Search Results (27)

In this work, the simple fabrication of a new superhydrophobic magnetic sponge based on CNTs, NiFe₂O₄ nanoparticles, and PDMS was investigated. CNTs were synthesized by chemical vapor deposition (CVD) on a nickel ferrite catalyst supported on aluminum oxide (NiFe₂O₄/Al₂O₃). The synthesis of nickel ferrite (NiFe) was accomplished using the sol–gel method, yielding magnetic nanoparticles (43 Am²kg⁻¹, coercivity of 93 Oe, 21–29 nm). A new superhydrophobic magnetic PU/CNT/NiFe₂O₄/PDMS sponge was fabricated using a polyurethane (PU) sponge, CNTs, NiFe₂O₄ nanoparticles, and polydimethylsiloxane (PDMS) through the immersion coating method. The new PU/CNT/NiFe₂O₄/PDMS sponge exhibits excellent superhydrophobic/oleophilic/mechanical properties and water repellency (water absorption rate of 0.4%) while having good absorption of oil, olive oil, and organic liquids of different densities (absorption capacity of 21.38 to 44.83 g/g), excellent separation efficiency (up to 99.81%), the ability to be reused for removing oil and organic solvents for more than 10 cycles, and easy control and separation from water using a magnet. The new PU/CNT/NiFe₂O₄/PDMS sponge is a promising candidate as a reusable sorbent for collecting oil and organic pollutants and can also be used as a hydrophobic filter due to its excellent mechanical properties. Full article

Rapid industrial development has led to increased crude oil extraction and oily wastewater discharge. Achieving oil–water separation and marine oil adsorption in a cost-effective, efficient, and environmentally friendly manner remains a global challenge. In this work, natural wood was chemically treated to prepare a degradable and environmentally friendly wood sponge structure. In situ polymerization and spraying methods were used to produce an environmentally friendly oil–water separation sponge with superhydrophobic and superoleophilic properties (Fe₃O₄@P-P@WS). Fe₃O₄@P-P@WS had excellent superhydrophobicity (WCA = 154.2°) and self-cleaning properties. Additionally, Fe₃O₄@P-P@WS could convert solar and electrical energy into thermal energy, reaching a surface temperature of 74 °C under sunlight irradiation with an intensity of 1.0 kW m⁻². When a voltage of 9 V was applied, the surface temperature reached 120.5 °C. Moreover, under the suction of a vacuum pump or the action of gravity, the continuous separation of highly fluid oil substances was achieved. The designed Fe₃O₄@P-P@WS offers advantages such as easily obtained raw materials, energy efficiency, simple preparation, and the ability to solve secondary pollution issues, providing a new technology for cleaning organic matter in industrial wastewater discharge and for round-the-clock cleaning of high-viscosity crude oil leaked during offshore oil exploitation. Full article

In addition to filtering some sediments, hydrophobic wood sponges can also absorb many organic solvents, particularly crude oil. The leakage of crude oil poses a serious threat to the marine ecosystem, and oil mixed with water also generates great danger for its use. From the perspective of low cost and high performance, wood sponges exhibit great potential for dealing with crude oil pollution. Wood sponge is a renewable material. With a highly oriented layered structure and a highly compressible three-dimensional porous frame, wood sponges are extremely hydrophobic, making them ideal for oil–water separation. Currently, the most common approach for creating wood sponge is to first destroy the wood cell wall to obtain a porous-oriented layered structure and then enhance the oil–water separation ability via superhydrophobic treatment. Wood sponge prepared using various experimental methods and different natural woods exhibits distinctive properties in regards to robustness, compressibility, fatigue resistance, and oil absorption ability. As an aerogel material, wood sponge offers multi-action (absorption, filtration) and reusable oil–water separation functions. This paper introduces the advantages of the use of wood sponge for oil–water separation. The physical and chemical properties of wood sponge and its mechanism of adsorbing crude oil are explained. The synthesis method and the properties are discussed. Finally, the use of wood sponge is summarized and prospected. Full article

The fabrication of durable materials with excellent oil-adsorption capacity and separation performance for the treatment of oily wastewater is meaningful based on the special property of smart responsiveness. Herein, a solvent-responsive melamine sponge (MS) was developed via silanization and the in situ growth of a zeolitic imidazolate framework-8 (ZIF-8). Detailed characterization of the resultant composite MS was conducted using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and X-ray diffraction (XRD). The multiscale hierarchical MS substrate exhibited highly hydrophobic properties in the pH range of 1–11, along with a satisfactory adsorption capacity in the range of 65.4–134.2 g/g for different oils. The modified surface transformed from superhydrophobic/superlipophilic to superhydrophilic/underwater superoleophobic upon ethanol wetting, reverting to its original superhydrophobic state upon drying. The separation flux of the MS substrate was above 1.5 × 10⁴ L/m²h for both oil and water removal, and the separation efficiency was greater than 98.7%. The absence of obvious changes in separation performance after 50 successive immiscible oil−water separations indicated the excellent durability and robustness of the anchored ZIF-8 nanoparticles on the surface of the modified MS substrate. More importantly, oil-in-water emulsion separation was successfully carried out via the ZIF-8 MS composite, showing high separation efficiency (over 99.1%). The developed smart sponge, which had high oil-adsorption capacity, excellent chemical stability, and fire resistance, has a wide range of potential practical applications in the convenient treatment of oily wastewater. Full article

