Abstract: Cross-linked polydimethylsiloxane (PDMS)/polyvinylidene fluoride (PVDF) composite nanofiltration (NF) membranes were prepared for recovery of hexane from soybean oil/hexane miscalls. Various reagents, such as tetraethoxylsilane (TEOS), phenyltrimethoxylsilane, octyltrimethoxylsilane and γ-aminopropyltriethoxylsilane, were used as cross-linking agents.Physical and chemical characteristics of the tailor made NF membranes were characterized by contact angle, FTIR, SEM, density, etc.The membranes were applied in the solvent recovery from soybean oil/hexane miscella.For each membrane, the effect of feed pressure upon the flux and oil retention was investigated.The permeate flux increases linearly with feed pressure, while oil retention increases first quickly and then slowly.With the increase of feed oil concentration, both flux and retention decrease significantly.It is found that the PDMS membrane cured with TEOS is the best for the separation.The observed osmotic phenomena similar to those of aqueous systems are interpreted using the van't Hoff equation.

Key words: polydimethylsiloxane, nanofiltration, solvent recovery, hexane, soybean oil

摘要： 以聚二甲基硅氧烷(PDMS)为分离层材料,聚偏氟乙烯(PVDF)超滤膜为底膜,采用正硅酸乙酯(TEOS)、苯基三甲氧基硅烷(PTMOS)、辛基三甲氧基硅烷(OTMOS)、γ-氨基丙基三乙氧基硅烷(APTEOS)4种不同的交联剂对PDMS进行交联,制备了PDMS/PVDF纳滤膜。采用接触角、红外谱图、扫描电镜等对膜的物理和化学结构进行了分析和表征。以大豆油/己烷混合油为实验体系,考察了压力和料液浓度对纳滤膜分离性能的影响。结果表明,纳滤膜的通量随压力线性增长,截留率初始随压力上升较快,随后增幅减慢而趋于稳定。随料液浓度的增加,纳滤膜的通量和截留率都有较大幅度的下降。相比较而言,以TEOS为交联剂所制得的纳滤膜分离性能最佳。大豆油/己烷混合油体系同水溶液体系的渗透特性类似,其渗透压可用van't Hoff方程计算。

关键词: 聚二甲基硅氧烷, 纳滤膜, 溶剂回收, 己烷, 大豆油