Preparation of oil-water separation network based on the novel strategies of SiO2 ceramic micro-nano structure and PDMS modification

In this study, we adopted the novel strategies of the soot template method to construct SiO₂ ceramic micro-nano structure surface and polydimethylsiloxane (PDMS) modification to reduce the surface energy. We fabricated a superhydrophobic/superoleophilic NS-PDMS oil–water separation screen by depositing coarse nano-SiO₂ ceramic on the surface of 100-mesh stainless-steel screen used as a substrate under the soot template method, which reduced the surface energy with PDMS. The fabricated NS-PDMS screen exhibited excellent superhydrophobic and self-cleaning properties. In particular, the superhydrophobic properties were stably maintained under various harsh conditions. Overall, the screen manifested self-cleaning ability for various water-containing stains, for example, coffee, milk, beer, and soy sauce. The mechanically damaged screen surface still retained its high roughness, and re-modification with PDMS could recover the superhydrophobic surface and oil–water separation performance. This suggests the re-use potential of the damaged NS-PDMS screen, which is vital for cost reduction and resource recycling. We believe that our study makes a significant contribution to the literature, because the fabricated NS-PDMS screen is superhydrophobic, superoleophilic, resistant toward several water-based solutions, chemically and mechanically stable under certain conditions, and can be reused with modification and repair after damage. Therefore, this screen can be broadly used as an oil–water separator.     

ZnO nanorod array-coated mesh film for the separation of water and oil

Dense and vertically aligned ZnO nanorod arrays with a large area have been fabricated successfully on the stainless steel mesh by a simple chemical vapor deposition method. The coated mesh exhibited both superoleophilic and superhydrophobic properties, even if it was not modified by low surface energy materials. The separation efficiencies were more than 97% in the filtration of water and oil. Besides, the wettability of the coated mesh was still stable after it was soaked in the corrosive solutions for 1 h. A detailed investigation showed that the coated mesh has the best superhydrophobic property when the stainless steel mesh pore size was about 75 μm.     

Pressure Response through Valve for Continuous Oil-Water Separation Based on a Flexible Superhydrophobic/Superoleophilic Thermoplastic Vulcanizate Film

Highly efficient oil-water separation shows urgent demand in industrial applications, especially in oil-spill accidents and organic solvent separation. Herein, a novel method is proposed for continuous oil-water separation by a pressure response through valve, which is loaded in a flexible convolute superhydrophobic/superoleophilic film based on low-density polyethylene (LDPE)/ethylene-propylene-diene terpolymer (EPDM) thermoplastic vulcanizate (TPV). The superhydrophobic/superoleophilic LDPE/EPDM TPV film (with contact angles of oil and water are 0° and 161.9°± 2.2°) is prepared only via a molding process where sandpaper is used as the template. The superhydrophobic/superoleophilic property of the TPV film shows robust performance in the activity endurance test. More importantly, the flexible LDPE/EPDM TPV film can be easily rolled up and loaded in through valve, which is the pressure response channel in oil-water separation. The typical separation pressure of oil and water is 3.01 and 6.17 kPa, which means the oil can be completely separated from the oil-water mixture under proper pressure in the pressure response through valve.     

One-step fabrication of superhydrophobic sponge with magnetic controllable and flame-retardancy for oil removing and collecting

