Abstract:

As a renewable, abundant, and cost-effective natural polymer, cellulose can be developed into a high-performance membrane separation material, which is of great significance for sustainable chemical processes and effective utilization of biomass resources. In this work, using the ionic liquid 1-allyl-3-methylimidazolium chloride (AMIMCl) as solvent and water as a non-solvent, the cellulose based composite membranes for pervaporation were prepared via non-solvent induced phase separation (NIPS) method on polyacrylonitrile (PAN) support layer. The physicochemical properties of the membrane materials were characterized by scanning electron microscopy (SEM), contact angle measurements, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and swelling tests, etc. The separation performance of the composite membranes in ethyl acetate/water system was evaluated through steady-state pervaporation experiments. The effects of composition of the casting solution, water content in the feed liquid, and temperature on permeation flux and separation factor were investigated. The results showed that the crystalline structure of cellulose transformed from typeⅠto typeⅡafter dissolution and film formation, significantly improving its thermal stability. When the cellulose concentration in the casting solution ranged from 2% to 8%, the dense and defect-free membranes could be formed. The prepared cellulose membrane had good stable cycling performance. The maximum pervaporation separation index (PSI) was obtained at cellulose content of 6%, with the permeation flux of 378g/(m²·h), and separation factor of 10218.

Key words: cellulose, non-solvent induced phase separation (NIPS), pervaporation, ethyl acetate dehydration, composite membranes

摘要：

纤维素作为一种可再生、储量丰富且成本低的天然高分子聚合物，将其开发成功能型膜分离材料，对化工过程绿色可持续发展以及生物质资源有效利用具有重要意义。本文采用纤维素作为制膜材料，以1-烯丙基-3-甲基氯化咪唑（AMIMCl）离子液体为溶剂，水为非溶剂，在聚丙烯腈（PAN）支撑层上通过非溶剂致相分离法（NIPS）制备获得纤维素渗透汽化复合膜。利用扫描电子显微镜（SEM）、接触角测量、热重分析（TGA）、傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）和溶胀度测试等手段表征分析纤维素膜材料的物理化学性质，并用稳态渗透汽化实验测试其在乙酸乙酯/水体系的脱水分离性能，考察铸膜液配比、进料组成和温度对渗透通量与分离因子的影响规律。结果表明，纤维素原料在溶解成膜过程中晶型由Ⅰ型转变为Ⅱ型，热稳定性显著提高，铸膜液中纤维素质量分数在2%~8%时，均能形成致密无缺陷的膜材料。该膜循环稳定性良好，在纤维素质量分数为6%时渗透汽化分离指数（PSI）最大，渗透通量为378g/(m²·h)，分离因子为10218。

关键词: 纤维素, 非溶剂致相分离, 渗透汽化, 乙酸乙酯脱水, 复合膜