434. [Google Scholar] [CrossRef]
  59. Wang, S.; Pang, M.; Wen, Z. The structure and property of polyacrylonitrile-based microfiltration membranes for oil-water emulsion separation. J. Ind. Text. 2022, 51 (Suppl. 5), 8788S–8803S. [Google Scholar] [CrossRef]
  60. Cai, Y.W.; Chen, Y.; Wang, R.R.; Li, J.X.; Yang, H.; Li, Y.J.; Qu, D.N. Durable polyvinylpyrrolidone superhydrophilic modified ZIF-8 mesh membrane for gravitational oil-water separation and oil recovery. Colloids Surf. A Physicochem. Eng. Asp. 2024, 688, 133509. [Google Scholar] [CrossRef]
  61. Wang, C.F.; Wang, W.N.; Kuo, S.W.; Chiang, Y.W.; Hung, J.H.; Lee, K.J. Biocompatible Meshes with Appropriate Wettabilities for Underwater Oil Transportation/Collection and Highly Effective Oil/Water Separation. Langmuir 2018, 34, 11442–11448. [Google Scholar] [CrossRef]
  62. Yu, J.S.; Zhao, T.; Li, C.T.; Pan, H.W.; Tan, Z.Y.; Yang, H.L.; Zhang, H.L. Preparation and characterization of biodegradable polylactic acid/poly (butylene adipate-co-terephthalate) melt-blown nonwovens for oil-water separation. Colloid Polym. Sci. 2024, 302, 43–56. [Google Scholar] [CrossRef]
  63. Li, Z.Q.; Wang, M.L.; Li, Y.; Ren, J.M.; Pei, C.H. Effect of cellulose nanocrystals on bacterial cellulose hydrogel for oil-water separation. Sep. Purif. Technol. 2023, 304, 122349. [Google Scholar] [CrossRef]
  64. Zhao, X.Q.; Wahid, F.; Cui, J.X.; Wang, Y.Y.; Zhong, C. Cellulose-based special wetting materials for oil/water separation: A review. Int. J. Biol. Macromol. 2021, 185, 890–906. [Google Scholar] [CrossRef]
  65. Hu, M.X.; Niu, H.M.; Chen, X.L.; Zhan, H.B. Natural cellulose microfiltration membranes for oil/water nanoemulsions separation. Colloids Surf. A Physicochem. Eng. Asp. 2019, 564, 142–151. [Google Scholar] [CrossRef]
  66. Li, D.; Huang, X.; Huang, Y.; Yuan, J.; Huang, D.; Cheng, G.J.; Zhang, L.; Chang, C. Additive Printed All-Cellulose Membranes with Hierarchical Structure for Highly Efficient Separation of Oil/Water Nanoemulsions. ACS Appl. Mater. Interfaces 2019, 11, 44375–44382. [Google Scholar] [CrossRef] [PubMed]
  67. Fu, C.H.; Yao, L.; Guo, Z.G. Biomass chitosan-based complexes with superwettability for oil-water separation. Mater. Today Chem. 2024, 40, 102265. [Google Scholar] [CrossRef]
  68. Cheng, X.; Li, T.; Yan, L.; Jiao, Y.; Zhang, Y.; Wang, K.; Cheng, Z.; Ma, J.; Shao, L. Biodegradable electrospinning superhydrophilic nanofiber membranes for ultrafast oil-water separation. Sci. Adv. 2023, 9, eadh8195. [Google Scholar] [CrossRef]
  69. Krasian, T.; Punyodom, W.; Worajittiphon, P. A hybrid of 2D materials (MoS2 and WS2) as an effective performance enhancer for poly(lactic acid) fibrous mats in oil adsorption and oil/water separation. Chem. Eng. J. 2019, 369, 563–575. [Google Scholar] [CrossRef]
  70. Torsello, M.; Ben-Zichri, S.; Pesenti, L.; Kunnath, S.M.; Samorí, C.; Pasteris, A.; Bacchelli, G.; Prishkolnik, N.; Ben-Nun, U.; Righi, S.; et al. Carbon dot/polylactic acid nanofibrous membranes for solar-mediated oil absorption/separation: Performance, environmental sustainability, ecotoxicity and reusability. Heliyon 2024, 10, e25417. [Google Scholar] [CrossRef]
  71. Mo, J.; Wang, Y.; Wang, J.; Zhao, J.; Ke, Y.; Han, S.; Gan, F.; Wang, L.; Ma, C. Hydrophobic/oleophilic polylactic acid electrospun fibrous membranes with the silicone semi-interpenetrated networks for oil–water separation. Polym. Biopolym. 2022, 57, 16048–16063. [Google Scholar]
  72. Yang, J.; Li, F.; Lu, G.; Lu, Y.; Song, C.; Zhou, R.; Wu, S. Electrospun Biodegradable Poly(L-lactic acid) Nanofiber Membranes as Highly Porous Oil Sorbent Nanomaterials. Nanomaterials 2022, 12, 2670. [Google Scholar] [CrossRef]
  73. Jiang, C.; Hua, M.; Mu, G.; Zhao, S.; Chen, H.; Yao, L.; Ge, J.; Zhang, L.; Pan, G. Superhydrophilic and underwater superoleophobic polylactide/cellulose diacetate composite nanofibrous membranes for effective oil-in-water emulsions separation. Sep. Purif. Technol. 2024, 348, 127806. [Google Scholar] [CrossRef]
  74. Wu, H.Z.; Geng, Q.; Li, Y.H.; Song, Y.Q.; Chu, J.Q.; Zhou, R.; Ning, X.; Dong, S.J.; Yuan, D. CuMOF-decorated biodegradable nanofibrous membrane: Facile fabrication, high-efficiency filtration/separation and effective antibacterial property. J. Ind. Eng. Chem. 2022, 114, 475–482. [Google Scholar] [CrossRef]
  75. Jeeshma, R.; Lakshmi, V.V.A.; James, A.; Stephen, R. Polyhedral Oligomeric Silsesquioxane Coated Electrospun Nanofibrous PLA Membranes: Properties and Application. J. Polym. Environ. 2024, 32, 5982–5993. [Google Scholar] [CrossRef]
  76. Li, X.H.; Zhang, S.L.; Li, J.Z.; Hu, X.Y.; Zhang, J.J.; Wei, Q.; Zhang, C.P.; Zhang, D.D.; Liu, Y. Bio-degradable fibrous membranes for oil/water separation by melt electrospinning. J. Appl. Polym. Sci. 2024, 141, e56018. [Google Scholar] [CrossRef]
  77. Zhang, D.; Jin, X.Z.; Huang, T.; Zhang, N.; Qi, X.D.; Yang, J.H.; Zhou, Z.W.; Wang, Y. Electrospun Fibrous Membranes with Dual-Scaled Porous Structure: Super Hydrophobicity, Super Lipophilicity, Excellent Water Adhesion, and Anti-Icing for Highly Efficient Oil Adsorption/Separation. ACS Appl. Mater. Interfaces 2019, 11, 5073–5083. [Google Scholar] [CrossRef] [PubMed]
  78. Li, K.X.; Feng, G.N.; Li, G.M.; Zhang, Z.B.; Xiang, J.H.; Jiao, F.; Chen, T.; Zhao, H.L. Structurally integrated janus polylactic acid fibrous membranes for oil-water separation. J. Water Process Eng. 2024, 68, 106525. [Google Scholar] [CrossRef]
  79. Liu, W.; Wu, X.; Liu, S.; Cheng, X.; Zhang, C. CNT@LDH functionalized poly(lactic acid) membranes with super oil–water separation and real-time press sensing properties. Polym. Compos. 2022, 43, 6548–6559. [Google Scholar] [CrossRef]
