正渗透浓缩浓盐水影响因素研究初探

Concentration of Brine by Forward Osmosis

采用反渗透海水淡化后的浓盐水为原料液,考察了驱动液种类、切向流速(泵转速)、原料液浓度、活性层朝向等变量对正渗透过程水通量的影响。结果表明,在相同浓度下的驱动溶液,氯化钙作为驱动溶液产生的水通量最高;氯化纳次之;葡萄糖最小,但膜对氯化钠的截留率最高,随着驱动液浓度的增大,对应的水通量增大,但水通量的增加量随驱动液浓度的增大而减小;当膜的活性层朝向原料液(正渗透模式)时,初始水通量远小于膜的活性层朝向驱动液(压力阻尼渗透模式)的水通量,但在驱动液浓度相同时正渗透模式下的平均水通量更高。在切向流速达到1 L/min后,水通量受切向流速的影响较小。最后采用HTI膜在正渗透模式下以5 mol/L NaCl溶液为驱动液、切向流速为1 L/min的条件下连续运行进行浓缩,约30 h后,在原料液的容器壁上发现了少许的沉淀物,原溶液的Na Cl回收率可达到52.6%。

The concentrated brine solution after reverse osmosis desalinationwas used as feed solute in forward osmosis, and the effect of types of draw solution, liquid flow rate （pump speed）, feed solution （FS） concentration and membrane orientations was Investigated.It was found that when the concentration of draw solution is same, Calcium chloride as the draw solution to produce the water flux is supreme;Sodium chloride second, Minimum of glucose, but the highest membrane intercept rate of sodium chloride, water flux increased with the increase of the draw solution concentrations, but the increased water flux decreased. When membrane orientation was Support LayerFacing Draw Solution （FO mode）, the initialwater flux was far less than membrane orientation was Support LayerFacing Feed Solution （PROmode）. But in both ofmembrane orientations, when the concentration of draw solution is same, the average water flux in the FO mode was more than that in the PRO mode. Meanwhile,after the cross-flow rate reached to 1 L/min,the flux was smaller influenced by the change of cross-flow rate.Results showed that using HTI membrane in the conditions of that a draw concentration of 5 mol/L and the cross-flow rate is 1＂ L/min, about aRer 29 h, found white mineral deposits on the front side of the vessel wall, the original solution of NaC1 recovery can reach 52.6%.