Toward Sustainable CO2 Reduction and Brine Utilization: Investigating Alkaline-Enhanced Solvay Processes

The pressing environmental challenge of carbon dioxide (CO2) emissions necessitates efficient CO2 sequestration methods, while managing concentrated brine from desalination plants remains critical. This study investigates the efficacy of modified Solvay processes for brine desalination management and CO2 capture, beginning with ammonia and subsequently replacing it with other alkaline materials including calcium hydroxide, potassium hydroxide, aluminum oxide, and carbide lime. Experimental analyses in a semi-batch reactor assessed the impact of different process parameters on CO2 capture efficiency and ion removal. Optimum conditions yielded peak sodium removal (25.0%) and CO2 capture efficiency (76.0%) using ammonia. Subsequently, calcium oxide replaced ammonia, achieving 33% sodium reduction and 86.2% CO2 capture efficiency. Additionally, potassium hydroxide and carbide lime demonstrated substantial brine desalination efficiencies of 44.1 and 47.1%, respectively, with carbide lime exhibiting superior CO2 capture efficiency (80%). Conversely, aluminum oxide showed low reactivity but effectively recovered 24.0% of magnesium ions from reject brine, indicating potential use as a coagulant. These findings underscore the potential of modified Solvay processes for addressing CO2 capture and brine management challenges while reducing environmental impacts of ammonia. Further research is warranted to optimize these processes for enhanced CO2 capture and sustainable brine desalination. This study contributes valuable insights into CO2 capture mechanisms and offers pathways toward more sustainable CO2 capture and brine desalination technologies.