Search Results (94)

Polymer flooding is a highly promising enhanced oil recovery (EOR) technique for improving sweep efficiency, particularly in complex reservoirs at advanced stages of water production. While polymer flooding effectively improves sweep efficiency, efficient mobilization of residual oil requires further reduction in interfacial tension. Surfactant systems capable of forming microemulsions have therefore been introduced to enhance oil displacement through improved oil mobilization. The underlying oil displacement mechanisms of microemulsions are strongly dependent on phase behavior, which is governed by Winsor phase conditions. In this study, the pore-scale oil displacement mechanisms of Winsor I, II, and III microemulsion systems were systematically investigated using glass micromodel experiments. Winsor I mainly promoted oil detachment and emulsification, leaving residual oil as corner-bound oil and dispersed droplets. Winsor II showed limited efficiency due to its oil-continuous nature and viscous water-in-oil emulsions, resulting in persistent columnar residual oil. In contrast, Winsor III formed a continuous middle-phase microemulsion, enabling a solubilization-migration mechanism that effectively mobilized and transported oil. Accordingly, Winsor III achieved the highest recovery (81.37%), followed by Winsor I (75.6%) and Winsor II (64.9%). Optimized microemulsion slug injection further improved performance, with Winsor II-III-I reaching 82.2% and Winsor III-I sequence achieved the highest recovery of 85.6%. This study provides a mechanistic framework linking Winsor phase behavior to oil mobilization and demonstrates that both phase optimization and slug design are critical for improving microemulsion flooding performance in complex reservoir conditions. Full article

The performance of shampoo is determined by complex interactions between surface active agents (SAAs), polymers, and formulation modifiers, which directly influence consumer-relevant properties. However, the formulation principles governing these interactions and their impact on product quality remain insufficiently characterized. Therefore, the aim of this study was to evaluate the formulation principles underlying the interaction between thickeners and surfactant systems in shampoo formulations and to assess how these interactions influence the overall performance and quality of the final product. For this purpose, two groups of shampoo formulations containing identical surfactant systems but different thickeners (acrylate copolymer and guar gum) were prepared and evaluated in terms of pH, cleansing power (wool thread method), foam volume and stability, and texture profile. The results demonstrated that pH values ranged from 6.52 to 7.23 in acrylate copolymer-based formulations and from 4.71 to 6.09 in guar gum-based formulations. Cleansing power reached up to approximately 35%, depending on surfactant composition and thickener type. Foam volume was higher in acrylate copolymer systems, with a maximum value of 161 mL, whereas guar gum-based formulations exhibited lower but more variable foam characteristics. Texture analysis revealed that guar gum formulations were more sensitive to changes in surfactant composition, whereas acrylate copolymer provided more consistent and controllable texture characteristics. Full article

Microplastics (MPs) and nanoplastics (NPs) are emerging aquatic contaminants that pose environmental and public health risks due to their persistence, ubiquity, and ability to adsorb co-contaminants. This scoping review synthesises findings from 57 experimental studies and five review studies published between 2019 and 2025 on the use of biochar-based materials for the removal of microplastics from water and wastewater. Guided by the hypothesis that surface-modified biochars, such as magnetised, surfactant-coated, or chemically activated forms, achieve high removal efficiencies through multimodal mechanisms (e.g., electrostatic attraction, hydrophobic interactions, π–π stacking, and physical entrapment), this review applies PRISMA-based protocols to systematically evaluate biochar feedstocks, pyrolysis conditions, surface modifications, polymer types, removal mechanisms, and regeneration approaches. Scopus, Web of Science, and PubMed were searched until 30 May 2025 (English-only), and 62 studies were included. The review was not registered, and no protocol was prepared. The results confirm a high removal efficiency (>90%) in most experimental studies, particularly under controlled laboratory conditions and using pristine polystyrene. However, the performance declines significantly in complex matrices (e.g., wastewater and surface water) owing to dissolved organic matter, ionic competition, and particle heterogeneity, thus supporting the guiding hypothesis. This review also identifies critical methodological gaps, including narrow plastic typologies, a lack of standardised testing protocols, and limited field-scale validation. Addressing these gaps through environmentally realistic testing, regeneration optimisation, and harmonised methods is essential for transitioning biochar from a promising sorbent to a practical water treatment solution. Full article

