Oil Contact Angle Research Articles

Superhydrophilic photocatalytic g-C3N4/SiO2 composite membranes for effective separation of oil-in-water emulsion and bacteria removal

Conventional membrane processes, e.g., microfiltration and ultrafiltration, suffer from severe permeation flux decline and fouling during the oily wastewater treatment. The superhydrophilic surface decoration provides an important and effective strategy to address this challenge. Herein, a surperhydrophilic/underwater superoleophobic nanocomposite surface with the photocatalytic properties was constructed via one-step facile vacuum-assisted filtration of a g-C3N4 nanosheet/SiO2 nanoparticle dispersion onto a microfiltration membrane substrate. Specifically, with the intercalation of 20 mg∙L−1 SiO2 nanoparticles into the g-C3N4 nanosheets, the g-C3N4/SiO2 composite membrane showed the superhydrophilic/underwater superoleophobic properties with an underwater oil contact angle of 170.0 ± 0.3°. Such a g-C3N4/SiO2 composite membrane yielded a permeation flux of >1290 LMH·bar−1 with an oil rejection of >99.91% during the vacuum filtration of oil-in-water emulsions. The g-C3N4/SiO2 composite membrane significantly outperformed the pristine microfiltration substrate that had severe fouling caused by oil blockage. Additionally, the g-C3N4/SiO2 composite membrane not only effectively retained the E. coli bacteria through size exclusion effect, but also promoted the inactivation of bacteria via visible-light photocatalysis. Therefore, our membrane has a great promise in practical oily wastewater treatment due to its excellent separation performance and biofouling resistance.

Effect of Fluid Contact Angle of Oil-Wet Fracture Proppant on the Competing Water/Oil Flow in Sandstone-Proppant Systems

Ceramic fracture proppants are extensively used for enhancing the recovery of fossil energy and geothermal energy. Previous work has reported the attracting-oil-repelling-water (AORW) property of oil-wet proppants at the faces of fractures. Because of the lack of a method for measuring the contact angle of proppant packs, the terms water-wet proppant and oil-wet proppant were defined based on observations of liquid droplets on the surfaces of proppant packs without quantitative measurement. An innovative method was developed in this study to determine the contact angles of fracture proppant packs. The effect of the oil contact angle of the oil-wet fracture proppant pack on the competing water/oil flow from sandstone cores to the packs was investigated. It was found that, for a given fracture proppant pack, the sum of the water contact angle and oil contact angle measured in the liquid–air–solid systems is less than 180°, i.e., the two angles are not supplementary. This is believed to be due to the weak wetting capacity of air to the solid surfaces in the liquid–air–solid systems. Both water and oil contact angles should be considered in the classification of wettability of proppant packs. Fracture proppant packs with water contact angles greater than 90° and oil contact angles significantly less than 90° can be considered as oil-wet proppants. Reducing oil contact angles of oil-wet proppants can increase capillary force, promote oil imbibition into the proppant packs, and thus improve the AORW performance of proppants. Fracture proppant packs with water contact angles less than 90° and oil contact angles less than 90° may be considered as mixed-wet proppants. Their AORW performance should be tested in laboratories before they are considered for well fracturing operations.

Porous Al2O3 ceramics with directional gradient pore structure modified by cobweb-bridged WO3 nanowires for oil/water emulsions separation

A novel Al2O3 ceramic membrane modified by cobweb-bridged WO3 nanowires was successfully fabricated for oil/water emulsions separation. Freeze-casting was employed to obtain directional gradient Al2O3 porous ceramics at first. Then, the cobweb-bridged WO3 nanowires were successfully introduced into the separation layer by in-situ hydrothermal synthesis to construct the WO3 nanowires/Al2O3 membrane. Results showed that WO3 nanowires increased the surface roughness from 45.9 nm to 54.8 nm, the instantaneous water contact angle (WCA) and underwater oil contact angle (UOCA) reached the optimum values of 8.5° and 157.8°, respectively. Construction of cobweb-bridged WO3 nanowires not only achieved a high separating efficiency of oil/water emulsions up to 92.35%, but also maintained high permeation fluxes at around 1600 L/m2·h·bar. After 10 cycles, the separation efficiency of the membrane remained above 90%. Moreover, the WO3 nanowires/Al2O3 membrane still maintained underwater superoleophobicity after being immersed in strongly acidic, alkaline, and saline solutions, showing a high UOCA above 150° for all tested oil. The WO3 nanowires/Al2O3 membrane is promising in oil/water emulsions separation application for its high separation efficiency, durability, and excellent chemical stability.