Water pollution arising from oil spillage and chemical leakage has emerged as a critical problem imposing threat to the human and animal health. Effective removal of oils and chemical from water has become a global challenge. Recently, superhydrophobic/superoleophilic magnetic controllable (SHPB-SOPI-MC) porous materials have attracted more attention in the field of oil-removing because of the high selectivity, large absorption capacity, easy collection, and ideal recyclability. Moreover, in order to keep safety, the fire proofing performance should be taken into consideration. Therefore, fabricating SHPB-SOPI-MC porous materials with flame-retardancy through a low cost and simple strategy is necessary but also challenging. In this work, an ultrasound-assisted dip-coating method was applied to fabricate polydimethylsiloxane-vermiculite-Fe₃O₄ (PDMS-VMT-Fe₃O₄) coating onto discarded polyurethane (d-PU) sponge, which exhibited superhydrophobic, superoleophilic, magnetic controllable, and flame-resistant properties. The PDMS-VMT-Fe₃O₄@d-PU sponge owned excellent mechanical durability, chemical stability, and long-term storage stability. Importantly, the PDMS-VMT-Fe₃O₄@d-PU sponge instantly adsorbed oil floating on water under magnetic field driving. Furthermore, PDMS-VMT-Fe₃O₄@d-PU sponge absorbed various oils and chemical with ideal selectivity, absorption capacity (up to 40 times of its own weight), speed, and recyclability (exceeding 100 cycles). These findings suggested that PDMS-VMT-Fe₃O₄@d-PU sponge was a promising oil-removing material for practical application of oil spills cleanup.     

Fabrication of durable superhydrophobic and superoleophilic cotton fabric with fluorinated silica sol via sol–gel process

Superhydrophobic and superoleophilic cotton fabric was successfully prepared with fluorinated silica sol via a facile sol–gel method. A fluorinated polymeric sol–gel precursor (PHFBMA-MTS) was synthesized via free-radical polymerization by using hexafluorobutyl methacrylate (HFBMA) in the presence of (3-mercaptopropyl)trimethoxysilane (MTS) as the chain transfer agent, which led to the formation of fluoropolymer with alkoxysilane end groups. Then the fluorinated silica sol was prepared by introducing PHFBMA-MTS as the co-precursor of tetraethylorthosilicate (TEOS) in the sol–gel process with ammonium hydroxide as the catalyst, which was then used to fabricate superhydrophobic and superoleophilic fabric coatings through a simple dip-coating method. The coated fabrics showed superhydrophobic property with a high water contact angle of 154.1° and superoleophilic property with an oil contact angle of 0°. Moreover, the coated fabrics still kept superhydrophobicity even after ultrasonic treatment, as well as for organic solutions, acidic solutions. Thus, the coated fabrics were successfully applied to separate oil–water mixture with separation efficiency up to 99.8%. More importantly, the separation efficiency had no significant change after 20 cycles of oil–water separation. These present a simple, low-cost, and durable approach to achieve industrialized application of coated fabrics in oil–water separation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47005.     

One-step fabrication of superhydrophobic and superoleophilic cigarette filters for oil-water separation

To develop a simple and efficient way to recycle used cigarette filters, we report on a one-step method for preparing superhydrophobic and superoleophilic cigarette filters for oil–water separation. The robust coating layer on the surface of the cellulose acetate fiber, along with the inherent rough texture of the cigarette filter, could lead to its surface that displayed superhydrophobicity and superoleophilicity. Water droplets can retain in spherical shapes on the modified cigarette filters, while oils were immediately absorbed by the cigarette filters with high absorption capacity. As a result, free oil–water mixtures were separated with efficiency of above 98.0% by the driving force of gravity, and water-in-oil emulsion was also separated with a promising flux of about 2500 L m^?2 h^?1. The purity of oil for the tested emulsion was above 99.96%, indicating extremely high separation efficiency. This method for the fabrication of the superhydrophobic and superoleophilic cigarette filters would be a good candidate for recycling the solid wastes and developing an economic oil–water separation material to meet emerging needs in practical applications.     

