Acetic acid and methanol recovery from dimethyl terephthalate process wastewater using pressure membrane and membrane distillation processes

Abstract

In this study, acetic acid and methanol were recovered from dimethyl terephthalate process wastewater using cross flow membrane and membrane distillation processes. Different types of ultrafiltration (UP150 and UP005) and nanofiltration (NF270 and NF90) were tested in cross flow membrane filtration to recover acetic acid from wastewater. NF90 membrane supplied maximum acetic acid rejection efficiency and it increased from 39.6% to 46.9% when applied pressure increased from 10 to 20 bar. The effect of solution pH was also tested and the rejection efficiency of acetic acid increased from 46.9% to 100% when the pH was increased from 2.5 to 7.0. However, methanol rejection efficiency did not affect with pressure and pH change. Methanol rich solution obtained from NF90 membrane permeate was recovered by vacuum membrane distillation. 95 % methanol recovery was obtained by hydrophobic polypropylene (PP) membrane at 250 mL/min flow rates. SEM images and contact angles of clean and used membranes were also provided and the results showed that hydrophilic organic acids deposited on the membrane surface increased the hydrophilicity.