Search

Due to the rapid advancement of technologies, there has been a significant increase in the discharge of industrial wastewater, and freshwater is becoming a scarce resource. Currently, research on solar evaporators is mainly focused on the efficient production of clean water, with less emphasis on the removal of residual pollutants remaining in the original solutions. Through this study, problems, including the difficult recovery of catalyst powder and the difficult removal of floating organic matter are solved by co-depositing low-surface-tension zirconia particles and bismuth tungstate onto the floating layer. Hydrogels and melamine sponges were combined to solve the problem that traditional hydrogels lack mechanical strength. An excellent water-repellent effect can be seen from the contact angle between the liquid globule and canvas/felt, which is greater than 155°. The steam generation rate of the assembled evaporation system is 1.78 kg m−2 h−1, and its purification efficiency for methyl orange and rhodamine B exceeds 99%. This study presents a novel strategy for treating wastewater contaminated with organic dyes, aiming to solve problems including environmental damage, water pollution, and water scarcity. [ABSTRACT FROM AUTHOR]

Polymer-textile liner composites have potential applications in aerospace applications for reducing the abrasion damage of moving parts during operation owing to their self-lubrication, light weight, and high loading capacity. Herein, Au nanoparticles (AuNPs) are successfully loaded into the lumen of halloysite nanotubes (HNTs) to construct an HNTs-Au peasecod core-shell nanosystem to optimize the wear resistance of phenolic resin-based poly(p-phenylene benzobisoxazole) (PBO)/polytetrafluoroethylene (PTFE) textile composites. Transmission electron microscope (TEM) characterization reveals that the AuNPs are well-dispersed inside the HNTs, with an average diameter of 6–9 nm. The anti-wear performance of the HNTs and Au-reinforced PBO/PTFE composites is evaluated using a pin-on-disk friction tester at 100 MPa. Evidently, the addition of HNTs-Au induces a 27.9% decrease in the wear rate of the composites. Possible anti-wear mechanisms are proposed based on the analyzed results of the worn surface morphology and the cross-section of the tribofilm obtained by focused ion beam transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Recently, great effort has been devoted to prepare various reinforce fillers to improve polymer performances, but ignoring the importance of raw polymer powders which are indispensable parts of hot-pressed polymer composites. Herein, we engineer raw polyimide (PI) powders with the assistance of polydopamine (PDA) in aqueous solutions. After the modification, polymer powders change from hydrophobic to hydrophilic, which makes it is possible to further modification of polymer powders in liquid phase. During the curing process of modified polymer powders, the partial dehydration of the catechol groups and crosslinking of PDA via C-O-C bonds are confirmed. Based on the features of PDA, a non-destructive mixing method is utilized to realize homogeneous dispersion of multi-walled carbon nanotubes (MWCNTs) in polymer matrix. In comparison with ball milling method, this way can preserve the integrated innate structure of MWCNTs effectively. Besides, by taking full advantage of the reducing and metal-coordination capability of PDA, Cu2+ is successfully loaded onto the surfaces of polymer powders. The related characterizations demonstrate that Cu2+in situ converts to metallic copper rather than copper oxide during the hot pressing process. The tribological properties of corresponding polymer composites are also studied. These results indicate that modifying polymer powders with PDA is multi-profit and presents practical application prospect. [ABSTRACT FROM AUTHOR]

The high specific-strength of glass fibers and exceptional self-lubrication of polytetrafluoroethylene (PTFE) fibers promote the potential application of hybrid PTFE/glass fabric composites in the tribological field, but their weak interfacial adhesion and inferior thermal properties significantly inhibit their tribological performance and reliability. Herein, a hybrid of polydopamine/silicon carbide/polyethyleneimine (PDA/SiC/PEI) functional coating was co-deposited onto the hybrid PTFE/glass fabric surface through a one-step impregnation method, leading to increased surface roughness and abundant amine groups. Tensile and peeling tests showed that this functional coating offered 47.8% enhancement in the fabric/matrix interfacial adhesion without compromising the strength of the pristine fabric. Moreover, the additional incorporation of WS2, and aluminum nitride (AlN) micro-fillers contributed to the development of a high-quality tribofilm and improved the thermal properties of fabric composites. The results of wear tests proved that the hybrid-fabric composites, after the introduction of functional coating and micro-fillers, exhibited outstanding tribological performance, which was attributed to the superior interfacial adhesion as well as the synergistic enhancement effects between WS2 and AlN micro-fillers. [ABSTRACT FROM AUTHOR]

