Oil Contact Angle Research Articles

Fabrication of a superhydrophobic-superoleophilic particle material for oil-water separation and oil extraction

Oil-water separation has become a serious issue due to the increasing oily wastewater discharged in the environment and oil spills from time to time. Superhydrophobic and superoleophilic materials are a promising approach in oil-water separation. However, the preparation procedures for these materials are often complex and expensive, and their stability is not robust enough. In this study, superhydrophobic and superoleophilic particles are successfully prepared via a facile and green mixing method. Fluorocarbon resin, CaCO3 and SiO2 are coated on fly-ash cenospheres to form a stable superhydrophobic-superoleophilic surface, which exhibits a water and oil contact angle of 153.3° and 0°, respectively. To our knowledge, we’re unaware of any previous study reporting a superhydrophobic-superoleophilic material prepared in such a convenient way. The as-prepared superhydrophobic material can serve as high-performance filters for separating various oil-water mixtures, with a separation efficiency up to 99.2%. And it can be applied in water-in-oil emulsion separation. Meanwhile, the as-prepared particles are able to extract oils from oil-water mixtures and the oil-extraction capacity is up to 0.56 g/g. Furthermore, the obtained material has a robust stability against various hash conditions and a good recyclability. The simply-prepared superhydrophobic cenospheres are expected to be a promising candidate for application in diverse oil-water separation situations.

Transparent and anti-smudge ladder-like polysilsesquioxane coating with high wear resistance and UV aging resistance

With the rapid development of multi-function touch panels, more requirements are raised for touch screens including anti-smudge, anti-fingerprint, and high wear resistance, hardness, and UV resistance. Herein, ladder-like poly(2-(3,4-epoxycyclohexyl)ethyltrimethoxy-co-1H,1H,2H,2H-perfluorodecyltriethoxysilsesquioxane)s (LPEFSQs) were synthesized by the sol-gel reaction of 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane (ECTMS) with 1H,1H,2H,2H-Perfluorodecyltriethoxysilane (PFDTES) to reduce the surface energy of the coating. The incorporation of fluorine chains resulted in an improvement of water contact angle from 77.1° to 115.5°, and oil contact angle from 35.4° to 94.7°, respectively. The omniphobic property rendered the coating excellent anti-smudge and anti-fingerprint properties while maintaining an extraordinary visible light transparency of 90.1 %. A proper PFDTES fraction of 5 % and the curing agent of I-250 are desired for the coating to simultaneously realize excellent pencil hardness of 6H, anti-smudge, and wear resistance performance. The optimized LPEFSQ coating could withstand a steel wool abrasion for 500 cycles. In addition, the developed LPEFSQ coating maintained excellent omniphobicity when subjected to ultraviolet (UV) irradiation for 200 h demonstrating excellent UV resistance. Therefore, this work provides insights into the synthesis of multifunctional coatings integrated with high transparency, wear resistance, and hardness as well as anti-smudge, and anti-fingerprint properties for touch screens.

A novel and facile preparation of superhydrophilic/superoleophobic Mg(OH)2/ZnO coated mesh for fast and efficient oil/water separation

This study presents a new method for the rapid preparation of a superhydrophilic/underwater superoleophobic Mg(OH)2/ZnO coated mesh. Through one-step electrodeposition, a high underwater oil contact angle of 168.54° was achieved on the coated mesh. The electrodeposition process involved the deposition of ZnO nanoparticles on the cathode due to the presence of Mg2+ in the electroplating solution, while Mg(OH)2 was simultaneously formed on the surface of the cathode copper mesh. The cathode surface, where hydrogen is generated, leads to the formation of micropores and nanosheets on the Mg(OH)2/ZnO coated mesh structure. This structural feature traps more water molecules, further enhancing the superhydrophilicity of the coated mesh. The oil/water separation efficiencies for p-xylene, kerosene, paraffin liquid, and mineral oil were 99.8 %, 99.3 %, 99.5 %, and 99.4 %, respectively. The separation efficiency remained higher than 99.2 % even after conducting 350 p-xylene/water separation experiments. Additionally, the coated mesh displayed a strong oil/water separation ability after being immersed in alkali and salt solutions (pH = 7, 9) for 10 h. The coated mesh exhibited an enhanced water flux of (2.99 ± 0.20) × 105 L·m−2·h−1, along with a heightened invasion pressure (>2.8 kPa) and excellent oil-resistance performance. Overall, the Mg(OH)2/ZnO coated mesh developed in this study shows promising potential as a membrane for fast and efficient oil/water separation, with outstanding durability.