Oil‐absorbent polyurethane sponge coated with KH‐570‐modified graphene

Polyurethane (PU) sponge has become a preferred oil adsorbent in recent oil‐spill accidents. To make the sponge superhydrophobic and superoleophilic, this study used graphene (GN), which was modified with γ‐methacryloxypropyl trimethoxy silane (KH‐570), to coat the PU sponge (called the KH–GN sponge). This study showed the best loading capacity (11.96%) of the KH‐570‐modified GN on the sponge. The contact angles of the KH–GN PU sponge were 161° for water and 0° for soybean, diesel, and pumping oil. It had good selectivity for oil over water, and the KH–GN sponge achieved adsorption equilibrium within a few seconds. The absorption capability of the KH–GN sponge was up to 39 times greater. Additionally, the KH–GN PU sponge could be reused for oil–water separation for more than 120 cycles without losing its superhydrophobic and superoleophilic properties. Therefore, the sponge prepared in this study could be a desirable material for the cleanup of oil spills. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41821.     

Superhydrophobic/superoleophilic micro/nanostructure nickel particles for oil/water mixture and emulsion separation

Nowadays, developing reusable and highly efficient materials for separating nano/micro-sized oil droplets from oil/water mixture and emulsion remains very challenging. Herein, hedgehog-like micro/nanostructure nickel particles were fabricated via a hydrothermal route. Thanks to its unique morphology, the octadecyltrichlorosilane (ODTS)-modified nickel particles show suitable superhydrophobicity/superoleophilicity properties with water contact angle, oil contact angle, and contact angle hysteresis values of 169.17° ± 2.13°, 0°, and 2.32°± 0.34°, respectively, making the potential sorbent for oil/water separation. The dense narrow thorns of superhydrophobic/superoleophilic nickel particles help the maximum scattering of particles on the surface and in the solutions. Hence, superhydrophobic/superoleophilic nickel particles demonstrated outstanding sorption capacity ranging from 3.86 to 5.27 (g/g) for a wide range of organic solvents and oils. Also, sorption capacities were retained even after 10 sorption cycles. Additionally, sorption capacities remain steady under acidic, alkaline, and high-saline conditions, indicating the high resistance in the harsh media. More importantly, ODTS-modified particles could also be used in oil/water emulsion separation with efficiencies of higher 99%. The appropriate resistance of hedgehog-like micro/nanostructure nickel particles to various environmental conditions as well as reusability and recyclability provides good opportunities for industrial applications of oil uptake from the oil/water mixture and emulsion.     

耐腐蚀超疏水超亲油不锈钢网的制备及其在油水分离过程中的应用

以不锈钢网为基底,通过化学刻蚀法制备微米级粗糙表面,通过一步浸泡法将st9ber法制得的疏水亲油纳米Si O2颗粒沉积到粗糙的不锈钢网表面,制备了具有微纳二级粗糙结构的超疏水超亲油不锈钢网。利用扫描电子显微镜(SEM)、傅里叶变换红外光谱仪(FT-IR)和接触角测量仪(CA)表征了超疏水超亲油不锈钢网的表面形貌、化学组成和润湿性能,并将其用于油水分离过程中。结果表明,疏水亲油纳米Si O2颗粒成功的沉积到不锈钢网表面;水滴在超疏水超亲油不锈钢网上的接触角最大为151°,煤油的接触角为0°;制备的超疏水超亲油不锈钢网不仅能高效的分离不同种类油和水的混合物,还能高效的分离油和腐蚀性液体(强酸或强碱水溶液)的混合物,其耐腐蚀特性可满足复杂环境下的油水分离要求。     

Superhydrophobic–superoleophilic electrospun nanofibrous membrane modified by the chemical vapor deposition of dimethyl dichlorosilane for efficient oil–water separation

