Rational design of multifunctional membrane material with underwater superoleophobicity for dye contaminated emulsion separation

Tailored fabrication of biodegradable polymer/ Fe3O4 doped WO3 nano star-based porous membrane with enhanced photo fentonic activity for environmental remediation

The accelerated development of special-wetting polymeric materials with hierarchical pores for membrane applications is crucial to effectively separating water-soluble and insoluble pollutants, such as oily wastewater, emulsion, organic pollutants, and heavy metals. This pressing environmental and socioeconomic issue requires the implementation of effective remediation technologies. In this study, we successfully fabricated an environmentally friendly membrane with a flexible property by combining biopolymers and magnetic nanohybrids of iron oxide (Fe3O4)-doped tungsten oxide (WO3) through a thermal-induced phase separation process (TIPS). The resulting membrane exhibited a well-defined 3D-interconnected porous network structure when blending poly (ε-caprolactone)/poly (D,L-lactide) (PCL)/(PDLLA) in an 8:2 volume ratio. The Fe3O4@WO3 nanohybrids were synthesized using a hydrothermal process, resulting in a star-shaped morphology from the sea urchin-like WO3 clusters, which showed great potential to efficiently separate water/oil contamination and facilitate visible-light-driven photocatalytic degradation of organic dyes (MB, Rh B, BY, and CR) and photoreduction of hexavalent chromium (Cr (VI)). The obtained PCL/PDLLA/Fe3O4@WO3 nanocomposite membrane demonstrated hydrophobic properties, showing a water contact angle of 95 ± 2° and an excellent oil adsorption capacity of ∼4-4.5 g/g without fouling. The interconnected porous structure of the composite membrane enabled the efficient separation of emulsions (≥99.4 %) and achieved a high permeation flux of up to 1524 L m-2 h-1 under gravity separation. Overall, we obtained a novel high-performance composite material with specialized wetting properties, offering significant potential for effectively removing insoluble and soluble organic contaminants from wastewater.

Carrageenan derived polyelectrolyte complexes material: An effective bifunctional for electrochemical sensing of sulfamethazine and antibacterial activity

Biopolymer-derived polyelectrolyte complexes (PECs) are a class of materials that have emerged as promising candidates for developing advanced electrochemical sensors due to their tunable properties, biocompatibility, cost-effective production, and high surface area. PECs are formed by combining positively and negatively charged polymers, resulting in a network with intriguing properties that can be tailored for specific sensing applications. The resultant PECs-based nanocomposites were used to modify the glassy carbon electrode (GCE) to detect the sulfamethazine (SFZ) antibiotic drug. In addition, electrochemical studies using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) are used to evaluate the SFZ detection ability. Similarly, various microscopic and spectroscopic studies investigated the nano composite's structural features and morphological behavior. The κ-CGN/P(Am-co-DMDAAc)-GO modified GCE demonstrated excellent detection ability of SFZ with the nano molar range and without interference with similar structural components. Furthermore, the newly fabricated electrode κ-CGN/P(Am-co-DMDAAc)-GO was derived from naturally available materials, water-soluble, low cost, biocompatible, exhibits good conductivity, and excellent catalytic properties. Finally, κ-CGN/P(Am-co-DMDAAc)-GO- modified GCE has versatile, practical applications for detecting SFZ in real-time samples and determining the efficacy of an antibacterial activity.

Effective separation of water-in-oil emulsions using an under-medium superlyophilic membrane with hierarchical pores

Separating water-in-oil emulsions is important in terms of environmental protection and resource recovery. To address the challenges posed by the water-oil interface, superwetting materials have been designed to accomplish separation through filtration and adsorption. Superhydrophobic membranes prevent the permeation of water droplets owing to extreme repellence and their size-sieving abilities. However, their use in remediating water-contaminated oil is limited by high oil viscosities. Meanwhile, in-air superhydrophilic sorbents are rarely employed for the separation of water-in-oil emulsions due to the thermodynamic and kinetic limitations of water adsorption in oil. Herein, the integration of an under-medium superlyophilic membrane with the hierarchical porous structure of wood is presented for filtration-driven selective adsorption of water from surfactant-stabilized (10 g/L) water-in-oil emulsions. Compared to filtration through a natural wood membrane or direct adsorption using an under-oil superhydrophilic wood membrane, the under-medium superlyophilic wood membrane demonstrated high separation efficiencies of > 99.95% even when applied to the regeneration of high-viscosity lubricating (6.3 mPa s) and edible (50.5 mPa s) oils, exhibiting viscosity-dependent fluxes and excellent stability. Moreover, the cost of purifying 200 mL of lubricating oil using the modified wood membrane was much lower than the oil's market price and required a low energy consumption of ca. 1.72 kWh. ENVIRONMENTAL IMPLICATION: The ever-growing use of petroleum and industrial/domestic oil products has led to excessive (estimated at a million tons per year) output of waste oils. Because direct discharge of waste oils into the environment causes serious pollution problems, separating water-in-oil emulsions is important in terms of environmental protection and resource recovery. Here filtration-driven water adsorption has been demonstrated to be a feasible method for the remediation of water-contaminated waste oils, even those that are highly viscous.

