Membranes For Oil-water Separation Research Articles

Enhanced superhydrophobicity and durability of modified cotton cloth for efficient oil-water separation

The development of simple, low-cost, and efficient oil/water separation membranes is still a major challenge in the field of wastewater treatment. In this study, an oil/water separation membrane is prepared based on low-cost cotton cloth (CF) through a simple solution soaking treatment without using organic solvents. Pristine CF is treated first with concentrated alkali and then chemically grafted by sodium methyl silicate (SMS) onto the surface to obtain oil/water separation membrane (SMS-O-CF). This process not only increases the roughness of the CF but also endows the surface with superhydrophobicity due to the outward extension of methyl groups, resulting in a water contact angle (WCA) of 155° and good self-cleaning ability. The SMS-O-CF achieves efficient separation for various oil/water mixtures and maintains a separation efficiency up to 96 % and a flux of over 11,557 L·m−2·h−1 after 220 cycles under neutral conditions. Moreover, the modified CF also exhibits excellent acid/alkaline resistance and wear resistance. Regardless of the 12 h acid/base immersion, 100 min water wash, or 200-cycle mechanical abrasion, SMS-O-CF still exhibits high flux and separation efficiency. Raw material cost for preparing SMS-O-CF is as low as 1.0 dollar/m2. The preparation of SMS-O-CF has provided a green manufacturing method for developing low-cost and efficient oil–water separation membranes.

Polyvinyl alcohol gel/micro-arc oxidation 3D-printed porous structural aluminium for oil-water separation

Traditional oil-water separation membranes still face challenges in designing membrane structures and pore sizes. In this study, we successfully prepared a PVA@MAO 3D-Al material with an internal porous structure using 3D printing technology and micro-arc oxidation (MAO). Compared to the base 3D-Al material, the fabricated PVA@MAO 3D-Al exhibits excellent wear resistance, with an average friction coefficient reduced by 66% in dry friction and 22% in water lubrication. In electrochemical experiments, corrosion current density decreased by an order of magnitude, indicating higher stability of PVA@MAO 3D-Al in corrosive environments. In oil-water separation experiments, PVA@MAO 3D-Al achieved separation efficiencies exceeding 97% for mixtures of white oil, kerosene, liquid paraffin, and cyclohexane with water. Moreover, even after undergoing 600 cycles of reciprocating friction and exposure to various environmental solutions, the separation efficiency of PVA@MAO 3D-Al for white oil/water mixtures remained above 96%, demonstrating outstanding physical and chemical stability. This suggests that PVA@MAO 3D-Al is suitable for use in extremely harsh environments. This study introduces a simple and efficient approach to manufacturing oil-water separation membranes using 3D printing technology, coupled with MAO technology to enhance the base material's performance. The combination of these techniques opens up new avenues in the field of oil-water separation.

Nanofiber membranes fabricated by coaxial electrospinning with porous channel structure for high-efficiency oil-water separation

The electrospinning nanofiber membranes modified by nanoparticles can effectively improve anti-oil adhesion and separation performance. However, the low stability of nanoparticles on the fiber membrane surface substantially limits the operational lifespan of the membrane. Herein, poly(vinylidene fluoride) (PVDF) nanofiber membranes with multi-scale microporous channel structures are prepared using coaxial electrospinning and a sacrificial template strategy. Subsequently, iron phytate nanoparticles are grown in situ on the fibers to fill the porous structures by utilizing the hollow and porous nanofibers as a framework. The interlocking structure between the nanoparticles and the porous fibers significantly enhances the stability and durability between nanoparticles and the fiber membrane. Even after being subjected to ultrasonic treatment for 7 h, there is no discernible shedding of nanoparticles from the fiber membrane. The prepared nanofiber membrane demonstrates exceptional superhydrophilicity and underwater superoleophobicity, exhibiting remarkable self-cleaning capability and resistance to crude oil contamination. Additionally, the membrane efficiently separates various oil-in-water emulsions, achieving a high separation efficiency of over 99%. Moreover, the membrane also demonstrates excellent adsorption capability towards cationic dyes. Therefore, this interlocking structure composed of nanoparticles and nanofibers presents new ideas and insights for the preparation of high-performance and durable oil–water separation membranes.

