Oil-water Separation Ability Research Articles

Wood Sponge for Oil-Water Separation.

In addition to filtering some sediments, hydrophobic wood sponges can also absorb many organic solvents, particularly crude oil. The leakage of crude oil poses a serious threat to the marine ecosystem, and oil mixed with water also generates great danger for its use. From the perspective of low cost and high performance, wood sponges exhibit great potential for dealing with crude oil pollution. Wood sponge is a renewable material. With a highly oriented layered structure and a highly compressible three-dimensional porous frame, wood sponges are extremely hydrophobic, making them ideal for oil-water separation. Currently, the most common approach for creating wood sponge is to first destroy the wood cell wall to obtain a porous-oriented layered structure and then enhance the oil-water separation ability via superhydrophobic treatment. Wood sponge prepared using various experimental methods and different natural woods exhibits distinctive properties in regards to robustness, compressibility, fatigue resistance, and oil absorption ability. As an aerogel material, wood sponge offers multi-action (absorption, filtration) and reusable oil-water separation functions. This paper introduces the advantages of the use of wood sponge for oil-water separation. The physical and chemical properties of wood sponge and its mechanism of adsorbing crude oil are explained. The synthesis method and the properties are discussed. Finally, the use of wood sponge is summarized and prospected.

Synthesis of a demulsifier for treating crude oil-in-water emulsion through a straightforward low-temperature process

The separation of oily wastewater is a significant issue in the petroleum industry. In current work, a highly efficient demulsifier (TCDA) was synthesized through a one-step low-temperature method for the purpose of demulsifying O/W emulsions. The structure was characterized using FT-IR and 1H NMR spectra. The oil–water separation ability was evaluated through light transmittance (T%) and oil removal rate (η%) of separated water. The results showed that T% of 88.6 % and η% of 99.8 % could be obtained with the dosage of 30 mg/L at ambient temperature. In addition, TCDA demonstrated good acid and salt resistance. The relative solubility number (RSN), three-phase contact angle, dynamic interfacial tension, zeta potential and optical micrograph were characterized to explore possible demulsification mechanism. It was found that TCDA effectively reduced interfacial tension and penetrated the interfacial membrane, thereby facilitating the separation of O/W emulsion. Overall, these results indicate that the TCDA demulsifier shows promise for using in the demulsification of oily wastewater.

NH2-MIL-88B(Fe)/TiO2/PAN electrostatically spun nanofiber membrane for photocatalytic degradation of tetracycline and oil–water separation

Excessive discharge of tetracycline (TC) poses a threat to the environment and human health, and finding a cost-effective treatment method to remove TC from water remains a challenge. In this study, NH2-MIL-88B(Fe)/TiO2/PAN (NMTP) electrostatically spun nanofibrous membranes (ENMs) were prepared, and the NMTP nanofibrous membranes were characterized by water contact angle test, UV–vis and other characterization methods. The results showed that the introduction of NH2-MIL-88B(Fe) expanded the light response range of ENMs, accelerated the production of active substances (•O2– and •OH) and improved the hydrophilicity of the membranes, which resulted in the excellent photocatalytic performance and oil–water separation ability of NMTP ENMs. Among them, the degradation efficiencies of NMTP-4 ENMs for tetracycline (TC), chlortetracycline (CTC), and oxytetracycline (OTC) were up to 93.0 %, 94.9 %, and 86.5 % and the removal rate of TC was still maintained at about 80 % after four photocatalytic regenerations. In addition, the NMTP ENMs exhibited excellent separation performance and high throughput for oil-in-water emulsions, with separation efficiencies of 98.15 %, 97.43 % and 84.87 % for toluene-in-water, n-heptane-in-water and n-hexane-in-water emulsions. Based on the above results, this study provides a new idea for the development of an efficient and stable simultaneous catalytic separation technology for oil-in-water emulsions.

