Abstract: This study aims at the enhancement in nanofiltration process of aqueous solutions of inorganic salts and provides reference values for industrial application.Gas-sparged nanofiltration experiments with aqueous solution of MgSO₄ were performed using a DK2540F element spiral nanofilitration membrane module.The permeate flux and the enhancement from gas sparging were measured in the following operation ranges:temperature 28-36℃,feed concentration 20-50 g·L^-1,transmembrane pressure 0.4-0.7 MPa,air/liquid ratio 1.0-3.5,and air velocity 1.0-3.5 m·s^-1.The effects of different conditions on the permeate flux,rejection and increment rate of permeate flux of nanofiltration membrane were investigated.The experimental results show that gas sparging can significantly increase the permeate flux and rejection of MgSO₄ aqueous solution,appropriate temperature is between 30℃ and 40℃ and feed concentration,transmembrane pressure,and air/liquid have profound effects on the permeate flux and rejection rate of MgSO₄ aqueous solution,and the flux enhancement is more significant at higher feed concentration,lower transmembrane pressure,and higher air/liquid.

Key words: spiral nanofiltration membrane, permeate flux, rejection, air/liquid ratio

摘要： 气液两相流强化卷式纳滤膜分离实验是针对DK2540卷式纳滤膜,采用气液两相流强化分离技术,对硫酸镁溶液进行研究,较系统地研究了温度、料液浓度、过膜压力、料液流速、气体流速等因素在分离硫酸镁溶液时,对膜通量、截留率和膜通量增加率的影响,并总结了气液两相流强化效果。结果表明,气液两相流强化卷式纳滤膜分离有明显的效果。温度宜在30~40℃。料液浓度越大、过膜压力越小、气液比越大,气液两相流强化效果越明显。

关键词: 卷式纳滤膜, 膜通量, 截留率, 气液比