CMPs membranes prepared using electrostatic spinning as a template for efficient oil-water separation

The development of efficient oil-water separation membrane technology is of great important for elimination of the serious environmental pollution issues caused by the frequent oils-spill or organics leakages in modern industry. Herein, we report the creation of conjugated microporous polymer membranes (CMPs@PMMA/PVDF), which were synthesized by a Sonogashira-Hagihara cross-coupling reaction using 1,3,5-triethynylbenzene and 2,6-dibromophenol as monomers in the presence of a template membrane prepared using poly (vinylidene fluoride) and poly (methyl methacrylate) as mixed solution via electrostatic spinning method, for efficient oil-water separation. The as-synthesized CMPs membrane shows excellent hydrophobicity with a water contact angle (WCA) of 150.8º and high permeate flux ( 865.8 L m−2 h−1). The tensile strength of CMPs@PMMA/PVDF was measured to be 3.13 MPa with an elongation of 10.32%. The TGA curve of CMPs@PMMA/PVDF membranes shows high thermal stability with mass loss decreasing by only 15.89% when the temperature rises to 414.3 ºC. Driven by gravity alone, the resulting membrane shows outstanding oil-water selectivity for oil-water separation (with a separation efficiency of up to 99.9%), its separation efficiency almost remains unchanged after 10 cycles with cyclohexane as the oil phase, and the separation efficiency still maintains up to 98.9% even after 50 cycles. In addition, the 3D-CMPs membrane also performs well in the separation of oil-water mixtures, and the separation efficiencies of various water-in-oil mixtures are maintained above 98.6% after ten cycles, showing that the CMPs membrane materials may have great potential for a broad application in the field of separation of oil-water mixtures.

Double-drying 3D lamellar-structured aerogel membrane for efficient oil-water separation and long-lasting antibacterial activity

Conventional oil-water separation membranes are difficult to establish a trade-off between membrane flux and separation efficiency, and often result in serious secondary contamination due to their fouling issue and non-degradability. Herein, a double drying strategy was introduced through a combination of oven-drying and freeze-drying to create a super-wettable and eco-friendly oil-water separating aerogel membrane (TMAdf). Due to the regular nacre-like structures developed in the drying process and the pores formed by freeze-drying, TMAdf aerogel membrane finally develops regularly arranged porous structures. In addition, the aerogel membrane possesses excellent underwater superoleophobicity with a contact angle above 168° and antifouling properties. TMAdf aerogel membrane can effectively separate different kinds of oil-water mixtures and highly emulsified oil-water dispersions under gravity alone, achieving exceptionally high flux (3693 L·m−2·h−1) and efficiency (99 %), while being recyclable. The aerogel membrane also displays stability and universality, making it effective in removing oil droplets from water in corrosive environments such as acids, salts and alkalis. Furthermore, TMAdf aerogel membrane shows long-lasting antibacterial properties (photothermal sterilization up to 6 times) and biodegradability (completely degraded after 50 days in soil). This study presents new ideas and insights for the fabrication of multifunctional membranes for oil-water separation.

Anti-fouling underwater superoleophobic membranes based on hierarchical double networks for high efficiency oil–water separation

Oil fouling is a key problem of superwettable oil–water separation membranes because the membranes are inevitably susceptible to varying degrees of oil contamination during the ongoing separation processes, which usually results in a severe impact on separation performance. Consequently, it is a great challenge to construct oil-removal membranes with superior resistance to oil contamination. Herein, we fabricated hierarchical double networks (HDT)-modified porous glass membrane with superhydrophilicity/underwater superoleophobicity. Firstly, a layer of silicone nanofilament (SNF) network bearing tremendous C = C double bonds were fabricated on a porous glass membrane surface by one-step chemical vapor deposition (CVD) using vinyltrichlorosilane (VTCS) as a precursor. Subsequently, the second network layer was constructed by copolymerization of the C = C double bonds on the SNF network and those in sulfobetaine-derived monomer (sulfobetaine methacrylate, SBMA), using N,N′-methylenebisacrylamide (MBA) as the cross-linkering agent. It was observed that the obtained HDT-modified glass membranes displayed excellent superhydrophilicity/underwater superoleophobicity accompanied with superior self-cleaning performance and oil-resistance properties. As a result, the HDT-modified membranes showed high separation flux and high efficiency for both oil/water mixtures (7500 L m−2h−1, above 99.98%) and surfactant-stabilized oil-in-water emulsions (1100 L m−2h−1, above 99.96%) with excellent cyclability. The outstanding advantages with characteristics of excellent oil resistance and superior separation performance enable the HDT-modified glass membrane promising applications in a wide range of industries related to oil–water separations.