Ultralight, shapeable, and superhydrophobic polyacrylonitrile/polybenzoxazine aerogel for high oil-water separation capacity

Environmental and human health are significantly threatened by oily wastewater emission and oil spills. Polymeric porous aerogels are ideal materials to absorb oils or organic solvents selectively, thereby mitigating environmental pollution and protecting human health. In this study, a shapeable, super-hydrophobic, polyacrylonitrile fiber/polybenzoxazine (PAN/PBOZ) aerogel with high oil-water separation ability were successful designed. The preparation process of PAN/PBOZ aerogel is as follows: Firstly, PAN micro-nanofibers were prepared by electrospinning, and then benzoxazine was uniformly dispersed into PAN fibers. After freeze-drying and thermal curing, the aerogel was obtained. For comparative analysis, a pure polyacrylonitrile (PAN) fiber aerogel is also presented. The resulting PAN/PBOZ aerogel exhibits ultralight (0.017 g/cm3), remarkable hydrophobicity, as evidenced by a water contact angle of 156°, high adsorption capacity up to 157.7 g/g for oil or organic solvents, and a high water-in-oil emulsion separation flux (9718 ± 45 L m−2 h−1) efficiently. Notably, the rigid cross-linking structure of PBOZ and the toughness structure of PAN make the aerogel exhibit synergistic strengthening and toughening effects. When the PAN/PBOZ fiber aerogel is compressed to 60 %, an outstanding recovery stability of its original size is displayed. While the springback of pure PAN fiber aerogel is poor under the same compression test condition. In conclusion, this study provides a preparation method and design concept of aerogel that can meet the requirements of low density, high toughness and high oil adsorption capacity. The rationally designed PAN/PBOZ aerogel shows significant potential for practical applications in treating oily and organic wastewater.

Silica-Based Superhydrophobic and Superoleophilic Cotton Fabric with Enhanced Self-Cleaning Properties for Oil-Water Separation and Methylene Blue Degradation.

Superhydrophobic textiles with multifunctional characteristics are highly desired and have attracted tremendous research attention. This research employs a simple dip-coating method to obtain a fluorine-free silica-based superhydrophobic and superoleophilic cotton fabric. Pristine cotton fabric is coated with SiO2 nanoparticles and octadecylamine. SiO2 nanoparticles are anchored on the cotton fabric to increase surface roughness, and octadecyl amine lowers the surface energy, turning the hydrophilic cotton fabric into superhydrophobic. The designed cotton fabric exhibits a water contact angle of 159° and a sliding angle of 7°. The prepared cotton fabric is characterized by attenuated total reflectance-fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. In addition, the coated fabric reveals excellent features, including mechanical and chemical stability, superhydrophobicity, superoleophilicity, and the self-cleaning ability. SiO2 nanoparticles and octadecylamine-coated cotton fabric demonstrate exceptional oil-water separation and wastewater remediation performance by degrading the methylene blue solution up to 89% under visible light. The oil-water separation ability is tested against five different oils with more than 90% separation efficiency. This strategy has the advantages of low-cost precursors, a simple and scalable coating method, enhanced superhydrophobicity and superoleophilicity, self-cleaning ability, efficient oil-water separation, and exceptional wastewater remediation performance.

Comparative study between bulk and surface modification on hy-drophobic membrane for dyeing and oily wastewater treatment

Surface modification could remarkably improve the oil–water separation ability of membrane, but suffers from limited survival positive effect layer after long-term operation. Herein, we report a systematic comparative study between bulk and surface modification (i.e., synchronous or sequential electrospun/elecrospraying) on hydrophobic polyvinylidene difluoride (PVDF) membrane. A hydrophilic UiO-66-NH2@polyacrylic acid micro/nanospheres (UiO@PAA) was selected as functional layer to improve the separation and adsorption capability of PVDF. The surface modification (SMM) and bulk modification membranes (BMM) exhibited the similar water wetting behavior in air as the same surface layer. The spider filament-like nanofibers of BMM could enhance the mechanical stability and dispersion uniformity of active sites among the PVDF fibers. In terms of oil-in-water emulsions separation ability, the BMM was superior to the SMM with the maximumly increase of separation efficiency and filtration flux to 1.3 % and 192.6 L m-2h−1, respectively. As for dye absorption, the BMM showed better adsorption capacity with a removal efficiency over 96 %. For the low concentration of methylene blue, the removal efficiency of SMM was only 94 %, while the removal efficiency of the BMM reached 98 % at room temperature. In addition, the BMM exhibited higher removal efficiency over 94 % compared with that less than 84 % of SMM after eight cycling tests, confirming its advantages in repeatability. This study demonstrates that the bulk modification can endow the initial membrane with better performance and durability, showing more promising prospects in actual wastewater treatment.

