Continuous Oil Water Separation Research Articles

Robust photopolymerized superoleophobic/superhydrophilic mesh for oil-water separation

Selective superwetting surfaces preserve the opposite superwetting properties of oil and water and have attracted considerable attention for their application in oil-water separation owing to their efficient surface energy since 2000. Among these surfaces, superoleophobic/superhydrophilic surfaces are considered remarkable because of their anti-oil properties. The coexistence of superoleophobicity and superhydrophilicity poses a challenge based on the traditional surface/interface theory. However, the fabrication of superoleophobic surfaces requires extremely low surface energy, which is achieved by introducing compounds with long fluorocarbon chains. However, these compounds are harmful to the environment. Herein, a mesh with superoleophobic/superhydrophilic properties was developed by coating a chemically etched copper mesh substrate with photopolymerized short fluorocarbon chains and water-insoluble hydrophilic monomers. This mesh can separate different types of oil-water mixtures with a separation efficiency of >99 %. The mesh demonstrated excellent underwater stability as well as chemical and mechanical durability. The water resistance and chemical durability of the mesh are stronger than those of the control copper mesh using metal ions and long fluorocarbon chains. Moreover, oil-water separation was achieved even after immersion in deionized water and salt, acid, and alkali solutions. In addition, the mesh preserves the ability of oil-water separation after being cleaned and reused for 10 times. The proposed superoleophobic/superhydrophilic mesh offers a solution for continuous oil-water separation and has prospects for developing anti-fouling/sweat-absorbing fabrics and self-cleaning surfaces.

Enhanced separation flux and compressive strength for oil-water separation by adding sodium lignosulphonate

Oil-water separation materials have been deeply developed to solve oil spill problems. However, mechanical strength and separation efficiency remain challenging. Based on the electrostatic repulsion, we design and prepare oil-water separation materials to enhance the separation flux and resistance to pressure by adding sodium lignosulphonate nanoparticles (LSs) to the reduced graphene oxide (rGO), followed by surface modification with trimethoxymethylsilane (MTMS). XRD patterns prove the positive action of LSs for improving interlayer spacing of rGO, which contributes to an excellent separation flux (carbon tetrachloride/water, 43209.71 L⋅m-2⋅h-1) of MLNGA. The compressible recovery ability is enhanced to 49.91 kPa under 80 % strain. The MLNGA presents excellent separation efficiency (∼99.12 %) on a continuous oil-water separation device. All these results indicate the outstanding performances and potential of MLNGA in oil–water separation applications. Moreover, this design concept involves electrostatic repulsion and may be promoted to other anionic macromolecules such as sodium alginate, tannic acid, and pectin.

Continuous oil–water separation by utilizing novel natural hollow fibers: evaluation and potential applications

Continuous oil–water separation by utilizing novel natural hollow fibers: evaluation and potential applications

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.

Facile preparation of durable superhydrophobic DTMS@HKUST-1 wood membrane for continuous oil-water separation in harsh conditions

Manufacturing durable wood membranes that demonstrate both high efficiency and ultra-high flux for continuous oil-water separation utilizing scalable and cost-effective processes remains a serious challenge. In this study, a facile two-step approach is employed to prepare a novel superhydrophobic/oleophilic wood-based MOF (metal-organic framework) membrane. This method involves in-situ anchoring of the octahedral Cu-HKUST-1 (copper benzene-1,3,5-tricarboxylate) onto the wood sponge (WS), which inherently features internal micro-channels. The structure is then modified using the eco-friendly hydrophobic long-chain coupling agent dodecyltrimethoxysilane (DTMS). Due to its unique micro/nanoscale rough surface morphology and low surface energy, the functional wood membrane (DTMS/HKUST-1@WS) exhibited a high contact angle of 162.98±1.10° for water and was able to effectively separate various immiscible oil/water mixtures. Notably, the DTMS/HKUST-1@WS membrane can be integrated into a pump drive system, serving as an advanced filter element for the sustained and efficient oil-water constituents. Results showed that this membrane possesses attractive permeability toward CCl4 (56689.34 L·m−2·h−1) and toluene (47241.12 L·m−2·h−1), achieving separation efficiencies over 99.0%. Furthermore, this novel membrane exhibits remarkable resistance to physical damage, high/low temperatures, and corrosive solutions, thereby showcasing stable superhydrophobic and superoleophilic interfaces suitable for oily wastewater treatment in harsh environments. Thus, this work offers an innovative approach for designing functional wood-based MOF membranes to achieve highly efficient continuous oil-water separation.