Biomimetic dendritic‐networks‐inspired oil-water separation fiber membrane based on TBAC and CNC/PVDF porous nanostructures

Inspired by the multi-level structure of trees in nature, using cellulose nanocrystals/polyvinylidene fluoride (CNC/PVDF) fibers as the support layer and CNC/PVDF/organic branched salt (TBAC) fibers as the filtering layer, to construct oil–water separation membrane with tree-like structure. The membrane's surface (nano spherical) and internal (interconnected pores) structures were regulated by phase separation of CNC induced. The high conductivity of TBAC was utilized to construct branched fibers (d = 53.3 nm) on the backbone fibers (d = 1.2 μm). The impact of TBAC on the microstructure, wetting behavior, and oil–water separation performance of membranes was investigated. Note, TBAC concentration was 0.02 mol/L, the membrane exhibits a highly porous dendritic network structure (with porosity of 85 % and pore size of 6.1 nm), and outstanding wetting properties (water contact angle underoil ˃ 150°). This distinctive structure endows membranes with a high oil adsorption capacity (64.1 g/g of engine oil), oil flux (22873 L/m−2h−1 of toluene). Following ten testing cycles, the toluene adsorption capacity remains at 83.1 % of the initial adsorption, while the separation flux of emulsion (5645 L/m−2h−1) remains nearly constant. Overall, successfully fabricating CNC/PVDF/T-0.02 fibers with a tree-like structure provides a novel approach to designing and developing efficient membrane separation materials.

A novel poly (lactic-acid) and poly (butylene adipate-co-terephthalate) blend membrane modified with hesperidin for oily water emulsions separation

The oily wastewater produced by a variety of industrial operations presents a serious threat to both humans and the environment. Separation efficiency, good mechanical stability, high flux, and recyclability are critical parameters for a suitable oil-water separation membrane. In this study, a novel blend membrane of (poly (lactic acid)/poly (butylene adipate-co-terephthalate)) with hesperidin-NPs was synthesized by using the phase inversion technique to effectively separate oily-water emulsions. Herein, hesperidin (HSP) was harnessed for the first time as a green agent to optimize its content in the polymeric matrix. (FTIR) Fourier transform infrared spectroscopy, (FESEM) Field emission scanning electron microscopy, (CA) contact angle, mechanical tester, pore size and porosity were utilized to comprehensively characterize the manufactured (PLA/PBAT/HSP) membranes. The current work presents the proposed interaction mechanism between the contents of PLA/PBAT/HSP and the interaction mechanism of PLA/PBAT/HSP membrane with H2O molecules. The synthesized (PLA/PBAT/HSP) membrane manifested high wettability and has a 49° water contact angle and oleophobicity under a water contact angle of 146±2° for diesel oil. The PLA/PBAT membrane exhibited a homogeneous and symmetric spongy-like structure from top to bottom across its entire cross-section with very tiny active layer observed at the top surface of the membrane in FESEM images. Meanwhile, incorporating of 0.0125 wt% HSP into the casting solution has resulted in a significant change in the structural morphology. Furthermore, upon adding the HSP to the polymeric matrix, distinct changes in the structure were formed, which resulted in enhancing the mechanical features (tensile strength) of the membranes. Modified membrane with 0.025 wt% HSP displayed an optimal flux for pure water (220.5 L/m2.h1) and the modified membranes maintained a high rejection (more than 99%) against oil-water emulsions. Outcomes demonstrated that the improved permeation and separation characteristics of the (PLA/PBAT/HSP) membranes could present a potential option to treat applications that use oily wastewater.

