As-prepared Mesh Research Articles

All-electrochemical-prepared, efficient and robust superhydrophilic/underwater superoleophobic meshes for synchronously achieving oil-water separation and water-soluble pollutant photodegradation

Superhydrophilic/underwater superoleophobic “water-removing” type membranes can overcome the issue of surface themselves easily fouled or even blocked by oils that seriously affects the oil-water separation capacity and limits the recycle use, and thus attract a great deal of research attention. In this work, we employed the electrochemical deposition method to fabricate Cu3(PO4)2 nanosheets (NSs) vertically grown on a copper mesh (COM) to achieve efficient oil-water separation, followed by the deposition of titanium dioxide (TiO2) nanoparticles and graphitic carbon nitride (g-C3N4) nanosheets on the surface of Cu3(PO4)2 nanosheets-wrapped mesh (Cu3(PO4)2@COM), respectively. The composited meshes of TiO2@Cu3(PO4)2@COM and g-C3N4@Cu3(PO4)2@COM not only showed the considerable superhydrophilic/underwater superoleophobic property in the application of oil-water separation, but also simultaneously exhibited the desirable photocatalytic activity for the degradation of water-soluble pollutants as the water passed through the meshes. The oil-water separation efficiency of TiO2@Cu3(PO4)2@COM and g-C3N4@Cu3(PO4)2@COM can reach as high as 97 % and 96 % that both of meshes have the water flux of various water-oil mixtures above 3250 L/m2h, along with their degradation efficiency of 79 % and 90 % for RhB pollutant under full spectrum light irradiation, respectively. In addition, the as-prepared meshes have the robust, sustainable and stable properties through ten-cycles test of oil-water separation and photocatalytic degradation without significant performance decay. Our primary results provide a potential and simple route to construct multifunctional membrane materials for synchronously achieving water purification in oily wastewater.

Solvent-tolerant lignosulfonate-attapulgite/calcium carbonate coating on nylon filter mesh for oily water treatment

Due to the rapid increasing drainage of oily wastewater, robust and durable filtration materials with underwater superoleophobic coatings are highly desired. The existing underwater superoleophobic filter materials for oil/water separation are always subject to mechanical and chemical damages, causing the significant loss of superoleophobicity. Herein, a robust and tolerant nylon filter mesh (NFM) with underwater superoleophobicity was fabricated through simple layer-by-layer (LBL) assembly of lignosulfonate (LS), attapulgite (APT) nanorods, calcium ion, and carbonate on NFM. Compared with LS@CaCO3 assembly, the obtained LS-APT@CaCO3 assembly on NFM exhibits good micro/nano-structure, uniform distribution, and excellent underwater superoleophobicity (oil contact angle: > 156°). Moreover, after the fabricated mesh is subjected to the immersion in corrosive environments (acid, base, and salt aqueous solutions) and hot water as well as severe mechanical scratch, the oil contact angle are still higher than 147.5°, implying superb durability. More importantly, the as-obtained NFM is able to treat a variety of oil/pure water and oil/corrosive solution mixtures with separation efficiencies of over 98.2 %. Therefore, the as-prepared mesh has a huge application potential in oil-polluted water remediation due to the simple, facile, and eco-friendly preparation process.

Fabrication of a Janus Copper Mesh by SiO2 Spraying for Unidirectional Water Transportation and Oil/Water Separation.

Massive discharge of oily wastewater and frequent occurrence of offshore oil spills have posed an enormous threat to the socioeconomic and ecological environments. Janus membranes with asymmetric wettability properties have great potential for oil/water separation applications and have attracted widespread attention. However, existing Janus membranes still suffer from complex and costly manufacturing processes, low permeability, and poor recyclability. Herein, a novel and facile strategy was proposed to fabricate a Janus copper mesh with opposite wettability for unidirectional water transport and efficient oil/water separation. The hydrophilic side of the Janus copper mesh was prepared by coating it with Cu(OH)2 nanoneedles via a chemical oxidation method. The hydrophobic side was fabricated by coating it with hydrophobic SiO2 nanoparticles via a facile spraying method. The as-prepared Janus copper mesh showed asymmetric surface wettability, which can achieve unidirectional water transport and efficient oil/water separation with excellent recyclability, exhibiting great application potential for droplet manipulation and wastewater purification.