  80. Nugraha, M.W.; Wirzal, M.D.H.; Ali, F.; Roza, L.; Sambudi, N.S. Electrospun polylactic acid/tungsten oxide/amino-functionalized carbon quantum dots (PLA/WO/N-CQDs) fibers for oil/water separation and photocatalytic decolorization. J. Environ. Chem. Eng. 2021, 9, 106033. [Google Scholar] [CrossRef]
  81. Deng, Y.F.; Zhang, N.; Huang, T.; Lei, Y.Z.; Wang, Y. Constructing tubular/porous structures toward highly efficient oil/water separation in electrospun stereocomplex polylactide fibers via coaxial electrospinning technology. Appl. Surf. Sci. 2022, 573, 151619. [Google Scholar] [CrossRef]
  82. Guo, X.; Feng, C.; Huang, L.; Wang, H.; Liu, F.; Li, J. Superhydrophobic PBAT/PLA Fibrous Membrane with Excellent Mechanical Performance for Highly Efficient Oil–Water Separation. Fibers Polym. 2025, 26, 1479–1492. [Google Scholar] [CrossRef]
  83. Yu, W.T.; Song, X.F.; Wang, Y.H.; Zhang, L.K.; Liu, Y.; Liu, Y.H. Enhancing the oil/water separation efficiency of polylactic acid fiber membrane via polydimethylsiloxane-polycaprolactone copolymer. J. Environ. Chem. Eng. 2024, 12, 114738. [Google Scholar] [CrossRef]
  84. Xu, Q.Y.; Wang, Y.M. The Effects of Processing Parameter on Melt-Blown Filtration Materials. Adv. Mater. Res. 2013, 650, 78–84. [Google Scholar] [CrossRef]
  85. Li, H.; Zhang, H.; Hu, J.J.; Wang, G.F.; Cui, J.Q.; Zhang, Y.F.; Zhen, Q. Facile Preparation of Hydrophobic PLA/PBE Micro-Nanofiber Fabrics via the Melt-Blown Process for High-Efficacy Oil/Water Separation. Polymers 2022, 14, 1667. [Google Scholar] [CrossRef] [PubMed]
  86. Sayed, M.M.; Mousa, H.M.; El-Shazly, A.H.; Zkria, A.; Yoshitake, T.; ElKady, M. Novel post-heat treatment green biodegradable PLA@SiO2 nanocomposite membrane for water desalination. J. Environ. Chem. Eng. 2024, 12, 114378. [Google Scholar] [CrossRef]
  87. Scaffaro, R.; Lopresti, F.; Sutera, A.; Botta, L.; Fontana, R.M.; Gallo, G. Plasma modified PLA electrospun membranes for actinorhodin production intensification in Streptomyces coelicolor immobilized-cell cultivations. Colloids Surf. B Biointerfaces 2017, 157, 233–241. [Google Scholar] [CrossRef]
  88. Shi, J.; Zhang, L.; Xiao, P.; Huang, Y.; Chen, P.; Wang, X.; Gu, J.; Zhang, J.; Chen, T. Biodegradable PLA Nonwoven Fabric with Controllable Wettability for Efficient Water Purification and Photocatalysis Degradation. ACS Sustain. Chem. Eng. 2018, 6, 2445–2452. [Google Scholar] [CrossRef]
  89. Karthikeyan, A.; Girard, M.; Dumont, M.-J.; Chouinard, G.; Tavares, J.R. Surface Modification of Commercially Available PLA Polymer Mesh. Ind. Eng. Chem. Res. 2022, 61, 17297–17305. [Google Scholar] [CrossRef]
  90. Lu, J.; Wen, J.X.; Yu, Q.H.; Cui, C.F.; Su, J.J.; Han, J. Cellulose nanospheres coated polylactic acid nonwoven membranes for recyclable use in oil/water separation. Cellulose 2021, 28, 11417–11427. [Google Scholar] [CrossRef]
  91. Gu, J.; Xiao, P.; Chen, P.; Zhang, L.; Wang, H.; Dai, L.; Song, L.; Huang, Y.; Zhang, J.; Chen, T. Functionalization of Biodegradable PLA Nonwoven Fabric as Superoleophilic and Superhydrophobic Material for Efficient Oil Absorption and Oil/Water Separation. ACS Appl. Mater. Interfaces 2017, 9, 5968–5973. [Google Scholar] [CrossRef] [PubMed]
  92. Chen, T.C.; Guo, J.; Xu, H.; Zhang, J.L.; Hu, N.N.; Liu, H.T. One-step fabrication of biodegradable superhydrophobic PLA fabric for continuous oil/water separation. Appl. Surf. Sci. 2022, 576, 151766. [Google Scholar] [CrossRef]
  93. Ren, D.; Guo, Z.; Song, W.; Guo, Z.; Liu, H.; Huang, M.; Liu, W. Modification of Poly(Lactic Acid) Non-Woven Fabric for Enhanced Oil–Water Separation. Fibers Polym. 2024, 25, 1727–1736. [Google Scholar] [CrossRef]
  94. Yuan, H.; Zhang, M.; Pan, Y.; Liu, C.; Shen, C.; Chen, Q.; Liu, X. Microspheres Modified with Superhydrophobic Non-Woven Fabric with High-Efficiency Oil–Water Separation: Controlled Water Content in PLA Solution. Macromol. Mater. Eng. 2022, 307, 2100919. [Google Scholar] [CrossRef]
  95. Lu, J.; Cui, C.F.; Yu, Q.H.; Su, J.J.; Han, J. Robustly superhydrophobic polylactic acid nonwoven membranes for efficient oil/water separation. J. Porous Mater. 2022, 29, 241–247. [Google Scholar] [CrossRef]
  96. Li, B.; Zhao, G.Q.; Wang, G.L.; Zhang, L.; Gong, J.; Shi, Z.L. Biodegradable PLA/PBS open-cell foam fabricated by supercritical CO foaming for selective oil-adsorption. Sep. Purif. Technol. 2021, 257, 117949. [Google Scholar] [CrossRef]
  97. Wang, S.; Yang, W.; Li, X.; Hu, Z.; Wang, B.; Li, M.; Dong, W. Preparation of high-expansion open-cell polylactic acid foam with superior oil-water separation performance. Int. J. Biol. Macromol. 2021, 193 Pt B, 1059–1067. [Google Scholar] [CrossRef]
  98. Li, D.; Zhang, S.; Zhao, Z.; Miao, Z.; Zhang, G.; Shi, X. High-Expansion Open-Cell Polylactide Foams Prepared by Microcellular Foaming Based on Stereocomplexation Mechanism with Outstanding Oil-Water Separation. Polymers 2023, 15, 1984. [Google Scholar] [CrossRef]
  99. Yuan, J.; Gao, X.; Chen, Y.; Zhao, L.; Hu, D. Green Fabrication of Biobased and Degradable Poly(lactic acid)/Poly(butylene succinate) Open-Cell Foams for Highly Efficient Oil–Water Separation with Ultrafast Degradation. ACS Sustain. Chem. Eng. 2024, 12, 18101–18113. [Google Scholar] [CrossRef]
  100. Zeng, Q.T.; Ma, P.M.; Lai, D.H.; Lai, X.J.; Zeng, X.R.; Li, H.Q. Superhydrophobic reduced graphene oxide@poly(lactic acid) foam with electrothermal effect for fast separation of viscous crude oil. J. Mater. Sci. 2021, 56, 11266–11277. [Google Scholar] [CrossRef]
  101. Cui, S.; Wu, M.; Xu, M.; Li, X.; Ren, Q.; Wang, L.; Zheng, W. Supercritical CO2 extrusion foaming of highly open-cell poly(lactic acid) foam with superior oil adsorption performance. Int. J. Biol. Macromol. 2024, 269 Pt 2, 132138. [Google Scholar] [CrossRef]
