Effects of coagulant bath temperature toward separation performance and antifouling properties of PVDF/CA membranes for filtration of dyes

Abstract

Phase inversion is used to prepare poly(vinylidene fluoride) (PVDF) microfiltration membranes by combining it with the hydrophilic polymer additive cellulose acetate (CA). For the filtration of methylene blue (MB) and acid yellow 17 (AY17), the effects of coagulant bath temperature (CBT) on the separation performance and antifouling properties are thoroughly investigated. SEM analysis shows that the membrane at higher CBT has a larger pore diameter than at lower CBT, resulting in differences in membrane surface hydrophilicity. It is found that the increase in surface hydrophilicity causes the permeability of PVDF/CA membranes to be higher at higher CBT than at lower CBT. Rejection values above 90% indicate that the membranes are more effective for MB separation at both lower and higher CBT. Otherwise, lower CBT provides better AC rejection than higher CBT. The Flux Recovery Ratio, which is higher at higher CBT, remains in the 75–95% range at lower CBT. As a result, lower CBT is better for membrane fouling resistance than higher CBT. In addition, the fouling observed at lower CBT is similar to the fouling observed at higher CBT, but lower CBT has a higher percentage of reversible fouling than higher CBT. The membranes with more reversible fouling are therefore easier to clean using the backwashing process. As a result, PVDF/CA membranes manufactured at lower CBT have better separation performance and antifouling characteristics than those manufactured at higher CBT.