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.

Design of a super-hydrophilic/super-oleophobic g-C3N4/Ti(OH)4/PFOA nanocomposite coated mesh as a smart nanofilter with robust anti-fouling properties for separation of oil and water emulsions

The design and development of efficient approaches for water–oil separation have had widespread interest. This study aimed to synthesize nanocomposites based on Ti(OH)4 and g-C3N4 nanosheets (CN-NS) to show experimentally that the inclusion of Ti(OH)4 nanoparticles of 9.2 nm size into CN-NS leads to an improved oil-water separation efficiency and anti-fouling performance. So, a novel, reusable, and recyclable super-hydrophilic/underwater super-oleophobic CN-NS/Ti(OH)4 nanocomposite-coated stainless steel mesh was developed to separate oil-in-water emulsions. Super-wettability was obtained in the CN-NS/Ti(OH)4 nanocomposite with WCA = 0° and UOCA = 154°, respectively, showing significant super-hydrophilicity and underwater super-oleophobicity. Surface hydrophilicity increased after anchoring Ti(OH)4 on the CN-NS surface, resulting from oxygen-containing functional groups and consequently making defects on the mesh surface. Enhanced underwater oleophobicity of nanocomposite coated mesh is attributed to its higher surface roughness, which is a result of its micro-nano meter and mesoporous hierarchical structure. Moreover, the self-cleaning property of the as-prepared mesh was demonstrated by visible light irradiation on the contaminated mesh. In addition, perfluorooctanoic acid (PFOA) reduced energy in CN-NS/Ti(OH)4/PFOA mesh, resulting in a super-hydrophilic/super-oleophobic mesh. The CN-NS/Ti(OH)4/PFOA nanocomposite-coated filter was observed to separate water from a 1 wt% water-in-oil emulsion at 0.2 bar pressure with a filtration flux of 317.2 L m−2 h−1 and 95% separation efficiency.

One-step fabrication of robust liquid-repellent mesh induced by femtosecond laser

Super liquid-repellent surfaces are deemed as an ideal candidate for self-cleaning and liquid separation. However, these surfaces still confront challenges in the aspect of inadequate mechanical durability, environmentally harmful reagents and complex fabrication procedures. Herein, a one-step femtosecond laser ablation process on various porous mesh with PDMS-assisted coverage was conducted. Then, the uniform and hierarchical micro-groove structures were formed on the cylindrical wires during the successive laser pyrolysis, accompanying by the hydrophobic silica deposited inside the micro-groove structures. The whole processing has no chemical solvents and complicated modification, which is of great significance for time-saving and eco-friendly preparation of mesh with super-hydrophobicity. Significantly, the super-hydrophobic mesh can bear 2000 abrasion cycle tests, 400 ℃ heat treatment and violent outdoor robustness tests, verifying its strong mechanical durability and thermal stability. The mechanisms involved in liquid-repellence and abrasion-resistance have been elucidated systematically. Furthermore, self-cleaning and on-demand oil water separation could be accomplished via tailoring the wettability of the mesh according to the oxygen plasma treatment and re-heating. The unique advantages of the as-prepared porous mesh provide feasibilities for wettability-oriented application such as protective surface with self-cleaning ability, multitasking immiscible liquid separation.

Underwater Superoleophobic and Underoil Superhydrophilic Copper Benzene-1,3,5-tricarboxylate (HKUST-1) Mesh for Self-Cleaning and On-Demand Emulsion Separation.