Study on the Influence of the Reduced Graphene Oxide Coating on the Hydrophobicity of PU Sponge for Oil Recovery

In order to produce a hydrophobic material for oil removal from surface waters, in this study, the reduced graphene oxide coated PU sponges (rGO@PU) were prepared by ultrasonication of PU sponges with suspension of rGO in ethanol. The chemical structure of the rGO coatings was investigated by X-ray diffraction and FT-IR spectroscopy methods. The surface morphology of the obtained materials was also examined by SEM. The influence of the rGO loadings and the number of coatings on the hydrophobicity of the materials was investigated. The testing on the surface hydrophobicity indicated that the water drops were remained on the surface of rGO@PU for 4.5 - 5 hours. The results indicated that the best hydrophobic sponge was obtained at the rGO loading of 3 mg/mL and after three times of coatings. The water contact angle (WCA) of the optimal rGO@PU was up to 119°. The kerosene oil absorption capacity of the rGO@PU in 5 minutes is 32.34 g/g. Besides, the oil-water separation ability of the material was also investigated by passing the kerosene-water mixture through a filter funnel containing the synthesized porous material rGO@PU. The result indicated that the separation efficiency of the material was 85%. The recyling test was conducted by squeezing the saturated absorbed sponges and applying the desorbed sponges for the next cycle tests. After 10 times of recycling, the amounts of kerosene absorption on the rGO@PU were maintained from 4.39 - 5.33 g, implying the excellent recyclability of the material.

Superhydrophobic melamine sponge-sorbent fabricated using WS2, halloysite nanotube, octyltriethoxysilane, tetraethoxysilane, and polydimethylsiloxane for the selective uptake of oil from water

Here, a novel coating formulation was developed using WS2, halloysite nanotube (HNT), octyltriethoxysilane (OTES), tetraethoxysilane (TEOS), and polydimethylsiloxane (PDMS) to fabricate a new melamine sponge (MS)-based superhydrophobic sorbent material for the treatment of wastewater polluted with oily substances and organic solvents. The innovative aspect of this study lies in the alteration of WS2 particle size within the sorbent material and the chemical modification of HNT with silane compounds through the formation of reactive -OH groups on the cylindrical outer surface of clay mineral by chemical activation. The effect of nano- and micro-WS2 particle sizes on the wettability of sorbent material was investigated systematically. Successful coating of MS with the developed coating formulation was confirmed using SEM, mapping, EDS, and FTIR analyses. Sorbent material showed remarkable superhydrophobicity (WCA: 170.3°), excellent thermal and mechanical stability, good chemical durability, high sorption capacity (34.0–73.8 g/g), good reusability, outstanding oil-water separation ability (>99.8 %) and flux (11,774 L/(m2.h)), and efficient separation ability for water-in-oil emulsions (up to 99.6 %). The results of this study exhibit that MS/WS2/HNT/OTES-TEOS/PDMS sorbent material is of a great potential for the selective and effective removal of oily substance and organic solvent spills from water.

