Electrodialysis-distillation hybrid process for the recovery of dimethylsulfoxide (DMSO) solvent from industrial effluent

摘要

The invention relates to the removal of the impact-sensitive and hazardous sodium azide (NaN3) salt along with ammonium chloride (NH4Cl) for the recovery of dimethyl sulfoxide (DMSO) solvent present in a pharmaceutical industrial effluent generated during the manufacture of antiretroviral drugs. The wastewater cannot be directly distilled for DMSO recovery in the presence of NaN3, which could cause explosions. Moreover, disposal of the DMSO increases the chemical oxygen demand (COD) load on the effluent treatment plant (ETP). The developed process includes pretreatment of the effluent for the removal of colloidal impurities and suspended solids followed by electrodialysis using cation and anion-exchange membranes stacked alternately for reduction of the salts concentration to ppm levels. The desalted liquor is then subjected to two vacuum distillation steps for recovering pure DMSO solvent.