Surfaces with underoil superhydrophilic (UOSHL) and underwater superoleophobic (UWOHB) have great potential for on-demand emulsion separation. However, the fabrication of underoil superhydrophilic based on wetting thermodynamic principles is quite challenging. Several previous studies have shown that some sarcocarps are able to spontaneously absorb water to moisturize themselves and have a unique UOSHL ability. By mimicking this unique ability of the sarcocarp, an outstanding UWOHB and UOSHL membrane was prepared. We choose 2300 mesh stainless steel mesh (SSM) as the substrate, then grow Cu and Cu(OH)2 on SSM by a simple electrochemical method, and finally grow HKUST-1 crystals via a fast in situ growth method. The whole preparation process is simple, low cost, and does not require complex and long-term hydrothermal reactions. By growing HKUST-1 crystals, the prepared surface successfully achieved the required UOSHL and UWOHB properties. When the water droplets come into contact with the membrane under n-hexane, it will diffuse and can completely spread out in 2 s. The as-prepared membrane exhibits outstanding anti-fouling and self-cleaning properties for rapeseed oil and crude oil with high viscosity underwater due to the special wetting. By prewetting the surface with an appropriate amount of the dispersion medium, it can rapidly and efficiently on-demand separate different emulsions. The separation efficiencies of water-in-oil emulsions and oil-in-water emulsions are above 99.00 and 97.00%. With their outstanding performance in self-cleaning, on-demand emulsion separation, low cost, and fast preparation, the as-prepared UOSHL and UWOHB HKUST-1 meshes show excellent potential for treating oily wastewater in practical applications.

Enhanced energy storage performance of the three-dimensional nickel nitride mesh with mesoporous structure derived from nickel hydroxide nanowires for advanced hybrid supercapacitors

Nickel nitrides are considered to be promising for hybrid supercapacitors (HSCs) as electrochemical energy storage materials, owing to their good electrical conductivity. However, nickel nitride is prone to agglomeration in high-temperature preparation process, resulting in lower specific surface area and higher porosity, further inhibiting its energy storage performance in HSCs. Consequently, a three-dimensional Ni3N mesh with a mesoporous structure (3D Ni3N Mesh) was constructed as the electrode material for HSCs via a facile hydrothermal reaction and nitrogenization treatment in this work. The as-prepared 3D Ni3N Mesh was built from Ni3N nanoparticles as the bricks that employed the nickel hydroxide nanowires as the precursors. The electrochemical tests demonstrated that the specific capacity of the as-prepared 3D Ni3N mesh could reach 254.2 mAh g−1 at 1 A g−1 in the three-electrode cell. The specific capacity of the 3D Ni3N mesh is still up to 108.3 mAh g−1, even at a high current density of 30 A g−1. The changes of the micro-nano structure, chemical composition and energy storage mechanism of the 3D Ni3N mesh electrode materials in the charge-discharge process were also analyzed and discussed. To further demonstrate its potential applications, a HSCs was also assembled with the 3D Ni3N mesh and the activated carbon (AC) as the positive and negative electrode respectively. It is worth mentioning that the specific capacity of the 3D Ni3N mesh//AC HSCs is 59.3 mAh g−1 at 0.5 A g−1, while the energy density also reaches 56.2 Wh kg−1 at a power density of 468 W kg−1. In addition, the 3D Ni3N Mesh//AC HSCs still maintains 77.4 % capacity along with an average coulombic efficiency of 98.7 % after 5000 continuous cycles, demonstrating good cyclic reversibility.

Selective and Continuous Oil Removal from Oil-Water Mixtures Using a Superhydrophobic and Superoleophilic Stainless Steel Mesh Tube.

