Economical-effective purification of brackish water through an integrated capacitive desalination & boron adsorption system

Abstract

The escalating scarcity of high-quality water for potable, industrial, and agricultural use necessitates innovative methods to augment freshwater supply from unconventional sources. This study primarily aims to lower boron (B) and chloride (Cl−) levels in brackish water to meet water quality standards of B < 0.5 mg/L and Cl− < 250 mg/L. To meet this goal, an innovative adsorbent, OQAS-AC@NGO, was used for boron removal. It combines organosilicon quaternary ammonium chloride (OQAS) modified activated carbon (AC) within a self-assembled nitrogen-doped graphene oxide (NGO) structure. Before boron removal, a capacitive deionization (CDI) system was used, employing OQAS-AC as the anode and COOH-modified AC as the cathode for chloride ion electrosorption. Through this cooperation procedure, the treated water meets the required quality standards while significantly reducing chemical costs by approximately 13.5 times when compared to conventional ion exchange resin methods for adsorbent regeneration. Moreover, the OQAS-AC@NGO adsorbent sustains its efficiency through multiple cycles, outperforming non-assembled N-GO in terms of yield, performance, and water flux. This underscores the cost-effective adsorbent preparation and enhanced water productivity. Economic analysis endorses the integrated CDI & B adsorption approach, advancing both sustainable water treatment processes and practical industrial applications.