纳滤膜法脱除离子膜制碱系统淡盐水中硫酸根的研究

Study on the Removal of Sulfate Ions in the Weak Brine of Ion Exchange Membrane Electrolysis System with Nanofiltration

针对目前国内制碱行业普遍采用氯化钡法脱除盐水中SO42-的弊端,提出采用纳滤膜法脱除离子膜制碱系统淡盐水中SO42-的方法,并对其工艺条件进行了系统的研究。通过实验确定了纳滤膜脱除盐水中SO42-的工艺条件。在本实验条件下,最佳的操作压力为1.2MPa、进料流量为28L/min。盐水通量随操作压力增大而增大,随盐水中SO24-浓度的增大而减小,进料流量对膜通量影响较小。随操作压力的增加,纳滤膜对NaCl和SO24-的截留率均有增大的趋势但增加的幅度较小;进料流量对NaCl和SO24-的截留率没有影响;淡盐水中SO42-的浓度在5～15g/L的范围内时对SO24-的脱除率没有影响。在本实验条件下,纳滤膜对NaCl的截留率较小;但对SO42-的脱除率较高,在96%以上,透过液中SO42-的浓度低于1g/L,符合工业生产要求。其次,进行了纳滤膜法脱除盐水中SO24-的浓缩实验,确定了适宜的浓缩比。纳滤可以将NaCl含量为220g/L的淡盐水进行浓缩,最终使浓缩液中SO42-的浓度达到60g/L。

In this paper,the Removal of Sulfate Ion in the Weak Brine of Ion Exchange Membrane Electrolysis System with Nanofiltration Membrane Method（RSINM） is proposed on the basis of the disadvantages of the barium chloride methods in the chlor-alkali industry which is popular explored in our country these days.The process conditions of the RSINM were investigated sysmatically.The process conditions of RSINM were determined with the continuous dia-Nanofiltration experiments.Under the optimum conditions,the operation pressure and the feed flux were 1.2MPa and 28L/min,respectively.The brine flux increased with the operation pressure increase,decreased with the concentration of the sulfate ions increase in the feed,but the feed flux influenced the brine flux minor.The retention efficiency of NaCl and SO4^2- increased with the operation pressure,but the additional extent is less.The feed flux did not impact on the retention efficiency of NaCl and SO4^2-.The concentration of SO4^2- between 5-15mg/L had no effect on the removal efficienty of SO4^2-.The removal efficiency of SO4^2- was more than 96%,and the concentration of SO4^2- was less than 1g/L in the permeate which reached the standard of the industrial production.The Concentrated Ratio（CR） was determined with concentrated experiments for removal SO4^2- by Nanofiltration membrane.The weak brine containing NaCl with 220g/L could be concentrated to make the concentration of SO4^2- obtain to 60g/L.