Oil/water separation processes have garnered significant global attention due to the quick growth in industrial development, recurring chemical leakages, and oil spills. Hence, there is a significant demand for the development of inexpensive superwetting materials in an eco-friendly manner to separate oil/water mixtures and emulsions. In this study, a superwetting melamine sponge (SMS) with switchable wettabilities was prepared by modifying melamine sponge (MS) with sodium dodecanoate. The as-prepared SMS exhibited superhydrophobicity, superoleophilicity, underwater superoleophobicity, and underoil superhydrophobicity. The SMS can be utilized in treating both light and heavy oil/water mixtures through the prewetting process. It demonstrated fast permeation fluxes (reaching 108,600 L m⁻² h⁻¹ for a light oil/water mixture and 147,700 L m⁻² h⁻¹ for a heavy oil/water mixture) and exhibited good separation efficiency (exceeding 99.56%). The compressed SMS was employed in separating surfactant-stabilized water-in-oil emulsions (SWOEs), as well as surfactant-stabilized oil-in-water emulsions (SOWEs), giving high permeation fluxes (reaching 7210 and 5054 L m⁻² h⁻¹, respectively). The oil purity for SWOEs’ filtrates surpassed 99.98 wt% and the separation efficiencies of SOWEs exceeded 98.84%. Owing to their remarkable capability for separating oil/water mixtures and emulsions, eco-friendly fabrication method, and feasibility for large-scale production, our SMS has a promising potential for practical applications. Full article

Wastewater treatment from oil, oil products and organic mixtures is a very relevant topic that can be successfully utilized to solve problems of severe environmental pollution, such as oil spills, industrial oily wastewater discharges and water treatment in the water treatment process. In this work, we have developed new superhydrophobic magnetic polyurethane (PU) sponges, functionalized with reduced graphene oxide (RGO), MgFe₂O₄ nanoparticles, and silicone oil AS 100 (SO), as a selective and reusable sorbent for the purification and separation of wastewater from oil and organic solvents. The surface morphology and wettability of the sponge surface were characterized by scanning electron microscopy (SEM) and a contact angle analysis system, respectively. The results showed that the obtained PU sponge PU/RGO/MgFe₂O₄/SO had excellent mechanical and water-repellent properties, good reusability (lasted more than 20 cycles), as well as fast (immersion time 20 s) and excellent absorption capacity (16.61–44.86 g/g), and additional good magnetic properties, which made it easy to separate the sponge from the water with a magnet. The presence of RGO in the composition of the nanomaterial improves the separating and cleaning properties of the materials and also leads to an increase in the absorption capacity of oil and various organic solvents. The synthesized PU sponge has great potential for practical applications due to its facile fabrication and excellent oil–water separation properties. Full article

Oil spills and chemical leakages are a serious source of pollution in oceans and rivers, and have attracted worldwide attention. Many scientists are currently engaged in the development of oil–water separation technology. In this study, the umbrella skirt of a discarded silicone rubber insulator was utilized as feedstock, and polydimethylsiloxane (PDMS) was employed to immobilize the prepared powder (FXBW) onto a polyurethane (PU) sponge skeleton. Without any modifications using chemical reagents, a novel oil–water separation material, FXBW-PU, was developed, with a water contact angle of 155.3°. The FXBW-PU sponge exhibited an absorption capacity ranging from 11.79 to 26.59 g/g for various oils and organic solvents, while maintaining an excellent selective adsorption performance, even after undergoing ten compression cycles, due to its exceptional chemical and mechanical stability. With the assistance of a vacuum pump, the FXBW-PU sponge was utilized in a continuous separation apparatus, resulting in a separation efficiency exceeding 98.6% for various oils and organic solvents. The separation efficiency of n-hexane remains as high as 99.2% even after 10 consecutive separation cycles. Notably, the FXBW-PU sponge also separated the dichloromethane-in-water emulsions, which achieved the effect of purifying water. In summary, FXBW-PU sponge has great potential in the field of cleaning up oil/organic solvent contamination due to its low preparation cost, environmental friendliness and excellent performance. Full article

