Direct removal of nitrate and phosphate anions together in a continuous fixed bed column down flow technique

Abstract

Synthetic adsorbent was used for the direct removal of nitrate and phosphate anions from aqueous solution. Synthetic absorbent was prepared in laboratory using different processes, which have high adsorption capacities for effective removal of selected ions in a column chromatography. Chitosan-reduced graphene-SiO2 in a column was used as a potent adsorbent for this selected method and final results were compared with another approach using chitosan-SiO2 in a Photo Catalytic Reactor (PCR). PCR process is easier, but the removal efficiency is less when compared with the Fixed Bed Column (FBC). The removal percentage using fixed bed column with a potent adsorbent was greater than 60% whereas it is less than 35% using photocatalytic reactor. Adsorption of nitrate and phosphate from aqueous solutions on both photocatalytic reactor and continuous fixed-bed column are studied with effects of various parameters such as contact time, dosage of adsorbent and pH of the aqueous solutions. Absorbents were fabricated using sol-gel for nano silica, chitosan and thermal heating method for reduced graphene oxides. Out of these, fixed bed columns with chitosan-reduced graphene oxide - SiO2 performed better when compared with the chitosan-SiO2 in a photocatalytic reactor.