Hydrophobic organogel sorbent and its coated porous substrates for efficient oil/water emulsion separation and effective spilled oil remediation

Frequent offshore oil leakage accidents and large quantities of oily-wastewater produced in industry and daily life bring huge challenges to global water purification. The adaptability and stability of organogels as adsorbent materials have shown wide application prospects in the field of oil-water separation. Herein, the organogels displayed stable hydrophobic/lipophilic properties with high absorption ability (1200 wt./wt%), efficient sorption of multiple emulsions (>99.0%), and good reusability. More importantly, the organogels were successfully assembled with 2D/3D substrates to achieve excellent sorption capacity (102.5 g/g) and recycling performance (50 cycles). The gel-carbon black assembled on MS (GCB-MS) sorbent with excellent photothermal conversion performance, and can rapidly heat the surface to 70.4 °C under 1.0 sunlight radiation (1.0 kW/m2) and achieved an ultra-high sorption capacity of about 103 g/g for viscous crude oil. Meanwhile, the GCB-MS was combined with a pump to build continuous oil spill cleaning equipment to achieve a super-fast cleanup rate of 6.83 g/min. The developed hydrophobic organogels had been expanded unprecedentedly to realize the comprehensive treatment of oily-wastewater in complex environments, including layered oils, emulsions, and viscous crude oil spill, which provided an effective path for the comprehensive treatment of oily wastewater in complex environments.

Constructing a highly tough, durable, and renewable flexible filter by epitaxial growth of a glass fiber fabric for high flux and superefficient oil-water separation

The separation and purification of complex and stable stubborn oily sewage is extremely challenging. To respond to this challenge, we developed a powerful flexible filter with ultrahigh strength, durability, flux, separation efficiency, and a multiobjective separation function based on a universal epitaxial growth process of glass fiber fabric (Gf). The underwater oil contact angle (UOCA) of the silicate@Gf (MgSi@Gf) filter is 156.3°, so it can achieve both an ultrahigh permeation flux (5632.7 L·m^-2·h^-1) and oil-water separation efficiency (99.5%) under gravity (≈ 1 kPa) in purifying surfactant-stabilized emulsions, actual industrial oily sewage and mechanical cold rolling emulsions. The filter with a high tensile strength (66.5 MPa) and oil invasion pressure (4626 Pa) can withstand the impact of much sewage or intense water flow. The filter can tolerate extreme conditions and can maintain high separation performance in acid or alkaline (pH 1-13), high or low temperature (100 °C, 200 °C, -18 °C) conditions or natural salty waters such as seawater. The filter can remove methylene blue (MB) dye (99.8%) by filtration, and can be repeatedly and easily reconstructed (renewable advantage). The filter shows great potential for efficiently eliminating the hazards of contaminants in actual oily sewage and thus protect human health.

Biomimetic cellulose-nanocrystalline-based composite membrane with high flux for efficient purification of oil-in-water emulsions

The massive discharge of oily wastewater and oil spills are causing serious pollution to water resources. It is urgent to require clean and efficient method of purifying oily emulsions. Although the separation membranes with selective wettability have been widely used in the efficient purification of oil/water emulsions. It is still very challenging to develop functional films that are environmentally friendly, fouling resistant, inexpensive, easy to prepare, easy to scale, and highly efficient. Cellulose nanocrystalline-based composite membranes (CCM) were prepared by surface-initiated atom transfer radical polymerization (SATRP) and vacuum self-assembly. The prepared CCM is superhydrophilic and superoleophobic underwater due to the hydrophilic nature of the modified cellulose-nanocrystalline and the micro-nano surface structure. The CCM shows high separation efficiency (> 99.9 %), high flux (16,692 L^-1·m^-2·h^-1·bar^-1) for surfactant-stabilized oil-in-water emulsions, good cycle stability and anti-fouling performance. This biomass-derived membrane is green, cheap, easy to manufacture, scalable, super-wettability, and durability, it promises to be an alternative to separation membranes in today's market.