Superhydrophobic materials has attracted considerable attention due to their usage in wide range of practical applications. However, in practical conditions, inevitable high discharge of VOC and dust particles in the common spraying method could be very harmful to the environment and workers as well. Herein, modified silica nanoparticles were combined with a commercial PDMS to obtain a non-fluoride transparent superhydrophobic coating cured at ambient temperature via an environment-friendly method of brushing. The coating can be fabricated on a wide range of substrates in a short time of only two minutes. The coating demonstrated excellent thermal stability upto 360 °C and corrosion resistance in electrochemical testing. Owing to the short fabrication process, the coating can be readily repaired by prompt brushing after being destroyed. With ultra-easy fabrication, it is expected that the coating has a great potential for practical application with different requirements such as low pollutant discharge, high transmittance, good thermostability or corrosion resistance. [ABSTRACT FROM AUTHOR]

It is a challenge to endow the material with the ability to pollutants degradation while maintaining the oil/water separation performance. Herein, the mixed dispersion of BiOBr photocatalyst and silicone sol was adsorbed in melamine foam. Superhydrophobic BiOBr-silicone aerogel (WCA=154°) was obtained through the transfer melamine foam to an autoclave and reaction at 80°C for 20 h. The prepared superhydrophobic BiOBr-silicone aerogel can effectively remove the water soluble pollutants which remain within the water phase after oil/water separation. The band gap of the superhydrophobic BiOBr-silicone aerogel was calculated to be 2.71 eV, which shows sensitivity to visible light (458 nm). Through mechanism analysis, it is found that the VB position of BiOBr is at 1.07 eV and the position of CB is at -1.64 eV. Finally, we prepared a superhydrophobic BiOBr-silicone aerogel (5 cm×5 cm×3 cm) for the verification of the large scale preparation. [ABSTRACT FROM AUTHOR]

Fabric composites are widely applied as self-lubricating liner for radial spherical plain bearings owing to their excellent mechanical and tribological properties. Nevertheless, the poor interfacial strength between fibers and the resin matrix limits the performance of composites utilized as tribo-materials. To overcome this drawback, a mild layer-by-layer (LbL) self-assembly method was successfully used to construct hybrid fabric composites in the present work. In addition, this investigation addressed the effect of self-assembly cycles on the friction and wear behaviors of hybrid fabric composites under dry sliding condition. The results demonstrate that fabric composites with three or more self-assembly cycles have significantly enhanced surface activities and anti-wear performances. The results obtained in this work can provide guidance in the preparation of selflubricating liner composites and highlight how the LbL self-assembly techniques could influence the properties of hybrid fabric composites. [ABSTRACT FROM AUTHOR]

Sewage discharge produced by homes and industries contains both oil and water-soluble components. In order to remove oil from water, materials with specific wettability can be used; however, these materials cannot remove dissolved contaminants from water. In this research, we prepared a superhydrophobic CdS cotton for water purification. This material has the ability to adsorb different types of oil due to its non-wettability (WCA = 152°). Moreover, its response behavior towards visible light enables it to remove water-soluble pollutants as well. The highest oil absorption rate of superhydrophobic CdS cotton is nearly 30 times, and it can absorb light below 564 nm and produce •OH to degrade water soluble pollutants. Finally, based on Mott-Schottky curve, the position of Fermi energy level was determined (−0.55 eV). Also, the positions of valence and conduction bands were calculated based on the analysis of band gap which helps in proving photoelectric response characteristics. [ABSTRACT FROM AUTHOR]

MoS2-multi-walled-carbon-nanotube (MWCNT) hybrids containing two-dimensional MoS2 and one-dimensional MWCNTs were synthesized through a one-step hydrothermal reaction. X-ray-diffraction and transmission-electron-microscopy results demonstrated that MoS2 nanosheets were successfully synthesized, and uniformly anchored on the MWCNTs' surfaces. Furthermore, the effects of the MoS2-MWCNT hybrids on the tribological performances of polyurethane composite coatings were investigated using a UMT-2MT tribo-tester. Friction and wear test results revealed that the friction coefficient and wear rate of a 3 wt% MoS2-MWCNT-1 filled polyurethane composite coating were reduced by 25.6% and 65.5%, respectively. The outstanding tribological performance of the MoS2-MWCNT-1 reinforced polyurethane composite coating was attributed to the excellent load-carrying capacity of the MWCNTs and good lubricant ability of MoS2. The surface morphologies of the worn surfaces and counterpart ball surfaces were investigated to reveal the wear mechanisms. [ABSTRACT FROM AUTHOR]