TiO2 modified basalt fiber cloth with superhydrophilicity and underwater superoleophobicity for oil-water separation

Titanium mesh, stainless steel mesh and other substrate materials for oil-water separation membranes have excellent acid and alkali resistance. However, the preparation process pollutes the environment and is costly. Therefore there is an urgent need for an economical and eco-friendly new material to replace them. Here, this research found that eco-friendly basalt fibers can replace them. In this work, superhydrophilic/underwater superoleophobic TiO2/basalt fiber cloths were prepared by solvothermal method. It has a contact angle of 0° for water in air and maximum 161° for n-hexadecane underwater. The oil-water separation efficiency was up to 99.75%, which indicated its efficient oil-water separation capability. The underwater n-hexadecane contact angle was 154° after immersing it in 6 mol of HCl and NaOH for 2 h respectively. This indicates that it has excellent acid and alkali resistance. And with titanium mesh, stainless steel mesh separation membrane acid and alkali resistance is not much different. However, the price is only one percent of titanium mesh. In addition, the softness of basalt fiber can be folded to enhance the pressure-bearing capacity. Therefore, this work provides a green, acid and alkali resistant, inexpensive new material for oil-water separation membranes, which has great potential in the field of oil-water separation.

Bio-inspired superhydrophobic fiber membrane for oil-water separation and non-destructive transport of liquids in corrosive environments

Conventional polymer separation membranes or coatings suffer from poor separation performance and serious failure in highly corrosive environments, due to their low chemical and mechanical stability. Herein, a simple electrospraying and electrospinning strategy was used to prepare flexible superhydrophobic carbon fiber membranes (FSCFM). The wettability of FSCFM was improved by forming a lotus leaf-like hierarchical rough structure on its surface. The FSCFM exhibited an excellent permeation flux of immiscible oil-water mixtures (up to 15,800 L m−2 h−1) and water-in-oil emulsions (over 5500 L m−2 h−1), while the separation efficiencies were always kept at more than 99 % after 25 consecutive separations. Even in corrosive environments, its separation performance did not show any degradation. Notably, except for recovering floating oil under external driving forces with excellent cyclic stabilities, FSCFM was also able to transport various corrosive solutions with high efficiencies (99.9 %). After multiple mechanical damages and bending cycles, the FSCFM remained superhydrophobic. It could also maintain its repellency in strong acids/bases, high salt solutions and even under high-temperature environments (94.5 °C). These superior properties make it a strong candidate for oil-water mixture/emulsion separation and non-destructive transport of highly corrosive fluids.

Hollow hydroxyapatite constructs dual channel structured separation membranes for ultra-fast oil-water separation

The discharge of industrial wastewater and frequent oil spills have caused serious harm to the environment, and in order to achieve sustainable development of the environment, membrane separation technology stands out among the many methods for treating oil and water. In this work, hollow hydroxyapatite was grown in situ on Mg Al LDH to construct an oil–water separation membrane with dual channels, and water molecules could not only pass through the porous structure of HAP, but also pass through the gap between HAP and LDH, and the opening of the dual channels greatly improved the oil–water separation speed, and the flux of the petroleum ether emulsion was up to 5208.93 ± 117.62 L/(m2·h·bar) with the separation efficiency up to 99.4 %, and still has 98.8 % rejection rate after 10 cycles, it can efficiently separate many kinds of heavy metal ions and dyes. In order to evaluate the practical performance of the membrane, we found a high rejection rate of 87 % after several cycles of the shale gas fracking wastewater, and this work provides a new idea for the development of oil–water separation membranes with practical applications.

An eco-friendly and facile method for oil-water separation using the bio-Zn oxide-based superhydrophobic membrane.