Nature inspired Ficus Religiosa leaf mesh coated with antibacterial ZnO/PANi@PMMA nanocomposite for separation and water purification

In this article, we fabricate a nature inspired Ficus religiosa leaf mesh with a micro/nano hierarchical structure utilizing the ZnO/PANi@PMMA nanocomposite having exceptional hydrophobic and oleophilic characteristics, with a water contact angle of ∼130° and an oil contact angle of ∼2°, respectively. Different oil/water mixtures were subsequently separated using the mesh, and after 8 cycles, the separation efficiency was ∼96.86 ± 0.8% for gasoline. In contrast, the reported mesh carries antibacterial properties and has successfully degraded the methylene orange (MO) dye solution in 140 min with ∼91% efficiency in the presence of sunlight, envisioning its potential use in water purification applications.

Fully biobased hydrogel based on chitosan and tannic acid coated cotton fabric for underwater superoleophobicity and efficient oil/water separation

Underwater superoleophobic (UWSO) materials have garnered significant attention in separating oil/water mixtures. But, the majority of these materials are made from non-degradable and non-renewable raw materials, polluting the environment and wasting scarce resources while using them. Against this backdrop, this study aimed to fabricate an environmental-friendly UWSO textile using biobased materials. To achieve this, hydrogel consisting of chitosan (CS) and poly(tannic acid) (PTA) were formed and coated on cotton fabric (CTF) via dip-coating followed by oxidative polymerization. CS&PTA hydrogel endowed the CTF with a rough surface and high surface energy, leading to an UWSO CTF with an underwater oil contact angle as high as 166.84°. The CS&PTA/CTF had excellent separation capability toward various oil/water mixtures, showing separation efficiency above 99.84 % and water flux higher than 23, 999 L m−2 h−1. Moreover, CS&PTA/CTF possessed excellent mechanical and environmental stability with underwater superoleophobicity unchanged after sandpaper friction, ultrasonication, organic solvents, NaCl (m/v, 30 %) solution, and acid/base solution immersion, due to the strong interaction between the hydrogel and cotton fabric generated by the mussel-inspired adhesion owing to the presence of PTA. The fully biobased UWSO CTF exhibits great promising to be an alternative to traditional superwetting materials for separation of oil/water mixtures.

Superhydrophilic fluorinated heterogeneous membranes with boosting antifouling property and high stable permeance for efficient emulsion separation

It is yet a query that whether chemically heterogeneous superwetting surface is able to enhance the permeability and anti-fouling capability of membrane contemporaneously, heretofore which is lacking and well worth creating. Here, we propose a bio-adhesion coupled with self-assembly strategy, to construct superhydrophilic fluorinated heterogeneous membranes, through in-situ biomimetic adhesion of the hydrophilic polyphenol-silane coating (TAT) on the porous PVDF membrane, as a secondary reaction platform, and subsequently self-assembly of amphoteric fluorocarbon surfactant (FS-50). Unsurprisingly, we find that introducing FS-50 not only significantly strengthens the permeability, but also improves the anti-fouling self-cleaning, thanks to the formation of robust hydration layer and slippery micro-domains with low friction, to realize the dual anti-fouling effects of pollution resistance and release. The champion PVDF/TAT/FS-2.0 % composite membrane exhibits superhydrophilic and underwater superoleophobic (oil contact angle above 162.3°) property with very low oil-adhesion. This composite membrane possesses an ultrahigh water permeance of 29214.6 L m−2 h−1 bar−1, which is 2.8 times larger than that of pristine PVDF membrane. The PVDF/TAT/FS-2.0 % composite membrane presents the high separation efficiencies (above 99.5 %) for various surfactant-stabilized oil-in-water emulsions and high permeances of 3193.2–4212.3 L m−2 h−1 bar−1. Especially, the membrane at continuous operation for 1.0 h can reach a high stable permeance of 2505.1 L m−2 h−1 bar−1. Moreover, this composite membrane shows strong chemical stability and robustness. This research answers the initial question, and provides the insight for further design and production of chemically heterogeneous superwetting membranes with high permeability, selectivity and antifouling ability.