Designing multifunctional and fluorinate-free liquid-repellent materials via a facile and scalable method is highly desired. Herein, a transparent, durable, and self-cleaning superhydrophobic coating based on trimethoxypropylsilane-silica nanoparticles sol solution was prepared by one-step process. Once spray deposited on glass substrates, the transparent superhydrophobic self-cleaning glass with high water contact angle (158.5°) as well as low sliding angle (3.9°) was obtained. The transmittance of coated glass substrates is above 80 % in visible-light region (400-800 nm). Moreover, the prepared coatings kept stable superhydrophobicity under extreme environment conditions of high temperature and humidity, high or low temperature, and UV light irradiation. Water droplets could still roll off the obtained surface easily after examined by water impact and lacerating the surface with a knife. In addition, this versatile and environmentally benign approach can be applied on wide substrates readily by using spraying or dipping technique without any extra surface treatments. Therefore, our method may provide extensive applications in optoelectronics, liquid-repellent coatings, and oil-water separation. [ABSTRACT FROM AUTHOR]

The filtration membranes have been acknowledged as efficient way for separation of emulsion. Nevertheless, most of the methods have limitations of high cost and complex fabrication process. Here, we present a simple method for preparing superhydrophobic/superoleophilic filter paper by solution immersion process. The superhydrophobic filter paper exhibited high selectivity for oil-water mixture. Importantly, the filter paper can be applied to separate surfactant-stabilized water-in-oil emulsion. Separation process is achieved by one step under gravity. Moreover, the superhydrophobic filter paper maintains stable superhydrophobicity and emulsion separation property after using for five cycles. We expected that this low-cost process can be used for water-in-oil emulsion separation. [ABSTRACT FROM AUTHOR]

Fabricating functional materials that can solve environmental problems resulting from oil or organic solvent pollution is highly desired. However, expensive materials or complicated procedures and unidirectional oil-water separation hamper their applications. Herein, a magnetic superhydrophobic carbon fiber aerogel with high absorption capacity was developed by one-step pyrolysis of Fe(NO)-coated cotton in an argon atmosphere. The obtained aerogel can selectively collect oils from oil-polluted region by a magnet bar owing to its magnetic properties and achieves fast oil-water separation for its superhydrophobicity and superoleophilicity. Furthermore, the aerogel performs recyclable oil absorption capacity even after ten cycles of oil-water separation and bears organic solvent immersion. Importantly, the obtained aerogel turns to superhydrophilic and underwater superoleophobic after thermal treatment, allowing it as a promising and efficient material for bidirectional oil-water separation and organic contaminants removal. [ABSTRACT FROM AUTHOR]

The polyimide (PI)/carboxyl-functionalized multi-walled carbon nanotube (MWCNTs-COOH) nanocomposite films were synthesized by situ polymerization method. The results showed that the incorporation of MWCNTs-COOH greatly enhanced thermal stability and mechanical property of PI. PI/MWCNTs-COOH nanocomposites exhibited better tribological properties under seawater lubrication than other conditions because of excellent lubricating effect of seawater. Besides, the wear resistance of PI under seawater lubrication had been greatly improved by filling MWCNTs-COOH, because strong interfacial adhesion between PI matrix and MWCNTs-COOH nanofillers could transfer load effectively between contact surfaces. In particular, when the content of MWCNTs-COOH was 0.7 wt%, the corresponding PI/MWCNTs-COOH nanocomposites had the best tribological properties under seawater lubrication. Graphical Abstract: The polyimide (PI)/carboxyl-functionalized multi-walled carbon nanotube (MWCNTs-COOH) nanocomposite films were synthesized by in situ polymerization using 4,4′-oxydianiline (ODA), carboxyl-functionalized multi-walled carbon nanotube (MWCNTs-COOH) and pyromellitic dianhydride (PMDA). The tribological properties of PI/MWCNTs-COOH nanocomposite films were measured under dry sliding condition, pure water condition and seawater lubrication condition. This study can provide some guidance to develop polymer materials with excellent wear resistance suitable for ocean environment.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Silica gel shell microcapsules containing ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF]) have been successfully synthesized through an interfacial self-assembly process and solgel reaction. They are further developed as filler to improve the tribological property of polyurethane composite coatings. The tribological behaviors of the polyurethane composite coatings filled with microcapsules have been systematically investigated using ball-on-disk tribological test. The results showed that the polyurethane composite coating filled with microcapsules displayed much lower friction coefficient and wear, compared with that of unfilled one. It is demonstrated that the ionic liquid released from the broken microcapsules during the friction process lubricates the rubbing surfaces and prevents a direct contact between steel ball and coating, leading to a lower friction coefficient and a lower wear width and depth. [ABSTRACT FROM AUTHOR]

The development of a convenient method for oil-removal is of great significance for environmental protection. Here, we present a simple method for the removal of oils from water surface based on sponges that we fabricated by solution-immersion processes. The sponges exhibited high selectivity and absorption capacities for various kinds of oils when they were employed as absorptive materials. More importantly, the superhydrophobic sponge could be sustained 400 cycles of compressing test without losing their superhydrophobicity, exhibiting the high elasticity, robustness, and durability. To extend application field, superhydrophobic filter paper was used for oil-water separation. Interestingly, tunable wettability was received when oleophobic silica was employed instead of hydrophobic silica. We expected that this low-cost process can be used for oil-spill cleanup. [ABSTRACT FROM AUTHOR]