The development of continuous oil-water separation processes has applications in the treatment of industrial oily wastewater and effective management of oil spills. In this research, the performance of a superhydrophobic-superoleophilic (SHSO) membrane in oil-water separation is investigated through dynamic tests. We investigate the effects of the total flow rate and oil concentration on the separation efficiency using an as-fabricated SHSO mesh tube. To construct the SHSO membrane, a tubular stainless steel mesh is dip-coated into a solution, containing a long-chain alkyl silane (Dynasylan F8261) and functionalized silica nanoparticles (AEROSIL R812). The as-prepared SHSO mesh tube illustrates a water contact angle of 164° and an oil contact angle of zero for hexane. A maximum oil separation efficiency (SE) of 97% is obtained when the inlet oil-water mixture has the lowest flow rate (5 mL/min) with an oil concentration of 10 vol %, while the minimum oil SE (86%) is achieved for the scenario with the highest total flow rate (e.g., 15 mL/min) and the highest oil concentration (e.g., 50 vol %). The water SE of about 100% in the tests indicates that the water separation is not affected by the total flow rate and oil concentration, due to the superhydrophobic state of the fabricated mesh. The clear color of water and oil output streams also reveals the high SE of both phases in dynamic tests. The outlet oil flux increases from 314 to 790 (L/m2·h) by increasing the oil permeate flow rate from 0.5 to 7.5 (mL/min). The linear behavior of the cumulative amounts of collected oil and water with time demonstrates the high separation performance of a single SHSO mesh, implying no pore blocking during dynamic tests. The significant oil SE (97%) of the fabricated SHSO membrane with robust chemical stability shows its promising potential for industrial-scale oil-water separation applications.

Dual-functional superwetting CuCo2O4 coated stainless steel mesh for wastewater treatment: Highly efficient oil/water emulsion separation and photocatalytic degradation

Oily water and soluble contaminants from marine oil spills, industrial wastewater and domestic sewage has caused serious water pollution. Although advanced membranes with super-wettability have been used in oil/water separation, most of them lack the capacity to separate oil/water emulsions and remove water-soluble contaminants. Herein, a dual-functional CuCo2O4 nanoneedle array coated stainless steel mesh is successfully fabricated for water purification. The as-prepared mesh shows excellent superhydrophilicity-underwater superoleophobicity and superior anti-oil-fouling capability. The as-prepared mesh can efficiently separate oil/water emulsion and photodegrade soluble organic dyes under UV light irradiation. The as-prepared mesh exhibits the superior oil/water separation emulsion performance with separation efficiency > 99.5% and high flux (172 L m−2 h−1). In addition, the as-prepared mesh possesses excellent photodegradation performance toward organic dyes with a degradation efficiency of more than 96.95%. More importantly, the as-prepared mesh shows durability and stability. The as-prepared mesh has great potential for multi-functional water purification.

Fabrication of Superhydrophobic Copper via Chemical Etching and Modification

Biological superhydrophobic surfaces are relatively common in nature. Inspired by the superhydrophobic feature, plentiful materials with hydrophobic surfaces have been fabricated for various purposes such as anti-corrosion, anti-icing, self-cleaning, friction reduction, and oil-water separation. In the present work, we report a scalable, simple, and rapid method to fabricate superhydrophobic film on copper substrates via a simple route including a chemical etching step in sodium persulfate and sodium hydroxide solution and followed by a modification step in stearic acid solution. The effect of the etchants concentration as well as etching time was investigated exhaustively. From the obtained results it was found that when a copper plate was etched in an etching solution with low etchant concentration, the contact angle of copper was greatly influenced by etching time. In contrast, the etching time hardly affected the contact angle of the copper plate at the high concentration of the etchants. The superhydrophobic feature of the copper surface (with a contact angle larger than 150o) was only achieved in certain fabrication conditions. The superhydrophobic copper substrates demonstrated good anti-corrosion properties. The corrosion current density of superhydrophobic copper substrates was 85 times smaller than that of pristine ones when manufactured under optimal conditions. In addition, the as-prepared superhydrophobic copper mesh was used to successfully separate toluene from its aqueous mixture. The superhydrophobic copper has great potential for applications in oil-water separation and anti-corrosion in aqueous environments.

Periodic Heterogeneous Surface with Superhydrophilic/Superhydrophobic Stripes Processed by a Picosecond Laser.

