PDMS/ZSM-5膜的制备及渗透汽化分离水中乙酸正丁酯和乙酸乙酯

Preparation of PDMS/ZSM-5 membranes and pervaporation separation of n-butyl acetate and ethyl acetate from aqueous media

为探究出适合分离水中的乙酸正丁酯和乙酸乙酯的新型渗透汽化膜材料,选用沸石ZSM-5对聚二甲基硅氧烷(PDMS)材料进行填充改性,以聚偏氟乙烯(PVDF)为支撑层,采用刮涂法制备PDMS/ZSM-5/PVDF复合膜渗透汽化分离水中的乙酸正丁酯和乙酸乙酯。采用SEM、接触角测量仪、FTIR、TGA和XRD等对膜材料物理化学性能进行表征,考察了膜材料的溶胀行为及渗透汽化性能。结果表明,ZSM-5在PDMS膜中分散均匀,且没有发生化学作用,并提高了膜材料的疏水性和热稳定性。随着ZSM-5添加量的增加,膜在乙酸正丁酯和乙酸乙酯的溶胀度和待分离组分在膜材料中的扩散速率不断增加。随着进料浓度和温度的增加,渗透通量不断增大,分离因子先增大后减小。随着ZSM-5在PDMS/ZSM-5/PVDF复合膜中含量的增加,总渗透通量增加,而分离因子呈现先增加后减小的趋势。当添加量为10%(质量)时,分离因子达到最大值。对于乙酸正丁酯/水体系,渗透通量和分离因子最大值分别为319 g·m^-2·h^-1和131;而对于乙酸乙酯/水体系,渗透通量和分离因子最大值分别为1385 g·m^-2·h^-1和121。

To explore a new type of pervaporation membrane material suitable for the separation of n-butyl acetate and ethyl acetate from aqueous media,the zeolite ZSM-5 was used to modify the polydimethylsiloxane(PDMS)material with polyvinylidene fluoride(PVDF)as the support layer.The PDMS/ZSM-5/PVDF hybrid membrane was prepared by coating for pervaporation of n-butyl acetate and ethyl acetate from aqueous solution.SEM,contact angle measuring instrument,FTIR,TGA and XRD were used to characterize the physical and chemical properties of the membrane material,and the swelling behavior and pervaporation performance of the membrane material were investigated.The results indicated that ZSM-5 dispersed uniformly in the membrane material and no chemical change occurred between ZSM-5 and PDMS polymer chain.The hydrophobic and thermal stability properties of the filled film were obviously improved by incorporation of ZSM-5.With the increase of ZSM-5 content,the swelling degree and diffusion rate of the membrane in n-butyl acetate and ethyl acetate solvents increased.The permeation flux increased while the separation factor increased firstly and then decreased with the rise of the feed concentration and temperature.With the increase of ZSM-5 content in the PDMS/ZSM-5/PVDF hybrid membrane,the total flux increased,while the separation factor increased first and then decreased.The separation factor reached a maximum when ZSM-5 filling content was 10%(mass).For n-butyl acetate/water systems,the permeate flux and maximum separation factor are 319 g·m^-2·h^-1 and 131.For ethyl acetate/water systems,the permeate flux and maximum separation factor are 1385 g·m^-2·h^-1 and 121.