PDMS/magnetic lignin sponge for oil/water separation

Recyclable, non-toxic, and degradable biological substrates contribute significantly to super-wetting surfaces. In this work, we prepared magnetic micro-nano super-hydrophobic surfaces through a robust solution with magnetic modified lignin particles as the supporting structure. A novel PDMS (polydimethylsiloxane)/magnetic lignin particle (lignin@Fe3O4)/PDA sponge composite was fabricated. Through dopamine (DA) self-polymerization, covalent deposition of magnetic lignin (ML), and PDMS silane modification, the magnetic super-hydrophobic polyurethane sponge composite (Sponge-P) was synthesized so that the Fe3O4 nanoscale microspheres wrapped with microscale lignin magnetic particles adhered to the sponge surface tighter and were barely dislodged. The as-prepared Sponge-P displayed excellent flexibility and a water contact angle of up to 152.2°. The super-hydrophobic sponge prepared with the proposed method was acid-base stable (pH = 2–12), self-cleaning, and suitable for high-salinity seawater. The magnetic super-hydrophobic sponge has good oil-water separation ability and can absorb 43 times its own weight of oil. In the meantime, due to the introduction of magnetic materials into lignin, we not only constructed micro-nanostructures to improve the surface super-hydrophobicity, but also made Sponge-P have the function of magnetic recovery, which has a unique advantage in treating oily wastewater.

Light-Propelled Super-Hydrophobic Sponge Motor and its Application in Oil-Water Separation.

Self-propelled separation materials, that is, motor, are one of the keys to realizing smart oil-water separation. Although three-dimensional sponges such as commercial melamine sponge (MS) exhibit excellent oil-water separation ability, they cannot move by themselves on water. Aiming at solving this problem, a polydimethylsiloxane (PDMS) and molybdenum disulfide (MoS2) modified MS motor (PDMS@MS/MoS2) with an asymmetric multilayer structure was prepared, in which the photothermal layer MoS2 provided the propelling force for the motor under infrared light irradiation, and the middle layer PDMS was used as the superhydrophobic modified agent and adhesive agent between commercial MS and MoS2 powder. PDMS coated MS (PDMS@MS) as the superhydrophobic layer showed good superhydrophobic ability (153.1°) and oil-water separation capacity (52.33 g/g to liquid paraffin). Furthermore, the introduction of MoS2 made the speed of the sponge motor reach 8.27 mm s-1 with a removal quantity of 12.20 g/g for cyclohexane. After recycling 8 times, the contact angle, cyclohexane capturing amount, and average velocity of the motor were 150.3°, 11.40 g/g, and 8.41 mm/s, respectively. Meanwhile, PDMS@MS/MoS2 kept a similar light-propelling velocity (∼8 mm) at different pH values and in simulated seawater, demonstrating that the light-propelling motor possessed a good cycle and practical performance, which provides a possibility for the directional light propulsion of a sponge motor in oil-water separation.

One-step spraying route to construct a bio-inspired, robust, multi-functional and superhydrophobic coatings with corrosion resistance, self-cleaning and anti-icing properties

Aimed at getting rid of the complicated preparation procedure, multi-functional superhydrophobic coatings inspired by natural plants have been successfully constructed on different matrix via a facile and effective spraying technology in this paper. The innovation of this paper lies in directly employing the unmodified fillers to establish the superhydrophobic coatings system with high performance. The results have revealed that the water contact angle (WCA) and water sliding angle (WSA) of as-prepared coatings can reach 155.4° and 8°, confirming the superhydrophobicity with low surface adhesion is achieved. And the potential superhydrophobic mechanism can be ascribed to the enrichment of low surface energy components on the homogeneous and rough grain structure of as-prepared coatings. Simultaneously, as-prepared coatings have exhibited the good self-cleaning property, anti-fouling property, and anti-icing property. Surprisingly, the mechanical stability of superhydrophobic coatings can be maintained after 50 cycles during the friction experiments. And the oil-water separation ability for the coated metal meshes was also obtained with high separation efficiency of 95%. Moreover, the anti-corrosion ability was also systematically investigated and its potential anti-corrosion mechanism of superhydrophobic coatings is primarily deduced. Therefore, the multifunctional and robust superhydrophobic coatings with biomimetic structure were established via a simple strategy, which is expected to be applied in field of metal corrosion and protection and multi-functional surface material in the future.

Facile fabrication and application of highly efficient reduced graphene oxide (rGO)-wrapped 3D foam for the removal of organic and inorganic water pollutants.

