Removal of azoic dyes from aqueous solutions by chitosan enhanced ultrafiltration

A cationic chelating polymer, namely biopolymer chitosan CHI with a molecular weight of 117 kDa is employed in the present study to bring about the retention of azoic dyes from its aqueous solutions by way of polymer enhanced ultrafiltration (PEUF). The effects of process parameters, namely, operating time, CHI and sodium chloride concentrations, transmembrane pressure, and pH of solution on the retention rate and permeate flux were examined. CHI enhanced ultrafiltration achieved in the presence of CHI shows an increasing in the retention rate up to 86% for methyl orange (MO) and 89% for Direct Blue 71 (DB71). The retention rate of the studied azoic dyes decreases with sodium chloride concentration increasing. High retention percentage was also obtained at pH range from 2 to 6. In addition, the permeate flux decreases when both, feed chitosan concentration and pH of solution increase.