Application In Oil-water Separation Research Articles

Fluoropolymer-based hybrid superhydrophobic nanocomposite coating with antifouling and self-cleaning properties for efficient oil/water separation

The production of industrial and domestic effluents possessing oily contaminated water has become a global concern as a result of environmental contamination and pollution. Newly synthesized organic-inorganic hybrid nanocomposites with special wetting and anti-wetting properties have been adopted in recent times to address this problem. However, this method has faced a few setbacks in curbing the situation, which leaves the problem persistent. In order to realize the full potential of hybrid composites in combating oil/water contamination, we synthesize a robust organic-inorganic superhydrophobic hybrid nanocomposite containing Polyvinylidene fluoride (PVDF) and silicon hydroxide (SiO2) to coat cellulose filter paper for effective and efficient separation of oil/water mixtures. With a simple dip-coating technique, the superhydrophobic hybrid composite obtain a superhydrophobicity with a water contact angle as high as 161˚ on the filter paper. The coated membrane possessed a robust mechanical property as well as chemical stability which withstands a sandpaper abrasion test of up to 80 cycles and could retain its superhydrophobicity in acidic, neutral and alkaline media after 24hrs of immersion respectively. Moreover, the coated surface possessed nanopores which allows it to be used in oil water separation applications both under pressure and gravity with a separation efficiency of up to 99.7 % and can also be recycled many times for use. The excellent antifouling and self-cleaning ability of the coated membrane also prevents the adhesion of contaminants from the surface. The outstanding performance of the facilely and cost-effective fabricated superhydrophobic hybrid composite reveals a great potential for curbing the problems of oil contamination while addressing some existing barriers to the full potential realization of hybrid composites.

Facile preparation of hybrid coating-decorated cotton cloth with superoleophobicity in air for efficient light oil/water separation

Superwetting materials have attracted broad attention in oil-water separation application in the last few years. In our work, a kind of modified cotton cloth with superoleophobicity/superhydrophilicity in air is obtained by using polydopamine and nano silica powder to construct micro-nanostructure on cotton cloth and subsequent sodium perfluornonanoate decoration to reduce the surface energy. The results show that the modified cotton cloth has high contact angle (CA) to various oils, and the CAs to canola oil, flaxseed oil, corn oil, and sesame oil are 164.5°, 153°, 152.5°, 144.5°, respectively. The constructed cloth has high oil-water separation efficiency to the mixtures of corn oil, linseed oil, rapeseed oil and water. Even after 25 cycles, the efficiency is still higher than 97%. Besides, the modified cloth can resist severe friction damage and the CA to oil is still greater than 135° after 18 cycles of friction on sandpaper. Especially, the separation efficiencies to rapeseed oil in pH 2 solution, pH 12 solution, 3.5% NaCl solution, hot water, ice water are above 96%, implying the applicability of the cloth in harsh water environments.

A simple method for developing efficient room temperature reduced graphene oxide-coated polyurethane sponge and cotton for oil-water separation

ABSTRACT Oil spilled during transportation, domestic, and industrial usage causes grave water and soil pollution. Therefore, oil recovery through absorption or separation from water has been a challenge to the scientific community. The 3D porous structure of polyurethane (PU) sponge attracted significant attention in oil-water separation applications. However, its poor hydrophobicity decreases and limits its oil-absorption efficacy dramatically. In this paper, we focused on improving the hydrophobicity of the sponge by modifying it with graphene oxide (GO) followed by its reduction to reduce graphene oxide (rGO) via a commonly available green reducing agent, L-ascorbic acid (L-AA). The rGO modified PU sponge was used to absorb and collect oil from an oil-water mixture with satisfactory recoveries of up to ~ 97%. Moreover, the prepared rGO-PU sponge exhibited excellent reusability and compressibility without any crack or leaking. Finally, we compared the results of this study with rGO modified cotton (rGO-cotton) surfaces prepared via the same protocols. The results show that the high compressible and porous nature of sponges (rGO-PU) outperformed the rGO-cotton. Furthermore, this research work was proven to be environmentally friendly and cost-effective absorbent for efficiently extracting oil from oil-water mixtures with fewer toxic chemicals and cheap raw materials utilization.

