Kinetics-based process design of integrated CO₂ and NO_x capture using desalination reject brine-derived sorbents

Desalination reject brine is widely treated as a waste stream despite being rich in reactive ions that can be exploited for pollutant capture and mineralization. At the same time, simultaneous CO₂ and NO_x removal from flue gas remains underexplored, particularly in systems that integrate waste-stream valorization with process-level kinetics. This study presents an integrated process for the simultaneous capture and utilization of CO₂ and NO_x using sorbents derived from desalination brine. The key contribution is the development of a kinetics-informed, rate-based process framework that links brine electrolysis, selective NO oxidation, gas-liquid absorption, ion separation, and downstream carbonation-mineralization in a unified system. Beyond emission control, the process converts NO_x into nitrate and nitrite products and captured CO₂ into carbonate and bicarbonate species and mineralized carbonates. The proposed system achieved about 90% NO_x removal and 92% CO₂ capture under near-ambient conditions. Preliminary techno-economic analysis further showed that revenues from carbonate products and CO₂ credits can significantly offset operating costs. Overall, the results highlight a promising circular-economy pathway for coupling desalination brine valorization with integrated multi-pollutant capture and utilization.