Chitosan solubilization by bipolar membrane electroacidification: Reduction of membrane fouling

Chitosan, a biopolymer obtained from chitin deacetylation, was solubilized by bipolar membrane electroacidification (BMEA). We showed earlier that limitation in solubilization process was mainly due to chitosan precipitation in the acidified compartment. If fouling can be reduced or prevented, BMEA could be an environmentally attractive method for chitosan solubilization. The purpose of the present work was to identify process conditions that could reduce chitosan fouling in BMEA. The factors studied were: the type of salt in the acidified compartment (NaCl or CH₃COONa); the type of electrolyte in the basified compartment (KCl or HCl); and the current density (4 or 20 mA/cm²). Chitosan fouling was successfully reduced by a combination of NaCl salt and HCl electrolyte, while 98% chitosan solubilization yield was achieved by operating at a current density of 4 mA/cm² with NaCl/KCl configuration with no apparent fouling. This work showed that water dissociation at the interface of the anionic membranes was the main factor responsible for chitosan precipitation.