Research on the influence of polyaluminum chloride and benzotriazole on membrane fouling and membrane desalination performance

The behavior and mechanism of nanofiltration membrane fouling in the process of membrane water treatment, as well as the effect of fouling on membrane desalination efficiency are studied. NF90 was selected as the experimental membrane, and the target pollutants were 5 kinds of inorganic salts (NaCl, Na2SO4, CaCl2, MgCl2 and KCl), polyaluminum chloride (PAC) and benzotriazole (BTA). Various membrane samples were characterized by SEM, and the cation concentration was measured by ion chromatograph (HPIC) quantitatively evaluate the influence of membrane fouling on ion rejection efficiency. The results showed that PAC, followed by inorganic salts and BTA, mainly caused membrane fouling. PAC always preferentially formed larger and loosely attached fouling layer on the membrane surface. BTA is adsorbed on the surface of the membrane and the fouling layer, increasing the adhesion between the fouling and the membrane and the cohesion between the fouling. Contrary to BTA, PAC has the opposite interception effect on inorganic salts, and the denudation effect of cross-flow shear force on the membrane surface keeps the membrane pores always high permeability. The effect of fouling on the rejection of inorganic salts is consistent with the results of ion concentration determination.

Automated summary

The study focused on the behavior and mechanism of nanofiltration membrane fouling in membrane water treatment, as well as the impact of fouling on membrane desalination efficiency. Results showed that PAC caused the most severe membrane fouling, followed by inorganic salts and BTA. PAC formed larger and loosely attached fouling layer on the membrane surface, while BTA increased the adhesion and cohesion between fouling and membrane. Contrary to BTA, PAC had a reverse interception effect on inorganic salts and the denudation effect of cross-flow shear force on the membrane surface maintained high permeability of membrane pores.