Superhydrophobic porous polyvinylidene fluoride monolith with outstanding environmental suitability for high-efficient continuous oil/water separation under harsh conditions

The actual cleanup of oil spill and chemical leakage is usually implemented in harsh environments, thus oil absorbents possessing excellent environmental suitability are urgently required for high-efficiency oil/water separation. Herein, a novel three-dimensional porous polyvinylidene fluoride (PVDF) monolith with multi-environmental tolerance was facilely prepared via thermally impacted nonsolvent-induced phase separation method. In view of its unique pore structure and low surface energy, the PVDF monolith owned super-hydrophobicity (water contact angle = 154°) and super-oleophilicity (oil contact angle = 0°) without any modification. As an oil absorbent, the porous monolith exhibited outstanding oil/water separation performance for various oils/organic solvents, such as preeminent separation efficiency, high saturation absorption capacity (21.3 g g−1) and rapid absorption speed (reaching saturation state within 15 s). More importantly, the monolith revealed stable and prominent oil/water separation capability under harsh conditions involving intense ultraviolet radiation (72 h), rapidly alternating temperature (−20 to 65 °C), extreme pH, oil-water emulsion, strongly turbulent water, suspended solids (sand and tea leaf). It is worth noting that the monolith was capable of continuously and efficiently separating oil/organic solvent from water by a simple pump-assisted system (soybean oil flux reached 3520 L m−2 h−1 at 0.06 MPa). A small piece of PVDF monolith (0.132 g) was able to continuously separate at least 16,000 times its own weight of soybean oil and could be reused for 5 cycles. Based on the superior environmental suitability and continuous oil/water separation capability, the porous PVDF monolith has a tremendous potential to clean up large-scale oil contaminants in leakage accidents.

Poly (methyl methacrylate) grafted wheat straw for economical and eco-friendly treatment of oily wastewater

The sustainable development of oil–gas and petrochemical industries necessitates the development of cost-effective and eco-friendly technologies to treat mass-produced oily wastewater discharge from these industries. This study applied a simple radical polymerization to enhance the oil adsorption efficiency of agricultural waste biomass wheat straw (WS) by grafting biocompatible poly(methyl methacrylate) (PMMA). Diesel oil adsorption from oil-in-water emulsion using the PMMA grafted WS was thoroughly studied for the first time in the quest of developing an economical and eco-friendly adsorbent for the adsorptive treatment of oily wastewater. The success of pre-treatment of pristine WS and the subsequent PMMA grafting were evaluated by SEM morphology, BET analysis, EDX and XPS elemental analysis, FTIR, and contact angle measurements. SEM images indicated that the inner interconnected tubular pore channels of WS are exposed significantly upon alkaline hydrogen peroxide pre-treatment. PMMA grafting substantially improved oil adhesivity, as evident from the 0° oil contact angle for WS-g-PMMA film. Oil absorptivity was thoroughly evaluated by batch oil adsorption study using variable adsorbent dosages and oil emulsion concentrations. The WS-g-PMMA exhibited explicitly higher adsorption capacity (ca. 1129 mg/g) compared to that of the pristine (ca. 346 mg/g) and pretreated (ca. 741 mg/g) due to high accessibility to exposed inner interconnected tubular pore channels and strong hydrophobic interactions between the WS-g-PMMA surface and oil droplets. Langmuir and Freundlich adsorption isotherms were applied to evaluate the adsorption mechanism. The experimental data fit well with the Freundlich isotherm, clearly indicating the heterogeneity of adsorption sites, as well as multilayer adsorption of oil. The experimental adsorption data fit well with the pseudo-second-order rate equation with R2 as high as 0.999, which confirmed the multilayer adsorption of oil. The high oil adsorption capacity of the WS-g-PMMA makes it a very promising material for oily wastewater treatment. The oil removal efficiency declined by < 4% at the end of 3 adsorption-regeneration cycles, indicating the possibility for long-term usage, which is beneficial for cost-effectiveness and lower frequency for end-use waste management. This will simultaneously resolve issues with the treatment of oily wastewater and facilitate the recycling of abundant quantities of waste WS. This study serves as a reference for analyzing the suitability of wheat straw for treating extremely challenging waste streams, such as steam assisted gravity drainage (SAGD) produced water containing BTEX and PAHs that are also hydrophobic like diesel oil.