Serious damage caused by oily wastewater makes the development of efficient superhydrophobic and superoleophilic materials for oil/water separation processes critical and urgent. Herein, durable superhydrophobic nanometer-scale TiO₂ grains with low-surface-energy substance composite-modified materials were fabricated by using a cost-effective and facile synthesis method for the gravity-driven separation of oil/water mixtures under harsh conditions. Different substrates, such as sawdust, wheat straw, cotton, sponge and fabric, were applied for superhydrophobic surface preparation, and various low-surface-energy reagents could interact with deposited TiO₂ nanoparticles, including cetylamine, dodecanethiol, stearic acid and HDTMS. The resultant materials showed superhydrophobic properties with a water contact angle (WCA) higher than 150.8°. The separation of various oil/water mixtures with high efficiency and purity was acquired by using the as-prepared sponge. More importantly, the coated sponge exhibited good resistance to various harsh environmental solutions. Moreover, its superhydrophobicity also remained even after 12 months of storage in air or 10 cycles of abrasion. The durable superhydrophobic coating prepared in this work could be practically used for the highly efficient separation of oil/water mixtures under various harsh conditions. Full article

Superhydrophobic metal−organic framework (MOF)-based sponges have received increasing attention in terms of treating oil−water mixtures. However, highly fluorinated substances, commonly used as modifiers to improve the hydrophobicity of MOFs, have aroused much environmental concern. Developing a green hydrophobic modification is crucial in order to prepare superhydrophobic MOF-sponge composites. Herein, we report the preparation of a porous composite sponge via a polydopamine (PDA)-assisted growth of zeolitic imidazolate frameworks (ZIF-90) and eco-friendly hydrophobic short-chain fluorinated substances (trifluoroethylamine) on a melamine formaldehyde (MF) sponge. The composite sponge (F-ZIF-90@PDA-MF) exhibited superhydrophobicity (water contact angle, 153°) and superoleophilicity (oil contact angle, 0°), which is likely due to the combination of the low surface energy brought on by the grafted CF₃ groups, as well as the rough surface structures that were derived from the in situ growth of ZIF-90 nanoparticles. F-ZIF-90@PDA-MF showed an excellent adsorption capacity of 39.4–130.4 g g⁻¹ for the different organic compounds. The adsorbed organic compounds were easily recovered by physical squeezing. Continuous and selective separation for the different oil−water mixtures was realized by employing the composite sponge as an absorbent or a filter. The separation efficiency and flux reached above 99.5% and went up to 7.1 ×10⁵ L m⁻² h⁻¹, respectively. The results illustrate that the superhydrophobic and superoleophilic F-ZIF-90@PDA-MF sponge has potential in the field of water−oil separation, especially for the purposes of large-scale oil recovery in a water environment. Full article

Currently, frequent oil spill accidents caused by transportation, storage, and usage may lead to extensive damage to marine ecosystems. Effective methods for oil spillage recovery from offshore environments are still urgently in demand. A superhydrophobic sponge (MS@PVC@SiO₂) was obtained via a facile two-step method for rapid oil adsorption, and a piece of novel collection equipment loaded with MS@PVC@SiO₂ was developed for in situ continuous oil/seawater separation. The results showed that MS@PVC@SiO₂ exhibits excellent water repellence, compressibility, and durability. Furthermore, the obtained MS@PVC@SiO₂ shows high diesel oil adsorption capacity (32 g/g), and excellent recyclability (up to 200 times). The collection equipment demonstrates highly selective oil adsorption capacity and good stability in real seawater. The maximum possible recovery capacity of collection equipment was 557.784 L/h with 98% efficiency, which was much higher than that of commercial disc oil collectors (119.8 L/h). The recovery performance was effectively improved by introducing MS@PVC@SiO₂, due to its large specific area and enough storage space. Moreover, even after continuous operation for 58 h in seawater, the collection equipment remained at a high recovery capacity. The results indicate that both MS@PVC@SiO₂ and the collection equipment have great application perspectives in practical marine oil spillage recovery. Full article

Photothermally assisted superhydrophobic materials play an important role in a variety of applications, such as oil purification, waste oil collection, and solar desalination, due to their facile fabrication, low-cost, flexibility, and tunable thermal conversion. However, the current widely used superhydrophobic sponges with photothermal properties are usually impaired by a high loading content of photothermal agents (e.g., gold or silver nanoparticles, carbon nanotubes), low photothermal efficiency, and require harmful processes for modification. Here, a one-pot, simple composite consisting of two-dimensional (2D) selenium (Se) nanosheets (NSs) and commercially used melamine sponge (MS) is rationally designed and successfully fabricated by a facile dip-coating method via physical adsorption between 2D Se NSs and MS. The loading content of 2D Se NSs on the skeleton of the MS can be well controlled by dipping cycle. The results demonstrate that after the modification of 2D Se NSs on the MS, the wettability transition from hydrophilicity to hydrophobicity can be easily achieved, even at a very low loading of 2D Se NSs, and the highly stable photothermal conversion of the as-fabricated composites can be realized with a maximum temperature of 111 ± 3.2 °C due to the excellent photothermal effect of 2D Se NSs. It is anticipated that this composite will afford new design strategies for multifunctional porous structures for versatile applications, such as high-performance solar desalination and photothermal sterilization. Full article