Synthesis of sustainable poly(S-Abietic-co-Pinene) through inverse vulcanization of Kurdica gum and used to fabricate durable and recyclable super-hydrophobic cotton wool filter: Oil-water separation application

The renewable and sustainable poly(S-Abietic-co-Pinene) with a high sulfur content was synthesized by inverse vulcanization of elemental sulfur and natural kurdica gum (extracted from the Pistacia atlantica tree). This hydrophobic polysulfide (KPS) is dip-coated on cotton wool to obtain a super-hydrophobic filter with a water contact angle of 165°. All polysulfide and coated filters are characterized by the FTIR, 13CNMR, TGA, SEM, X-ray map, EDX, and WCA. The 3-Aminopropyltriethoxysilan (APTES) reagent was used to enhance the adhesive forces between cotton and the KPS coating. The super-hydrophobic cotton-KPS wool filters were conducted for six bi-phasic oil-water separations. The high separation efficiencies and permeate fluxes as well as the 100% rejection of the aqueous phase are advantages of cotton-KPS wool filters. Also, no significant change was observed in the separation efficiency after 20 recycling numbers, implying the high durability and stability of the super-hydrophobic coating on the cotton-KPS filter. The use of renewable natural materials for the synthesis of novel polymers and the fabrication of robust super-hydrophobic filters for oil water separation can be based on green chemistry and sustainable development principles.

Green and Rapid Preparation of Fluorosilicone Rubber Foam Materials with Tunable Chemical Resistance for Efficient Oil-Water Separation.

Polydimethylsiloxane (PDMS) foam materials with lightweight, excellent oil resistance and mechanical flexibility are highly needed for various practical applications in aerospace, transportation, and oil/water separation. However, traditional PDMS foam materials usually present poor chemical resistance and easily swell in various solvents, which greatly limits their potential application. Herein, novel fluorosilicone rubber foam (FSiRF) materials with different contents of trifluoropropyl lateral groups were designed and fabricated by a green (no solvents used) and rapid (<10 min foaming process) foaming/crosslinking approach at ambient temperature. Typically, vinyl-terminated poly(dimethyl-co-methyltrifluoropropyl) siloxanes with different fluorine contents of 0–50 mol% were obtained through ring-opening polymerization to effectively adjust the chemical resistance of the FSiRFs. Notably, the optimized FSiRF samples exhibit lightweight (~0.25 g/cm−3), excellent hydrophobicity/oleophilicity (WCA > 120°), reliable mechanical flexibility (complete recovery ability after stretching of 130% strain or compressing of >60%), and improved chemical resistance and structural stability in various solvents, making them promising candidates for efficient and continuous oil–water separation. This work provides an innovative concept to design and prepare advanced fluorosilicone rubber foam materials with excellent chemical resistance for potential oil–water separation application.

Superhydrophobic polyurethane sponge based on sepiolite for efficient oil/water separation

Massive oil leakage accidents and illegal discharge of oily wastewater have not just destroyed the sustainability of the ecological environment but caused permanent damage to marine ecosystems, which makes it urgent to handle it. In this paper, by means of sol-gel, micro-nan silica that grew from the surface of fibrous sepiolite was organically modified with 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane (PFDS). The superhydrophobic sepiolite/silica firmly attached to the surface of polyurethane sponge under the action of oily epoxy resin with strong adhesion. The sponge exhibited superhydrophobicity and excellent selective oil adsorption capacity (19.98–40 times of their own weight). More importantly, besides the effective separation of immiscible oil-water mixtures (the separation rate reached 98.72%), it could also efficiently separate oil with water and oil with salt solution emulsions. In addition, the sponges kept hydrophobic even after floating in extremely corrosive liquids for 20 h, showing a strong resistance to strong acidic as well as alkaline liquids. After 100 times of mechanical compression, the three-dimensional structure of sponge held still and the water contact angle was greater than 144°, demonstrating an excellent mechanical stability, which provided a reference for its practical application in oil-water separation.