Wettability Improvement in Oil-Water Separation by Nano-Pillar ZnO Texturing.

The nanostructure-based surface texturing can be used to improve the materials wettability. Regarding oil–water separation, designing a surface with special wettability is as an important approach to improve the separation efficiency. Herein, a ZnO nanostructure was prepared by a two-step process for sol–gel process and crystal growth from the liquid phase to achieve both a superhydrophobicity in oil and a superoleophobic property in water. It is found that the filter material with nanostructures presented an excellent wettability. ZnO-coated stainless-steel metal fiber felt had a static underwater oil contact angle of 151.4° ± 0.8° and an underoil water contact angle of 152.7° ± 0.6°. Furthermore, to achieve water/oil separation, the emulsified impurities in both water-in-oil and oil-in-water emulsion were effectively intercepted. Our filter materials with a small pore (~5 μm diameter) could separate diverse water-in-oil and oil-in-water emulsions with a high efficiency (>98%). Finally, the efficacy of filtering quantity on separation performance was also investigated. Our preliminary results showed that the filtration flux decreased with the collection of emulsified impurities. However, the filtration flux could restore after cleaning and drying, suggesting the recyclable nature of our method. Our nanostructured filter material is a promising candidate for both water-in-oil and oil-in-water separation in industry.

Facile fabrication of underwater superoleophobic membrane based on polyacrylamide/chitosan hydrogel modified metal mesh for oil–water separation

AbstractUsing chemically etched stainless steel mesh (SSM) as matrix, chitosan (CS) as the hydrophilic component and acrylamide as (AAm) monomer, the underwater superoleophobic membrane (PAAm/CS@SSM) for oil–water separation was prepared by free radical polymerization initiated by ultraviolet light. The composition, morphology, underwater oil contact angle, and structure of PAAm/CS@SSM were characterized by Fourier‐transform infrared spectroscopy, x‐ray powder diffraction, scanning electron microscopy, and confocal laser scanning microscopy. The underwater oil contact angles of PAAm/CS@SSM could reach 154.5°. When the number of oil–water cycles reached 20 times, the oil–water separation efficiency of PAAm/CS@SSM was larger than 99%. When the oil–water ratio is 1:3, 1:2, 1:1, 2:1, 3:1, the oil–water separation flux of PAAm/CS@SSM was 2096.8, 4457.9, 4735.7, 5395.7, and 3606.9 L·m·−2·h−1, respectively. When oils are n‐hexane, petroleum ether, vegetable oil, and liquid paraffin, the oil–water separation efficiency of PAAm/CS@SSM was 99.0%, 97.7%, 97.2%, and 99.3%, respectively. After the wear resistance test, the PAAm/CS@SSM membrane still exhibited underwater super‐oleophobicity (&gt;150°).

Superhydrophilic/underwater superoleophobic oil-in-water emulsion separation membrane modified by the co-deposition of polydopamine and chitosan-tripolyphosphate nanoparticles

Environmentally friendly separation materials are essential for separating emulsified oil-water mixtures. The nylon membrane has been facilely converted into highly hydrophilic and underwater superoleophobic via a simple one-step co-deposition of polydopamine and chitosan-tripolyphosphate (CS-TPP) nanoparticles, wherein the CS-TPP particles were prepared by the ion gel method. The modified membrane exhibited excellent antifouling performance with the underwater oil contact Angle (UOCA) at 179.6°. The prepared environmental CS-TPP@PDA@nylon membrane was characterized by SEM, EDS, FTIR, and XPS. The membrane could separate various oil-in-water emulsions in a wide range of average particle sizes (50.9–1832.0 nm). In addition, the CS-TPP@PDA@nylon membrane demonstrated high permeation flux (221.0–1770.5 L m−2 h−1) and good regeneration ability. The flux could still maintain more than 89% even after fifteen cycles. The degradable modification materials and simple preparation process would highlight the potential of modified membranes in large-scale production and green oily wastewater treatment.

