Using magnetite/zirconium-comodified attapulgite as a novel phosphorus (P) sorbent for the efficient removal of P and the adsorption mechanism allowing this effect

Magnetite/zirconium-comodified attapulgite (Fe/ZrATP) acting as a novel phosphorus (P) sorbent was synthesized, characterized and applied to control P in an aquatic environment. Batch experiments demonstrated that at an adsorption dose of 0.2 g, 97.8% of the phosphate was rapidly sequestered from aqueous solution within 24 h, and the composite reached a maximal sorption capacity of 3 mg/g. The adsorption performance of the adsorbent Fe/ZrATP was minimally affected by changes in the initial pH (pH = 2–11). In addition, Fe/ZrATP presented excellent selectivity for phosphate when coexisting ions that often occur in water bodies were present; the solution ionic strength exerted little influence on phosphate sorption behavior. Adsorption and desorption experiments indicated that the removal of phosphate was mainly due to adsorption. The Fe/ZrATP adsorption isotherm was fitted to the Freundlich adsorption model. Moreover, the composite demonstrated excellent recyclability performance. The P adsorption mechanism of Fe/ZrATP involves electrostatic interactions, ligand exchange and surface precipitation. Our findings indicated that the separable Fe/ZrATP demonstrated high efficiency and sustainable phosphate removal, which is promising in phosphate removal and recovery applications