The pace of water contamination is increasing daily due to expanding industrialisation. Finding a feasible solution for effectively remediating various organic and inorganic pollutants from large water bodies remains challenging. However, a nano-engineered advanced hybrid material could provide a practical solution for the efficient removal of such pollutants. This work has reported the development of a highly efficient and reusable absorbent comprising a porous polyurethane (PU) and reduced graphene oxide (rGO) nanosheets (rGOPU) for the removal of different organic oils (industrial oil, engine oil and mustard oil), dyes (MB, MO, RB, EY and MV) and heavy metals (Pb(II), Cr(VI), Cd(II), Co(II) and As(V)). The structure, morphology and properties of the rGOPU hybrid absorbents were analysed by using Raman spectroscopy, field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunner-Emitte-Teller (BET) analysis. The rGOPU possessed both superhydrophobicity and superoleophilicity with water and oil contact angles of about 164° and 0°, respectively. The prepared rGOPU has demonstrated an excellent oil-water separation ability (up to 99%), heavy metals removal efficiency (more than 75%), toxic dye adsorption (more than 55%), excellent recyclability (> 500 times for oils), extraordinary mechanical stability (90% compressible for > 1000 cycles) and high recoverability. This work presents the first demonstration of rGOPU's multifunctional absorbent capacity in large-scale wastewater treatment for effectively removing a wide variety of organic and inorganic contaminants.

Facile fabrication of hydrophobic covalent organic framework decorated melamine sponge for efficient separation of immiscible oil-water mixture and water-in-oil emulsion

Frequent oil spills and oily sewage have caused serious environmental problems. Sponges have attracted great attention in oil-water separation due to their low cost and high porosity, but it still remains challenge to hydrophobic modification of sponge in facile and scalable manner. Here is reported a facile fabrication of porous and hydrophobic sponge composite (MS@COF) with effective oil-water separation by in-situ growth of hydrophobic TFB-BD(Me)2 COF on the surface of melamine sponge. Combining the porous structure of the sponge and hydrophobicity of COF, the composite can separate oil-water mixture and water-in-oil emulsions in a fast way. The prepared MS@COF showed oil adsorption capacity up to 160 g g-1. In addition, continuous separation of oil-water mixture was demonstrated using a peristaltic pump with a separation rate of 50 mL min-1. More importantly, the composite could separate surfactant-stabilized water-in-oil emulsions with separation efficiency of 98.8%. The oil-water mixture and oil-water emulsion separation ability of the composite persisted after 50 separation cycles thereby demonstrating good recyclability. The composite also showed good chemical stability, mechanical and flame retardancy. This work introduces a new approach for the synthesis of hydrophobic sponge decorated with COF nanoparticles for oily wastewater treatment and organic pollutant removal on water surfaces.

Converting pomelo peel biowaste into multifunctional sponges integrated underwater superoleophobicity and catalytic ability for sewage treatment

Fabricating practical multitasking materials integrating efficient oil-water separation ability and excellent catalytic performance is significant for water remediation but challenging for substrates and subsequent surface modification causing high cost, high power consumption, and poor reusability. Herein, a multitasking sponge was designed for water purification by successively modifying the biomass pomelo peel (PP) with polypyrrole (PPy), Au nanoparticles (NPs), and polydopamine (PDA). The cost-effective and renewable PP substrates, facile surface decoration of PP with PPy coating, in-situ spontaneous growth of Au NPs, and the protection of the outermost PDA coating endowed the as-obtained PP/PPy-Au/PDA sponges high sewage treatment efficiency and the potential for large-scale preparation. The PP/PPy-Au/PDA sponges exhibited high catalytic reduction activity for 4-nitrophenol (4-NP) and excellent reusability without remarkable decline in catalytic activity even after 10 recycles due to the synergistic effect among PPy, Au NPs and PDA. In addition, this sponge also displayed superior separation efficiency and high filtration flux towards both immiscible oil-water mixtures and O/W emulsions due to its underwater superoleophobicity. Integrating above properties, the PP/PPy-Au/PDA sponge could perform catalytic degradation of organic molecules and meanwhile separation of oil-water mixtures.