  102. Wang, X.; Pan, Y.; Liu, X.; Liu, H.; Li, N.; Liu, C.; Schubert, D.W.; Shen, C. Facile Fabrication of Superhydrophobic and Eco-Friendly Poly(lactic acid) Foam for Oil-Water Separation via Skin Peeling. ACS Appl. Mater. Interfaces 2019, 11, 14362–14367. [Google Scholar] [CrossRef] [PubMed]
  103. Hua, M.Q.; Chen, D.; Xu, Z.S.; Fang, Y.Q.; Song, Y.M. Fabrication of high-expansion, fully degradable polylactic acid-based foam with exponent oil/water separation. J. Appl. Polym. Sci. 2022, 139, e53234. [Google Scholar] [CrossRef]
  104. Chen, P.F.; Bai, D.Y.; Tang, H.; Liu, H.L.; Wang, J.C.; Gao, G.Y.; Li, L. Polylactide aerogel with excellent comprehensive performances imparted by stereocomplex crystallization for efficient oil-water separation. Polymer 2022, 255, 125128. [Google Scholar] [CrossRef]
  105. Liu, H.L.; Chen, P.F.; Peng, Q.; Bai, D.Y. Ultralight, superhydrophobic and biodegradable stereocomplex polylactide aerogel with superior oil-water separation and thermal insulation performances. Ind. Crops Prod. 2024, 222, 119983. [Google Scholar] [CrossRef]
  106. Xu, J.; Seeger, S. Silicone nanofilament embedded, superhydrophobic polylactic acid composite aerogel. Chem. Eng. J. 2025, 507, 160208. [Google Scholar] [CrossRef]
  107. Qu, W.; Wang, Z.; Wang, X.; Wang, Z.; Yu, D.; Ji, D. High-hydrophobic ZIF-67@PLA honeycomb aerogel for efficient oil–water separation. Colloids Surf. A Physicochem. Eng. Asp. 2023, 658, 130768. [Google Scholar] [CrossRef]
  108. Fily, Y.; Marchetti, M.C. Athermal phase separation of self-propelled particles with no alignment. Phys. Rev. Lett. 2012, 108, 235702. [Google Scholar] [CrossRef]
  109. Lloyd, D.R.; Kim, S.S.; Kinzer, K.E. Microporous membrane formation via thermally-induced phase separation. II. Liquid—Liquid phase separation. J. Membr. Sci. 1991, 64, 1–11. [Google Scholar] [CrossRef]
  110. Guillen, G.R.; Pan, Y.; Li, M.; Hoek, E.M.V. Preparation and Characterization of Membranes Formed by Nonsolvent Induced Phase Separation: A Review. Ind. Eng. Chem. Res. 2011, 50, 3798–3817. [Google Scholar] [CrossRef]
  111. Fernandez-Rico, C.; Sai, T.; Sicher, A.; Style, R.W.; Dufresne, E.R. Putting the Squeeze on Phase Separation. JACS Au 2022, 2, 66–73. [Google Scholar] [CrossRef]
  112. Li, L.; Li, X.; Wu, H.; Chen, Y.; Zhang, J. Tailoring the cell morphology and characteristics of poly(lactic acid) foams via a stereocomplex crystallization-assisted phase separation strategy. Int. J. Biol. Macromol. 2025, 308 Pt 3, 142583. [Google Scholar] [CrossRef]
  113. Sun, X.; Wang, K.; Meng, Y.; Hu, K.; Huang, C.; He, Q.; Sun, J.; Bai, L.; Zhang, C.; Ma, Z. Fabrication of Poly(lactic acid)/Glycerol–Poly(ε-caprolactone)–Poly(d-lactic acid) Foam by Star Copolymer-Induce Stereocomplexed Microcrystalline Network for Oil–Water Separation. ACS Appl. Polym. Mater. 2025, 7, 331–342. [Google Scholar] [CrossRef]
  114. Rezabeigi, E.; Wood-Adams, P.M.; Drew, R.A.L. Production of porous polylactic acid monoliths via nonsolvent induced phase separation. Polymer 2014, 55, 6743–6753. [Google Scholar] [CrossRef]
  115. Dong, X.; Lu, D.; Harris, T.A.L.; Escobar, I.C. Polymers and Solvents Used in Membrane Fabrication: A Review Focusing on Sustainable Membrane Development. Membranes 2021, 11, 309. [Google Scholar] [CrossRef]
  116. Xin, Y.; Fujimoto, T.; Uyama, H. Facile fabrication of polycarbonate monolith by non-solvent induced phase separation method. Polymer 2012, 53, 2847–2853. [Google Scholar] [CrossRef]
  117. Ramachandran, J.; Thomas, S.P.; Thomas, S.; Stephen, R. Effect of annealing on the morphology and properties of poly(lactic acid)/polyhedral oligomeric silsesquioxane asymmetric porous membranes prepared through non-solvent induced phase separation and its application. Polym. Adv. Technol. 2024, 35, e6328. [Google Scholar] [CrossRef]
  118. Ma, Y.; Shao, T.; Niu, Q.; Jilili, Y.; Zhen, W. Superhydrophobic poly(lactic acid) membrane prepared with the induction of modified carbon dots for efficient separation of water-in-oil emulsions. Int. J. Biol. Macromol. 2024, 280 Pt 3, 136001. [Google Scholar] [CrossRef] [PubMed]
  119. Chen, M.; Uyama, H.; Wang, X.; Sun, X. A green and facile approach to prepare polylactide/kapok monoliths for a sustainable and reusable oil sorbent. Colloid Polym. Sci. 2023, 301, 1261–1270. [Google Scholar] [CrossRef]
  120. Su, Y.; Zhao, Y.; Zheng, W.; Yu, H.; Liu, Y.; Xu, L. Asymmetric Sc-PLA Membrane with Multi-scale Microstructures: Wettability, Antifouling, and Oil-Water Separation. ACS Appl. Mater. Interfaces 2020, 12, 55520–55526. [Google Scholar] [CrossRef]
  121. Abuhantash, F.; Hegab, H.M.; Aljundi, I.H.; Hasan, S.W. Synergistic design of polylactic acid/functionalized multi-walled carbon nanotubes composite membrane for enhanced oil-water separation. J. Environ. Chem. Eng. 2023, 11, 111566. [Google Scholar] [CrossRef]
  122. Ghadhban, M.Y.; Rashid, K.T.; Abdulrazak, A.A.; Ibrahim, I.T.; Alsalhy, Q.F.; Shakor, Z.M.; Hamawand, I. Modification of Polylactide-poly (butylene adipate-co-terephthalate) (PLA/PBAT) Mixed-Matrix Membranes (MMMs) with Green Banana Peel Additives for Oil Wastewater Treatment. Water 2024, 16, 1040. [Google Scholar] [CrossRef]
  123. Deville, S. Freeze-Casting of Porous Biomaterials: Structure, Properties and Opportunities. Materials 2010, 3, 1913–1927. [Google Scholar] [CrossRef]
  124. Santos, L.N.R.M.; Silva, J.R.S.; Cartaxo, J.M.; Rodrigues, A.M.; Neves, G.A.; Menezes, R.R. Freeze-casting applied to ceramic materials: A short review of the influence of processing parameters. Cerâmica 2021, 67, 1–13. [Google Scholar] [CrossRef]
Polymers 17 03135 g001
Figure 1. Sources responsible for oil spills.