Heterogeneous surface with superhydrophilic/superhydrophobic stripes (HS-s/sS) has great practical significance, which can be used in fuel cell water management, condensation heat transfer enhancement, underwater drag reduction. Herein, a fast and simple method for uniform HS-s/sS on several mesh materials, including copper, stainless steel, and nickel, is achieved by using picosecond (ps) laser line-by-line scanning. Note that the scanning period between the lines is kept constant during processing, the HS-s/sS is formed by self-organized, while the similar structure cannot be processed on solid metal surfaces using the same parameters. The processing parameters, including scanning speed, defocus amount (DA), scanning period, and single pulse energy are systematically investigated to optimize HS-s/sS fabrication. It is found that the period of processed stripe on the mesh material is ∼1 mm, which is much larger than the scanning period. Interestingly, the as-prepared mesh surface show superhydrophobicity in the convex striped surface and superhydrophilicity in concave striped parts. The scanning electron microscopy results show that the structures on convex stripe are mainly composed of disordered hill-like structures, while the structures on the concave stripe mainly consist of periodic nanostripe structures. Moreover, the proportion of oxygen on the convex stripe is obviously higher than that on the concave stripe. The underlying mechanism of the HS-s/sS formation can be attributed to the interference between surface phonon polaritons (SPP) and the incident picosecond laser, as well as surface shock wave caused by the picosecond laser. We believe that such functional surfaces will be promising candidates for controlling liquid motion and fluid diversion processes.

Fabrication of superhydrophobic stainless-steel mesh for oil-water separation by jet electrodeposition

A method for fabricating superhydrophobic stainless-steel meshes based on magnetic field-assisted jet electrodeposition is proposed. Ferromagnetic nickel particles (Nip) were added to the electroplating solution to prepare Ni/Nip coatings with mountain-like rough structure on stainless-steel meshes, followed by application of a parallel magnetic field in the cathode region. Magnetic fields play an indispensable role in the preparation of coatings. Exposure to air for 6 days resulted in a spontaneous switch of the coating from superhydrophilicity to superhydrophobicity and exhibited superoleophilicity. X-ray photoelectron spectroscopy revealed that this transition in wettability was related to spontaneous adsorption of hydrocarbons in the air induced by the coating. Based on the superhydrophobicity and superoleophilicity of the as-prepared Ni/Nip-coated meshes, high-efficiency, high-throughput, and high-purity separation of oil-water mixtures was achieved with a 300-mesh mesh. Furthermore, the as-prepared meshes continue to exhibit a separation efficiency greater than 97.0% and stable reusability even after 50 repeated separations.

Underoil superhydrophilic CuC2O4@Cu-MOFs core-shell nanosheets-coated copper mesh membrane for on-demand emulsion separation and simultaneous removal of soluble dye

Underoil superhydrophilic surface is of great significance for the separation of water-in-oil emulsions, but its preparation is still a great challenge due to limited wetting thermodynamics. Herein, a well-designed hierarchical CuC2O4@Cu-MOFs (HKUST-1) core-shell nanosheets-coated copper mesh membrane was fabricated by facile immersion processes for on demand separation of oil-in-water and water-in-oil emulsions as well as highly efficient removal of soluble dyes. The as-fabricated hierarchical CuC2O4@HKUST-1 core-shell nanostructure endowed the mesh membrane with underwater superoleophobicity, underoil superhydrophilicity and excellent underwater oil anti-adhesion capability. Such superwetting MOFs-coated membrane delivered an outstanding separation performance for oil-in-water emulsion with high water flux of up to 1800 L m−2 h−1and the chemical oxygen demand (COD) value of lower than 110 mg L−1 by selective water filtration, whilst it efficiently separated water-in-oil emulsion by adsorption with a water content of lower than 120 ppm. Furthermore, the as-prepared mesh membrane also exhibited high removal efficiency of soluble dyes at circa 94% within 165 min by the adsorption-photocatalytic coupled process. The postulated photocatalytic mechanism of CuC2O4@HKUST-1 composite was ascribed to the photogenerated superoxide (O2−) and hydroxyl radicals (OH). With the desirable separation performance to complex oil-in-water emulsion containing both emulsified oil droplets and soluble dyes, the as-synthesized mesh membrane enriches the preparation path of underoil superhydrophilic surface, and expands the application of MOFs-based membrane for complex oily wastewater treatment.

Facile Fabrication of Highly Hydrophobic Onion-like Candle Soot-Coated Mesh for Durable Oil/Water Separation.