Superhydrophobic and superoleophilic functionalized electrospun poly(vinylidene fluoride) (PVDF) membranes with water repellence, breathability, and oil-sorption and oil–water separation properties were achieved with a combination of an electrospinning technique and the chemical vapor deposition of dichlorodimethyl silane. The samples were laterally characterized by scanning electron microscopy, atomic force microscopy, water contact angle measurement, and Fourier transform infrared spectroscopy. The maximum water contact angle value was 152.0 ± 2.5° for the PVDF nanofibrous membranes with 500 μL of deposited silane (PMS2) obtained under certain conditions. The PMS2 membranes showed 100.0, 93.7, 23.3, 35.0, and 100.0% separation efficiencies for n-hexane, kerosene, crude oil, frying oil, and toluene, respectively. The understudy membrane exhibited reasonable waterproofness and remarkable breathability (water vapor transition rate = 215.21 g/m².h). Moreover, the superhydrophobic and superoleophilic nanofibrous membranes also showed good reusability, stability, moderate water-repellent properties, breathability, antifouling properties, and oil–water separation ability after several cycles. These properties confirmed potential in feasible applications, including protective cloths and in the purification of oil-polluted water. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47621.     

Facile fabrication of robust superhydrophobic cotton fabrics modified by polysiloxane nanowires for oil/water separation

The removal of oil and organic pollutants from water is highly desired due to increasing industrial oil-contaminated wastewater, as well as frequent oil spill accidents. In this paper, superhydrophobic and superoleophilic fabrics were facilely fabricated for oil/water separation application via in situ growth of polysiloxane nanowires on cotton fabrics. The polysiloxane nanowires were immobilized on the cotton fabrics through a self-assembly process of alkylsilane on the microfibers of fabrics. The combination of the hierarchical structure and the low-surface-energy polysiloxane nanowires greatly contributed to the superhydrophobicity of the fabrics. Furthermore, the superhydrophobicity remained even after they were exposed to different chemicals for 72 h and strong ultraviolet irradiation and repeated abrasion, indicating excellent stability. More importantly, the as-prepared cotton fabrics were successfully used for separating various oil/water mixtures by a solely gravity-driven process with high separation efficiency and desirable durability. The cotton fabrics are commercially available, low-cost, and environmentally friendly materials, and thus such superhydrophobic and superoleophilic cotton fabrics could be very attractive for oil/water separation and oil spill cleanup when high flexibility, strength, and chemical resistance are taken into account.     

Fabrication of superhydrophobic electrospun polyimide nanofibers modified with polydopamine and polytetrafluoroethylene nanoparticles for oil–water separation

The oil–water separation technologies of removing oil pollutants from water in an efficient and economical way is a challenge. The current methods used for oil–water separation suffer many shortcomings, including a low separation efficiency, complex separation equipment, high operation costs, and secondary pollution. In this study, we fabricated a highly flexible, high-intensity, quite stable superhydrophobic and superoleophilic polyimide (PI) nanofibrous membranes, which are much more efficient and cost efficient for oil–water separation by modifying the membranes with a polydopamine (PDA) solution and polytetrafluoroethylene (PTFE) dispersion. The fabricated membrane (PDA–PTFE–PI) possesses both the high tensile stress of PI and the superhydrophobic and superlipophilic properties of the PDA–PTFE coating. The modified membrane could separate various oil–water mixtures efficiently at a high flux (6000 L·m⁻²·h⁻¹) and an extremely high efficiency (>99%). Furthermore, even when the membrane was under an extremely hostile environment (with an ultrahigh temperature, strong acidity, or strong basicity), it still remained quickly stable with a good separation efficiency and recyclability after 10 cycles. We anticipate that our study will provide a new technology for the highly efficient mass production of oil–water mixture management. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47638.     

Vertically zeolitic imidazolate framework-L coated mesh with dagger-like structure for oil/water separation

The novel functional superwettable materials for high-efficiency oil/water separation are urgently required due to oil pollution in water body caused by oil tanker accidents, seabed oil production, and oil from refineries and petrochemical plants. Here, the superhydrophobic and superoleophilic zeolitic imidazolate framework-L (ZIF-L) mesh with antimicrobial effect was successfully fabricated by in-situ growth, composed of vertically ZIF-L with micro-/nanodagger-like structure and exhibited the water contact angle of 155.4 ± 1.8° and the oil contact angle of 0° in air. Furthermore, ZIF-L was verified to have an excellent antimicrobial activity, which endowed ZIF-L mesh with good antimicrobial performance. ZIF-L mesh provided a permeation flux with 1.75 × 10⁵ L m⁻² hr⁻¹ and 99.7% separation efficiency after 10 cycles operations for water mixtures with isooctane and presented optimal stability. Accordingly, the results demonstrated that ZIF-L as a new material shows an attractive applied promise for oil/water separation in industry.     