Figure 1. Sources responsible for oil spills.
Polymers 17 03135 g001
Polymers 17 03135 g002
Figure 2. Evolution of publications obtained from the Web of Science database using “PLA & oil–water separation” as key topic terms. The ratio represents the number of publications with “PLA & oil–water separation” relative to the total number of publications with “membrane & oil–water separation”.
Figure 2. Evolution of publications obtained from the Web of Science database using “PLA & oil–water separation” as key topic terms. The ratio represents the number of publications with “PLA & oil–water separation” relative to the total number of publications with “membrane & oil–water separation”.
Polymers 17 03135 g002
Polymers 17 03135 g003
Figure 3. Melt-blowing process used for PLA [62].
Figure 3. Melt-blowing process used for PLA [62].
Polymers 17 03135 g003
Polymers 17 03135 g004
Figure 4. Methods for modifying membrane surfaces used for oil–water separation.
Figure 4. Methods for modifying membrane surfaces used for oil–water separation.
Polymers 17 03135 g004
Polymers 17 03135 g006
Figure 6. Procedure of some PLA aerogels.
Figure 6. Procedure of some PLA aerogels.
Polymers 17 03135 g006
Table 1. General classification of materials used for membranes in oil–water separation [21].
Table 1. General classification of materials used for membranes in oil–water separation [21].
Technology TermSecondary CategoryTertiary CategoryTypical ComponentsAdvantagesRef.
Membrane MaterialsInorganic Porous MaterialsCeramicsAlO3/ZrO2/TiO2/SiO2Thermally stable
Chemically resistant		[37]
Carbon-based MaterialsCNT/GOHigh surface area
Low density
Excellent mechanical performance
Chemically resistant
Eco-friendly
Large pore volume		[38]
Metal–Organic Framework Membranes (MOFs)Highly crystalline solid compounds
High surface area
Adjustability of the structure
Unique functionality caused by flexibility
Rich in physical and chemical functions
Easy modifiability		[39]
Organic Porous MaterialsPolymeric MembranesPVDF/PES/PSF/PP/PAN/
PLA/PE/PEG/PI/PTFE		High efficiency
Emulsified and dispersed oil
Small size
Low energy requirements
Cheap		[40]
Aerogels/
Foams		Polymer-based aerogels
Biomass-based aerogels
Inorganic-based aerogels
Carbon-based aerogels		Adjustability of the structure[41]
Hybrid MaterialsPolymer + SiO2/TiO2 nanoparticles
Polymeric Membranes + GO/MOF coating
Sponge + Fe3O4/GO coating		Integrating multiple advantages
Natural Porous MaterialsCellulose/CA/Chitosan/Sodium alginateEasy processing
Utilization
Cheap
High porosity		[42]
Table 2. Some of the main polymers and their characteristics used for oil–water separation.
Table 2. Some of the main polymers and their characteristics used for oil–water separation.
PolymerFeaturesRef.
Polysulfone
(PSF)		High porosity, high flux and excellent mechanical properties
Highly resistant to mineral acids, alkali, and electrolytes; resistant to oxidizing agents; resistant to surfactants and hydrocarbon oils; easily applicable for the conventional phase inversion processes; and able to modify the properties through blending with other polymers
Hydrophobic, tendency to contaminate		[44,45,46]
Polyvinylidene difluoride
(PVDF)		Hydrophilic
Hydrophobic, low surface energy, outstanding chemical and thermal stability, environmentally sustainable and reusable.
Forms isotropic, spherulitic microstructures that often include large macro voids		[47,48,49]
Polyether-
sulfone
(PES)		Hydrophobic, thermal stability and chemical resistance
Small flux and poor mechanical properties
less flexibility and expensive		[50,51,52]
Polypropylene
(PP)		Exceptional chemical stability, filtration efficiency, and mechanical properties; large pore size
Low cost, low water uptake, excellent mechanical robustness and excellent physical and chemical resistance		[53,54]
Polyimide
(PI)		Excellent mechanical strength, flexibility, and stability
Excellent corrosion resistance and strong separation performance		[55,56]
Polyacrylonitrile (PAN)High hydrophilic property, rich chemical modification spots, easy obtainment of the raw material and low cost
Thermal stability
Good stability in solvents, excellent mechanical and film-forming properties		[57,58,59]
Polyvinyl pyrrolidone (PVP)Hydrophilic, abundant carbonyl functional groups, nontoxic and biocompatible
Facility at forming complexes, strong adhesiveness, and resistance to thermal degradation in solution		[60,61]
Polylactic acid (PLA)Derived from the fermentation of starch, it can be obtained from cellulose, kitchen waste, or fish waste as raw materials
Excellent biodegradability
Eventually completely degraded into CO2 and H2O, sustainable
Limited oil adsorption capacity, low adsorption selectivity, and poor mechanical properties		[31,57,62]
CelluloseAbundance, low cost, environmental protection, biodegradability, and sustainability
Improved water retention, water absorption, antibacterial, and thermal properties, nontoxic, degraded by microorganisms into natural nontoxic compounds
Low flux
Hydrophilicity, high specific surface area, and high mechanical strength, pore size limitation of supporting membranes, restricted the formation of a uniform structure		[63,64,65,66]
ChitosanLow cost, environment-friendly, biodegradable, and abundant sources, special wettability, poor chemical modification ability, and harsh modification conditions[67]
Table 3. Recent advances in the fabrication of PLA-based membranes via electrospinning for oil–water separation, highlighting structural characteristics (fiber diameter, pore size, porosity), surface wettability (water and oil contact angles), and separation performance (efficiency, absorption capacity, and flux).
Table 3. Recent advances in the fabrication of PLA-based membranes via electrospinning for oil–water separation, highlighting structural characteristics (fiber diameter, pore size, porosity), surface wettability (water and oil contact angles), and separation performance (efficiency, absorption capacity, and flux).
Membrane/AdditivesFiber DiameterPore SizePorosity (%)Water Contact Angle * (°)Oil Contact Angle (°)Separation Efficiency (%)Separation Flux
(L/m2h)		Static Water Contact Angle Under Oil (°)Oil Takes (g/g)
/Absorption Capacity (g/g)		Ra (μm)Ref.