Although sundry superhydrophobic filtrating materials have been extensively exploited for remediating water pollution arising from frequent oil spills and oily wastewater emission, the expensive reagents, rigorous reaction conditions, and poor durability severely restrict their water purification performance in practical applications. Herein, we present a facile and cost-effective method to fabricate highly hydrophobic onion-like candle soot (CS)-coated mesh for versatile oil/water separation with excellent reusability and durability. Benefiting from a superglue acting as a binder, the sub-micron CS coating composed of interconnected and intrinsic hydrophobic carbon nanoparticles stably anchors on the surface of porous substrates, which enables the mesh to be highly hydrophobic (146.8 ± 0.5°)/superoleophilic and resist the harsh environmental conditions, including acid, alkali, and salt solutions, and even ultrasonic wear. The as-prepared mesh can efficiently separate light or heavy oil/water mixtures with high separation efficiency (>99.95%), among which all the water content in filtrates is below 75 ppm. Besides, such mesh retains excellent separation performance and high hydrophobicity even after 20 cyclic tests, demonstrating its superior reusability and durability. Overall, this work not only makes the CS-coated mesh promising for durable oil/water separation, but also develops an eco-friendly approach to construct robust superhydrophobic surfaces.

Facile strategy for the construction of a robust underbrine superoleophobic membrane for highly efficient oil-brine separation

Developing an effective and sustainable method for the separation of oil and brine mixture is highly necessary for the restoration of environmental pollution caused by the loss of organic solvents during the lithium extraction process from brine. Herein, we report a facile and cost-efficient method to fabricate an underbrine superoleophobic mesh by one-step hydrothermal method. The synthesized CrOx(OH)3–2x/nickel mesh possesses flower-like nanostructure, exhibiting superior superhydrophilicity/underbrine superoleophobicity for different ratios of tributyl phosphate and sulfonated kerosene mixtures. Simultaneously, the CrOx(OH)3–2x /nickel mesh manifests high efficiency for oil and brine separation with an ultrahigh permeation flux (78136 L∙m−2∙h−1) and excellent oil rejection efficiency (>99.17%). Furthermore, the as-prepared mesh exhibits high chemical stability, outstanding salt tolerance, and excellent mechanical properties. Importantly, the surface wettability can be changed from superhydrophilicity to superoleophobicity for several times only by ignition of the CrOx(OH)3–2x/NM on an alcohol burner for 10 s or modified by OTS. Altogether, the CrOx(OH)3–2x/nickel mesh has tremendous potential in practical oil-brine applications.

A novel and facile preparation of Superhydrophilic/Superoleophobic nanofilter using carbon nitride nanosheet for W/O emulsion separation

In this research, a novel superhydrophilic/ superoleophobic thermoplastic polyurethane@graphitic-carbon nitride@perflourooctanoic acid (TPU@g-C3N4 @PFOA) coated stainless steel mesh was prepared to separate water/oil emulsion. g-C3N4 nanosheets were synthesized with a facile thermal condensation process followed by exfoliation using acid. TPU as a binder is commercially available and provides strong bonding of the nanocomposite coating to the substrate. Wettability characteristics of nanocomposite coated mesh showed the water contact angle of 18.9° and oil contact angle of 151°, which confirmed the special wettability of superhydrophilicity and superoleophobicity. The prepared nanocomposite-coated filter with the surface energy of 92.87 mN/m (dispersive and polar surface energy of 0.199 and 92.68 mN/m) was able to separate water from a 10 wt % water/oil emulsion. Ultimately excellent water–oil separation efficiency of 99% and the filtration flux of 50.5 L.m−2.h−1 were attained under gravity. The particular behavior of the surface is justified with small pore size of mesh, higher roughness and superoleophobic wettability due to the presence of g-C3N4 nanosheets, as well as with the reduction of the surface energy of the synthesized TPU@g-C3N4 by PFOA, as a surfactant with the fluorine tail groups. As-prepared mesh can also separate free crude oil–water mixtures with the separation efficiency and flux of 99.9% and 2157.4 L.M−2.h−1, respectively.The anti-fouling and mechanical stabilities of the as-prepared coated mesh were investigated. This result implied that the as-prepared water-removing filter has great potential for separation of the water-in-oil emulsion, which has long been a problem in industry and is often separated using oil-removing filters in the literature.