Exploring effective lubricant fillers to improve the tribological performance of the fabric composites would have practical applications. Herein, we developed nano- and micro-dimensional WS as fillers to improve the tribological property of the hybrid PTFE/Nomex fabric/phenolic composite. Sliding wear tests showed that the WS-filled fabric composites displayed improved antiwear behavior under all the test conditions, compared to the unfilled one. The optimum content of WS to fill the fabric composites was 2 wt% for nano-dimensional WS and 4 wt% for micro-dimensional WS. We also investigated the unfilled, nano-dimensional WS-filled, and micro-dimensional WS-filled fabric composites under varied test conditions, and the corresponding wear mechanisms were discussed based on the characterizations. [ABSTRACT FROM AUTHOR]

Bionic self-cleaning surfaces with well-ordered polymer nano-fibers are firstly fabricated by disturbing crystallization during one-step coating-curing process. Orderly thin (100 nm) and long (5-10 μm) polymer nano-fibers with a certain direction are fabricated by external macroscopic force ( F) interference introduced by H gas flow, leading to superior superhydrophobicity with a water contact angle (WCA) of 170° and a water sliding angle (WSA) of 0-1°. In contrast, nano-wires and nano-bridges (1-8 μm in length/10-80 nm in width) are generated by 'spinning/stretching' under internal microscopic force ( F) interference due to significant temperature difference in the non-uniform cooling medium. The findings provide a novel theoretical basis for controllable polymer 'bionic lotus' surface and will further promote practical application in many engineering fields such as drag-reduction and anti-icing. [ABSTRACT FROM AUTHOR]

To improve the antiwear property and load carrying capacity of hybrid PTFE/Nomex fabric/phenolic composites, graphene and graphene oxide (GO) had been synthesized and were employed as fillers, together with graphite. Sliding wear tests show that the wear rates of filler-reinforced PTFE/Nomex fabric composites were reduced greatly when compared to unfilled fabric composite. Besides, it was found that the 2 wt% GO filled PTFE/Nomex fabric composites exhibited the optimal tribological properties. It was proposed that the self-lubrication of GO, the favorable interface stability of the composite, and the uniform transfer film on the counterpart pin contributed together to the reinforced tribological property of GO filled PTFE/Nomex fabric composite. We also investigated the influence of filler content, applied load, sliding speed, and tensile and bonding strength on the tribological properties of PTFE/Nomex fabric composites. [ABSTRACT FROM AUTHOR]

A new method was presented to impart polymer substrate with superoleophobic properties. Aluminum/polymer composite was created by a hot-pressing process, and rough surface textures needed to establish superoleophobicity were created by HCl etching and boiling water treatment. After surface fluorination, the surface became super-repellent towards water and several organic liquids, such as hexadecane. The effect of geometrical structure on hydrophobicity and oleophobicity was investigated, and the result showed that the synergistic action of microterraces and nanoflakes played a key role in establishing oleophobicity. A waterfall/jet test demonstrated that the obtained surface can keep its superoleophobicity after a long time exposure to water. Moreover, the obtained surface did not lose the superoleophobicity after placing it under cold condition for 7 days. [ABSTRACT FROM AUTHOR]

We described a facile and time-saving method to fabricate superoleophobic surfaces on copper sheets. Surface textures suitable for superoleophobicity establishment were created by sandblasting and the Ag deposition process. After surface fluorination, the Ag treated sandblasted surface became superrepellent toward water, several organic liquids, and corrosion solutions. Electrochemical measurements show that the resulting superoleophobic surface possessed enhanced corrosion resistance, with a more positive corrosion potential as well as a more negative corrosion current density. Importantly, the surface can restore its superoleophobicity by an easily regeneration process when loss of superoleophobicity occurred. This study represents a key addition to functional superoleophobic materials. [ABSTRACT FROM AUTHOR]

Sewage not only contains water-soluble contaminants but water-insoluble contaminants as well. Superhydrophobic CdS–melamine foam prepared in this research satisfies the requirements of water purification. The photocatalyst CdS effectively adsorbs light energy to generate active species (⋅O2−) for degrading water-soluble pollutants. At the same time, superhydrophobic/superoleophilic characteristic of the melamine sponge can be utilized to remove water-insoluble pollutants. Finally, the degradation mechanism of materials was obtained by studying the parameters such as band gap and valence band structure, as well as by analyzing the experimental data of active species. [ABSTRACT FROM AUTHOR]