A novel coalescing material for high efficiency oil-water separation

Among numerous oil-water separation materials, coalescence materials have received widespread attention. In this work, we prepared a lotus leaf-shaped Janus coalescing material by physically mixing polyethylene (PE) and polypropylene (PP) first, pressing it into sheets, then single-face hydrophilic modifying by chemical oxidation method, followed by pressing into a lotus leaf shape. Finally, holes were physically punched at the upper and lower sides of the coalescing material to let the oil drops pass through freely, greatly reducing the time for oil droplets to float. The shape of lotus leaves could provide more opportunities for oil droplets to collide and coalesce. The coalescing materials had asymmetric wettability, with specific surfaces that were oleophilic on the one hand and hydrophilic on the other. The oil droplets adhered to the oleophilic side of the coalescing material, coalesced and grew, then floated up and passed through the coalescing sheet layer by layer until they reached the oil collecting port to realize oil-water separation. The structural parameters of the coalescing material were progressively optimized. The obtained coalescing material exhibited a high oil-water separation efficiency of 99.40 ± 0.5% with good stability during a 48 h continuous oil-water separation, which provided a reference for the development of efficient coalescing materials.

Recycling polycarbonate wastes to prepare hydrophobic and super mechanically robust aerogels with excellent oil–water and emulsion separation performance

With the development of our society, plastic pollution is becoming more and more prominent. It is attractive and challenging to recycle plastic wastes to prepare valuable products at low cost. In this study, we report a unique strategy to obtain hydrophobic and super robust aerogels from polycarbonate wastes: (1) 4,4-diaminodibenzomethane is used to decompose polycarbonate (PC) waste, (2) the degradation product is compounded with organically modified montmorillonite (OMMT) to gel up through sol–gel transition, (3) solvent exchange and ambient-drying are performed to obtain the final aerogel samples. The addition of OMMT not only promotes the ring opening of the oxazine rings in the polymer matrix and the gelation rate of the system, but also strengthen the prepared aerogels due to the formation of stronger honeycomb network structure as a result of hydrogen bonding between OMMT and polymer matrix. The resulting aerogels can withstand up to 46,000 times its own weight and exhibits superb hydrophobic properties with contact angle up to 146.2°, as well as being suitable for use in a wide range of pH values. Besides, the aerogels possess good capacity for continuous oil–water separation, whose oil absorption performance does not deteriorate perceptibly after 50 cycles of oil absorption and degreasing. The aerogel obtained by this simple method not only has superb mechanical properties, hydrophobic properties, and oil–water emulsion separation, but also has many potential industrial applications and, most importantly, solves the waste disposal dilemma.

Liquid-assisted strategy for dual-purpose oil-water separation with super-omniphobic mesh

Sustainable methods for oil–water separation are highly desirable for industries globally as their significant role in various applications, such as the treatments for industrial wastewater or marine oil leakage, which harms the environment and ecology deeply. However, existing super-hydrophobic/super-oleophilic and super-oleophobic/super-hydrophilic surfaces fail to satisfy the requirement of continuous oil–water separation owing to either affinity to viscous oil or poor water resistance. Novel methods available for sustainable oil–water separation are widely desired. Until now, there has been no research conducted on the application of super-omniphobic meshes for oil–water separation. Herein, a liquid-assisted strategy for dual-purpose oil–water separation with super-omniphobic meshes was proposed. The strategy can be applied for oil–water separation by removing either water or oil with high separation efficiency. Meanwhile, by taking advantage of the anti-liquid property of the super-omniphobic mesh, the existing common problems such as viscous oil contamination and caustic aqueous corrosion could be avoided. Moreover, since this strategy adopts super-omniphobic meshes, oil–water separation using this strategy in a harsh environment can also be guaranteed. Compared with the conventional super-wetting meshes for oil–water separation, the strategy proposed in this work ensures that the separation mesh always maintains super-oleophobicity during the oil–water separation process and is universally applicable to a variety of super-omniphobic meshes. The present novel strategy provides a general guide for dual-purpose oil–water separation and a sustainable method for anti-contamination wastewater treatment, which indicates promising applications.