PLA1.2 μm 81.296.1 0 Motor oil: 7.75 ± 0.460.759 ± 0.252[69]
PLA-MoS2(3 phr)911 ± 156
nm		 83.8104.6 Motor oil: 14.66 ± 0.920.264 ± 0.025
PLA-WS2(2 phr)1447 ± 316
nm		 86.2108.8 Motor oil: 15.65 ± 1.240.351 ± 0.029
PLA-MoS2-WS2
(1 phr/1 phr)		1649 ± 406
nm		 88.2121.4 94.68–97.17%390–762 Motor oil: 22.45 ± 0.150.416 ± 0.071
PLA1.41 μm 110.52 >95% Peanut oil: 31.09
Motor oil: 25.61
Silicone oil: 32.65		 [71]
PLA(1 g)–Vinyltrimethoxysilane(0.1 g)0.71 μm >95% Peanut oil: 60.20
PLA(1 g)–Vinyltrimethoxysilane(0.25 g)
PLA(1 g)–Vinyltrimethoxysilane(0.5 g)0.62 μm Sunflower oil: 86.90
Motor oil: 52.11
Silicone oil: 64.42
PLA(1 g)–Aminopropyltrimethoxysilane (0.1 g)0.22 μm 103.63 136.56 **Peanut oil: 24.09
Motor oil: 24.15
PLA(1 g)–Aminopropyltrimethoxysilane (0.25 g) 125.25
PLA(1 g)–Aminopropyltrimethoxysilane (0.5 g) 104.67 162.58 **
PLA770 ± 330 nm Silicon oil: 20 times deadweight [70]
PLA–Carbon dot (3.5 w.%)740±420 nm Higher than PLA
PLA–Carbon dot (21.5 w.%)620±280 nm Low than PLA Silicon oil: 40 times deadweight
PLA–Carbon dot (37.0 w.%)720±280 nm Low than PLA
PLA~700 nm ~72%131.8 [74]
PLA-CuMOF (1.5 w.%)~500 nm 134.5
PLA-CuMOF (3 w.%)~480 nm 138.1
PLA-CuMOF (4.5 w.%)~400 nm ~83%140 99.47%
PLA-CuMOF (6 w.%)~500 nm 136.5
PLA (8 wt./v%)237 nm [75]
PLA (10 wt./v%)489 nm
PLA (15 wt./v%)695 nm 117.2 70%Hexane: 351.64  ±  86.58 Palm oil: 60.45
Used engine oil: 66.03
PLA (20 wt./v%)1.129 μm
PLA (15 wt./v%)-
POSS (5 wt./v%)		983 nm 121.4 75%Hexane: 338.62  ±  65.18 Palm oil: 51.10
Used engine oil: 58.78
PLA (15 wt./v%)-
POSS (5 wt./v%) coating		 132.9 Hexane: 325.68  ±  56.00 Palm oil: 48.86
Used engine oil: 49.85
PLA6.47 μm 71.67%12210 ***84.55% Diesel oil: 11.63
Peanut oil: 9.77		 [76]
PLA-CNF (2%)~4.2 μm 73.81% 90.39% Diesel oil: ~13
Peanut oil: ~10
PLA-CNF (4%)~3.7 μm 74.10% 91.63% Diesel oil: ~13.5
Peanut oil: ~11
PLA-CNF (6%)~3 μm 74.47% 92.26% Diesel oil: ~14
Peanut oil: ~11.5
PLA-CNF (8%)2.35 μm 73.46% 91.95% Diesel oil: ~14.3
Peanut oil: ~12.5
PLA-CNF (10%)3.16 μm 76.29%133.1 93.54% Diesel oil: ~14.5
Peanut oil: ~13.5
PLA-NaCl (2%)~5.8 μm 74.46%109.2 87.42% Diesel oil: ~12.5
Peanut oil: ~10.4
PLA-NaCl (4%)~4.6 μm 76.05% 88.97% Diesel oil: ~15
Peanut oil: ~12
PLA-NaCl (6%)~3.4 μm 77.70% 88.73% Diesel oil: ~14.5
Peanut oil: ~11.7
PLA-NaCl (8%)~2.5 μm 72.23% 90.29% Diesel oil: ~15.2
Peanut oil: ~11.5
PLA-NaCl (10%)1.69 μm 79.90%119.2 90.14% Diesel oil: ~15.2
Peanut oil: ~14
PLA 86.51330 **** 17.7–104.9 [77]
PLA-γ-Fe2O3 (6 wt.%) 91.2 23–268.6
PLA-γ-Fe2O3 (8 wt.%) 92.2
PLA-γ-Fe2O3 (10 wt.%) 92143.10 ****
PLA-γ-Fe2O3 (12 wt.%) 90.7
PLA-γ-Fe2O3 (14 wt.%) 90.3
PLA–γ-Fe2O3 (10 wt.%)–Glycine (0.25 wt.%) 90.3137.7
PLA–γ-Fe2O3 (10 wt.%)–Glycine 0.5 wt.%) 92148
PLA–γ-Fe2O3 (10 wt.%)–Glycine (1 wt.%) 92.4144.4
PLA–γ-Fe2O3 (10 wt.%)–Glycine (1.5 wt.%) 92.6140.4
PLA 120.7 [78]
PLA-CNT (0.25 wt.%)
PLA-CNT (0.5 wt.%)2.41 μm
PLA-CNT (0.75 wt.%)2.81 μm
PLA-CNT (1 wt.%)3.71 μm 133.9 1.274
PLA (75 wt.%)-CDA (25 wt.%)1.59 μm 0 0.864
PLA (60 wt.%)-CDA (40 wt.%)1.46 μm
PLA (50 wt.%)-CDA (50 wt.%)1.99 μm
PLA773 nm1430 nm 96.96 Soybean oil: 21 [79]
PLA-CNT@LDH (1 wt.%)764 nm1100 nm 103.37 Soybean oil: 25
PLA-CNT@LDH (3 wt.%)403 nm539 nm 109.31 Soybean oil: 28
PLA-CNT@LDH (5 wt.%)192 nm414 nm 113.27 Soybean oil: 32
PLA-ACNT@LDH (1 wt.%)226 nm599 nm 105.11 Soybean oil: 27
PLA-ACNT@LDH (3 wt.%)160 nm361 nm 110.68 Soybean oil: 30
PLA-ACNT@LDH (5 wt.%)158 nm337 nm 114.01 Soybean oil: 35
PLA1.125 μm 113.70 ***** Heptane: ~5600
Hexane: ~5000
Hexadecane: ~2600		 N-heptane: 18.94
N-hexane: 19.11
Hexadecane: 18.54		 [80]
PLA-WO32.946 μm 121.810 ***** Heptane: ~6500
Hexane: ~6000
Hexadecane: ~2800
PLA-WO3-N-CQDs EDTA8.149 μm 123.330 ***** Heptane: ~6600
Hexane: ~7200
Hexadecane: ~2800
PLA-WO3-N-CQDs EDA1.848 μm 132.370 ***** Heptane: ~11,500
Hexane: ~8200
Hexadecane: ~5800		 N-heptane: 27.90
N-hexane: 35.72
Hexadecane: 32.51		25.72 nm
PLA-γ-Fe2O3 80/30/173.655 μm 90.9135.4 151.8 ******Castor oil: ~150; Motor oil: ~135
Silicon oil: ~133; Corn oil: ~130
Soybean oil: ~100; Olive oil: ~105
Sunflower oil: ~98		 [81]
PLA-γ-Fe2O3 70/20/17 138.06 154.24 ******Castor oil: ~160; Motor oil: ~145
Silicon oil: ~140; Corn oil: ~125
Soybean oil: ~110; Olive oil: ~98
Sunflower oil: ~95
PLA-γ-Fe2O3 60/15/17 139.06 151.38 ******Castor oil: ~200; Motor oil: ~175
Silicon oil: ~180; Corn oil: ~130
Soybean oil: ~140; Olive oil: ~105
