Desalination of brackish groundwater from Al-Batinah region on functionalized graphene and activated carbon derivatives for irrigation purposes

About 92 % of the fresh water resources in the Sultanate of Oman comes from groundwater. However, high level of salinization of groundwater is taking place in the coastal region of Al Batinah North and South governorates, the main agricultural land in the country, turning the ground freshwater to brackish. Brackish water irrigation has adversely affected the agricultural productivity of the soil. Based on our previous studies at SQU, Na+, Ca2+ and Mg2+are the major cations, however, Cl-, SO42- and NO3- are the major anions in brackish groundwater. Currently, the farm crop culture is under stress and a change to crops of more tolerance to salinity is taking place. However, in the long term, this might not be a solution as salinity increases with time deteriorating the soil quality and crops. The current desalination methods such as reverse osmosis is expensive and not affordable by many farm owners. In this research, different techniques will be tested for brackish groundwater desalination for irrigation purposes including ion exchange and capacitive deionization. Activated carbon and 3D Graphene hydrogels will be prepared and functionalized to produce cation and anion exchangers for the removal of cations and anions from the brackish groundwater. This includes strong cation exchange groups, ?SO3H, chelating ion exchange groups (amine derivatives) for removing cations, and quaternary ammonium groups (anion exchangers) to remove anions. Produced sorbents will be tested for the removal of cations and anions from brackish groundwater in batch and dynamic sorption system. A multilayer column will be investigated for complete desalination. In addition, conductive activated carbon with high nitrogen content will be prepared. Both the conductive activated carbon and 3D graphene hydrogels loaded and unloaded with metal nanoparticles will be examined for ions removal from the brackish groundwater using capacitive deionization. Recycle and reuse of developed ion exchangers will be also tested. For high levels of salt, precipitation technique using ammonium carbonate will be involved prior to ion exchangers / capacitive deionization stages. It is expected that this study will provide an efficient, cheap, sustainable, and recyclable integrated method of desalination of brackish groundwater for irrigation.