Adsorption of Phosphate by Synthesized Silver/Calcium Oxide-Activated Carbon Nanocomposite

Developing adsorbents with appreciable morphology will create new approaches for better phosphate adsorption performance. This study aims to investigate the design of an adsorbent by impregnating silver nanoparticles (AgNPs) onto calcium oxide-activated carbon (CaO-AC). The Ag/CaO-AC nanocomposite was used as an adsorbent to remove phosphate. Batch adsorption studies were performed to evaluate the effects of adsorbent dose, initial phosphate concentration, contact time, and pH on removing phosphate from an aqueous solution. The optimized conditions were applied to a real wastewater sample. The optimum condition for phosphate adsorption on Ag/CaO-AC nanocomposite was at an adsorbent dose of 0.02 g, an initial phosphate concentration of 40 mg∙L-1, an equilibrium contact time of 45 minutes, and pH 7. Pseudo-second-order proved to be more accurate in representing the data of phosphate adsorption onto Ag/CaO-AC nanocomposite. The adsorption isotherm fitted well on the Langmuir model with a maximum adsorption capacity of 77.4 mg∙g-1. From the kinetics and isotherm studies, chemisorption was the primary adsorption mechanism through ion exchange and ligand exchange mechanisms. The results of this study show that Ag/CaO-AC nanocomposite is a promising adsorbent for removing phosphate from wastewater.