Superelastic chitin nanofibril/chitosan aerogel for effective circulating and continuous oil-water separation

Elastic and hydrophobic aerogels have received a lot of attention in dealing with the increasing oil pollution due to their recyclable properties. Herein, we present an ultralight and superelastic aerogel with highly oriented polygon structure based on chitin nanofibril (ChNF) and chitosan (CS) by directional freezing. The chemical cross-linking enables good mechanical strength at low aerogel density. After 500 compression-release cycles, the aerogel can retain the deformation recovery rate of 88 % in air, demonstrating the excellent resilience. The bio-based aerogel has high absorption capacity (52-114 g/g) for various oils and organic solvents, and it is able to achieve the absorption retention of 90 % even after 20 absorption-extrusion cycles. Moreover, owing to the good elasticity, the pore size of the aerogel can be adjusted by compression to selectively separate water-in-oil emulsions of different particle sizes with separation efficiencies higher than 99.5 %. The bio-based aerogel with good cycle performance has broad application prospects in the field of oil-water separation.

Self-rotation induced regeneration of filter media to enhance the oil-water separation in a microchannel filter

The regeneration of filter media was crucial to the filtration performance of the oily wastewater. Herein, a novel hydrocyclone-induce approach was proposed for filter media regeneration, followed by an exploration of oil desorption feasibility and mechanism. The effect of structural and operation parameters of a hydrocyclone on the particle self-rotation was extensively analyzed by numerical simulation, and its feasibility for oil desorption from the filter media was subsequently investigated. A hydrocyclone-intensified filtration method that combined by the unit of filtration and hydrocyclone self-rotation regeneration was proposed, and the effect of hydrocyclone-induced filter media regeneration on the subsequent oily wastewater filtration was also explored. The ideal specifications of the hydrocyclone were concluded to be an overflow pipe insertion of 120 mm, and a cone angle of 60° for the optimal self-rotation velocity. The hydrocyclone-induced regeneration presents a remarkable oil desorption efficiency, and the oil concentration of filter media reduced from 9.43 % to 6.94 %, 4.33 %, and 3.43 % as the flowrate increased from 1.8 × 105 L·m−2·h−1 to 5.4 × 105 L·m−2·h−1. The adhered oil was exfoliated due to the centrifugal force caused by the revolution and self-rotation of the media particles, while the filter media spun in a hydrocyclone. The average effluent oil concentration in the raw oily wastewater was reduced to 12.2 mg/L during the pilot-scale test, indicating that the hydrocyclone regeneration benefits the continuous oil-water separation. It is believed that this work might provide a unique and efficient method for oily wastewater treatment with the integration of filtration and hydrocyclone regeneration.

Superhydrophobic and superoleophilic polyurethane: Effect of different sponge densities, magnesium stearate loadings, harsh environmental conditions

AbstractReferring to catastrophic damages of oil and organic pollution leakage to the aquatic environment, providing a high efficiency technique for the oil–water separation becomes a hot research topic during the recent decade. This study focused on effects of the sponge density and magnesium stearate loadings on the separation performance of superhydrophobic magnesium stearate coated‐polyurethane. The sponges with three densities of 8, 13, and 18 kg m−3 were coated with different magnesium stearate loadings of 5 and 10 wt% by dip‐coating method. A set of various analyzes, including field‐emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray spectroscopy (EDX), contact angle, absorption rate and capacity, continuous oil–water separation, were conducted in neutral, acidic, and basic conditions. FESEM results demonstrated the sponges became increasingly rough after coating with magnesium stearate. The wettability measurements revealed the sponge density had no significant impacts on the water contact angle, all samples presenting around 175° ± 2° and oil absorption rate less than 1 s. Finally, the absorption capacity of the unmodified and modified sponges for treating various oils and solvents demonstrated that the coated spongy could absorb a wide range of oils and organic solvents with capacity range of 15–75 times their weight, depending on the different densities and loadings.

Superhydrophobic wood sponge with intelligent pH responsiveness for efficient and continuous oil-water separation

In recent years, the leakage of crude oil and the discharge of oily wastewater in industrial production have seriously endangered the water environment and ecological safety. Adsorbent materials with excellent oil-water separation performance play an important role in water purification. In this work, we employed a simple yet effective strategy to prepare highly compressible wood sponges. And with the prepared wood sponge as the substrate, the prepared pH-responsive copolymer was coated on the surface of the wood sponge by spraying method, and the pH-responsive superhydrophobic wood sponge was successfully prepared. The experimental results show that the wood sponge has excellent pH-responsive properties and can complete the transition of surface wettability between superhydrophobicity and hydrophilicity according to the change of pH value. The wood sponge has good oil adsorption capacity (12.72 g g−1), and reusability. Continuous oil-water separation can be carried out under the vacuum pump, and the oil-water separation efficiency in one separation cycle is above 92%. It has great application potential in the treatment of oily wastewater.

