含甲基纤维素的NaA沸石膜的制备和表征

NaA沸石膜具有规则的孔道结构，利于分子传输，在有机物脱水领域有一定的应用。为使沸石膜生长更连续均匀，提高渗透汽化性能，本文以甲基纤维素作为空间限制剂加入合成液，探究碱度、晶化温度以及晶化时间对膜的影响，按最优条件制备合成液，并依据质量比m(MC)∶m(H₂O)=1∶100添加甲基纤维素，制备NaA沸石膜。表征方法采用XRD、SEM和渗透汽化3种方式，结果表明添加甲基纤维素的沸石膜表面结构完整，生长致密且性能优良，在75℃下对0.6mol/L的NaCl水溶液做渗透汽化测试时，通量达8.33kg/(m²·h)，盐离子截留率为99.95%。在0.6mol/L的NaCl的水溶液中测试72h，结果表明添加甲基纤维素的NaA沸石膜时间依存性更好，通量保持在8.30kg/(m²·h)左右，离子截留率稳定在99.90%。渗透汽化分离ω(C₂H₆O)=90%乙醇的水溶液，随着温度从60℃升高到75℃，沸石膜的通量由1.55kg/(m²·h)升高到2.56kg/(m²·h)，渗透侧水含量保持在99.90%左右。

Preparation and characterization of NaA zeolite membrane with methylcellulose

The NaA zeolite has a regular pore structure and strong hydrophilicity which make it a favorable material for molecular transport. Favorable characteristics of this material can be used for the development of NaA zeolite membrane with an excellent selectivity for dehydration of organic matter. Secondary growth method was employed to improve the pervaporation performance of NaA zeolite membrane. The effects of alkalinity, crystallization temperature and crystallization time were investigated. The synthetic fluid was prepared according to the optimal conditions. A NaA zeolite membrane was prepared by adding methylcellulose and water with a ratio of 1∶100. The SEM, XRD and pervaporation performance tests showed that the NaA zeolite membrane prepared by the improved method has a dense growth, compact structure and excellent pervaporation performance. The synthesized membrane exhibited a high flux and salt rejection of 8.33kg/(m²·h) and 99.95% at 75℃ for 0.6mol/L of NaCl aqueous solution respectively. The results showed that the NaA zeolite membranes for the desalination of 0.6mol/L of NaCl solution displayed a good stability over a period of 72 hours while the flux remains constant at 8.30kg/(m²·h) with a rejection rate of 99.90%. Moreover, the aqueous solution of ω(C₂H₆O) = 90% ethanol was separated by pervaporation at a temperature of 60℃ to 75℃. The flux of the zeolite membrane was increased from 1.55kg/(m²·h) to 2.56kg/(m²·h). The rejection rate was maintained around 99.90%.