Effect of preparation conditions on arsenic rejection performance of polyamide-based thin film composite membranes

Abstract

Herein, a polyamide-based thin film composite (TFC) membrane was fabricated for the removal of arsenic (As) from water. The polyamide thin film was synthesized through interfacial polymerization (IP) onto a polysulfone porous substrate. A Box-Behnken design of response surface methodology was used to investigate the effect of preparation conditions, including piperazine (PIP) concentration, trimesoyl chloride (TMC) concentration, and reaction time on the As rejection and permeate flux of the synthesized membrane. The separation performance of the prepared membranes from 15 designed experiments was conducted with an arsenate (Na₂AsHSO₄) solution of 150 ppm at a pressure of 40 psi and a temperature of 25^oC. The analysis of variance revealed the regression models to be adequate. From the regression analysis, the flux and As rejection were expressed by quadratic equations as a function of PIP concentration, TMC concentration, and reaction time. It was observed that the PIP concentration, TMC concentration, and reaction time had a significant effect on the flux and As rejection of the polyamide membrane. Moreover, a strong impact from the interaction of PIP and TMC was also observed on rejection of the resulting membrane. Using the desirability function approach to analyse the regression model, the optimal preparation conditions of the polyamide membrane were a PIP concentration of 2.5 wt.%, TMC concentration of 0.11 wt.%, and reaction time of 40 sec. The membrane exhibited a good As rejection of 95%.