Qingpeng Li,Jiaxing Liu,Tiancheng Jiang,Xiaoyun An,Na Wang,Zhixiu Xu,Wanyuan Guo,Liang Zhang,Xiaofeng Liu
To improve the storage stability and conductivity of aluminum powder in an aqueous environment, the surface of aluminum powder was treated to form silica film by the sol–gel method, then was treated with conductive modification to introduce nanocarbon black particles so that conductive aluminum powder could be prepared to solve the application bottleneck of aluminum powder in water-borne heavy-duty anticorrosive coatings. The structure, surface morphology, and composition of the modified aluminum powder were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD). The corrosion resistance and electrochemical properties were measured using a hydrogen evolution test and an 2electrochemical test. The results showed that there was a compact SiO2film formed on the surface of the prepared conductive aluminum powder, and the conductive filler nanocarbon black was uniformly grafted on the surface. According to the hydrogen evolution test at 100 h/50 °C, conductive aluminum powder with 5 wt% carbon black exhibited the best hydrogen evolution effect, with a hydrogen evolution amount of only 0.5 mL. The prepared conductive aluminum powder was applied to the water-borne coatings, and the storage stability test, electrochemical polarization test, and neutral salt spray test were further conducted. The water-borne coatings prepared with conductive aluminum powder still showed good performance and had no reaction after 6 months of storage. Compared with the coating containing SiO2-modified aluminum powder, the coating exhibited better corrosion resistance.
Cellulose is a widely used hydrophilic material due to its rich hydrophilic hydroxyl groups. However, the presence of its lipophilic segment will affect the antifouling performance. Finding strategies to improve this problem has attracted considerable attention. In this work, a layer of silica was applied to a cellulose-deposited polyvinylidene fluoride membrane through a straightforward in-situ bionic silicification process of tetraethyl orthosilicate. The contact angle and oil droplet contact test proved that the high-hydrophilicity and underwater superoleophobicity of the silicified membranes were significantly enhanced. The surface structure and composition were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results of show that this improvement was mainly attributed to the presence of silicon hydroxyl groups, buried cellulose chains, and micro-nanostructures composed of cellulose and silica. The stable silica coating also provided protection for the polymeric membrane against degradation after water washing for 24 h, ultrasonic treatment (40 KHZ) for 10 min or exposure to different pH levels (pH=1, 4, 9 and 12) and saturated sodium chloride solution for 24 h. Furthermore, the silicified membrane showed outstanding oil adhesion resistance and permeation flux, enabling effective purification of different oil-in-water emulsions that were stabilized by emulsifiers. Notably, the membrane achieved a high oil removal rate (> 99.4 %) of various emulsions (toluene-in-water, cyclohexane-in-water, tetrachloroethane-in-water, soybean oil-in-water, toluene-in-salt solution, toluene-in-acid solution and toluene-in-alkaline solution emulsions). In particular, for toluene-in-water emulsions (oil droplets in the emulsion ranged from 58.77 nm to 615.1 nm), a significantly enhanced permeation flux (4777 L·m −2 ·h −1 ·bar −1 ) was obtained at 0.8 bar pressure. Even after multiple cycles of separation, the flux was higher than that of the unsilicified membrane. Overall, this approach is mild, simple, efficient, and easily scalable, making it an ideal method for producing superhydrophilic coatings with substantial application potential.
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