Preparing a wettability-controllable stainless-steel mesh and its oil–water separation performance

The ability to regulate and apply surface wettability has attracted much attention in the surface engineering field. In this study, a simple chemical etching method was used to construct a rough micro/nano structure on 304 stainless steel mesh; this rough surface was subsequently decorated with fatty acids of varying chain length to regulate wettability. The wettability, composition, and morphology of the surface were characterized and analyzed by measuring contact angles, and by atomic force microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy . The superhydrophobic and superoleophilic properties of the mesh modified with long-chain fatty acids were examined for oil-water separation performance and reusability. The surface had a micro/nano hierarchical morphology with ordered carbon chains, and the hydrophilic-to-superhydrophobic transformation was achieved by adjusting the chain length of the fatty acid to deliver contact angles in the range of 30°~154°. The oil contact angle was always 0°, irrespective of the chain length fatty acid, and oil drops quickly penetrated the mesh surface. A fatty acid with a longer chain afforded a more hydrophobic and oleophilic mesh surface and better oil–water separation efficiency (up to 96%), which still exceeded 85% after 50 cycles of oil–water separation testing. Consequently, the prepared surface with controllable wettability has excellent prospects for use in intelligent response interfaces and oil–water separation applications.

Preparation and mechanism of hydrophobic modified diatomite coatings for oil-water separation

It remains a significant challenge to separate oil and water in the metallurgical industry. Therefore, there is an urgent need for a low-cost process to prepare hydrophobic and lipophilic materials in order to improve oil-water separation performance. The hydroxyl group on the surface of diatomite was modified by a polysiloxane reaction. The microstructure, chemical composition, and hydrophobicity before and after modification were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Diatomite@POS/EP coating was prepared using the spraying suspension method, to endow various materials with excellent hydrophobic properties (ceramic, sponge, stainless steel, paper, and gauze). The SEM results show that many spherical particles were stacked on the modified diatomite disk, and new elements and structures were observed. The Diatomite@POS floated on the water indicates that the modification was successful. The contact angle between coating on porous diatomite ceramics and water could reach 147.5° when the mass ratio of Diatomite@POS: EP was 7:5. After 0–1000 cm wear test, and soaked in acid and alkali solution for 4 h, the coating could keep hydrophobicity, indicating that it features excellent wear resistance, acid, and alkali resistance. Ceramic sprayed with Diatomite@POS/EP and melamine sponges soaked in Diatomite@POS/EP were capable of effectively separating vacuum pump oil from water, which showed the promising self-cleaning performance of the ceramic surface. Besides, modified diatomite powder had great potential for application in waterproofing, self-cleaning, oil-water separation, and other fields.

Functionally Integrated Device with Robust and Durable Superhydrophobic Surface for Efficient, Continuous, and Recyclable Oil–Water Separation

AbstractA cost‐efficient, universal adhesive layer‐involved strategy is demonstrated for the construction of robust superhydrophobic surfaces on a variety of materials. This strategy uses recycled rubber particles (RRPs) and low‐surface‐energy coating to generate superhydrophobicity, which are fixed on the substrates by a precoated E‐44 resin (ER) adhesive layer. Benefitting from the robust ER adhesive layer and wear‐resistant rubber particles, the ER/RRPs composite coated low‐surface‐energy coating (ER/RRPs/LSEC composite) shows high robustness under various harsh conditions including repeated abrasion, sunlight radiation, and acid/basic corrosion. When evaluated as functionally integrated device for oil spill cleanup, these superhydrophobic structures show excellent oil‐absorption and oil–water separation properties. For example, the copper foam device coated with the ER/RRPs/LSEC composite shows a high oil–water separating efficiency of 95% before and after mechanical abrasion. This strategy provides a new toolbox for constructing robust superhydrophobic surfaces with oil–water separation applications and offers a novel insight into the durability of artificial superhydrophobic surfaces.

Multiphase media superwettability regulated by coexisting prewetting phase

Understanding the wetting behaviors of a given superwetting surface in multiphase media is important for elaborately tailoring superwettability. Here the surface chemistry of two types of superhydrophobic surfaces was programmed to reveal crucial effect of a coexisting prewetting phase rather than the prewetting process on their wetting states in water and oil–water separation application. After prewetting with ethanol to remove the air layer, underwater contact angles of superhydrophobic surfaces for oil droplet and bubble gradually decreased from over 150° along with the reduced surface energy. When the superhydrophobic surfaces were directly immersed in water or prewetted with oil, a stable air layer or infused oil as the prewetting phase enabled oil droplet and bubble to rapidly spread out. Moreover, air-prewetting superhydrophobic/underwater superoleophobic fabric can selectively adsorb oils from water, whereas it showed an excellent antifouling property without the air layer. For the separation of oil-in-water emulsions using superhydrophobic/underwater superoleophilic sponge, the stable air layer obstructed emulsions into three-dimensional porous structures. After removing the air layer, emulsion separation can be efficiently realized. This discovery provides a feasible approach for the regulation and development of unusual superwettability in multiphase media.