Polyvinyl Alcohol/Graphene Oxide Nanocomposite Membrane for Highly Efficient Oil/Water Mixture Separation

The growing amount of oily wastewater caused by frequent oil spill accidents poses a severe threat to the ecological environment. Therefore, the development of highly efficient oil/water separation methods is highly necessary. This work reports the preparation of a nanocomposite membrane using graphene oxide (GO)/polyvinyl alcohol (PVA) coated on steel meshes for oil/water mixture separation. PVA firmly anchors GO nanosheets onto the mesh surface through strong hydrogen bonds using glutaraldehyde (GA) as a crosslinker. This nanocomposite membrane exhibited superhydrophilic and underwater superoleophobic properties, with the highest oil contact angle of 158º due to its highly rough structure. The synergistic effects of GO and PVA further improved the superhydrophilicity of the prepared membrane, due to the hydrophilic nature of both GO and PVA. The separation efficiencies and water flux for a variety of oil/water mixtures were above 97.8% and 6000.0 L m−2 h−1, respectively. The prepared membrane showed excellent chemical resistance under harsh conditions without evident change in its surface wettability. Moreover, its underwater superoleophobicity was maintained after 10 cycles of abrasion testing.

A smart superwetting PET-Anthocyanin membrane for pH monitoring in water and emulsion separation

Smart superwetting membranes with anti-oil pollutions and process water pH monitoring show great potential before downstream processing. Herein, a flexible intelligent monitoring membrane with strong anti-oil fouling properties was developed by utilizing a PET-Anthocyanin mixed solution through electrospinning. Specifically, using waste PET plastic bottles as raw materials, a dual-solvent system is used to dissolve the PET, and then anthocyanins are added to blend to form an electrospinning solution. The obtained A/PET showed excellent porous morphology and wettability, and its underwater oil contact angle could reach up to 150°. The introduction of anthocyanins (5 %) rich in hydroxyl functional groups reduced the formation of hydrophobic domains and promoted the hydration layer on the membrane surface, showing excellent oil resistance property. Furthermore, the stress–strain test of the A/PET5 membrane shows that the strain is significantly enhanced after the yield phenomenon, which shows that the membrane has a flexible mechanical property. Most importantly, based on the pH-sensitivity of anthocyanins, it can be intuitively found that color response changes from the original pink to light pink, and then to white, showing excellent monitoring the pH of the continuous phase. Moreover, the developed membrane possesses water flux of 7440 L m-2h−1 and oil rejection up to 99.4 % for O/W emulsions, surpassing that of the superhydrophilic PET base membrane (956 L m-2h−1, 99.3 %). Briefly, this work provides a novel multifunctional smart membrane with excellent anti-fouling, flexible mechanical, and outstanding separation performance, which can visually monitor the separation process of oily wastewater.

Superhydrophobicity PPS@MGFC composite membrane with nanofiber-like structure formed via TIPS and its oil-water separation performance