Facile Preparation of Robust Superhydrophobic/Superoleophilic TiO2-Decorated Polyvinyl Alcohol Sponge for Efficient Oil/Water Separation

Oily wastewater and oil spills pose a threat to the environment and human health, and porous sponge materials are highly desired for oil/water separation. Herein, we design a new superhydrophobic/superoleophilic TiO2-decorated polyvinyl alcohol (PVA) sponge material for efficient oil/water separation. The TiO2–PVA sponge is obtained by firmly anchoring TiO2 nanoparticles onto the skeleton surface of pristine PVA sponge via the cross-linking reactions between TiO2 nanoparticles and H3BO3 and KH550, followed by the chemical modification of 1H,1H,2H,2H-perfluorodecyltrichlorosilane. The as-prepared TiO2–PVA sponge shows a high water contact angle of 157° (a sliding angle of 5.5°) and an oil contact angle of ∼0°, showing excellent superhydrophobicity and superoleophilicity. The TiO2–PVA sponge exhibits excellent chemical stability, thermal stability, and mechanical durability in terms of immersing it in the corrosive solutions and solvents, boiling it in water, and the sandpaper abrasion test. Moreover, the as-prepared TiO2–PVA sponge possesses excellent absorption capacity of oils or organic solvents ranging from 4.3 to 13.6 times its own weight. More importantly, the as-prepared TiO2–PVA sponge can separate carbon tetrachloride from the oil–water mixture with a separation efficiency of 97.8% with the aid of gravity and maintains a separation efficiency of 96.5% even after 15 cyclic oil/water separation processes. Therefore, the rationally designed superhydrophobic/superoleophilic TiO2–PVA sponge shows great potential in practical applications of dealing with oily wastewater and oil spills.

Superamphiphilic Chitosan Cryogels for Continuous Flow Separation of Oil-In-Water Emulsions.

Chitosan is a typical hydrophilic biomass building block widely used in material science and engineering. However, its intrinsic amphiphilicity has been seldom noted so far. Herein, a series of glutaraldehyde-crosslinked chitosan cryogels with superamphiphilicity are fabricated at moderately frozen conditions through a freezing–thawing process. The micron-sized porous cryogel samples display a 0° contact angle toward both water and oil, 0° water contact angle under oil, and over 120° oil contact angle underwater. By comparing the wetting behavior of the tablet compressed by pure chitosan powders, the superamphiphilicity of the chitosan sample is proven to be independent on crosslinkers. This special wettability endows the chitosan cryogels with high separation efficiency for various surfactant-stabilized oil-in-water emulsions under continuous flow mode driven by gravity as well as a peristaltic pump.

Expanded Polytetrafluoroethylene/Mxene Nanosheet Composites with Hydrophilicity and Lipophilicity for Purification of Oil Spills and Wastewater

The frequent occurrence of oil leaks and air pollution has had devastating and long-term impacts on the aquatic environment. Therefore, it is urgent to effectively address water sources and environments polluted by oil leaks. In this study, expanded polytetrafluoroethylene (ePTFE)/Mxene nanosheet composites with nanoscale double pore structures were constructed by combining PTFE particles with Mxene nanosheets, which improved the hydrophilicity, oil absorption capacity, and oil–water separation performance of the material, which relied on the degree of expansion and the Mxene content. The composition of the ePTFE/Mxene composites was confirmed by Fourier transform infrared spectroscopy, and the microstructure and morphology of the composites were examined by scanning electron microscopy. Oil and water contact angle tests showed that the ePTFE/Mxene composites have good hydrophilicity and lipophilicity. Oil absorption tests showed that ePTFE/Mxene has good oil absorption capacity and reusability. Due to their amphiphilic nature and their efficient oil absorption capacities, the ePTFE/Mxene nanosheet composites with dual pore structures exhibited good potential for practical applications in oil spill remediation and water separation/remediation.

Fabrication of novel superhydrophilic/underwater superoleophobic composite coatings and study on the relationship between their long-term wettability and excellent oil-water separation performance

A superhydrophilic/underwater superoleophobic composite coating (ES@SSM) was fabricated through etching and subsequent modification of stainless steel mesh (SSM). It had a water contact angle of 0° in the air, an oleophobic angle of 162.7° underwater, and a sliding angle of 5°. Even after 15 days, the separation efficiency of crude oil-water was up to 98.6% and had a high water flux of 13535 L m−2 h−1. After 50 sandy impacts, the ES@SSM had an oil contact angle of 158.5° and sliding angles of 13° underwater. Experimental results show that the water flux and the contact angle were closely related, and there was a negative correlation between the water flux and the water contact angle. Furthermore, the ES@SSM was featured with long-term stability, chemical stability and excellent mechanical stability. Apart from that, it has potential application value in the field of oil and water treatment.

