Abstract:

The Al₂O₃ film and the SiC film with an average pore diameter of 500 nm were hydrophobically modified by n-octyltriethoxysilane and ethanol as modifiers and solvents, respectively. The concentration and modification of the modifer were investigated by graft polymerization. The wettability and oil-solid separation performance of the modified Al₂O₃ and SiC MF membranes were investigated. The backflushing operation and long-term stability test for the modified membranes were conducted. Under the optimal modification conditions with grafting agent concentration of 0.2 mol·L^-1, grafting temperature of 40℃ and grafting time of 12 h，the water contact angles (WCAs) of the modified Al₂O₃ and SiC membranes were as high as 134°±1°and 140°±1°, respectively. It was found that the hydrophobic SiC membrane showed higher hydrophobicity than that of the Al₂O₃ membrane. For oil-solid separation experiments, both modified membranes exhibited excellent rejection to impurities in oil phase. However, the hydrophobic modification had a more significant effect on the flux of SiC membrane. The fluxes of hydrophobic Al₂O₃ and SiC MF membranes were 1134 L·m^-2·h^-1 and 1408 L·m^-2·h^-1, respectively, with transmembrane pressure of 0.25 MPa. Backflushing operation was beneficial to the flux recovery of ceramic membrane, especially hydrophobic SiC membrane.

Key words: ceramic membrane, SiC, oil-solid separation, hydrophobic modification

摘要：

以正辛基三乙氧基硅烷和乙醇分别作为改性剂和溶剂，采用接枝聚合法对平均孔径为500 nm的Al₂O₃膜和SiC膜进行疏水改性，考察了改性剂浓度、改性液温度和改性时间对膜表面疏水效果的影响，并对比了疏水改性前后两种陶瓷膜的表面性质及疏水改性后的油固分离性能，进行了反冲实验和稳定性测试。结果表明，两种陶瓷膜材料在改性剂浓度为0.2 mol·L^-1，改性液温度为40℃，改性时间为12 h时，疏水改性效果最好，得到的疏水Al₂O₃膜和SiC膜的水接触角分别为134°±1°和140°±1°，经改性后的SiC膜的疏水效果优于Al₂O₃膜。在油固分离实验中，疏水Al₂O₃膜和SiC膜均对固体炭黑有良好的截留性能，但疏水改性对SiC膜的油品通量提升更为显著，两种膜的稳态通量分别为1134 L·m^-2·h^-1和1408 L·m^-2·h^-1。反冲操作对疏水SiC膜的通量恢复更有利。

关键词: 陶瓷膜, 碳化硅, 油固分离, 疏水改性