Oil/ water separation in extreme environments remains a challenging issue, with high requirements for material performance. Polyphenylene sulfide (PPS) has broad application prospects in extreme environments due to its unique performance. In this study, glass fiber cloth (GFC) modified with polydopamine/ phenyltriethoxysilane (PDA/PTES) (hereinafter referred to as MGFC) was used as the support, a superhydrophobic/ superlipophilic PPS nanofiber-like functional layer with low surface energy was prepared via thermally induced phase separation (TIPS) method, (hereinafter referred to as PPS@MGFC composite membrane). Relying on π-π conjugation between PTES and PPS, the composite interface was firmly bonded, effectively enhancing its structural stability. Meanwhile, when the PPS content was 4.2 wt%, the pure-water contact angle reached 156.8°, the oil contact angle reached 0 °. The prepared PPS@MGFC composite membrane showed strong oil-water separation performance in oil-water separation experiments. It could be used to separate various immiscible oil-water mixtures, the water content was less than 150 ppm and flux was higher than 6429 L·m−2·h−1 (gravity drive). For oil-in-water emulsions, the water content was less than 250 ppm, the flux was higher than 2500 L·m−2·h−1 (0.1 bar), and the separation efficiency was higher than 99.9%. In addition, the separation efficiency and flux remained stable in extreme environments and after recycling use. These results indicated that PPS@MGFC composite membrane created in this study has a significant deal of promise for use in the field of oil/water separation.

Robust PVA/GO@MOF membrane with fast photothermal self-cleaning property for oily wastewater purification

The poor mechanical durability and weak fouling resistance of oil/water separation membranes severely restrict their applications in industry. Herein, a robust PVA/GO@MOF membrane with fast photothermal self-cleaning capability was developed through facile chemical crosslinking and suction-filtration strategies. Attributed to the powerful underwater superoleophobicity, the PVA/GO@MOF membrane exhibited extraordinary anti-oil adhesion even for high-viscosity crude oil and continuous crude oil emulsion purification capability with stable flux (1020 L m−2 h−1 bar−1) and exceptional efficiency (> 99.3%) even after 60 min. Most importantly, in comparison to reported photocatalytic self-cleaning oil/water separation membranes, the PVA/GO@MOF membrane can degrade organic contaminants more rapidly with a higher degradation rate (99.9%) in 50 min due to the superior photothermal conversion capacity. The synergistic photothermal and photocatalytic effects significantly enhanced photodegradation efficiency, which created opportunities for in-depth treatment of complex oily wastewater. Besides, the obtained membrane displayed excellent chemical and mechanical durability with underwater oil contact angle (UWOCA) above 150° even in harsh environments, such as corrosive solutions, UV irradiation, ultrasound treatment, abrasion experiment and bending test. Therefore, the developed PVA/GO@MOF membrane with robust durability and fast photocatalytic self-cleaning property is highly expected to purify oily wastewater and degrade organic pollutants.

High-efficiency oil/water separation by simple fabrication of superhydrophobic nanocomposite (Zno-SiO2) coating mesh

Environmental sustainability and human health are globally imperilled by oil-contaminated water resulting from oil spill disasters or industrial disposal. Superhydrophobic materials have gained increasing attention in oil–water separation to fulfil the ever-growing need for highly effective oil–water separation. Due to the regeneration ability of silicon dioxide nanoparticles (SiO2), superhydrophobic/superolephilic nanocomposite (ZnO-SiO2) was created using a new, simple flame treatment procedure. ZnO(NRs) was coated on stainless steel mesh via water bath deposition method and modified with silicon rubber ( RTV-SR) solution. The mesh coated exhibited an excellent superhydrophobic surface with water at a contact angle 168±1°, a sliding angle 3.5° and superolephilic with oil contact angle OCA (0°). The x-ray diffraction, contact angle measurement, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive spectroscopy (EDS) were used to describe the coated mesh surface. Kerosene-water, diesel oil–water mixtures and sunflower oil–water are successfully separated by the simple filtering method using the coated mesh with a separation efficiency of 96%.

Superhydrophilic/underwater superoleophobic PVDF ultrafiltration membrane with pH-responsive self-cleaning performance for efficient oil-water separation