Flexible CuO-rGO/ PANI thermal absorber with high broadband photoresponse and salt resistance for efficient desalination of oil-contaminated seawater

Solar Steam Generation (SSG) is a promising and efficient technology to limit the global water scarcity issue. Nevertheless, it is challenging to utilize versatile photothermal absorbers with salt-resistance and anti-oil-fouling capability through a facile, scalable, and cost-effective fabrication technique. This work demonstrated the combination of cheap semiconductor material with a porous ionic polymer (PIP), emeraldine salt (ES) form of polyaniline (PANI), as salt-resistant and oil-repellent evaporator, which was synthesized through a facile and cost-effective one-step method. PANI enhanced the photoresponse of the CuO-rGO and its honeycomb-like structure increased the photothermal conversion due to the multi-scattering of the incident light. The CuO-rGO/PANI achieved an evaporation rate of 2.02 kg m−2 h−1 and a solar-to-steam efficiency of 94.2% under 1 sun illumination. Furthermore, the composite presented high in-water (138.5°) and in-air (135.2°) oil contact angles with simultaneously high-water affinity (<8°) which proved the hydrophilicity and oleophobicity of this membrane. CuO-rGO/PANI can work effectively in high-concentration brine with no activity loss, due to the “Donnan exclusion” effect generated from cationic quinonoid and benzenoid structure of ES-PANI against cations from saline solution, which exhibit superb durable evaporation performance over 10 cycles.

Enzymatic preparation of hydrophobic biomass with one-pot synthesis and the oil removal performance

Oil pollution is causing deleterious damage to aquatic ecosystems and human health. The utilization of agricultural waste such as corn stalk (CS) to produce biosorbents has been considered an ecofriendly and efficient approach for removing oil. However, most previous studies focused on the modification of the whole CS, which is inefficient due to the heterogeneity of CS. In this study, corn stalk pith (CP), which has excellent amphipathic characteristics, was selected to prepare a high-efficiency oil sorbent by grafting dodecyl gallate (DG, a long-chain alkyl) onto CP surface lignin via laccase mediation. The modified biomass (DGCP) shows high hydrophobicity (water contact angle = 140.2°) and superoleophilicity (oil contact angle = 0°) and exhibits a high oil sorption capacity (46.43 g/g). In addition, DGCP has good stability and reusability for adsorbing oil from the aqueous phase. Kinetic and isotherm models and two-dimensional correlation spectroscopy integrated with FTIR analyses revealed that the main sorption mechanism involves the H-bond effect, hydrophobic effect and van der Waals force. This work provides an ecofriendly method to prepare oil sorbents and new insights into the mechanisms underlying the removal of spilled oil from wastewater.

Fabrication and characterization of transparent underwater superoleophobic coatings based chitin nanofibers and polyvinyl alcohol

AbstractTransparent underwater superoleophobic coatings were prepared by blending chitin nanofibers (ChNFs) and polyvinyl alcohol (PVA) and then cross‐linked with glutaraldehyde (GA). The interactions among ChNFs, PVA, and GA in the coatings were analyzed via FT‐IR and XPS. Results of SEM observation and AFM analysis showed that higher concentrations of ChNFs and GA gave rise to rougher surface and lower transmittance of the coatings. By adjusting ratios of ChNFs, PVA, and GA, the coating surface could possess underwater superoleophobicity with oil (1, 2‐dichloroethane) contact angle up to 159.2° and slide angle ~3°, meanwhile, transmittance of the coatings in the wavelength range of 400–800 nm could be maintained between 40% and 90%. This work provides a new route to prepare environmentally friendly transparent underwater superoleophobic coatings.

Modified PVA membrane for separation of micro-emulsion

Release of liquefied hydrocarbons in domestic and industrial effluents, along with oil spills cause significant adverse effects on the soil, water, aquatic ecosystem, and humans. Thus, selective and cost-effective technology to address this challenge is highly desirable. Here, we report the fabrication of electrospun polyvinyl alcohol (PVA) membrane, modified with glutaraldehyde (GA) and a device thereof, for treatment of oil emulsions and recovery of precious fossil fuel. The modified PVA membranes are super-oleophobic with a high static underwater oil contact angle of 163 ± 3° for motor oil. Investigation of wetting properties suggests that the membrane can efficiently separate different oils such as sesame oil, motor oil, mustard oil, and sunflower oil from their emulsions. The motor oil emulsion with separation efficiency of >99% at an excellent permeate flux of 5128 L/m2·h·bar has been achieved. Thus, the prepared modified PVA membrane construes an easy solution for not only effective treatment of oily wastewater but also for oil recovery with high flux.