Fast and effective cleanup of oil spills remains a global challenge. A modified commercial sponge with superhydrophobicity, strong absorption capacity, outstanding magnetic response, and fire resistance were fabricated by a facile and inexpensive route of dip-coated melamine sponge carbonization. The low-cost petroleum asphaltene and kaolin nanoparticles were used as the dip-coating reagent. High absorption capacity of the fabricated sponges allowed rapid and continuous removal of oil contaminants. Taking advantage of the good refractory property, the sponges can be used in burning conditions and directly reused after burning out of the absorbed oil. Reusability tests showed that the modified sponges still maintained high absorption capacity (>85%) after six regeneration and reuse cycles. These characteristics make the fabricated sponge a promising aid to promote effective in situ burning cleanup of oil spills, contributing as a magnetic oil collector and a fire-resistant flexible boom. An example usage scenario of the sponges applied to in situ burning cleanup of oil spills is described. Full article

In this study, magnetic fly ash was prepared with fly ash and nano-magnetic Fe₃O₄, obtained by co-precipitation. Then, a magnetic fly ash/polydimethylsiloxane (MFA@PDMS) sponge was prepared via simple dip-coating PDMS containing ethanol in magnetic fly ash aqueous suspension and solidifying, whereby Fe₃O₄ played a vital role in achieving the uniformity of the FA particle coating on the skeletons of the sponge. The presence of the PDMS matrix made the sponge super-hydrophobic with significant lubricating oil absorption capacity; notably, it took only 10 min for the material to adsorb six times its own weight of n-hexane (oil phase). Moreover, the MFA@PDMS sponge demonstrated outstanding recyclability and stability, since no decline in absorption efficiency was observed after more than eight cycles. Furthermore, the stress–strain curves of 20 compression cycles presented good overlap, i.e., the maximum stress was basically unchanged, and the sponge was restored to its original shape, indicating that it had good mechanical properties, elasticity, and fatigue resistance. Full article

The problem of offshore oil leakage has wreaked havoc on the environment and people’s health. A simple and environmentally friendly impregnation method combined with marine mussel bionics was used to address this issue. Using the viscosity of polydopamine (PDA), nano- Fe₃O₄ and WS₂ adhered to the framework of the melamine sponge (MS), and then the magnetic sponge was modified with n-octadecanethiol (OTD), and finally the superhydrophobic magnetic melamine sponge (mMS) was prepared. The modified sponge has superhydrophobicity (WCA, 156.8° ± 1.18°), high adsorbability (40~100 g°g⁻¹), recyclability (oil adsorbability remains essentially unchanged after 25 cycles), efficient oil–water separation performance (>98%), and can quickly separate oil on the water’s surface and underwater. Furthermore, the modified sponge exhibits excellent stability and durability under harsh operating conditions such as strong sunlight, strong acid, strong alkali, and high salt, and can control the direction of the sponge’s movement by loading a magnetic field. To summarize, mMS has many potential applications as a new magnetic adsorption material for dealing with complex offshore oil spill events. Full article

The growing concerns about climate changes and environmental pollution have galvanized considerable research efforts in recent years to develop effective and innovative remediation technologies for contaminated soils and water caused by industrial and domestic activities. In this context, the establishment of effective treatment methods for wastewater has been critically important and urgent, since water pollution can take place on a very large scale (e.g., oceanic oil spills) and have massive impacts on ecosystems and human lives. Functional materials play a central role in the advancement of these technologies due to their highly tunable properties and functions. This article focuses on reviewing the recent progress in the application of various functional materials for wastewater treatment. Our literature survey is first concentrated on new modification methods and outcomes for a range of functional materials which have been actively investigated in recent years, including biofilm carriers, sand filters, biomass, biopolymers, and functional inorganic materials. Apart from the development of modified functional materials, our literature survey also covers the technological applications of superhydrophilic/superhydrophobic meshes, hybrid membranes, and reusable sponges in oil–water separation. These devices have gained significantly enhanced performance by using new functional materials as the key components (e.g., coating materials), and are therefore highly useful for treatment of oily wastewater, such as contaminated water collected from an oil spill site or oil–water emulsions resulting from industrial pollution. Based on our state-of-the-art literature review, future directions in the development and application of functional materials for wastewater treatment are suggested. Full article