Modified PU sponge for water purification

In this paper, poly-dopamine modified PU sponges were applied for water purification after being modified by different chemicals. Ag NPs were firstly in situ reduced on a polydopamine–modified polyurethane (PU) sponge under mild conditions (PU–PDA–Ag). Ag NPs could be uniformly dispersed and securely immobilized on the skeleton of PU sponge, which efficiently maintained the catalytic activity and stability. The soluble organic pollutants could be catalytically reduced by the PU–PDA–Ag sponge with the appearance of NaBH4. The target organic pollutants, including methylene blue (MB), methyl orange (MO), rhodamine B (RhB), and 4–nitrophenol (4–NP) could be completely reduced. In addition, the PU–PDA–Ag sponge was recycled for five cycles without a notable decrease in catalytic activity for the reduction of MB, exhibiting excellent reusability. To reverse the surface wetting characteristics for oil–water separation, the PU–PDA–Ag sponge was covalently grafted with mercaptan (dodecanethiol) to form a superhydrophobic/superoleophilic sponge (WCA=157.5°, OCA=0 °). The superhydrophobic/superoleophilic sponge (PU–PDA–Ag–SH) presented excellent sorption capacity in the range of 21.6–101.2 g/g for various insoluble oils and organic solvents and also showed superior reusability, which could be reused for 20 cycles without a significant decrease in sorption capacity. The PU–PDA–Ag–SH also provided the capability of continuous oil–water separation for both light oils and heavy oils with separation efficiency as high as 98.35% for diesel and 99.38% for chloroform, respectively.

The preparation of antifouling and superhydrophobic polyurethane sponge by grafting Econea to diisocyanate monomer for durable continuous oil/water separation and cleanup of oil spills

The oil-absorbent sponge is effective in the prevention and cleanup of offshore oil spills. However, biofouling in marine environments will significantly reduce its oil absorption capacity. Herein, a novel type of antifouling and superhydrophobic polyurethane (PU) sponge was successfully prepared via grafting Econea (antifouling agent) to diisocyanate monomer and hydrophobic modification of PDMS (Polydimethylsiloxane) and SiO2. The prepared PDMS-SiO2@PU-Econea sponge shows not only super-hydrophobicity with a WCA of 154.5° but also excellent antifouling properties with more than 99% of inhibition to Escherichia coli after immersed in artificial seawater (salinity ≈35‰) for 50 days. It can absorb 133.9 times of trichloromethane than its own weight and still maintain 98.5% of absorption after 50 cycles. In addition, the PDMS-SiO2@PU-Econea sponge exhibits excellent continuous oil–water separation performance. The separation fluxes of n-hexane and dichloromethane are 151.0 and 136.3 L·h−1·g−1, respectively, and the oil–water separation efficiency is up to 99.9%, it can absorb 50 times of crude oil than its own weight in 75 s. Therefore, the antifouling and superhydrophobic PDMS-SiO2@PU-Econea sponge is a promising and applicable oil absorbent sponge for long-term oil/water separation and cleanup of oil spills in marine environment.

Enhanced hydrophobicity of shell-ligand-exchanged ZIF-8/melamine foam for excellent oil-water separation

Oil and organic solvent spills have caused serious environmental issues. To address these issues, several novel materials have been developed for the efficient separation of oil/organic solvents from water. In this study, ZIF-8 was loaded onto a melamine foam (MF) skeleton a simple in situ growth method. ZIF-8/MF was modified via a shell-ligand-exchange reaction (SLER) to improve its hydrophobicity. The prepared D-ZIF-8/MF exhibited strong hydrophobicity, with a WCA of 145.1° and an OCA of 0°. D-ZIF-8/MF can absorb up to 68–165 times its weight in oil/organic solvents. D-ZIF-8/MF also exhibited excellent stability, corrosion resistance, recovery, and recyclability. Furthermore, D-ZIF-8/MF has a high oil-water separation efficiency for absorbing organic solvents through a continuous oil-water separation device. This study provides a novel strategy for the preparation of strong hydrophobic foams via surface modification and SLER for oil-water separation. It has immense potential for the scale-up practical treatment of oily wastewater.

Eco-Friendly Fluorine Functionalized Superhydrophobic/Superoleophilic Zeolitic Imidazolate Frameworks-Based Composite for Continuous Oil-Water Separation.

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

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.

MOF-derived LDH modified flame-retardant polyurethane sponge for high-performance oil-water separation: Interface engineering design based on bioinspiration.