Polyelectrolyte-based complexes have attracted attention, as the interaction of the oppositely charged components results in nanoparticle formation through an easy but highly efficient method, avoiding the use of strong solvents, extreme temperatures, and toxic chemicals. Sodium oleate (NaOL) is a widely used surfactant in the pharmaceutical industry due to its availability, eco-friendliness, and low cost. In the present study, the neutral-cationic block copolymer poly(oligo(ethylene glycol) methyl ether methacrylate)–b–quaternized poly(2-(dimethylamino) ethyl methacrylate) (POEGMA-b-Q(PDMAEMA)) is mixed with the anionic surfactant sodium oleate for the formation of nanoscale polyelectrolyte complexes through electrostatic interactions. Different weight ratios of copolymer to surfactant are studied. Then, the co-solvent protocol was implemented, and curcumin is successfully loaded in the formed particles for drug delivery applications. The size and morphology of the macromolecular complexes are examined via Dynamic Light Scattering (DLS) and Cryogenic Transmission Electron Microscopy (cryo-TEM). The methods that we have used have indicated that the polymer–surfactant complexes form spherical complexes, worm-like and vesicle-like structures. When curcumin was introduced, encapsulation was effectively achieved into micelles, giving rise to vesicle-like shapes. The success of curcumin encapsulation is confirmed by Ultraviolet–Visible absorption (UV–Vis) and fluorescence (FS) spectroscopy. POEGMA-b-Q(PDMAEMA)–sodium oleate polyelectrolyte complexes revealed promising attributes as efficient drug carrier systems for pharmaceutical formulations. Full article

Biosurfactants are amphipathic compounds produced by various microorganisms, including fungi and yeasts, with those produced by the latter being of particular interest as they are considered microorganisms of low or no sanitary risk. This article presents an analysis of the available information regarding the role these compounds play within the ecological habitat where yeasts inhabit, as well as their potential biotechnological applications in commercial areas. Some of the biological roles that biosurfactants play for their producing microorganisms are unknown and can be highly diverse, depending on the adaptive needs microorganisms have to survive the environmental conditions prevalent in their habitat. However, some of these roles that have been reported are related to nutrient availability, cellular communication, and competition, as well as surface colonization. The structures of biosurfactant molecules produced by yeasts are highly diverse, and so far, have been reported as sophorolipids, carbohydrate–protein–lipid complexes, carbohydrate–protein polymers, mixtures of lactones, and mannosylerythritol lipids. In addition to their properties as surfactants and/or emulsifiers, many of these molecules have also been reported to possess biological activities, including antimicrobial, antifungal, antitumoral, antioxidant, antiadhesive, antiviral, ultraviolet (UV)-protectant, anti-aging agent, moisturizing, and enzyme-activator/inhibitor properties. By understanding the functions that biosurfactants perform in nature, novel and efficient methods for their production can be proposed, as well as new applications in areas such as pharmaceuticals, food, and cosmetics. The latter is of particular interest due to the growing biosurfactant market and the processes that demand greater knowledge about their production, biological, and environmental interactions for their management and disposal. Full article