The treatment of various oily wastewaters generated in human production and life has been a huge challenge in recent years. Responsive materials for controlled wettability surface have a great potential for oil-water separation. Inspired by the superior pH-responsive of poly (2-(N, N′-dimethylamino) ethyl methacrylate) (PDMAEMA), a pH-responsive self-cleaning PVDF ultrafiltration membrane containing both carboxyl and tertiary amine groups were prepared by a simple grafting and co-blending method. The membrane fabrication process consisted of introducing 3-Dimethylaminopropylamine (DMPA) into the SMA side chain, resulting in the creation of the amphiphilic polymer DMPA@SMA. This polymer was then mixed with PVDF to produce DMPA@SMA/PVDF membranes. The optimized DMPA@SMA/PVDF membranes showed excellent superhydrophilicity/underwater superhydrophobicity, with a water contact angle of 0° and an underwater oil contact angle higher than 150° for crude oil. These endowed the as prepared membrane with a high pure water flux of 852 L·m−2·h−1 and anti-crude-oil-adhesion property. The separation efficiency exceeded 98% for various surfactant-stabilized oil-in-water emulsions, whether it’s positively charged emulsion or negatively charged emulsion. More interestingly, the carboxyl and tertiary amine groups presented the membrane with pH responsivity, and the membrane surface can be triggered by acid or alkali with self-cleaning performance. Strategy proposed in the present work offers a convenient and effective way to prepare membranes treating oil-in-water emulsions with either negative or positive charges.

Magnetic-responsive Fe3O4@PDMS@SiO2 omniphobic microciliary arrays for dynamic manipulation of droplets and spheres

Many biological organ surfaces exhibit unique micro/nano structures, which may be adopted for directional transportation of droplets and spheres for applications in microfluidics, biomedical analysis, chemical reactions and materials research. However, realizing efficient and dynamic manipulation of multi-form substances in different media remains a great challenge. In this study, magnetic-responsive Fe3O4@PDMS@SiO2 omniphobic microciliary arrays (MMAs) are fabricated by combining nanosecond laser machining of PTFE template and transfer replication process. Due to the modification by omniphobic SiO2, the optimized MMAs possess 40 wt% iron oxide content with water contact angle > 140°, rolling angle < 3°, and oil contact angle of 129°. Therefore, the MMAs can dynamically manipulate water, oil, air bubble, and solid. Under the stimulation of a moving magnet, microcilia pillars bend and deform sequentially in a wave-like manner, which generates the directional driving force and rapidly transports water and oil droplets, solid spheres and air bubbles in both water and oil media. A droplet up to 25 μL and a solid sphere up to 2 g can be continuously transported at a maximum velocity of 2.4 mm/s. The magnetic field intensity distribution is simulated by COMSOL Multiphysics software, and the force distributions are theoretically calculated. The multi-substances transportation strategy has potential applications in biomedical processes, targeted drug delivery and microfluidics.

Ultralight, superhydrophobic and fire-resistant nitrogen-doped graphene aerogel for oil/water separation

The simultaneous achievement of graphene aerogels with low density, high adsorption capacity and selectivity, as well as high mechanical strength, holds great significance but remains a challenging task. By adjusting the concentration and ratio of graphene oxide, dopamine and L-ascorbic acid, the hydrogel without obvious volume shrinkage and stability was synthesized by hydrothermal reaction at low temperature, after freeze-drying and calcination, nitrogen doped graphene aerogel (NGA) with ultralight, superhydrophobic, superoleophilic, fire-resistant, and compressible/recoverable were obtained. The density of NGA is only about 1.9 mg/cm3, and the water and oil contact angles in air are 153.3° and 0°, respectively. Given the aforementioned beneficial features, NGA can efficiently select and adsorb multifarious of oils and organic solvents in oil/water mixtures so as to achieve oil/water separation. Remarkably, NGA exhibits an impressive adsorption capacity of up to 150–305 times its own weight, and it also possesses excellent adsorption recyclability. Therefore, NGA has great potential in the treatment of oil pollution in the water environment.

