高岭土对不同污染物微滤过程的影响

Effect of kaolinite particles on different foulants during microfiltration

本研究采用原子力显微镜(AFM)结合自制的膜探针以及Zeta电位仪通过分别测量不同有机污染物,即腐殖酸(HA)、牛血清蛋白(BSA)和海藻酸钠(SA)与微滤膜之间的粘附力以及相应污染物的Zeta电位,对高岭土在不同有机物微滤过程的影响进行了系统性研究。结果表明,高岭土对污染膜通量衰减的影响主要发生在膜过滤的初期阶段,其存在使HA污染膜的初期通量衰减幅度增加,BSA和SA污染膜的初期通量衰减幅度减缓;清洗后HA污染膜的通量恢复率降低,而BSA和SA污染膜的通量恢复率增大。而且,高岭土的存在使膜-HA之间的粘附力变大以及HA溶液的Zeta电位变小,膜-BSA、SA之间的粘附力变小以及相应污染物的Zeta电位都增大。因此,膜-污染物之间粘附力以及溶液的Zeta电位的变化可以指示膜污染的变化趋势。

To investigate the effect of kaolinite particles on the organic fouling behavior during microfiltration( MF) systematically,atomic force microscope( AFM) combined with self-made membrane probe and Zetasizer were applied. Fouling experiments with humic acid( HA),bovine serum albumin( BSA) and sodium alginate( SA) were carried out with PVDF MF membrane. Results show that kaolinite particles aggravated the permeate flux decline extent of HA-fouled membrane but mitigated the permeate flux decline extent of BSA,SA-fouled membrane in the initial filtration stage,while the flux decline extent in the later filtration stage had no relationship with kaolinite particles for each type of foulant used. In the presence of the kaolinite particles,the flux recovery rate of HA-fouled membrane declined but the recovery rate of BSA,SA-fouled membrane increased. Moreover,contrary to BSA and SA,both the membrane-HA adhesion force and HA aggregations increased because of the presence of kaolinite particles. Consequently,it was evident that the change of corresponding foulant aggregation and membrane-foulant adhesion force can predict corresponding membrane fouling trend.