Sunflower oil: ~110
PLA-γ-Fe2O3 40/10/172.217 μm 95.6141.8 N-hexane: 57,324.8156.2 ******Castor oil:219; Motor oil: ~200
Silicon oil: ~190; Corn oil: ~145
Soybean oil: ~140; Olive oil: ~135
Sunflower oil: ~120
PLA312 nm ~50~120 ~98.5 Oil–water mixture: ~2400
Water-in-oil emulsion: ~320		 [82]
PLA-PBAT (0.05 g)~360 nm ~46~125 ~99 Oil–water mixture: ~290
Water-in-oil emulsion: ~490
PLA-PBAT (0.1 g)~415 nm ~43~130 ~99.3 Oil–water mixture: ~3100
Water-in-oil emulsion: ~500
PLA-PBAT (0.15 g)~450 nm ~38~136 ~99.5 Oil–water mixture: ~3800
Water-in-oil emulsion: ~520
PLA-PBAT (0.2 g)560 nm ~35~155 ~99.6 Oil–water mixture: ~6000
Water-in-oil emulsion: ~555
PLA-PBAT (0.35 g)~550 nm ~33~145 ~99.6 Oil–water mixture: ~4300
Water-in-oil emulsion: ~400
PLA-PBAT (0.3 g)621 nm ~33~142 ~99.3 Oil–water mixture: ~3800
Water-in-oil emulsion: ~400
PLA 89.91131.76 96.7N-hexane: 1978 ± 35
CCl4: 1721 ± 141		 [83]
PLA-PDMS/PCL (5 wt.%) 92.76
PLA-PDMS/PCL (10 wt.%) 93.35
PLA-PDMS/PCL (15 wt.%) 93.91155.10 *******99.3N-hexane: 3550 ± 50
CCl4: 3302 ± 181
PLA-PDMS/PCL (20 wt.%) 93.07
* Test Fluid is water. ** Water drops in sunflower seed oil. *** Test Fluid is diesel. **** Test Fluid is diiodomethane. ***** Test Fluid is hexane. ****** Water drops in hexane. ******* Test Fluid is n-hexadecane.
Table 4. Membranes based on PLA prepared by the melt-blowing process for oil–water separation.
Table 4. Membranes based on PLA prepared by the melt-blowing process for oil–water separation.
Membrane/AdditivesFiber SizeWater Contact Angle (°) *Separation Efficiency (%)Oil Takes
/Absorption Capacity		Ref.
PLA~5.5 μm122.3794.2 g/g[62]
PLA-PBAT (2 wt.%)~6.2 μm125.1824.5 g/g
PLA-PBAT (4 wt.%)~2.3 μm128.5885.18 g/g
PLA-PBAT (6 wt.%) 130.8914.9 g/g
PLA-PBAT (8 wt.%)~9.5 μm132.0944.7 g/g
PLA-PBAT (10 wt.%) 133.2964.5 g/g
PLA~5.7 μm125 4.64 g/g[85]
PLA-PBE (5 wt.%)~5.7 μm130 4.83 g/g
PLA-PBE (10 wt.%)~5.0 μm134 4.69 g/g
PLA-PBE (15 wt.%)~3.0 μm132 5.96 g/g
PLA-PBE (20 wt.%)~5.0 μm130 6.22 g/g
* Test Fluid is water.
Table 6. Some of the most promising foamed membranes for oil–water separation.
Table 6. Some of the most promising foamed membranes for oil–water separation.
Membrane/AdditivesPore SizePorosity (%)Expansion RatioDensity (g/cm3)Water Contact Angle * (°)Separation Efficiency (%)Separation Flux
(L/m2h)		Oil Takes/Absorption CapacityRef.
PLLA28.26 μm 3.030.42 [98]
PLLA-8-s-PDLA-13K-3% CCl4: 13.36 g/g
Silicone Oil: 7.97 g/g
PLLA-8-s-PDLA-13K-5%20.52 μm 14.450.09
PLLA-8-s-PDLA-15K-5%27.95 μm 8.630.15 CCl4: 6.82 g/g
Silicone Oil: 3.37 g/g
PLLA-8-s-PDLA-39K-3%23.55 μm 13.50.10
PLLA-8-s-PDLA-39K-5%14.6 μm 7.590.17 CCl4: 5.7 g/g
Silicone Oil: 3.56 g/g
PLA ~89 ~0.046~126 [102]
PLA–water (3 mL) ~90 ~0.0445~135
PLA–water (4 mL) 90.66 0.04396~140
PLA–water (3 mL)/peeling ~141
PLA–water (4 mL)/peeling 151 12–31 times its own weight
PLA61.7 μm ~36~0.03599.4 Ethyl Acetate: ~7.0 g/g[103]
PLA–Alkaline lignin59.7 μm ~37~0.034108.5 Ethyl Acetate: 4.3 g/g
PLA–m-Alkaline lignin73.2 μm 40.170.0303130.0 Ethyl Acetate: 12.44 g/g
PLA197 μm ~6069~126 ~10 g/g[99]
PLA-PBS (3 wt.%)177 μm ~58 ~128 ~12 g/g
PLA-PBS (6 wt.%)139.1 μm82.1~5452139 24.5 g/g
PLA-PBS (9 wt.%)296.8 μm ~48 ~118 18.8 g/g
PLA115 °C: 58.2 μm
110 °C: 48.6 μm
105 °C: 17.5 μm		115 °C:
110 °C: 105 °C: 		115 °C: ~58
110 °C: ~46
105 °C: ~17		 113CCl4: 12 (g/g)/135 minGeneral: 1.6–10.1 g/g [96]
PLA-PBS (10 wt.%)115 °C: 54.7 μm
110 °C: 57.1 μm
105 °C: 45.5 μm		 115 °C: ~55
110 °C: ~57
105 °C: ~47
PLA-PBS (20 wt.%)115 °C: 43.6 μm
110 °C: 50.6 μm
105 °C: 47.3 μm		115 °C: 97.7115 °C: 43.6
110 °C: ~48
105 °C: ~50		 118CCl4: 20 (g/g)/15 minCCl4: 21.9
C2Cl4: 19.4
Ethyl Acetate:18.0
Peanut Oil: 12.7
N-Octane: 11.7
Cyclohexane:10.1
Silicone Oil: 7.9
PLA-PBS (30 wt.%)115 °C: 5.3 μm
110 °C: 30.7 μm
105 °C: 27.2 μm		 115 °C: ~8
110 °C: ~28
105 °C: ~25
PLA10–50 μm 135.8 [100]
PLA-GO (1 cycle) 142.9
PLA-GO (2 cycle) 146.2
PLA-GO (3 cycle) 147.5
PLA-GO (4 cycle) 150.6>96 N-hexane: 8.11 g/g; Diethyl Ether: 8.58 g/g
Cyclohexane: 9.72 g/g; Toluene: 10.41 g/g
Carbon Tetrachloride: 19.21 g/g
Petroleum Ether: 7.79 g/g
PLA-GO (5 cycle) 148.2
PLA 114.3 [101]
PLA-TPU (15 wt.%)
PLA-TPU (30 wt.%)
PLA-TPU (50 wt.%) 124.7 CCl4: 18.8 g/g; Ethyl Acetate: 11.8 g/g
Silicone Oil: 8.5 g/g; Soybean Oil: 8.4 g/g
cyclohexane: 6.4 g/g; gasoline: 7.7 g/g
diesel: 7.2 g/g; corn oil: 4.7 g/g
* Test Fluid is water.
