Valorization of Seawater Reverse Osmosis Brine by Monovalent Ion-Selective Membranes through Electrodialysis

Abstract

This paper proposes the use of monovalent selective electrodialysis technology to concentrate the valuable sodium chloride (NaCl) component present in seawater reverse osmosis (SWRO) brine for direct utilization in the chlor-alkali industry. To enhance monovalent selectivity, a polyamide selective layer was fabricated on commercial ion exchange membranes (IEMs) through interfacial polymerization (IP) of piperazine (PIP) and 1,3,5-Benzenetricarbonyl chloride (TMC). The IP-modified IEMs were characterized using various techniques to investigate changes in chemical structure, morphology, and surface charge. Ion chromatography (IC) analysis showed that the divalent rejection rate was more than 90% for IP-modified IEMs, compared to less than 65% for commercial IEMs. Electrodialysis results demonstrated that the SWRO brine was successfully concentrated to 14.9 g/L NaCl at a power consumption rate of 3.041 kWh/kg, indicating the advantageous performance of the IP-modified IEMs. Overall, the proposed monovalent selective electrodialysis technology using IP-modified IEMs has the potential to provide a sustainable solution for the direct utilization of NaCl in the chlor-alkali industry.

Separation of Chloride and Sulfate Ions from Desulfurization Wastewater Using Monovalent Anions Selective Electrodialysis

“…Sharma et al enhanced the monovalent selectivity by fabricating a polyamide selective layer on commercial IEMs through interfacial polymerization (IP), which was then utilized for concentrating NaCl in seawater reverse osmosis brine. The results demonstrated that the IP-modified IEMs exhibited a divalent rejection rate exceeding 90%, whereas the commercial IEMs displayed a divalent rejection rate below 65% [36].…”