Stable anti-oil fouling of spray coated L-DOPA/APTES on mixed matrix membrane

Oily wastewater poses a significant environmental concern as it has adverse effects on both ecosystems and human health. The development of highly efficient and robust antifouling membranes for oily emulsion is in great demand to prevent these serious issues in oil/water emulsion filtration. Moreover, fouling was inevitable when dealing with membrane separation. In order to overcome the addressed matters, this paper reported sprayed hydrophilic surface coating using commercialized levodopa (L-DOPA). The coated solution was mixed with 3-amino-propyltriethoxysilane in various ratios to obtain a smooth coated layer. Based on the results, the highest pure water flux and rejection efficiency of 586.51 ± 23.95 L/m2‧h and 98.22% was achieved in this study, respectively. The abundant hydroxyl and carboxyl functional groups on the membrane surface from L-DOPA benefit the membrane in many ways, especially the membrane wetting properties. The water and oil contact angles of the coated membrane increased by approximately 75% and 85%, respectively. The fouling behaviors are influenced by the presence of the coated layer, resulting in the attainment of 90% fouling resistance ratio (FRR). This is mostly due to the reduction in adherence of oil droplets on the membrane surface, hence enhancing the effectiveness of the anti-oil fouling membrane. Additionally, this provides excellent properties of the membrane to be applied in oily wastewater treatment.

Anti-fouling and self-cleaning ability of BiVO4/rGO and BiVO4/g-C3N4 visible light-driven photocatalysts modified ceramic membrane in high performance ultrafiltration of oily wastewater

Oily wastewater is one of the most harmful and resistant types of wastewater that cannot be treated with the usual and traditional methods. In this study, the visible light-driven photocatalysts BiVO4/rGO and BiVO4/g-C3N4 were made using the hydrothermal method. After that, a simple sol-gel method was used to make a photocatalytic ultrafiltration membrane with good self-cleaning and anti-fouling properties that can effectively separate oily wastewater. Photocatalyst properties were identified by using XRD, FTIR, DRS, N2 absorption-desorption, and zeta potential analysis. The performance of photocatalytic membranes was then investigated in oily wastewater treatment. Antifouling parameters, underwater oil contact angle, surface roughness, and electrochemical properties were measured to look into the membrane's antifouling properties. The use of a BiVO4/rGO composition with 20 wt% of rGO produced an underwater oil contact angle of 158°. Also, after 3 h of 3000 ppm oily wastewater filtration, the permeate flux was double that of the UF membrane without a photocatalytic coating, and the TOC removal efficiency was more than 99%. Measurement of antifouling parameters revealed that flux recovery was 89% compared to 51% for the UF membrane, and the total fouling ratio was reduced from 57% to 21%.

Super-wetting and self-cleaning polyvinyl alcohol/sodium alginate nanofiber membrane decorated with MIL-88A(Fe) for efficient oil/water emulsion separation and dye degradation

Membrane separation is considered an effective approach to water purification. Nevertheless, membrane fouling dramatically decreases the separation efficiency and lifetime of membranes, thus limiting its further development and application. Herein, a multifunctional self-cleaning MIL-88A(Fe) decorated polyvinyl alcohol/sodium alginate (MIL-88A(Fe)@PVA-SA) nanofiber membrane was prepared by electrospinning and in-situ growth methods for the separation of oil/water emulsions and photo-Fenton degradation of dyes. The membrane possesses superhydrophilicity with a water contact angle (WCA) of 0° and superoleophobicity with underwater oil contact angle (UCA) of 161.7°, and exhibits superior separation efficiency (>99.5 %) and permeation flux (1140–2455 L/m2/h) for different oil/water emulsions. Moreover, the membrane exhibited an outstanding photo-Fenton performance under visible light, with degradation efficiencies (~99.9 %) towards methylene blue (MB) and reactive red 24 (RR24) within 90 min. Importantly, the membrane can be easily regenerated by simple rinsing and photo-Fenton self-cleaning treatment. In this study, MIL-88A(Fe)@PVA-SA nanofiber membrane has a promising application in dye removal and oil/water separation, providing a new idea to develop novel membrane materials.

Study on the effect of laser-induced oxidation on color change and hydrophilicity of 2D codes

