Desalination supplies the vast majority of drinking water in the Persian Gulf. The process creates concentrated brine waste that is usually dumped back into the Gulf, harming marine life and threatening future water supplies. At the same time, the region’s booming economies are producing increasing amounts of carbon dioxide.
Scientific American has reported that Farid Benyahia, a chemical engineer at Qatar University, has come up with an efficient way to address both problems.
The Solvay process is a 150-year-old, seven-step chemical conversion method that is widely used to produce sodium carbonate for industrial applications. By simplifying the process to produce sodium bicarbonate (baking soda) rather than sodium carbonate, the number of chemical conversion steps can be reduced to just two.
In the presence of ammonia, carbon dioxide reacts with waste brine from desalination, making solid baking soda and ammonium chloride solution. The ammonium chloride solution then reacts with calcium oxide to produce calcium chloride solution and ammonia gas. The ammonia is reused in the first step, reducing the cost of the process.
The process almost entirely eliminates the need for brine disposal and ends up with sodium bicarbonate and calcium chloride. Qatar already has natural gas processing plants venting pure CO2 close to brine disposal stations, making the process very cost-effective, at least in places with similar infrastructure.