Honeycomb-like cobalt hydroxide nanosheets induced basalt fiber fabrics with robust and durable superhydrophobicity for anti-icing and oil-water separation

The fiber-based membranes with superhydrophobic/superoleophilic features are highly desirable for oil-water separation applications. Herein, a superhydrophobic/superoleophilic basalt fiber fabric is constructed by using a general strategy of surface KMnO4 pre-oxidation, honeycomb-like cobalt hydroxide nanosheets in-situ deposition, and hydrophobization. The influence of morphology change on wettability and roughness of the fabric surface were investigated. Benefiting from the dual-scale micro-/nanostructures, the obtained composite fabric has outstanding superhydrophobicity (water contact angle > 161°) and sustains non-wettability against multifarious food liquids. Meanwhile, the fabric displays substantial superhydrophobic durability during sandpaper abrasion, tape-peeling, and bending treatment. Moreover, the fabric also demonstrates excellent anti-wetting, self-cleaning and anti-icing performance. With these properties, the fabric has outstanding separation efficiencies (> 99.31%) and recyclability for various oil-water mixtures and emulsions under gravity. Therefore, this work provides an idea for development of superhydrophobic fabrics with potential application in the rapid treatment of oily wastewater.

Preparation of super-hydrophobic/super-oleophilic quartz sand filter for the application in oil-water separation

In the present work, novel super-hydrophobic/super-oleophilic surface of quartz sand was prepared by constructing silica rough structure and modifying it with low-surface-energy hexadecyl-trimethoxysilane (HDTMS). The characterization results revealed that the water contact angle (WCA) of the modified quartz sand was more than 150° and the oil contact angle (OCA) was nearly 0°. Notably, the modified quartz sand could be used as a filter to separate oil and water and depicted a high separation efficiency. The water content in the filtrate was less than 0.5 wt%. In the meantime, the modified quartz sand can fully separate the oil film from water by adhesion. The WCA of the modified quartz sand remains above 148° even after repeated test, which indicated that the modified quartz sand had good stability and reusability.

Preparation of Sio2-G-Pmma Hybrid Materials Employing Different Photocatalysts of Metal-Free Atrp and its Application for Oil-Water Separation

Preparation of Sio2-G-Pmma Hybrid Materials Employing Different Photocatalysts of Metal-Free Atrp and its Application for Oil-Water Separation

Fabrication of magnetically responsive anti-fouling and easy-cleaning nanofiber membrane and its application for efficient oil-water emulsion separation

The magnetically responsive anti-fouling nanofiber membrane (MRANM) was fabricated for efficient oil-water emulsion separation, which could be cleaned using oscillating magnetic field. MRANM was prepared by grafting superparamagnetic Fe3O4 nanoparticles onto the surface of electrospun polyacrylonitrile nanofiber membrane (PANM). Compared with PANM, the water contact angle of MRANM decreased from 104° to 0°, indicating that the hydrophilicity of the membrane was significantly improved. For the emulsions of hexadecane, octane and rapeseed oil, the separation efficiency was 98.04%, 96.59% and 92.67%, respectively. After the treatments in oscillating magnetic field, the separation efficiency kept above 95% after 8 times recycling, which indicated that the MRANM had good regenerability and reusability. The as-fabricated membrane with magnetic responsiveness facilitated an effective method for solving the membrane fouling problem during practical applications of separation high viscosity oil-water emulsion.