The effect of laser-induced oxidation on color change and surface wettability of anti-oil and super-hydrophobic two-dimensional code (2D Code) is demonstrated, where the color change and wettability are very important to the reading quality and durability of 2D Code. The poor oleophobicity and hydrophobicity, which render laser direct part marking of 2D Code inadequate for application in oil pollution, corrosion environment, are greatly improved with combination method of accurate laser-induced oxidation and surface modification. To obtain the control mechanism for the color change and wettability of 2D Code, the influence of laser processing parameters on the oxidation and microstructure change of the modules laser-marked on titanium alloy were studied, and then the influence of oxidation, microstructure and surface modification processing parameters on the hydrophilicity of 2D Code were analyzed. From the experimental results, with the laser energy density increasing, the oxidation degree increases and the modules show platinum grey, violet blue, graphite black, light ivory, jet black and other color states, with its hydrophilicity of the modules laser processed becoming stronger first and weaker later. The modules also present various microstructures with different laser processing parameters, such as pits, cracks, wormlike protrusions, which also have an important effect on the color change and wettability of modules. By laser parameters optimizing, it is found that when laser power is 10 W, Q frequency 45 KHZ, scanning speed 200 mm/s and hatching spacing 0.03 mm, the 2D code with high contrast and hydrophilic oleophylic property was obtained, where the static water contact angle could be a minimum to about 6.0° and the static oil contact angle could be a minimum to 8.1°. After the surface modification processing, where a coating consisting of heptadecafluorotrichlorosilane and n-heptanea with specific ratio is sprayed by special process on the surface, the 2D code show anti-oil and super-hydrophobic property, within the static water contact angle being a maximum to about 178.7° and the static oil contact angle being a maximum to 132.8°. In addition, it is found that the stronger hydrophilicity of modules laser processed before coating spraying, the stronger hydrophobicity of 2D code after coating spraying shall show.

Improving anti-fouling properties of alumina tubular microfiltration membranes through the use of hydrophilic silica nanoparticles for oil/water separation

ABSTRACT In this study, hydrophilic silica nanoparticles (Si NPs) were used to modify α-alumina tubular membranes to improve their performance in terms of flux, oil rejection, and anti-fouling properties. Our work focuses on enhancing membrane performance, particularly for difficult applications such as produced water treatment. The prepared membranes were applied for oil-in-water emulsion treatment. After coating hydrophilic Si NPs, the oil contact angle improved from 133.8° to 171.4°. To prevent Si NPs from leaching off the surface of α-alumina tubular membranes, polyvinyl alcohol was used to coat the membranes as a pre-treatment step before Si NP modification. After coating the membrane with Si NPs, the roughness of the membrane surface decreased, likely leading to less fouling. After coating Si NPs, Total Organic Carbon rejection increased from 93.1% for pristine α-alumina tubular membranes to 97.7% for silica-modified membranes because of hydrophilic improvements of the modified membranes. The Si NP coating improved the anti-fouling property of membranes with the flux recovery ratio increasing from 71.3% for pristine α-alumina tubular membranes to 85.9% for silica-modified membranes. Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy, oil contact angle, and Atomic Force Microscopy characterization tests were done. The tests showed successful Si NPs impregnation and altered wettability.

Superamphiphobic interface-enhanced inorganic coating for multi-environments tolerant and zero-energy building radiative cooling

Passive radiative cooling (PRC) is a promising technology to achieve eco-friendly building cooling relying on automatic solar reflection and thermal emission. However, sewage, oil and even dust in actual application often cause irreversible damage of surface optical selectivity required by durable cooling. Herein, ZnAl LDO biomimetic microflowers are fabricated as optically selective substrate following by crosslinking of superamphiphobic (SAP) SiO2 nanoparticles to obtain inorganic SAP-PRC coating. Openly-porous micro-nano-structure from LDO microflowers imparts the coating excellent solar reflectivity (∼97.58% normalized with BaSO4) and thermal emissivity (∼98%) as well as efficient resistance for both water (contact angle >158°/slide angle <5°) and oil (contact angle >151°/slide angle <10°). As the result, the coating achieves about 7℃ of cooling effect under (>1400 W/m2) of solar radiation and ∼5℃ lower than the commercial coating. The superamphiphobic surface help SAP-PRC coating avoid over 7.5℃ increase of temperature under >1500 W/m2 after being immersed by oil pollution. It is estimated that the cooling coating can help achieve ∼26% energy saving in hot areas (Haikou in China) throughout a year also considering warming-energy consumption in winter. The synergistic self-cleaning and optical selectivity strategy will effectively promote the commercialization of building PRC materials and further contribute to energy and environment sustainability.