Removal of phosphate from wastewater by nano-Fe3O4 modified attapulgite

Abstract Natural clay minerals demonstrate potential as phosphate adsorbents; however, their practical application is hindered by challenges in material recovery and limited adsorption capacity, resulting in increased operational costs. In this study, magnetic attapulgite (MATP) was synthesized using a co-precipitation method for simulating phosphate adsorption in wastewater treatment. The adsorbent was characterized using SEM, XRD, FT-IR and VSM. The characterization results confirmed the successful loading of nano Fe 3 O 4 onto attapulgite (ATP). The saturation magnetization intensity of MATP achieved the threshold required for rapid solid-liquid separation and recyclability. The adsorption kinetics were best described by the pseudo-second-order model, while the adsorption isotherms followed the Langmuir model. MATP exhibited a maximum phosphate adsorption capacity of 4.83 mg·g⁻¹, with an optimal dosage of 0.15 g and optimal performance under acidic pH conditions. The presence of Ca²⁺ in solution was found to significantly enhance the phosphate adsorption capacity of the magnetic clay composite. The phosphate adsorption process was found to be primarily governed by ligand exchange induced by -OH in MATP. This study demonstrated that magnetic reusable MATP composites have great promise for phosphorus removal and recycling.