Lignin microparticles-reinforced cellulose filter paper for simultaneous removal of emulsified oils and dyes

The presence of multiple pollutants in wastewater, often with complex interactions, poses a significant challenge for conventional membranes to effectively remove multiple pollutants simultaneously. Herein, a lignin microparticles-reinforced cellulose filter paper (FP@AL-LS-DA) was fabricated via an aldol condensation between lignin and cellulose filter paper and cross-linking with dopamine hydrochloride (DA), which showed desired rejection of oil-in-water emulsions and dyes. Characterizations revealed that the addition of lignin and DA effectively narrowed the pore size (from 4.45 μm to 2.01 μm) and enhanced the rigidity and stability of the cellulose filter paper, thus making it not easily damaged in the water environment and showing excellent tolerance to strong acid and high-salt environments. The oil-in-water emulsions removal efficiency was higher than 99 % even after ten times usage, and the oil flux was kept stable at 52.54 L·m^-2·h^-1, indicating that FP@AL-LS-DA had outstanding reusability and stability. Remarkably, FP@AL-LS-DA showed excellent removal efficiency (>99 %) for complex pollutants containing dyes and oil-in-water emulsions. In this work, we demonstrate a lignin microparticles-reinforced cellulose filter paper that is simple to prepare and can efficiently separate oil-in-water emulsions and remove dyes.

Zero-Material Cost Production of Soil-Coated Fabrics with Underwater Superoleophobicity for Antifouling Oil/Water Separation

Soil-coated fabrics were fabricated by scrape-coating of soil slurry onto cotton fabrics. The raw materials, soil, and cotton fabrics were, respectively, obtained from farmland and waste bed sheets, making the method a zero-material cost way to produce superwetting membrane. The superhydrophilic/underwater superoleophobic soil-coated fabrics exhibit high efficiency (>99%), ultra-high flux (~45,000 L m^-2 h^-1), and excellent antifouling behavior for separating water from various oils driven by gravity. The simple fabrication and superior performance suggest that the soil-coated fabric could be a promising candidate as a filtration membrane for practical applications in industrial oily wastewater and oil spill treatments.

A multifunctional heterogeneous superwettable coating for water collection, oil/water separation and oil absorption

Herein, inspired by desert beetles, we fabricated a multifunctional heterogeneous superwettable coating (MHSC) for water collection and oily wastewater cleanup. The selective modifications of 1-octadecanethiol (ODT) treated CoO and P25 TiO₂ nanoparticles (NPs) were prepared, so hydrophobic CoO NPs and superhydrophilic P25 NPs were combined on the MHSC, showing the water contact angle (WCA) of 156.5° and rolling-off angle (RA) of 6.4°. With the aid of waterborne polyurethane (WPU), five kinds of substrates (i.e., glass slide, dish, wood, fabric, sponge) spray-coated by MHSC displayed high-efficiency water collection rates (WCRs) of 18.1 ± 0.7 mg min^-1 cm^-2. Moreover, MHSC coated fabric manifested robust oil/water separations with separation efficiencies (SEs) > 99.7 % and fluxes ranged from 9.7 to 11.0 L m^-2 s^-1. Efficient oil sorption from oily water was obtained by MHSC coated sponge with oil absorption capacities (OACs) of 6.5-29.5 g g^-1. Further, even dealt with the treatments of mechanical destructions, extreme temperature and UV illumination, the coated materials remained stable performances.

Protonated cross-linkable nanocomposite coatings with outstanding underwater superoleophobic and anti-viscous oil-fouling properties for crude oil/water separation

Superhydrophilic/underwater superoleophobic coatings that effectively prevent viscous oil contamination have been of considerable interest for the great potential in oil spill remediation and oilfield wastewater treatment. In the present work, a protonated cross-linkable nanocomposite coating with robust underwater superoleophobicity and intensified hydration capability is proposed through the synthesis of active polymeric nanocomplex (PNC), cross-linking reaction between PNC and hydrophilic chitosan (CS), and final protonation to further improve water affinity. Benefiting from the hierarchical structure and strong hydration capability induced by electrostatic interactions and hydrogen bondings, the nanocomposite coating coated textile exhibits excellent superhydrophilicity (within 0.28 s with water contact angle reaching 0°), underwater superoleophobicity (underwater crude oil contact angle at 160°), and ultralow oil adhesion even to highly viscous silicone oil. Moreover, the nanocomposite coating presents a robust chemical resistance, mechanical tolerance, and storage stability. Simultaneously, the nanocomposite coating adapts well to various porous substrates (e.g., stainless steel mesh and Ni sponge) with great anti-oil-fouling and self-cleaning performances. Importantly, the coating coated textile is successfully applied in crude oil/water separation with excellent efficiency and repeatability. The findings conceivably stand out as a new methodology to fabricate superhydrophilic/underwater superoleophobic materials with outstanding anti-viscous oil-fouling property for practically treating oily wastewater.