Frequent petrochemical spill accidents and secondary fire hazards have threatened the ecological environment and environmental safety. The traditional purification technology has the problems of high energy consumption and secondary pollution, which also brings new challenges to spill disposal. Herein, we demonstrate a biomimetic structure-based flame-retardant polyurethane (PU) sponge (FPUF@MOF-LDH@HDTMS) for continuous oil-water separation. Inspired by desert beetle and lotus leaf, the biomimetic micro-nano composite structure was constructed by in-situ growth of metal-organic framework-derived layered double hydroxide (MOF-LDH) on the surface of the PU sponge. After grafting MOF-LDH with hexadecyltrimethoxysilane, FPUF@MOF-LDH@HDTMS showed excellent superhydrophobic/superoleophilic performance (water contact angle=153° and oil contact angle=0°). FPUF@MOF-LDH@HDTMS can easily and quickly adsorb oily liquids suspended/settled in the water thanks to the unique bionic structure. FPUF@MOF-LDH@HDTMS has excellent oil/organic solvents absorption capacity; even after 20 cycles of use still maintains high adsorption capacity. More importantly, the continuous oil-water separation through FPUF@MOF-LDH@HTMS has achieved a separation efficiency of up to 99.1%. In addition, the bionic superhydrophobic sponge has excellent flame retardancy, which reduces the possibility of secondary fire caused by PU sponges. Thus, the biomimetic micro-nano composite structure provides a new design strategy for the more high-performance oil-water separation sponges.

Catalytic metal-organic framework-melamine foam composite as an efficient material for the elimination of organic pollutants.

Water-insoluble organic pollutants in environment, such as sea oil spill, industrial reagents, and the abused organic pesticides, bring great risks to global water systems, which thus requires effective approaches for organic pollutant elimination. In this study, we report a catalytic metal-organic framework (MOF)-melamine foam (MF) composite material (DDT-UiO-66-NH2@MF) showing excellent oil-water separation performance and enzyme-like degradation ability toward organophosphorus pesticides. The fabrication of DDT-UiO-66-NH2@MF is based on the immobilization of a MOF-derived nanozyme (UiO-66-NH2) on MF sponge, and followed by the hydrophobic modification of UiO-66-NH2 by 1-dodecanethiol (DDT). The obtained DDT-UiO-66-NH2@MF thus displayed superhydrophobic/superhydrophilic property with a high water contact angle (WCA = 144.6°) and specific adsorption capacity toward various oils/organic solvents (62.2-119.8g/g), which leads to a continuous oil-water separation on a simple device. In the meanwhile, owing to the enzyme-like property of UiO-66-NH2, DDT-UiO-66-NH2@MF also displayed good ability to hydrolyze paraoxon under mild conditions, which facilitates the elimination of toxic pesticide residuals in water systems. This work provides a simple, efficient, and green approach for the separation and treatment of water-insoluble organic pollutants, as well as expands the use of MOFs-MF sponge composite materials in environmental sustainability.

Robust superhydrophobic magnetic melamine sponge inspired by lotus leaf surface for efficient continuous oil–water separation

Inspired by the oily surface layer and hierarchical structure on the lotus leaf surface, a magnetic sponge with robust superhydrophobicity (water contact angle up to 155°) and surface protection was synthesized by one-pot solvothermal method by introducing (3-Mercaptopropyl)trimethoxysilane into the melamine sponge. After hydrolysis and self-polymerization, (3-Mercaptopropyl)trimethoxysilane can grow as a low surface energy polysiloxane coating on the surface of sponges and magnetic particles. It not only provides a hydrophobic surface layer for sponges, but also this cooperation of micro-submicron-nanostructure from micron sponge skeleton, submicron Fe3O4 particles and nanoscale polysiloxane builds rough surfaces at multiple scales. Based on the triadic Koch curve model, the theory of superhydrophobic surface is elucidated in detail from the surface fractal behavior, fractal dimension, and surface composition. The sponge can be integrated into a negative pressure system as a filter element for continuous and efficient oil–water separation. The formed polysiloxane can not only provide protection for the sponge skeleton and magnetic particles, but also provide strong cross-linking between the two materials, which can effectively resist the damage to the functional structure caused by oil erosion. In addition, a conceptual diagram of a portable oil suction device similar to a vacuum cleaner was proposed. Combining the basic theory of robust superhydrophobic surface and innovatively clarifying the influence of filter element structure on oil–water separation efficiency from the perspective of interface force, it is expected to bring more practical and potential ideas for the design of a portable vacuum cleaner-like oil–water separation device.