Combination of Multifunctional Cotton Fabrics Derived from Different Steps During One Preparation Process for Efficient Integration of Superhydrophobicity, Antibacterial Property and Photocatalysis in Oil-Water Separation and Dye Degradation Applications

Combination of Multifunctional Cotton Fabrics Derived from Different Steps During One Preparation Process for Efficient Integration of Superhydrophobicity, Antibacterial Property and Photocatalysis in Oil-Water Separation and Dye Degradation Applications

Rapid and Facile Fabrication Of Hierarchically Porous Graphene Aerogel for Oil-Water Separation and Piezoresistive Sensing Applications

Rapid and Facile Fabrication Of Hierarchically Porous Graphene Aerogel for Oil-Water Separation and Piezoresistive Sensing Applications

Preparation of Polyketone Micro/nanofiber Membrane based on Electrospinning Condition and Its Application in Oil-Water Separation

Preparation of Polyketone Micro/nanofiber Membrane based on Electrospinning Condition and Its Application in Oil-Water Separation

Fabrication of PDMS@Fe3O4/MS Composite Materials and Its Application for Oil-Water Separation.

The discharge of oily wastewater and oil spills at sea are the current difficulties in water pollution control. This problem often leads to terrible disasters. Therefore, the effective realization of oil-water separation is a very challenging problem. Superhydrophobic sponge is a promising oil-absorbing material. In this article, we reported a superhydrophobic sponge with nano-Fe3O4 for oil-water separation. The addition of nano-Fe3O4 allows the sponge to be recycled under the action of magnetic force. The sponge has the advantages of low cost, simple preparation and efficient oil-water separation. This kind of sponge is very worthy of promotion for the treatment of oily wastewater and marine oil spill accidents.

Superhydrophobic MS@CuO@SA sponge for oil/water separation with excellent durability and reusability

We present a superhydrophobic material based on commercially melamine sponge (MS) with great durability, recyclability, and excellent sorption performance. The fabrication process of this sponge is facile without using toxic reagents or sophisticated equipment and therefore it is simple to scale up. The CuO layer utilized to give a rough surface of the substrate (MS) was successfully prepared in a commercial microwave to seed copper nucleuses in an alkaline medium. Stearic acid (SA) plays a role as the self-assembled monolayer on the surface of the sponge skeletons. Throughout this study, the properties of the modified sponge were fully characterized, and the changes in wettability were carefully examined. Water contact angle (WCA) measurements revealed the excellent superhydrophobicity of the material with high static WCA of 165.1° and low dynamic WCA of 8°. Furthermore, the as-prepared sponge demonstrated high efficiency in separation (over 99.0%) of different oils from water. Notably, several unique properties of as-modified material were found, consisting of ultrafast sorption capacities of up to 32–52 times of its own weight by using 80 mL of each oil, outstanding reusability with good sorption capacity even after 40 cycles. Even under various harsh environments, the novel materials proved its outstanding durability and ultrafast sorption capacity of oils. The durability, recyclability, and superhydrophobic properties of the novel superhydrophobic sponge provide it a solid basis for oil-water separation applications through an ultrafast sorption capacity of oils as well as quick recovery of the oil by easy squeezing process.

Fabrication of recyclable, superhydrophobic-superoleophilic quartz sand by facile two-step modification for oil-water separation

With the highly frequency of oil spillages and chemical leakages, the application of superhydrophobic surface in oil-water separation is promising. Herein, the myristic acid/TiO2 @raw quartz sand (MATC@sand) with superhydrophobic-superoleophilic properties has been judiciously designed and synthesized that could be utilized for oil-water separation. The as-prepared samples were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectrometer (XPS) and Fourier transform infrared spectroscopy (FTIR). The wetting behavior was evaluated by contact angle measurer and the result showed that the MATC@sand had a water contact angle of 165.0°, a sliding angle less than 5° and an oil contact angle of 0°, which endowed the modified quartz sand with efficiently implement oil-water separation in various modes. The mechanism of oil-water separation using MATC@sand was exploited and it demonstrated the excellent ability of oil-water separation was mainly attributed to the synergistic effect between rough hierarchical micro/nanostructures and low surface energy. Moreover, for the sake of demonstrating its performance in practice application of oil-water separation, the durability, self-cleaning capacity, thermostability and anticorrosion of the MATC@sand are also measured to ensure the practical application. The results proved that the functional quartz sand is recyclable, economical and readily available, which made it have great prospects in practical application.