This manuscript presents a novel approach for developing an environmentally friendly and effective oil-water separation membrane. Achieving a superhydrophobic (SH) coating on textile fabric (TF) involved a two-step process. Initially, the surface roughness was enhanced by applying bio-zinc oxide (ZnO) nanoparticles obtained from Thymbra spicata L. Subsequently, the roughened surface was modified with stearic acid, a material known for its low surface energy. The bio-ZnO nanoparticles exhibit a circular morphology with an average size of 21 nm. The coating demonstrated remarkable mechanical stability, maintaining SH properties even after an abrasion length of 300 mm. Chemical stability studies revealed that the prepared membrane retained SH properties within a pH range of 5-11, which ensures robust performance. Absorption capacity measurements showcased different capacities for n-hexane (Hex), corn oil (C.O), and silicone oil (S.O), with consistent performance over 10 absorption-desorption cycles. High oil-water separation efficiencies were achieved for hexane, C.O, and S.O, emphasizing the coating's versatility. Flux rate measurements demonstrated that oil passed through the membrane efficiently, with the highest flux observed for Hex. The prepared SH membrane has superior mechanical and chemical stability and high separation efficiencies, which positions it as a promising candidate for diverse industrial applications.

Benzoxazine/ thermoplastic polyurethane nanofibrous membranes with superior mechanical properties for efficient oil-water separation

The integration of membrane separation and electrospinning technologies has significantly advanced oil-water separation processes. However, enhancing the mechanical robustness, corrosion resistance, and durability of oil-water separation membranes remains a challenge. In this paper, we utilized the electrospinning technique to fabricate a micro-nanostructured nanofibrous (NFs) membrane by blending benzophenone monomer (BPAF-an) with thermoplastic polyurethane elastomer (TPU). By optimizing the solid content, the mass ratio of compounds to polymers, and the solvent composition in the spinning precursor solution, we determined the optimal electrospinning parameters for fabricating the TPU/BPAF-an NFs membrane. The incorporation of BPAF-an, known for its low surface energy, significantly enhanced the hydrophobicity of the nanofiber membrane. The TPU/BPAF-an NFs membrane demonstrated excellent mechanical properties, exhibiting a tensile strength of 7.38 MPa and an elongation at break of 292 %. The membrane had good hydrophobicity and its water contact Angle is up to 145.2°. It also displayed exceptional separation efficiency, exceeding 99 % for oil-in-water emulsions and various oil-water mixtures. Even in harsh environments such as strong acids, alkalis and salts, they have prominent hydrophobicity, lipophilicity and chemical stability. In addition, the membrane maintained a high flux rate of 1995.37 L m−2 h−1 and a separation efficiency of 96 % even after 100 cycles of oil-water separation. Consequently, the TPU/BPAF-an NFs membrane, with its superior mechanical properties and cycle stability, holds substantial promise for application in oil-water separation.

A superhydrophilic and robust fabric, featuring self-assembled layers of chitosan and carbon nanotubes, facilitates high-throughput oil–water separation

Petroleum pollution and industrial emissions of organic pollutants have become significant issues affecting both ecological and human living environments. High-performance oil–water separation membranes, due to their advantages such as low cost, environmental friendliness, and ease of operation, hold vast application prospects. Therefore, the development of efficient oil–water separation membranes is crucial. We propose a clever approach involving the synergistic self-assembly of chitosan (CS) and hydroxylated multi-walled carbon nanotubes (MWCNTs) on cotton fabric to construct a rough structure. Combined with hydrophilic modification using polyvinyl alcohol (PVA), not only does this enhance wettability, but it also addresses challenges related to mechanical strength and dispersibility of cotton fabric. The resulting CMF-PVA fabric performs well under challenging conditions, exhibiting excellent separation efficiency and permeance. Particularly noteworthy is that CMF-PVA achieves separation efficiencies exceeding 99.33 % for various organic substances, with a water flux reaching 35,476.52 L m−2 h−1 and a surfactant-stabilized emulsion permeance of 1199.0 L m−2 h−1·bar−1. Furthermore, CMF-PVA demonstrates outstanding mechanical durability under harsh conditions and excellent acid-base resistance. This method harnesses the inherent properties of CS and MWCNT self-assembly while enhancing the material's applicability on cotton fabric through hydrophilic modification. CMF-PVA fabric is poised to enhance selectivity, efficiency, anti-pollution properties, and accessibility in oil–water separation technology.