A facile method to functionalize engineering solid membrane supports for rapid and efficient oil–water separation

A facile and low-cost method is developed to functionalize engineering metal membrane supports, such as stainless steel (SS), with epoxy-containing polymer poly(glycidyl methacrylate) (PGMA) to produce a versatile and universal platform for subsequent surface modification. With a PGMA anchoring layer, we have demonstrated that hydrogel particles, such as polyacrylamide-co-poly(acrylic acid) (PAM-co-PAA), can be subsequently grafted to form functional polymer membranes for rapid and efficient oil–water separation. By contact angle and AFM measurement, we have confirmed that PAM-co-PAA hydrogel particle layer grafted on a PGMA-modified SS surface exhibits excellent selectivity as required for liquid–liquid separation, showing high affinity to water but not to oils as an ideal membrane for oil–water separation. To evaluate the separation efficiency, a simple flow-through device is employed to separate free-floating oil from water in the mixture of varied initial oil volume fraction and oil composition. Under substantially high pump flow rate up to 1.3 L/min, PAM-co-PAA hydrogel treated SS mesh can achieve excellent separation efficiency with less than 5% oil or water in the respective filtrate at the flux of as high as 540 m³/(m²·h) and retentate at the flux of 1.95 m³/(m²·h). This separation efficiency is better than, or comparable to, the maximal performance achieved using conventional gravity methods at much lower flow rate. Similar approach could be also adapted to graft superhydrophobic and superoleophilic polymer membranes with PGMA-treated engineering support to separate water from oil.     

One-pot fabrication of robust hydrophobia and superoleophilic cotton fabrics for effective oil-water separation

A one-pot sonochemical irradiation method was developed for the fabrication of superhydrophobic and superoleophilic cotton fabric from a solution consisting of branched silica nanoparticles and tetraethoxysilane-dodecyltrimethoxysilane sol. The silica/sol-coated cotton fabric could be wetted by liquids of low surface tension, but was water repellent with a water contact angle of 159 ± 1.2° and water shedding angle of 6 ± 0.8°. The as-prepared cotton fabric could be used as effective materials for the separation of oil from water with separation efficiency as high as 98.2% and maintained separation efficiency above 94% after 30 separation cycles for the kerosene-water mixture. Moreover, the superhydrophobic and superoleophilic cotton fabric could maintain stable superhydrophobicity after treatment with strong acidic and alkali solutions, and harsh mechanical damage. Therefore, this reported robust superhydrophobic cotton fabric exhibits encouraging practical application for oil-water separation.     

A facile approach in fabricating superhydrophobic and superoleophilic poly (vinylidene fluoride) membranes for efficient water–oil separation

New preparation strategies for films that exhibit separation of emulsified oil/water mixtures through a simple, practical, and cost‐effective method are highly desirable. Herein a poly (vinylidene fluoride) membrane with superhydrophobic and superoleophilic surface had been successfully fabricated via a facile dip‐coating process. As‐prepared membrane exhibits good stability of wettability and can be applied for oil and water mixture separation. After cycles, the membranes still keep a relatively high flux, which indicates their great potential for practical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42077.     