Novel wood membrane decorated with covalent organic frameworks and palladium nanoparticles for reduction of aromatic organic contaminants

With the development of industry, environmental pollution has become increasingly serious. The removal of contaminants from wastewater remains an important challenge for environmental remediation. However, many nanomaterials with excellent properties are in powder form, which limits their practical application. To overcome these issues, we have developed a three-dimensional (3D) wood membrane (Pd@COF/wood) decorated with covalent organic frameworks (COFs) and palladium nanoparticles (Pd NPs) for the effective removal of aromatic organic pollutants. The COF with a large specific surface area can be used as support for immobilizing Pd NPs to improve catalytic activity. Benefiting from the elongated and partially aligned channels along the direction of the wood growth, the Pd@COF/wood displays superior catalytical efficiency for the reduction of 4-nitrophenol (4-NP) and methylene blue (MB) with the reaction rate constants of 0.72 and 0.85 min−1, respectively. As the filter membrane, the MB degradation efficiency of the Pd@COF/wood membrane reaches over 98 % with a permeance of 1.57 × 104 L·m−2·h−1·bar−1. Meanwhile, the resulting Pd@COF/wood possesses exceptional recyclability and oil–water separation ability. We believe that the Pd@COF/wood is of great significance for environmental remediation, and the synthetic strategy is applicable to establish more multifunctional hybrid nanomaterials, which derive from other COFs and NPs for catalysis.

TEPA-SiO2@PDA composite as a highly stable underwater oleophobic coating on copper mesh for oil-water separation with high flux

Specially wettable mesh can effectively separate the oil-water mixture. However, the pore blocking and poor stability limit the application. In this work, a tetraethylenepentamine-silica@polydopamine (TEPA-SiO2@PDA) coating is developed on the copper mesh for oil-water separation. By exploiting the rough structure and hydrophilic molecule, an underwater oleophobic surface is obtained, in which the aforementioned challenges can be addressed. As a result, the TEPA-SiO2@PDA modified mesh presents a high underwater oil contact angle and stability at various pH and temperature. Oil-water separation test confirms the high efficiency (>99 %) and high water flux. After 15 cycles of separation testing, it still exhibits a high efficiency of 98.21 % and water flux of 23,315.2 L m−2 h−1. High intrusion pressure and special rough structure contribute to the good oil-water separation ability and high stability. This work proposed a novel strategy for designing a highly stable underwater oleophobic mesh for oil-water separation.

Simple and Ultrahigh Efficient Superhydrophilic Polydopamine-coated TiO2 Cotton for Oil–water Separation

Oil–water mixing has brought many problems to a society, and it is of great significance to develop a simple, convenient, efficient, and durable separation material to solve the problem of oil–water mixing. In this paper, modified cottons were successfully prepared using polydopamine as the in situ mineralization site of TiO2 nanoparticles combined with synergistic crosslinking with KH550. A large number of hydrophilic groups endowed the cotton with superhydrophilic ability, which greatly shortened its water spreading time. The prepared modified cotton could be successfully separated from oil and water, and still had a separation efficiency of 99.999% after 50 cycles. In addition, after 24 h immersion in 1 M HCl, NaOH, and NaCl solutions and 50 abrasion experiments, the modified cotton showed excellent oil–water separation ability, and the separation efficiency was above 99.990%. Successfully provided a simple preparation method to prepare high-efficiency and clean cottons for oil–water separation.