Microplastics entering the gastrointestinal environment rapidly acquire protein coronas that alter their surface chemistry and analytical detectability. We investigated the physicochemical interactions between fluorescently labeled bovine serum albumin (BSA) and polyethylene terephthalate (PET) microplastics during simulated intestinal exposure and evaluated the stability of the resulting hard corona. Using fluorescence tracking, SDS-PAGE, and FTIR spectroscopy, we showed that BSA forms a persistent corona that resists oxidative-only treatments. Only a combination of oxidation with an alkaline (KOH) or surfactant step (SDS) effectively removed the corona. None of the protocols applied affected polymer integrity. Residual protein in less effective protocols did not show changes on PET spectra in ATR FTIR. To validate the protocol under physiologically relevant complexity, we extended it to PET incubated with single digestive enzymes. FTIR spectra confirmed the removal of protein-specific signals in both systems, with no degradation of PET ester or aromatic functional groups nor signals of protein–polymer interactions. Our results highlight the robustness of protein–PET interactions in biological conditions and provide a variety of protocols for protein corona removal, suitable for diverse applications of microplastic analysis and toxicological studies. Full article

Steady-shear rheology and surface activity of surfactant–polymer solutions were investigated experimentally. Four different polymers were studied as follows: cationic hydroxyethyl cellulose, nonionic hydroxyethyl cellulose, nonionic guar gum, and anionic xanthan gum. The influence of the following four surfactants on each of the polymers was determined: nonionic alcohol ethoxylate, anionic sodium lauryl sulfate, cationic hexadecyltrimethylammonium bromide, and zwitterionic cetyl betaine. The interaction between cationic hydroxyethyl cellulose and anionic sodium lauryl sulfate was extraordinarily strong, resulting in dramatic changes in rheological and surface-active properties. The consistency increased initially, reached a maximum value, and then fell off with the further addition of surfactant. The surface tension of surfactant–polymer solution dropped substantially and exhibited a minimum value. Thus, the surfactant–polymer solutions were much more surface-active compared with pure surfactant solutions. The interaction between anionic xanthan gum and cationic hexadecyltrimethylammonium bromide was also strong, resulting in a substantial decrease in consistency. The surfactant–polymer solution became less surface-active compared with pure surfactant solution due to the migration of surfactant from solution to polymer. The interactions between other polymers and surfactants were weak to moderate, resulting in small to modest changes in rheological and surface-active properties. Surface activity of surfactant–polymer solutions often increased due to the formation of complexes more surface-active than pure surfactant molecules. Full article

In the mining industry, key unit operations such as grinding, flotation, thickening, and tailings transport are negatively affected by the presence of clay minerals, which impart complex rheological behaviors to mineral suspensions by increasing their rheological properties. This deterioration arises from specific physicochemical characteristics of clay minerals such as fine particle size, anisotropic character, laminar morphology, and swelling capacity. This work reviews the effects of various rheology-modifying reagents on clay suspensions including kaolinite, illite, and montmorillonite. The reviewed reagents include inorganic salts, pH modifiers, polymers, surfactants, and nanoparticles. Their mechanisms of interaction with solid particles are analyzed, highlighting their influence on the degree of dispersion or aggregation. Furthermore, this review proposes research opportunities focused on the formulation of hybrid reagents, modified biopolymers, and the development of reagents effective under adverse conditions such as high salinity or elevated temperatures. This review provides a comprehensive basis for optimizing the use of rheological additives through more efficient and sustainable strategies for managing clay-rich suspensions in the mining industry. Full article

This study concerns the evaluation of adhesive and wettability energetic signatures of a model orthodontic wire exposed to commercial mouthrinses. The surface wetting properties were evaluated from the contact angle hysteresis (CAH) approach applied to dynamic contact angle data derived from the original drop on a vertical filament method. Young, advancing, receding CA apart from adhesive film pressure, surface energy, work of adhesion, etc. were chosen as interfacial interaction indicators, allowing for the optimal concentration and placement of the key component(s) accumulation to be predicted for effective antibacterial activity to eliminate plaque formation on the prosthetic materials. Surfactant compounds when adsorb at interfaces confer rheological properties to the surfaces, leading to surface relaxation, which depends on the timescale of the deformation. The surface dilatational complex modulus E, with compression elasticity E_d and viscosity E_i parts, determined in the stress–relaxation Langmuir trough measurements, exhibited the viscoelastic surface film behavior with the relaxation times (0.41–3.13 s), pointing to the vertically segregated film structure as distinct, stratified layers with the most insoluble compound on the system top (as indicated with the 2D polymer film scaling theory exponent y = 12.9–15.5). Kinetic rheology parameters could affect the wettability, adhesion, and spreading characteristics of mouthrinse liquids. Full article