Stainless steel mesh coated with defect engineered ZIF-67 toward pH-switchable wettability and efficient organic liquids separation

In this work, stainless steel mesh coated with stearic acid and tetradecanedioic acid modulated ZIF-67 (SA+TDA/mZIF-67@SSM) was prepared via facile electrodeposition. The composite modulators supply defect engineering on the MOFs, endowing the as-prepared meshes with pH-switchable wettability. The ratio of modulators significantly affected the crystal morphology and wetting property of SA+TDA/mZIF-67@SSM, resulting from the competitive coordination between the modulation and crystal growth process. The SA+TDA/mZIF-67@SSM exhibited highly hydrophobic, while it became amphiphilic after soaked in alkaline solution because some exposed carboxylic acid groups on the mesh were deprotonated. The SA+TDA/mZIF-67@SSM achieved efficient and adjustable organic liquids separation, with the separation efficiency both up to 98% before and after the wettability transition. In addition, the SA+TDA/mZIF-67@SSM could realize the separation of oil/water/oil mixtures, with the separation efficiency larger than 98%. This work introduces a new technique of modulated MOFs coated mesh with pH-responsivity for separating organic liquids based on defect engineering.

Structured Copper Mesh for Efficient Oil-Water Separation Processed by Picosecond Laser Combined With Chemical Treatment or Thermal Oxidation

Oil-water separation has great practical significance, and can be used to help cope with growing oily industrial sewage discharge or marine oil spills, avoiding water pollution. Smart artificial super-wettable materials used for oil-water separation have aroused enormous interest because of their advantages of energy efficiency and applicability across a wide range of industrial processes. Herein, we report a highly efficient, simple method for oil-water separation using copper mesh fabricated by picosecond laser processing combined with chemical treatment or thermal oxidation. After laser processing, the surfaces of copper mesh show superhydrophilicity (hydrophilicity) and underwater superoleophobicity, which can be used to separate water from oil. While, for the samples after laser and chemical treatment or laser treatment combined with thermal oxidation, the surfaces become superhydrophobic (hydrophobic) and underwater superoleophilic, which can separate oil from water. Moreover, these three kinds of super-wettability meshes show high separation efficiency, achieving more than 99% seperation. Furthermore, the as-prepared mesh can be used for various oil-water mixture separation, such as edible oil, kerosene, diesel, and so on. Thus, this work will provide insights for controllable oil-water separation, and will also be beneficial to the study of microfluidic devices, and smart filters.

Superhydrophilic fish-scale-like CuC2O4 nanosheets wrapped copper mesh with underwater super oil-repellent properties for effective separation of oil-in-water emulsions

The development of efficient, facile and stable approach to separate water from oilfield emulsified oily wastewater is highly desired. In our work, inspired by oil-repellent property of fish scales with a thin layer of mucus and hierarchical structures, pioneering fish-scale-like CuC2O4 nanosheets wrapped (i.e., CuC2O4 NSW) on copper mesh surfaces were fabricated by a facile in-situ chemical etching. The unique vertically grown crisscross CuC2O4 nanosheet layer delivered a strong water capture ability to form a firm water film for achieving rapid and super oil repellence functionality. The 300-mesh CuC2O4 NSW copper mesh exhibited superior underwater superoleophobicity and was proven to treat emulsified oily wastewater effectively (with a water permeation flux being circa 2200 L·m−2·h−1 and COD value in filtrate at circa 54 mg·L−1). Furthermore, the 500-mesh CuC2O4 NSW copper mesh was demonstrated to effectively separate surfactant-stabilized oil-in-water emulsions (with a water permeation flux of 1000–2000 L·m−2·h−1 and COD value in filtrate < 55 mg·L−1). The good chemical, mechanical and thermal stability of the as-prepared mesh was further ascertained by different stability tests. With the efficient separation capability, good underwater super oil-repellent and self-cleaning abilities, the novel membrane prepared by the easily scaled-up method shows great potential for industrial applications.