MXene sheets surface constructed a strong hydrogel coating for sustainable oily wastewater separation

Membrane separation technology can effectively address the issues of high energy consumption and low efficiency encountered in traditional separation processes. However, oil fouling hinders the widespread adoption of membrane technology in the field of oil-water separation. Therefore, preventing membrane fouling is crucial for overcoming this bottleneck. Titanium carbide (Ti3C2Tx, MXene), a recent addition to the two-dimensional material family, has garnered significant interest in the domain of water treatment owing to its controllable surface groups, hydrophilic nature, antimicrobial properties, and high electrical conductivity. Hence, we proposed a strategy to construct hydrogel coatings on carboxylated MXene surfaces. Moreover, the rigidity of the hydrogel framework was further improved by introducing CaCO3 nanoparticles. A stronger hydrogel layer ensured that the hydration layer is difficult to contaminate with oil and the fastness of the membrane material. Naturally, the as-prepared membrane showed excellent separation performance for a wide range of emulsions, maintaining high levels (3979.5 L m–2 h−1 bar−1 and 99.96 %) after 5 consecutive separation cycles of 200 min. Additionally, the membrane separated emulsions containing acids, salts, or alkali with a permeability of 2982.8 L m–2 h−1 bar−1 after 40 min; it also treated actual oily wastewater achieving a permeability of 238.9 L m–2 h−1 bar−1 and showed high removal efficiency (>99.9 %) for several heavy metals (Cu, Li, Pb, Se, and V), as well as antimicrobial (92.5 %) properties that enhance its potential for industrial applications. This study offers a new idea for designing anti-oil-fouling MXene oil-water separation membranes.

Long-lived nanoparticle-embedded superhydrophobic membranes with rapid photocatalytic properties and continuous oil–water separation

Superhydrophobic oil–water separation membranes have aroused widespread research interest as ideal candidates for treating oily wastewater. However, this type of membrane has difficulty simultaneously balancing the removal of organic matter in complex oily wastewater and achieving large-scale continuous oil–water separation. Herein, FeOOH/polydopamine/cotton (FPC) membranes with significant photocatalytic properties were prepared via the deposition of a complex formed by mineralizing polydopamine and Fe3+ on a cotton-based surface. Further modification with long-chain hexadecyltrimethoxysilane constructed multipurpose superhydrophobic hexadecyltrimethoxysilane/FeOOH/polydopamine/cotton (HFPC) membranes. The heterogeneous photo-Fenton system built from clipped FPC membranes rapidly degrades methyl blue pollutants with a 99.5 % degradation rate. Notably, HFPC membranes maintain exceptional superhydrophobicity even after enduring various severe damages, including 1000 sandpaper abrasions/hammer blows, 5 min running water impact, 12 h chemical immersion, 24 h UV aging, and 5 months of outdoor weathering. Additionally, HFPC membranes have separation efficiencies up to 99.5 % and continuous separation as long as 15 min, making them especially suitable for large-scale oil absorption. Long-lived nanoparticle-embedded membranes offer fast photocatalysis, long-lasting robustness, high separation efficiency and flux. Meanwhile, it has the advantages of large-scale continuous oil absorption, repeatability, low cost, and sustainability. This work merges rapid photocatalysis and efficient oil–water separation technologies, bringing a new breakthrough in expanding the multifunctional membrane field and opening a new door for the future development of related fields.