High-hydrophobic ZIF-67@PLA honeycomb aerogel for efficient oil–water separation

The ZIF-67 @PLA honeycomb aerogel was formulated by using the metal–organic frame (MOF) ZIF-67 through physical mixing and heat-induced phase separation interaction. Changing the mass fraction ratio of ZIF-67 in aerogels can effectively adjust the pore size, pore surface unevenness, and specific surface area of pure polylactic acid (PLA) aerogels. In comparison to PLA aerogels, the ZIF-67 @PLA honeycomb aerogels showed greater oil wettability combined with a notable increase in mechanical characteristics. In this paper, the morphology, oil adsorption capacity, oil wettability, oil–water separation ability and sample reuse of composite aerogels were studied in depth. The ZIF-67 @PLA aerogel with 3 wt% ZIF-67 has the highest oil wettability, highest oil–water separation function, maximum specific area and good reusability. Compared to pure PLA, which has a tensile strength and elongation at break of 0.1424 MPa and 13%, ZIF-67 @PLA has a tensile strength and elongation at break of 0.3344 MPa and 15%, respectively. After 20 cycles, the separation flux of ZIF-67 @PLA is still 98% of the initial flux. The experimental results show that the use of MOF as a nanofiller-filled pure PLA aerogel exhibits high oil wettability and has been demonstrated to be an ideal material for high-efficiency oil–water separation.

Study on the structure-activity relationship between oil dewetting self-cleaning and surface morphology for crude oil pollution treatment and crude oil/water separation

The oil dewetting self-cleaning performance is the most effective method to solve viscous oil pollution. The surface composition has a positive correlation with the property, and oil droplets tend to desorb on highly hydrophilic surfaces. But the influence of surface microstructure is more complex. Herein, we prepared a variety of surface structures with different morphologies and parameters, and performed the same surface modification to ensure compositional homogeneity. By testing the oil dewetting performance, we found that the surface microstructure has two modes of action: promotion and inhibition, and the final effect depends on the relative strength. The former comes from the amplifying effect of the structure on the wettability, and the latter refers to the hindering effect of the structure on the movement of oil droplets. The UOWCA reached 0° for the nanowire and honeycomb structures, and the oil droplets could quickly detach from the surface of the honeycomb structure in about 5 s. When the deposition of nanoparticles on the surface reaches 4 layers, the oil droplets can desorption from the surface within 2 min. The nanoparticle-deposition and the honeycomb structure also exhibit excellent crude oil pollution cleaning and crude oil-water separation ability. This study can not only provide two kinds of structures for crude oil treatment in practice, but also help us deeply understand the structure-activity relationship between surface morphology and oil dewetting performance in theory.

Fabrication of a novel superhydrophobic cotton by HDTMS with TiO2 supported activated carbon nanocomposites for photocatalysis and oil/water separation

The strong superhydrophobic and photocatalytic cotton was fabricated by a simple one-step dip rolling technique using activated carbon supported titanium dioxide (TiO2) composite with fluoride-free hexadecyltrimethoxysilane (HDTMS) coupling agent. The experimental result shows that the contact angle of cotton fabric treated with TiO2-AC/HDTMS reaches 158°. More importantly, 0.7 g TiO2-AC provided the same superhydrophobic effect as 5 g TiO2. Moreover, the surface physical morphology and chemical composition of modified cotton fabric were observed via scanning electron microscopy (SEM), atomic force microscope(AFM), X-ray diffractometer(XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) correspondingly. The experimental results show that the micro-/nano-scale rough structure, together with the long side chain alkyl in HDTMS and the siloxane (Si-O-Si) structure generated after hydrolysis and crosslinking, endows the modified cotton fabric with superhydrophobic properties. In addition, the thermogravimetric analysis shows that the modified sample exhibited excellent thermal stability. Besides, the degradation rates of methylene blue (MB) solution was 90 % when photocatalytic performance was tested on the modified fabric under simulated sunlight, and the contact angle still reached 150°. In addition, the modified fabric showed superior oil-water separation ability, with the separation efficiency higher than 98%, separation flux is greater than 1600 Lm−2 s−1, oil absorption is more than twice its own weight and it has excellent recyclability and reusability, because of its superhydrophobic surface, TiO2-AC/HDTMS fabric also showed superior stain resistance and self-cleaning ability. At the same time, the TiO2-AC/HDTMS treated fabric remained hydrophobic in acid and alkali immersion, 25 home washes, and high strength mechanical properties tests. In short, this simple porous nano-composite material combined with non-fluorosilane coupling agent finishing technology has a broad development prospect in the industrial production of multifunctional advanced textiles.