Table 7. Aerogels involved in membranes for oil–water separation.
Table 7. Aerogels involved in membranes for oil–water separation.
Membrane/AdditivesDensityPore SizePorosity (%)Water Contact Angle * (°)Separation Efficiency (%)Separation Flux
(L/m2h)		Oil Takes
/Absorption Capacity		Xc (%)Ref.
PLA68.53 mg/cm366.11 μm94.0137.6 [106]
PLA-H20 (2 wt.%)-SNFs (20 wt.%) 12.63 μm 150.2
PLA-H20 (4 wt.%)-SNFs (20 wt.%) 9.72 μm 156.7
PLA-H20 (6 wt.%)-SNFs (20 wt.%) 7.78 μm 164.4
PLA-H20 (8 wt.%)-SNFs (20 wt.%)48.08 mg/cm35.95 μm95.58174.6
PLA 19.3 nm 132 [57]
PLA-ZIF-8 (0.5 wt.%) 18.6 nm 131
PLA-ZIF-8 (1 wt.%) 17.1 nm 145Near to 100%Heptane–Water: 13 **
Carbon Tetrachloride–Water: 20 **
Pentane–Water: 7.1 **
N-hexane–Water: 35 **		Highest
PLA-ZIF-8 (2 wt.%) 18.4 nm 135
PLA-ZIF-8 (3 wt.%) 19.1 nm 133
PLA 7.1260 nm 107 [107]
PLA-ZIF-67 (1 wt.%) 6.8410 nm 112
PLA-ZIF-67 (2 wt.%) 8.1275 nm 117
PLA-ZIF-67 (3 wt.%) 5.8450 nm 132Near 100%Petroleum Ether–Water: 71.66 ***
Carb Tetrachloride–Water: 119.46 ***
Heptane–Water: 59.66 ***
Cyclohexane–Water: 32.56 ***
Isooctane–Water: 51.18 ***		highest: 15–30 times its own weight
PLA-ZIF-67 (4 wt.%) 7.3395 nm 121
PLLA-PDLA 21.1 nm 140.1 Ethanol: 38.5Anhydrous Ethanol: 19.7 g/g44.2[105]
PLLA-PDLA-PEO (10 wt.%) 24.2 nm96.40%145.4 Ethanol: 43.7 46.9
PLLA-PDLA-PEO (20 wt.%) 22.4 nm96.80%149.5 Ethanol: 53.2 46.7
PLLA-PDLA-PEO (30 wt.%) 23.1 nm97.00%153.2 Ethanol: 70.7 45.9
PLLA-PDLA-PEO (40 wt.%) 27.7 nm97.60%156.8 Ethanol: 99.5 44.5
PLLA-PDLA-PEO (50 wt.%) 24.2 nm97.90%160.7 Ethanol: 154.0Anhydrous Ethanol: 29.9 g/g
25 times its own weight		44.6
PLLA 52.18 μm 118.2 16.92 g/g40.46[104]
PLLA-PLDA (10 wt.%) 54.39 μm 124.5 18.55 g/g33.17
PLLA-PLDA (20 wt.%) 71.60 μm 128.3 19.1 g/g17.45
PLLA-PLDA (30 wt.%) 54.54 μm 131.1 20.15 g/g8.10
PLLA-PLDA (40 wt.%) 37.92 μm 136.7 20.53 g/g1.08
PLLA-PLDA (50 wt.%) 28.11 μm 140.1 20.94 g/g0
* Test Fluid is water. ** Oil/Water = 1:1. *** Proportion is not mentioned in the text.
Table 8. Thermally induced phase separation involved in membranes for oil–water separation.
Table 8. Thermally induced phase separation involved in membranes for oil–water separation.
Membrane/AdditivesTIPS MethodPore SizePorosity (%)Water Contact Angle * (°)Oil Takes
/Absorption Capacity		Xc (%)Ref.
PLAAt −4 °C for 12 h,
−80 °C for 72 h at 10 Pa		80.34 m2/g ~125 [20]
PLA-H2O (2 mL) ~130
PLA-H2O (3 mL) ~132
PLA-H2O (4 mL)94.6 m2/g 158Isooctane: ~15 g/g; Ethyl Acetate: ~20 g/g
Acetone: ~12 g/g; Ethyl Alcohol: ~17 g/g
P-xylene: ~16 g/g; Trie Thylamine: ~14 g/g
Pump Oil: ~20 g/g; Engine Oil: ~15 g/g
Phenixin: ~28 g/g; N-hexane: ~12 g/g
Xylene: ~13.5 g/g; Cyclohexane: ~14 g/g
PLLA/freezeAt −20 °C for 24 h50–100 μm 111.4~1.5 g/g~5[112]
PLLA-PDLA (10 wt.%)/freeze30 μm 116.2~1.6 g/g~20
PLLA-PDLA (30 wt.%)/freeze 117.7~1.7 g/g~45
PLLA-PDLA (50 wt.%)/freeze 119.7~1.8 g/g~57
PLLA/gelationAt 20 °C for 24 h, followed by freezing At −20 °C, followed freeze-drying14.5 μm66.998.3~1.4 g/g~5
PLLA-PDLA (10 wt.%)/gelation9.3 μm, 106.8~1.5 g/g~20
PLLA-PDLA (30 wt.%)/gelation4.0 μm 128.0~2.4 g/g~58
PLLA-PDLA (50 wt.%)/gelation3.3 μm>80137.2~2.5 g/g~62
PDLA (50 chain lengths)-GLYAt −18 °C for 12 h, −80 °C for 24 h at 10 Pa [113]
PDLA (70 chain lengths)-GLY-PCL10–60 μm94.01145.913.0 g/g21.22
PDLA (50 chain lengths)-GLY-PCL92.86142.212.8 g/g23.66
PDLA (30 chain lengths)-GLY-PCL89.14135.512.1 g/g35.9
* Test Fluid is water.
Table 9. Nonsolvent-induced phase separation involved in membranes for oil–water separation.
Table 9. Nonsolvent-induced phase separation involved in membranes for oil–water separation.
Membrane/AdditivesNIPS MethodPore Size Porosity (%)Water Contact Angle * (°)Separation Efficiency (%)Separation Flux
(LMH/bar)		Oil Takes
/Absorption Capacity 		Xc (%)Ref.