Superhydrophobic-superoleophilic heptafluorodecyl triethoxysilane/graphitic carbon spheres Co-modified porous monolith for water/oil separation

Water/oil separation has been a flourishing research focus due to severe oil-spill accidents. The current work reports on preparation, characterization and water/oil separation performance of heptafluorodecyl triethoxysilane (FAS) and graphitic carbon spheres (GCS) co-modified mullite porous ceramic (FAS/GCS-MC) with superhydrophobic and superoleophilic characters. The water contact angle of FAS/GCS-MC was determined as about 161°. The continuous water/oil separation rates for paraffin, vegetable and vacuum pump oils were 3.4 × 10⁴ g m⁻² min⁻¹, 2.2 × 10⁴ g m⁻² min⁻¹ and 1.3 × 10⁴ g m⁻² min⁻¹, respectively; even after 10 cycles, the separation rates remained almost unchanged in high selectivity (above 95%). The as-prepared FAS/GCS-MC was resistant to the temperature change and acid/base erosion, and showed stable superhydrophobicity and separation efficiency. In addition, the separation rate after applied a voltage to FAS/GCS-MC could be obviously enhanced by a self-heating process.     

One‐Pot Route for Fe@Poly(styrene‐co‐divinylbenzene) Foam with Robust Physical/Chemical Stability and Remote Magnetic Driven Capacity for Oil Removal

Magnetic and superhydrophobic materials with robust physical/chemical stability for controllable and remote magnetic driven capacity for oil removal under harsh environments are meaningful for oil–water separation but still a challenge. Herein, an alternative strategy to address this challenge is demonstrated by decorating poly(styrene‐co‐divinylbenzene) (PSDVB) on Fe foam via one‐pot solvothermal method. Different from previous magnetic and superhydrophobic materials, Fe foam is chosen to replace Fe₃O₄ nanomaterials. Thus, complicated preparation procedures and the high cost for Fe₃O₄ nanomaterials can be avoided. Additionally, PSDVB coating provides the whole foam with robust physical/chemical stabilities: i) the surface wettability can be maintained after 50 abrasion cycles or exposed in humid air (relative humidity: 90%) for 14 days, and ii) the surface wettability does not change under different pH solutions (3 < pH < 12) or highly salty solution (NaCl 10 wt%) for 6 h. Besides, outstanding separation efficiency (>99.9%), high durability (>70 times), and excellent oil flux (16 963–75 156 L m^?2 h^?1) can be realized under gravity. Most importantly, the foam continuously removes oil from confine place (on water surface or under water) under magnetic driven force.     

Porous carbon nanotube/polyvinylidene fluoride composite material: Superhydrophobicity/superoleophilicity and tunability of electrical conductivity

Porous carbon nanotube/polyvinylidene fluoride (CNT/PVDF) composite material can be fabricated via formation and freeze-drying of a gel. The field emission scanning electron microscopy, nitrogen adsorption–desorption and pore size distribution analysis reveal that the introduction of a small amount of carbon nanotubes (CNTs) can effectively increase the surface roughness and porosity of polyvinylidene fluoride (PVDF). Contact angle measurements of water and oil indicate that the as-obtained composite material is superhydrophobic and superoleophilic. Further experiments demonstrate that these composite material can be efficiently used to separate/absorb the insoluble oil from oil polluted water as membrane/absorbent. Most importantly, the electrical conductivity of such porous CNT/PVDF composite material can be tuned by adjusting the mass ratio of CNT to PVDF without obviously changing the superhydrophobicity or superoleophilicity. The unique properties of the porous CNT/PVDF composite material make it a promising candidate for oil-polluted water treatment as well as water-repellent catalyst-supporting electrode material.     

超疏水/超亲油SiO2薄膜的制备和表征

采用溶胶-凝胶法以正硅酸乙酯和甲基三乙氧基硅烷为共前驱体制备纳米疏水SiO2溶胶,经十二烷基三甲氧基硅烷(dodecyltrimethoxysilane,DTMS)改性后,制备出SiO2粒子薄膜,用红外光谱分析SiO2粒子的化学组成,用透射电镜观察凝胶时间对SiO2粒子形貌的影响,用扫描电镜和接触角表征SiO2涂膜的表...