Hydrogel particles, renowned for their high water content and biocompatibility in drug delivery and tissue engineering, typically rely on complex, costly microfluidic systems to reach sub 5 µm dimensions. We present a vortex-based inverse-emulsion polymerization strategy in which UV crosslinking of polyethylene glycol diacrylate (PEGDA) dispersed in n-hexadecane and squalene yields tunable micro- and nanogels while delineating the parameters that govern particle size and uniformity. Systematic variation in surfactant concentration, vessel volume, continuous phase viscosity, vortex speed and duration, oil-to-polymer ratio, polymer molecular weight, and pulsed vortexing revealed that increases in surfactant level, vortex intensity/duration, vessel volume, and oil-to-polymer ratio each reduced mean diameter and PDI, whereas higher polymer molecular weight and continuous phase viscosity broadened the size distribution. We further investigated how these same parameters can be tuned to shift particle populations between nano- and microscale regimes. Under optimized conditions, microhydrogels achieved a coefficient of variation of 0.26 and a PDI of 0.07, with excellent reproducibility, and nanogels measured 161 nm (PDI = 0.05). This rapid, cost-effective method enables precise and scalable control over hydrogel dimensions using only standard laboratory equipment, without specialized training. Full article

Cosmetic formulations are complex mixtures of ingredients that must fulfill several requirements. One of the challenges of the cosmetic industry is to find natural alternatives to replace synthetic polymers, preserving desirable sensory characteristics. The aim of this work is to induce the formation of gels, by replacing synthetic polymers with a low-molecular-weight gelator (LMWG), a small molecule able to self-assemble and form supramolecular networks. The impact of low-molecular-weight gelators on the environment is reduced as they are highly biodegradable. Thus, the behavior of solutions containing Boc-L-Dopa(Bn)₂-OH, an LMWG, together with ten different anionic surfactants, was studied to understand if the LMWG may act as a rheological modifier by increasing the viscosity of the formulation or forming gels with these ingredients. An amphoteric surfactant, cocamidopropyl betaine (CAPB), often used to increase cleansing gentleness, was also added to the solutions to better mimic a cosmetic formulation. In most cases, the addition of the gelator at only a 1% w/v concentration induces the gelification or an increase in the viscosity of the solutions, thus showing that this molecule is also able to self-assemble in complex mixtures. Full article

This study addresses the environmental challenge of surfactant removal from wastewater, focusing on the increased surfactant use during the COVID-19 pandemic. Polymeric waste, specifically polyurethane (PU) and polyamide (PA), was repurposed for surfactant adsorption to mitigate these environmental impacts. Methods included preparing surfactant solutions of sodium linear alkylbenzene sulfonate (LAS) and dodecyl pyridinium chloride (DPC) and the mechanical processing of polymeric residues. PU and PA were characterized by FTIR-ATR and by the pH at the point of zero charge, which yielded pH = 8.0 for both polymers. The adsorption efficiency was optimized using a central composite face-centered design, varying pH, temperature, and time. The results indicated that PU and PA effectively adsorbed anionic and cationic surfactants, with specific conditions enhancing performance. From the optimized experimental conditions, four assays were carried out to evaluate the adsorption isotherms and kinetics. Among the fitted models, the SIPS model was the most representative, indicating a heterogeneous surface. Regarding LAS, the maximum adsorption capacity values were ~90 and 15 mg g⁻¹, respectively, for PU and PA. Considering the DPC surfactant, lower values were obtained (~36 mg g⁻¹ for PU and 16 mg g⁻¹ for PA). The results are satisfactory because the adsorbents used in this study were second-generation waste and were used without treatment or complex modifications. The study concluded that using polymeric waste for surfactant removal offers a sustainable solution, transforming waste management while addressing environmental contamination. This approach provides a method for reducing surfactant levels in wastewater and adds value to otherwise discarded materials, promoting a circular economy and sustainable waste reuse. Full article