PLAImmersed in the coagulation bath filled with distilled water at ambient temperature1.04 μm26.43 Castor Oil: 2.96 g/g
Engine Oil: ~3.0 g/g		21.16[117]
PLA-POSS (1 wt.%)0.82 μm17.52 Castor Oil: 3.59 g/g
Engine Oil: ~3.1 g/g		27.59
PLA-POSS (3 wt.%)0.41 μm17.02 Castor Oil: ~3.56 g/g
Engine Oil: 3.05 g/g		22.52
PLA/annealing0.81 μm15.94 Castor Oil: 1.31 g/g
Engine Oil: ~2.0 g/g		84.54
PLA-POSS (1 wt.%)/annealing0.17 μm14.71 Castor Oil: ~1.85 g/g
Engine Oil: ~2.35 g/g		42.12
PLA-POSS (3 wt.%)/annealing0.21 μm13.37 Castor Oil: ~2.3 g/g
Engine Oil: 1.81 g/g		61.69
PLA1. Placed on the ice, and an equal volume of C2H5OH was slowly dripped in; 2. Placed in a container containing saturated CuSO4 (98% relative humidity)28.35 μm 12273.29N-Hexane: 7562.8
Kerosene: ~5000		N-Hexane: ~0.95 g/g
Kerosene: ~1.2 g/g		38.25[118]
PLA-Cys-CDs (1 wt.%)24.81 μm 132 N-Hexane: ~6800
Kerosene: ~4500		N-Hexane: ~1.65 g/g
Kerosene: ~2.2 g/g		39.48
PLA-Cys-CDs (3 wt.%)23.74 μm 140 N-Hexane: ~6300
Kerosene: ~4000		N-Hexane: ~1.55 g/g
Kerosene: ~1.6 g/g		42.75
PLA-Cys-CDs (5 wt.%)20.33 μm 159>99.9N-Hexane: ~4900
Kerosene: 3157.4		N-Hexane: ~1.45 g/g
Kerosene: ~1.5 g/g		47.86
PLA-Cys-CDs (7 wt.%)18.32 μm 15199.98N-Hexane: ~5200
Kerosene: ~3500		N-Hexane: ~1.2 g/g
Kerosene: ~1.3 g/g		46.12
PLA (7 wt.%)A certain amount of n-hexane was added dropwise as nonsolvent 86.10 ~6.1 g/g [119]
PLA (10 wt.%) 76.60 ~3.7 g/g
PLA (13 wt.%) 831285 μL/4 s ~4.5 g/g
PLA (15 wt.%) 80.80 ~4.1 g/g
PLA (13 wt.%)–Kapok (0.10 wt.%)0.09 m3/g ~5.5 g/g
PLA (13 wt.%)–Kapok (0.18 wt.%)0.077 m3/g 1415 μL/0.68 s ~6 g/g
PLA (13 wt.%)–Kapok (0.27 wt.%)0.066 m3/g ~7 g/g
PLA (7 wt.%)–Kapok (0.34 wt.%)0.079 m3/g ~7.5 g/g
PLA (7 wt.%)–Kapok (0.34 wt.%)–NaCl0.248 m3/g 17.34 g/g
PLLA-PLDA/400 μmA coagulation bath containing deionized water 109 33.66[120]
PLLA-PLDA/500 μm 129.5 32.78
PLLA-PLDA/600 μm 142.9 34.26
PLLA-PLDA/600 μm (Peeling) 151.9 Cyclohexane: ~2 s
Tetrachloromethane: ~4.3 s
Pump Oil: ~3.8 s; Vegetable Oil: ~3.7 s		34.26
PLASubmerged in a DI water coagulation bath for 24 h 659194.9Emulsion: 155 ** [121]
PLA-PVP-MWCNT ~788595.1
PLA-PVP-f-MWCNTs (0.5 wt.%) ~7779100Emulsion: 281 **
PLA-PVP-f-MWCNTs (1 wt.%) ~80<7998.9Water: 485 Emulsion: 260 **
PLA-PVP-f-MWCNTs (2 wt.%) 827299.2Water: 370
PLA-PBAT (4 wt.%)Immersed in water to facilitate its natural detachment from the glass surface23 nm5073.71 Pure Water: 62
Oil–water: 28.6 ***		 [122]
PLA–PBAT–Banana Peel (0.0125 wt.%)25 nm5850.893
PLA–PBAT–Banana Peel (0.025 wt.%)~27.5 nm6141.393.3
PLA–PBAT–Banana Peel (0.05 wt.%)29 nm6338.9995.2Pure Water: 52.655
oil–water: 40 ***
PLA–PBAT–Banana Peel (0.1 wt.%)~26 nm5751.8889.5Pure Water: 32.32
oil–water: 19.8 ***
* Test Fluid is water. ** Test Fluid is emulsion (1 g canola oil in 1 L water). *** Test Fluid is oil–water (diesel oil concentration of 100 ppm).
Table 10. Freeze solidification phase separation involved in membranes for oil–water separation.
Table 10. Freeze solidification phase separation involved in membranes for oil–water separation.
Membrane/AdditivesFSPS MethodPore SizePorosity (%)Water Contact Angle * (°)Separation Efficiency (%)Separation Flux
(L/m2h)		Oil Takes
/AbsorptionCapacity		RaRef.
PLACasting25.86 μm51.01117.80 23.4 nm[31]
PLAIn low temperature (below the freezing point of DiOX)0.46 μm77.60141.6796.42923 78.4 nm
PLA (H20)1. In low temperature (below the freezing point of DiOX and DCM)
2. Solution impregnation		 145.73 177 nm
PLA (acetic acid) 145.07 171 nm
PLA (H20:acetic acid = 1: 1) 151.0099.716,084n-hexane: 2.54 ± 0.55 g/g;
petroleum ether: 2.93 ± 0.21 g/g
ethyl acetate: 4.72 ± 0.28 g/g; methylbenzene: 5.37 ± 0.14 g/g		338 nm
PLA (DiOX: DCM = 10:0)In low temperature (below the freezing point of DiOX and DCM)0.54 μm 2923
PLA (DiOX: DCM = 9:1)0.98 μm 6266
PLA (DiOX: DCM = 4:1)1.32 μm 95.18287
PLA (DiOX: DCM = 1:1)0.35 μm 4278
PLA (DiOX: DCM = 0:10) 379
* Test Fluid is water.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Liang, W.; Verma, A.; Martin, O.; Sharma, G.; García-Peñas, A. Advances in Membranes Based on PLA and Derivatives for Oil–Water Separation. Polymers 2025, 17, 3135. https://doi.org/10.3390/polym17233135

AMA Style

Liang W, Verma A, Martin O, Sharma G, García-Peñas A. Advances in Membranes Based on PLA and Derivatives for Oil–Water Separation. Polymers. 2025; 17(23):3135. https://doi.org/10.3390/polym17233135

Chicago/Turabian Style

Liang, Weijun, Akshay Verma, Olga Martin, Gaurav Sharma, and Alberto García-Peñas. 2025. "Advances in Membranes Based on PLA and Derivatives for Oil–Water Separation" Polymers 17, no. 23: 3135. https://doi.org/10.3390/polym17233135

APA Style

Liang, W., Verma, A., Martin, O., Sharma, G., & García-Peñas, A. (2025). Advances in Membranes Based on PLA and Derivatives for Oil–Water Separation. Polymers, 17(23), 3135. https://doi.org/10.3390/polym17233135

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop