Superoleophilic Properties Research Articles

Fabrication of superhydrophobic copper stearate@Fe3O4 coating on stainless steel meshes by dip-coating for oil/water separation

A robust superhydrophobic surface coated with copper stearate (CS) and Fe3O4 nanoparticles was prepared on stainless steel mesh (SSM) by dip-coating method for oil/water separation. The superhydrophobicity of CS@Fe3O4 SSM was found to be superior to that of SSM coated with bare CS because of the enhanced surface roughness by Fe3O4 nanoparticles. The CS@Fe3O4 SSM shows good performance in water repellency, self-cleaning property, long-term storage, mechanical and chemical stability. And it is capable of separating various immiscible oil/water mixtures even in extreme environments (such as highly acidic, alkaline, and salty solutions) with the separation efficiency > 98% and excellent recyclability. Furthermore, various surfactant-stabilized water-in-oil emulsions were successfully separated by the CS@Fe3O4 SSM due to its good superhydrophobic and superoleophilic properties as well as dense hierarchical micro/nanostructure. The preparing approach of CS@Fe3O4 SSM presented in this work is facile, inexpensive and environment-friendly, which enables the CS@Fe3O4 SSM to be applied in actual oil/water separation.

Robust Superhydrophobic Polytetrafluoroethylene Nanofibrous Coating Fabricated by Self-Assembly and Its Application for Oil/Water Separation

A novel and facile method is developed to fabricate polytetrafluoroethylene (PTFE) nanofibrous coating on both flat surface and curved micro metal fibers via self-assembly technique. The process starts from PTFE nanoparticles as building blocks and utilizes electrostatic interaction as self-assembly driving force followed by molecular rearrangement through thermal aging treatment. The formation process of nanofibers from nanoparticles was experimentally investigated and its mechanism was discussed in detail. As-prepared PTFE nanofibrous coating presented ultrathin morphology with high uniformity and outstanding chemical stability. Porous metal fiber sintered felt (PMFSF) coated with nanofibers exhibited superhydrophobic and superoleophilic properties and could separate various oil/water mixtures with high efficiency and good reusability. The coated PMFSF also presented excellent anticorrosion. Overall, the self-assembling fabrication method presented in this paper is simple, cost-efficient, productive, an...

Multifunctional oil-water and immiscible organic liquid separation by micropore arrayed Ti foil

In this work a multifunctional micropore array (size from 5 to 42 μm) was produced by using one-step femtosecond laser microdrilling for oil-water and oil-oil separation. This novel method has many advantages, such as high precision (size error is less than 1 μm), simple operation (one step), extensible function (even complex microstructures) just to name a few. The prepared foil exhibited superhydrophilic and underwater superoleophobic properties, which can be used to separate the light oil (C8H18) and water mixtures. After heating in dark environment 0.5 h, the prepared foil showed superhydrophobic and underwater superoleophilic properties, and can be used to separate the heavy oil (C2H4Cl2) and water mixtures. In addition, the heated sample also showed robust ability to separate the immiscible organic liquid mixtures (formamide and C2H4Cl2), exhibiting multifunctional applications. Interestingly, the heated samples would recover its original superhydrophilicity after UV irradiation in ethanol for 1 h. The samples don’t contain any fluorinated compounds and display environmental stability even after sonic cleaning and scratch. This work will provide a new insight into the design of intelligent devices for oil/water mixtures separation, organic liquid mixtures separation, and water droplet manipulation.

Fabrication of an Oil Spill Collector Package by Using Polyurethane Foam Wrapped with Superhydrophobic ZnO Microrods/Carbon Cloth.

A new package, including polyurethane foam wrapped with superhydrophobic ZnO microrods/carbon cloth with long-life elasticity, was fabricated and was utilized for oil spill clean-up. First, the carbon cloth (CC) was coated with ZnO microrods, which were modified with stearic acid (SA) to obtain superhydrophobic and superoleophilic properties. The coating process was conducted in mild conditions, involving the hydrothermal growth of ZnO microrods on the surface of the carbon cloth. The obtained hydrophobic sample was modified to a superhydrophobic one by adsorption of stearic acid (SA) on its surface. The prepared sample (CC/ZnO/SA) was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and contact angle measurements. The prepared sample shows a water contact angle (WCA) of 160°. A piece of polyurethane foam was wrapped with the prepared superhydrophobic CC/ZnO/SA making an oil collecting package, which can float on the water surface and absorb various oils from the water surface in both static and turbulent conditions very quickly. The prepared package exhibits excellent mechanical robustness and can be used several times for oil/water separation without capacity decrease. The kinetics of oil spill absorption by the prepared package were studied, too.

Highly hydrophobic ZIF-8 particles and application for oil-water separation

ZIF-8(zinc-methylimidazolate framework-8) is reported for selective removal of oils from water surface, Experiment results show that the highly hydrophobic ZIF-8 particles could be reused in water-oil separation for 20 cycles. • The as-synthesized ZIF-8 exhibited highly hydrophobic and superoleophilic properties. • The highly hydrophobic ZIF-8 particles could be reused in water-oil separation for twenty cycles. • ZIF-8 particles could be regenerated by heating combined with reduced pressure treatment. ZIF-8(zinc-methylimidazolate framework-8), one of the zeolitic imidazolate frameworks (ZIFs), was put into a tea bag for selective removal of oils from water surface, and exhibits strong hydrophobicity with a water contact angle of 142°, ZIF-8 particles combined with highly hydrophobic and superoleophilic properties. Our Experiment results showed that the highly hydrophobic ZIF-8 particles and the ZIF-8/tea bag could be reused in oil-water separation for twenty cycles. More importantly, the oil could be readily removed from the surfaces of particles by heating combined with reduced pressure treatment whereas the particles still kept highly hydrophobic and superolephilic characteristics, which render its potential applications in the cleanup of oil spills and the removal of organic pollutants on water surface.

Superhydrophobic, ultralight and flexible biomass carbon aerogels derived from sisal fibers for highly efficient oil–water separation

With the massive discharge of industrial oily wastewater and the frequent occurrence of oil spills at sea in recent years, the fabrication of superhydrophobic and durable oil-absorbing materials is urgently required for oil recovery and disposal of oily water in practical applications. In this paper, ultralight, elastic, superhydrophobic and durable carbon fiber aerogels (CFAs) derived from sisal leaves were prepared via simple alkalization, bleaching, freeze-drying and carbonization. The prepared CFAs were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption, contact angle measurement and scanning electron microscopy. The as-prepared CFAs with 3D porous architectures and excellent flexibility under compression were found to be effective oil absorption material for various oils and organic solvents. Textural analyses showed that the CFAs consist of fiber morphologies with high porosity originating from vacancies between individual fibers. The nitrogen sorption analysis confirmed that the material is mesoporous with average pore diameter of 3.03 nm and Brunauer–Emmett–Teller surface area of 399.85 m2/g. The contact angle measurements revealed that CFAs show both superoleophilic and superhydrophobic properties simultaneously with an oil contact angle of 0° and a static water contact angle of 153 ± 1°, thus the aerogels possessed a good oil–water separation ability. Furthermore, the CFAs exhibited a superior absorption capacity in the range from 90 to 188 times of their own weight for different organic solvents and oils. After recycling 10 times, the CFAs still exhibit excellent oils absorption properties, as well as exhibit excellent stability under harsh conditions, showing that the CFAs has excellent reusability performance. This work provides a green strategy to utilize low-cost biomass as raw materials to fabricate superhydrophobic CFAs as an oil absorbent, which has great potential in application of disposal of oily water and environmental protection.

Facile fabrication of asphaltene-derived graphene-polyurethane sponges for efficient and selective oil-water separation

ABSTRACTBased on the natural graphene-structure in the raw asphaltene material, a graphene-polyurethane sponge (GPU) oil-absorption material was prepared via a facile and inexpensive route of dip-coated sponge carbonization, which used low-value petroleum asphlatene as the dip-coating reagent and polyurethane sponges as the template. The GPU presents high hydrophobic and super oleophilic properties, as well as the excellent oil absorption performance. And its chloroform absorption capacity could reach 123 times its original mass, which is significantly higher than that of most reported oil absorbents. Furthermore, the GPU exhibits good recyclability. It has the promising applications in the pollution control of spilt oil.

On-demand oil-water separation via low-voltage wettability switching of core-shell structures on copper substrates

A copper mesh with dendritic copper-oxide core-shell structure is prepared using an additive-free electrochemical deposition strategy for on-demand oil-water separation. Electrochemical manipulation of the oxidation state of the copper oxide shell phase results in opposite affinities towards water and oil. The copper mesh can be tuned to manifest both superhydrophobic and superoleophilic properties to enable oil-removal. Conversely, switching to superhydrophilic and underwater superoleophobic allows water-removal. These changes correspond to the application of small reduction voltages (<1.5 V) and subsequent air drying. In the oil-removal mode, heavy oil selectively passes through the mesh while water is retained; in water-removal mode, the mesh allows water to permeate but blocks light oil. The smart membrane achieved separation efficiencies higher than 98% for a series of oil-water mixtures. The separation efficiency remains high with less than 5% variation after 30 cycles of oil-water separation in both modes. The switchable wetting mechanism is demonstrated with the aid of microstructural and electrochemical analysis and based on the well-known Cassie-Baxter and Wenzel theories. The selective removal of water or oil from the oil-water mixtures is driven solely by gravity and yields high efficiency and recyclability. The potential applications for the relevant technologies include oil spills cleanup, fuel purification, and wastewater treatment.

Facile fabrication of superhydrophobic nanocomposite coating using modified silica nanoparticles and non-fluorinated acrylic copolymer

A superhydrophobic nanocomposite coating was fabricated using a simple procedure. The nanocomposite is composed of an acrylic copolymer and modified silica nanoparticles. The acrylic copolymer was prepared by free radical copolymerization of methyl methacrylate and dodeycl methacrylate monomers. Silica nanoparticles were synthesized and modified with an alkyl silane reagent, hexadecyltrimethoxysilane. A mixture of acrylic copolymer and modified silica nanoparticles, dispersed in dichloromethane, was then sprayed on glass and filter paper surface. Chemical composition and structure of the coatings were investigated by FTIR, FESEM, AFM, 1H-NMR and GPC. The wettability of the prepared coating was examined by water contact angle measurement. The results showed that superhydrophobic surfaces with contact angle above 150° and rough structures were obtained. The prepared coatings also exhibited superoleophilic and self-cleaning properties.

A novel Cu(OH)2 coated filter paper with superhydrophobicity for the efficient separation of water-in-oil emulsions

A novel filter paper (FP) with superhydrophobicity and superoleophilicity was prepared via adsorption and immersion process for the separation of surfactant-stabilized water-in-oil emulsions. The realization of superhydrophobicity with a water contact angle of 153° benefits from the Cu(OH)2 nanostructure formed on FP and subsequent stearic acid (STA) modification. The three-dimensional network of FP as well as superhydrophobic and superoleophilic property can facilitate the demulsification of emulsified oil, thus the only gravity-driven separations of various water-in-oil emulsions with high oil flux and good recyclability have been achieved. The superhydrophobic FP can be massively applied in emulsion separation due to its facile preparation and superior performance.

Investigating the effect of surface composition and morphology on oil/water separation efficiency of sponges coated with polymer nanocomposites

As a worldwide challenge, the oil spillage has gained tremendous attention within the last few years. In this work, a facile method is proposed to fabricate sponges treated with polydimethylsiloxane (PDMS) and modified/unmodified silica nanoparticles exhibiting superhydrophobic and superoleophilic properties for enhanced oil/water separation. The main aim is to delineate the role of surface composition versus surface morphology by employing different formulations. Scanning electron microscopy results demonstrated that a rough structure, induced by formation of a packed assembly of nanoparticles, gives a major contribution to the obtained superhydrophobic behavior. It was also proved that the surface modification of silica nanoparticles might play an even more important role in attaining superhydrophobicity. Once a combination of PDMS and modified silica was used, different oil/water mixtures were efficiently separated. On the other hand, surface composition of the coating was found to be the major factor affecting wettability of sponges and their capability to separate water/oil mixtures. Therefore, results of this study can be used as a hint for designing more efficient sponge‐based systems modified with polymer nanocomposites for oil/water separation applications. POLYM. COMPOS., 40:E431–E439, 2019. © 2018 Society of Plastics Engineers

Fabrication of a novel superhydrophobic and superoleophilic surface by one-step electrodeposition method for continuous oil/water separation

A novel superhydrophobic and superoleophilic surface was fabricated by one-step electrodeposition on stainless steel meshes, and the durability and oil/water separation properties were assessed. Field emission scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR) and optical contact angle measurements were used to characterize surface morphologies, chemical compositions, and wettabilities, respectively. The results indicated that the as-prepared mesh preformed excellent superhydrophobicity and superoleophilicity with a high water contact angle (WCA) of 162±1° and oil contact angle of (OCA) 0°. Meanwhile, the as-prepared mesh also exhibited continuous separation capacity of many kinds of oil/water mixtures, and the separation efficiency for lubrication oil/water mixture was about 98.6%. In addition, after 10 separation cycles, the as-prepared mesh possessed the WCAs of 155±2°, the OCAs of 0° and the separation efficiency of 97.8% for lubrication oil/water mixtures. The as-prepared mesh also retained superhydrophobic and superoleophilic properties after abrading, immersing in salt solutions and different pH solutions.

Preparation of nanoclay incorporated PAN fibers by electrospinning technique and its application for oil and organic solvent absorption

ABSTRACTIn this work, polymer nanofibers (PAN/n-OMMT clay) were successfully produced by using an electrospinning process. The PAN/n-OMMT nanofibers were studied as an oil and solvent absorbent material due to their super hydrophobicity and super oleophilic properties. The generated composite nanofibers were found to have a very high oil and solvent absorption capacity in the case of 3% n-OMMT clay loading. It showed excellent absorption capacity up to 160 times its own weight for motor oil. The findings reported in this work might provide a fast and facile approach for the removal of oils and organic solvents on water surfaces.

Superwetting polypropylene aerogel supported form-stable phase change materials with extremely high organics loading and enhanced thermal conductivity

The development of high efficient materials or devices for storage and utilization of sustainable thermal energy should be of great importance in alleviating energy crisis. Herein, we reported the fabrication of superwetting polypropylene (PP) aerogel as the support materials for construction of form-stable phase change materials (PCMs) composites. Due to its abundant porosity, light weight of aerogel in nature, inherent superhydrophobic and superoleophilic properties, lipophilic organic PCMs can be loaded into PP aerogel (PP/PCM) with a high PCMs loading of up to 1060wt%, which is nearly two orders of magnitudes higher than those mostly reported form-stable PCMs systems. The PP/PCM composites show high latent heat in the range of 141.1kJkg−1 to 159.5kJkg−1 and excellent thermal stability and recyclability where their latent heat nearly remains unchanged even after 50 times of melting/freezing cycles. Results obtained from the X-ray diffraction (XRD) show that the incorporation of organic PCMs into PP aerogel network decreases the crystal size of PCMs in the composites. More interestingly, the PP/PCM composites show an enhanced thermal conductivity, in the case of PP/Paraffin composite, which is over two times of that of paraffin. Having the advantages of low cost and abundant resource of PP, simple preparatory process, high PCMs loading, good stability, recyclability and thermal conductivity, this the PP/PCM composites may have great potential for renewable energy saving applications.

Special wettable nanostructured copper mesh achieved by a facile hot water treatment process

In this research, a special wettable copper mesh with superhydrophobicity and superoleophilicity properties is reported using a low-cost, eco-friendly, rapid, and scalable synthesis method. Hot water treatment (HWT) method is used to integrate the micro-textured copper mesh surface with a nanoscale roughness to achieve a hierarchical micro-nano structured surface. The surface energy of the nanoscale roughened copper mesh reduced by coating the hot water treated mesh with polymer ligands containing thiol or fluorine functional groups of low energy. Surface morphology characterization showed the formation of copper oxide nanostructures on the mesh surface by hot water process performed at 95 °C and under a low dissolved oxygen condition. X-ray diffraction patterns reveal the development of stable, uniformly distributed, and compactly arranged, cubic and plate-like nanostructures of cuprous oxide (Cu2O) on the copper mesh surface. The surface wettability of the as-prepared copper mesh was assessed by contact angle (CA) measurement for water and several oils and organic solvents. CA values showed the formation of special wettable copper mesh surface with superhydrophobic property with water contact angle of about 157° and superoleophilic property with oil contact angle as low as 0°. In addition, the effect of the mesh’s geometry on the wetting property was examined through correlations between wire diameter, pore size, and optimal values for the highest water CA.

On-demand oil/water separation of 3D Fe foam by controllable wettability

Oily pollution has become a worldwide problem due to the increasing of oil spill accidents as well as the discharge of oily wastewater. Material with superhydrophobic or underwater superoleophobic characteristic to deal with oily pollution have been reported frequently, but material with controllable wettability transition properties were still few been reported. Herein, we presented a facile, efficient, economical method to prepare a superwetting Fe foam that could achieve controllable wettability transition by modification and annealing alternately. The modified foam showed superhydrophobic and superoleophilic properties (oil-removing mode), which can be used for the filtration of heavy oil in the oil/water mixtures. With the annealing treatment, the as-prepared sample exhibited superhydrophilic/underwater superoleophobic characters (water-removing mode), which allowed water to pass through but blocked light oil. Besides, the as-prepared foam could separate various oil/water mixtures and show high separation efficiency. We are hoping that the controllable wettability filtration sample could realize on-demand oil/water separation and provide a new idea to solve the oil pollution problem.

Facile transformation of soot nanoparticles into nanoporous fibers via single-step electrospinning

A facile technique to transform candle soots into nanoporous fibers via electrospinning of mixed solution of candle soots and polyvinylidene fluoride (PVDF) has been demonstrated for the first time. Due to insolubility of soot nanoparticles and good solubility of PVDF polymer in DMF/acetone solvents, the soot molecules are heterogeneously dispersed in the mixed solutions. The selection of an appropriate polymer concentration resulted in a good dispersion of the low-density soot nanoparticles which can be held for electrospinning. The electrospinning experiment shows that soot nanoparticles can be smoothly bonded with PVDF molecules to form nanoporous fibers. The unique superhydrophobic and superoleophilic properties of the as-prepared electrospun fibrous membrane were demonstrated by subjecting it to various aqueous liquids and oils. This work provides a simple way to transform low-density nanoparticles into high-performance nanoporous nanofibers, which should broaden the applications of electrospinning.

Novel electrospun superhydrophobic sorbent for petroleum fingerprinting analysis

Development of affordable sorbents for solid phase extraction (SPE) in petroleum fingerprinting analysis is crucial in petroleum and petrochemical industries due to energy demand. In this paper, composite fibre based on expanded polystyrene and zeolite was nanostructured to nanoporous fibre with Type II + IV classification and superhydrophobic–superoleophilic properties. The potential of this composite fibre as SPE sorbent in petroleum fingerprinting was investigated and its efficiency was compared with commercial sorbents [alumina, silica and alumina/silica (hybrid)] cartridges. The chromatograms showed that the packed electrospun composite fibre demonstrated excellent cleaning and enrichment properties for SPE applications relative to the hybrid cartridges. This presents a novel re-use pathway for expanded polystyrene, promotes fast analysis and cost reduction in petroleum fingerprinting.

Nanosilica-decorated sponges for efficient oil/water separation: role of nanoparticle’s type and concentration

Oil absorption by porous materials is currently regarded as a very efficient method for water purification and oil spill cleanup. Simultaneous induction of superhydrophobic and superoleophilic properties into porous materials was conducted in this study via surface decoration of sponges by nanosilica. The main aim was to investigate the effects of nanosilica concentration on the final wetting behavior of the sponges. To this end, the sponges were treated with both modified and unmodified nanosilica particles through a simple dipping process. It was found that only a moderate concentration of nanoparticles (2 vol%) causes the sponges surface to be uniformly decorated with silica. Based on X-ray photoelectron spectroscopy results, it was postulated that surface energy of the sponges was a more influential factor in the final wetting behavior as compared with the surface roughness. The values of oil absorption capacity were varied in the range of 51–72 g/g (gram of oil per gram of sponge) for the superhydrophobic sample using four different oils and organic liquids. It was concluded that the prepared sponges definitely possess promising potential in the separation of oil/water mixtures provided that an optimum concentration of nanosilica with proper surface modification is used.

Superhydrophobic Rubber-Modified Polybenzoxazine/SiO2 Nanocomposite Coating with Anticorrosion, Anti-Ice, and Superoleophilicity Properties

The integration of nanometer-sized fillers into polymer matrices to create nanocomposite materials has attracted a great deal of interest, not only because these materials can be tailored to specific practical applications but also because they can exhibit synergistic combinations of properties that display multifunctionality. Herein, we successfully incorporated silica (SiO2) nanoparticles into the rubber-modified polybenzoxazine (PBZ) by mixing and applied as a nanocomposite coating that exhibits both superhydrophobicity and superoleophilicity through a facile dipping and spraying technique. We used PBZ, not only because of its near-zero shrinkage upon polymerization, chemical resistance, and good dielectric, thermal, and mechanical properties but also because, most importantly, of its low surface free energy and low water absorptivity. With superhydrophobicity coexisting with superoleophilicity in one material, potential anticorrosion, anti-ice, and organics/water separation applications of the coating...