A facile fabrication of PU/rGO/MoS2 self-cleaning fibrous membrane for oil-water separation

Electrospun membranes have unique properties to treat water containing various pollutants such as oils, dyes, bacteria, heavy metal ions, etc. The present work comprises the facile fabrication of the functionalized polyurethane (PU) fibrous membrane by doping reduced graphene oxide (rGO) and molybdenum sulfide (MoS2). Complete optimization of the fabricated PU/rGO/MoS2 fibrous membrane was performed to evaluate its ability in oil sorption, dye adsorption, and heavy metal ion removal. The increment in hydrophobicity of PU with functionalization paved the way for oil sorption studies. The improved porous nature and pronounced decrease in average fiber diameter on adding the fillers make the PU membrane potentially viable for adsorption applications. The self-cleaning ability, oil sorption capacity, and UV resistance nature of the functionalized membranes are experimented. Excellent self-cleaning nature, durability and good adsorption of water in oil emulsion were observed. The PU/rGO/MoS2 fibrous membrane showed a high-water permeation flux (˷1800 L/m2/hr) and 20 times recyclability in a continuous separation process. Tuning the wettability by decreasing the polymer concentration and increasing the filler quantity resulted in an improved hydrophilic nature. Additionally, these membranes showed excellent methylene blue removal ability and metal ion adsorption which proved its ability to act as a multi-functional membrane.

Solar-driven pH-responsive oil–water separation membranes for effective oil–water emulsion separation

The membrane (PP–PPy–pHR) prepared in this paper automatically switches the wettability according to the change of pH to separate oil water emulsions. It has great potential for intelligent response in oil water separation.

The optimized microbial-induced calcium carbonate precipitation process to fabricate underwater superoleophobic mesh for efficient oil-water separation

Microbial-induced calcium carbonate precipitation (MICP) is an environmentally-friendly and easy operation technique for separating oil-water mixtures. However, the effect of environmental factors on the wettability and oil-water separation performance of MICP remains unclear. In this study, three primary factors including mineralization solution (MS) concentration, bacterial suspension (BS) concentration, and temperature were carefully investigated. Under these varying conditions, stainless steel meshes (SSM) were chosen as the substrates for the growth of CaCO3 precipitations. Experimental results demonstrate a strong dependence of the morphology and wettability of CaCO3 precipitations on these factors. Higher MS concentration and temperature contribute to enhanced hydrophilicity of CaCO3 coatings due to the increased surface roughness. The water flux of MICP-coated SSMs decreases with the increase of BS concentration, MS concentration, and temperature. The MICP-coated SSM obtained with MS concentration of 0.15 M, BS concentration of 0.1 × 108 cells/mL, and mineralization reaction at 25 ℃ for 24 hours demonstrated the optimal comprehensive performance, exhibiting underwater superoleophobicity with an underwater oil contact angle (UWOCA) exceeding 151°, an ultra-high oil intrusion pressure (> 3.0 kPa), ultrahigh flux (28,644 L m−2 h−1), and a preferable oil rejection rate (> 99.9%). Additionally, the as-prepared mesh exhibited superior anti-oil-fouling property and reusability, while concurrently demonstrating excellent chemical and thermal stability. This work contributes to advancing our knowledge of the influence of various environmental factors on the wetting characteristics of MICP and provides a feasible solution for the highly efficient and low-cost preparation of oil-water separation membranes based on the MICP process.

Fabrication and oil-water separation properties of cerium oxide coated zirconium oxide composite membranes

Traditional oil-water separation membranes have high preparation costs and easy environmental pollution during the manufacturing process, so the development of new oil-water separation membranes with low cost and high environmental value is an important topic. In this work, cerium oxide coated zirconium oxide (CeO2/ZrO2) composite membranes are fabricated on cotton fabric by a combination of physical and chemical methods, where CeO2 is prepared using Gossypium sppas a template. The experimental results show that the surface of the composite membrane forms a rough structure with multiple pore channels and the CeO2/ZrO2 composite membrane shows super-hydrophobicity (152.2°) and superlipophilicity. At the same time, the CeO2/ZrO2 composite membrane shows very high separation efficiency (98.26 %−99.53 %) for four oil-water mixtures. After the long-term stability test and cycling performance test, the CeO2/ZrO2 composite membrane shows good separation performance, and the flux of the membrane reaches 34411.9 Lm−2h−1. Meanwhile, the contact angle of the composite membrane is tested for acidic and alkaline environments, and the result shows that it has certain corrosion resistance. This provides an extended strategy to reduce environmental pollution and improve separation efficiency.