Phosphate is considered the main cause of eutrophication and has received considerable attention recently. Several methods have been used to control the level of phosphate in water such as biological treatment, membrane filtration processes, ion exchange, chemical precipitation, and adsorption. Adsorption technology is highly effective in the removal of phosphate from wastewater even at low phosphate concentrations. Nanomaterials/nanoparticles, carbon-based materials (activated carbon and biochar), and their composites have been widely employed for the adsorptive removal and recovery of phosphate from wastewater due to their exceptional properties such as high surface area and high phosphate adsorption properties. This article is a review of the recently reported literature in the field of nanotechnology and activated carbon for the adsorption of phosphate from wastewater. Highlights of the adsorption mechanisms, adsorption behaviour, experimental parameters, effects of co-existing ions, and adsorbent modifications are also discussed.

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.