Comparative Efficacy Study of Different Types of Ion Exchange Membranes for Production of Ultrapure Water via Electrodeionization

High purity ultrapure water is required in the electronics and pharmaceutical industries. Herein, we report production of high purity ultrapure water (18.5 L/h) by electrodeionization (EDI) technique in a laboratory scale EDI unit (effective membrane area 24 cm × 6 cm) using polyethylene interpolymer based ion-exchange membranes. The ultrapure water also prepared by EDI process in the same EDI unit using two different types of commercial membranes (Ionsep and Fujifilm type II). The resistance of ultrapure water was 18.2 MΩ cm with the interpolymer based membranes at 25 V/cell pair applied potential, whereas with commercial Ionsep and Fujifilm type II membranes the final resistance of ultrapure water was 15 MΩ cm and 17.1 MΩ cm respectively at 30 V/cell pair applied potential. The power consumption (W) and current efficiency (CE) values were 0.324 KWhkg–1 and 58.86% respectively for interpolymer based ion-exchange membranes, whereas for Ionsep and Fujifilm type II membranes, W and CE values were 0.658 and 0.43 KWhkg–1 and 34.83% and 53.88%, respectively. The better quality of ultrapure water produced with interpolymer membrane and the better efficacy of the EDI process with the interpolymer membrane compared to other two membranes is ascribed to the lower water uptake, high transport number, and lower ion back diffusion through the former membrane.