Reservoir heterogeneity significantly affects reservoir flooding efficiency and the formation and distribution of residual oil. As an effective method for enhancing recovery, polymer–surfactant (SP) flooding has a complex mechanism of action in inhomogeneous reservoirs. In this study, the effect of reservoir heterogeneity on the SP drive was investigated by designing core parallel flooding experiments combined with NMR and CT scanning techniques, taking conglomerate reservoirs in a Xinjiang oilfield as the research object. The experimental results show that inter-layer heterogeneity significantly affects water flooding efficiency and SP driving in low-permeability cores—the larger the permeability difference is, the more obvious the effect is—while it has almost no effect on high-permeability cores. The limited recovery enhancement in low-permeability cores is mainly due to the small percentage of contributing pores. When the permeability difference undergoes an extreme increase, the polymer molecular weight is biased towards higher values; when the polymer molecular weight is fixed, the recovery enhancement of low-permeability cores may be comparable to that of high-permeability cores when the permeability difference is extremely small. However, the recovery enhancement of the former is smaller than that of the latter when the permeability difference is extremely large. Due to intra-layer heterogeneity, there is a serious fingering phenomenon in the flooding stage, while in the SP flooding stage, recovery enhancement is most significant in the 5–20 μm pore range. This study provides an important geological basis for the rational development of a chemical flooding programme. Full article

New requirements for the operational reliability of roads make the utilization of polymer-modified bitumen (PMB) more common in road construction. The application of polymer-modified bitumen based on traditional technology for the production of asphalt mixtures is associated with technological and economic difficulties and does not provide proper adhesion to the mixture’s mineral components. In addition, the method of producing a binder over a long time at high process temperatures leads to increased aging, which significantly reduces the service life of the material in the pavement. This paper presents the results of studies on the effect of polymer–bitumen concentrate (PBC) consisting of styrene–butadiene–styrene, plasticizer, and surfactant on the bitumen characteristics. It has been established that the use of PBC in the bitumen binder leads to an increase in the temperature range of plasticity, softening temperature, elasticity, and cohesive strength with a decrease in the viscosity of the modified bitumen. With a complex modifier rational content of 8% by weight of bitumen, the temperature range of plasticity is 79 °C, and elasticity is 82%, which exceeds the parameters of the factory PMB-60 based on SBS polymer. Tests of binders using the Superpave method allow classifying the modified binder to the PG 64-28, which shows an increase in the temperature range of viscoelastic properties by 6 °C compared with the binder produced by traditional methods. Thus, the expediency of using a complex additive containing a polymer and surface-active substances (surfactants) that can be distributed in bitumen without the use of a colloid agitator and plasticizer has been proven to improve the quality of an organic binder. Full article

In advanced powder metallurgy technologies such as metal injection molding (MIM) and material extrusion technology (MEX), the intricate synergy between binder components and metallic powders within feedstocks is predominant, dictating the technological boundaries of metal’s complexity, size, and thickness. This work suggests unique binder constituents (polymers, surfactants and melamine), aiming to boost the debinding efficacy and solid loading while ensuring processability. The interactions and role of melamine by thermal and rheological studies are detailed, spotlighting how, unlike traditional binder systems, the pioneering feedstock introduces beneficial modifications to storage modulus (G′) and loss tangent (tan δ), alongside a lubricating effect on metallic mixtures. This study highlights the potential of melamine to facilitate a more efficient debinding process, with superior formaldehyde management and environmental control. Through this material-centric lens, we offer new pathways to navigate the complexities of MIM and MEX, advancing towards technological enhancement and environmental protection. Full article