Hierarchically porous superhydrophobic sponge for oil-water separation

Superhydrophobic vinyl terminated polydimethylsiloxane embedded polystyrene sponge (V-PDMS/PS) with hierarchical structure for efficient oil-water separation was constructed by the dual-emulsion-template route, based on polymerization of the water-in-oil (W/O) type high internal phase emulsions (HIPEs). A series of vinyl terminated polydimethylsiloxane (V-PDMS) was adopted as the organic phase as well as the hydrophobic modification reagent. Finally, the sponge material was composed of polystyrene (PS) skeleton embedded with V-PDMS chain, which exhibited an enhanced thermal stability compared with the pure polystyrene sponge. The obtained sponge exhibited an outstanding oil collection performance of 55.6 g/g–119.5 g/g towards representative oil pollutant. The polystyrene sponge features excellent recyclability, with about 90% recovery rate just by simple compression. Besides, it showed superhydrophobicity with water contact angles (WCAs) exceeding 150°, deriving from the hierarchically porous structure and the low-surface-energy of the V-PDMS. It also exhibited superoleophilicity with oil contact angle approaching 0°.

Polydopamine-CaCO3 modified superhydrophilic nanocomposite membrane used for highly efficient separation of oil-in-water emulsions

A superhydrophilic/underwater superoleophobic CaCO3@PDA@nylon nanocomposite membrane was prepared by a simple dip-coating method using a nylon 66 membrane in dopamine and nano CaCO3 particle aqueous solutions. The prepared CaCO3@PDA@nylon membrane was characterized by SEM, EDS, FTIR, and XPS. The underwater oil contact angle reached 159.7°. The modified membrane showed highly efficient oil-in-water emulsion separation performance for various viscous oils or organic solvents over a wide range from 126.8 to 6029.6 nm. Furthermore, the CaCO3@PDA@nylon membrane also demonstrated high permeation flux and good regeneration ability. Even with continuous reuse of 15 cycles, the flux was still high, e.g., 517.3 L m−2 h−1 for chloroform-in-water emulsions with an average particle size of 126.8 nm. The modified membrane's possible oil-in-water emulsion separation mechanism was obtained by combining fluorescence-assisted dripping, continuous filtration, and emulsion contact angle experiments. This work might provide a simple and environmentally friendly membrane modification method for general separation studies of high oil concentration oil-in-water emulsions. The simple preparation process and efficient and fast separation ability highlight its great potential in large-scale production and oily wastewater treatment.

Mussel-inspired fabrication of superior superhydrophobic cellulose-based composite membrane for efficient oil emulsions separation, excellent anti-microbial property and simultaneous photocatalytic dye degradation

Flexible multiple functional cellulose-based membrane (CM) for oil/water separation, anti-microbial and photodegradation are in great demand in marine wastewater treatment due to its’ effective and ecologically benign. Based on this requirement, MnO2 micro/nanoparticles were in situ deposited on CM sample surface followed by decoration of stearic acid (STA) for very effective oil/water separation, anti-fouling, and dye photodegradation triggered by visible light. The results demonstrated that this as-prepared CM sample showed superhydrophobicity with a water contact angle of 162 ± 2° and superoleophilicity with an oil contact angle of 0°. It also demonstrated exceptional high stability in hostile environments (acid and alkali solution, high temperature, wear resistance, underwater writing, self-cleaning) and a 2.6% increase in tensile strength. In addition, it can successfully separate emulsified oils from typical oil-in-water emulsions with good separation efficiency all over 98% and comparatively high flux (145.8 L·m−2·h−1). After 8 cycles, the separation efficiency of the n-hexane/water emulsion is still over 98%. Moreover, over 98% of MB was degraded by using superhydrophobic CM sample, indicating strong photocatalytic activity. Meanwhile, in the maritime environment, this biomimetic sample decreased the adherence of green algae by more than 95%, demonstrating strong anti-biofouling adhesion potential. It indicates that this cost-effective, scalable, environmental friendly, and efficient methodology presented superhydrophobic CM sample has the potential to promote the widespread development of multipurpose superwetting materials, with enticing potential for the treatment of complex 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.