Adsorption of phosphate in water using one-step synthesized zirconium-loaded reduced graphene oxide

In this account, a one-step green hydrothermal method for zirconium-loaded reduced graphene oxide (RGO-Zr) adsorbent was developed in pure water. It is based on the formation of initially strong-coupling RGO-Zr nanocomposites followed by in situ reduction of GO to RGO during the hydrothermal treatment. The phosphate adsorption performance of the as-prepared nanocomposites was investigated in aqueous environment under various conditions. The characterization results of RGO-Zr nanocomposites showed that ZrO₂ was successfully integrated onto the RGO sheets in amorphous. The data from equilibrium phosphate adsorption on RGO-Zr revealed that the adsorption kinetics followed a pseudo-second-order kinetic model, where the adsorption isotherm fitted the Langmuir isotherm model with a maximum adsorption capacity of 27.71 mg P/g at pH 5 and 298 K. The improved phosphate adsorption on RGO-Zr was caused by the dispersion of ZrO₂ on the RGO surface. Furthermore, the phosphate adsorption was found insensitive to the increase in pH while it was sensitive to the increase in temperature. The coexisting anions of SO₄^2-, F^-, Cl^-, NO^3- and CO₃^2- affected the phosphate adsorption in a different way. Results suggest that the present RGO-Zr adsorbent has the potential for controlling phosphorus pollution in water.