多孔SiC陶瓷表面的超疏水改性及其对油-固体系的分离性能

Superhydrophobic modification of the surface of porous SiC ceramics and its performance towards oil-solid separation

以二水醋酸锌和氨水为原料,采用化学浴沉积法在平均孔径为250 nm的多孔SiC陶瓷表面构造花状ZnO微纳结构,并用正辛基三乙氧基硅烷接枝改性.考察了Zn^(2+)浓度、反应温度和反应时间对沉积在多孔陶瓷表面ZnO形貌的影响,进而考察其对多孔陶瓷表面超疏水性能的影响.对比了超疏水改性前后多孔陶瓷的表面性质及其油-固分离性能.结果表明,花状ZnO在多孔SiC陶瓷表面沉积的最佳条件是:Zn^(2+)浓度为75 mmol/L,反应温度为96℃,反应时间为3 h.此时硅烷接枝改性后多孔陶瓷表面超疏水效果最好,其表面水接触角和滚动接触角分别为173°±2.5°和2.5°±1°.在油-固分离实验中,超疏水多孔SiC陶瓷对固体炭黑具有良好的截留性能,当跨膜压差为0.25 MPa时,其稳态通量为498.3 L/(m^(2)·h).与空白样相比,通量提高了53.6%.

In this paper, using zinc acetate dihydrate and ammonia as raw materials, ZnO nanoflower(NF) structure was fabricated on the surface of porous SiC ceramics with an average pore size of 250 nm by chemical bath deposition, and then grafted with n-octyltriethoxysilane. Effects of Zn^(2+)concentration, reaction temperature and reaction time on the morphology and superhydrophobic properties of porous SiC ceramic surface were investigated. The wettability and oil-solid separation performance of the blank sample and superhydrophobic porous SiC ceramics were investigated, respectively. Results showed that the optimal conditions for ZnO NFs deposited on porous SiC ceramic surface were as follows: Zn^(2+) concentration of 75 mmol/L, reaction temperature of 96 ℃, reaction time of 3 h. In this case, the surface of porous ceramics grafted with silane provided with the best superhydrophobic properties. The surface water contact angle(WCA) and rolling contact angle were 173°±2.5° and 2.5°±1°, respectively. In the experiment of oil-solid separation, superhydrophobic porous SiC ceramics exhibited excellent retention towards solid carbon. The steady-state flux was 498.3 L/(m^(2)·h)(measured at a transmembrane pressure of 0.25 MPa), which was 53.6% higher in comparision with the blank sample.