Modification of activated carbon by ZnCl2, CaCl2, MgCl2 and their applications in removal of nitrate ion from drinking water

Nitrate is one of the most crucial pollutants in the urban and rural drinking water resources. Many techniques have been used to remove these contaminants. In this study, granular activated carbon (GAC) modified with the mixture of ZnCl2, CaCl2 and MgCl2 is utilized for the removal of nitrate from the water. Results of removing this adsorbent by batch method and changing the effective factors including contact time, adsorbent dose, nitrate concentration, pH, and temperature were investigated. Two theoretical adsorption isotherms namely Langmuir and Freundlich were used to describe the experimental results. The Langmuir isotherm model explained the sorption process well and showed the best coefficient of determination (0.9947). The nitrate sorption kinetic data were successfully fitted to pseudo-second order kinetic model. Adsorption was maximized between pH ranges 4-8. The overall results demonstrated potential applications of modified GAC for nitrate removal from the aqueous solutions.