Simple synthesis of mesoporous ferrite materials as magnetic adsorbents for phosphate removal

Abstract

Mesoporous MFe2O4 materials (M = Mn, Cu, and Co) as magnetic adsorbents for phosphate removal were synthesized by a simple coprecipitation method without annealing at high temperatures. Several techniques, including powder X-ray diffraction, field emission electron scanning microscopy, nitrogen adsorption-desorption and vibrating sample magnetometry were used to characterize the samples. The effects of M2+ ions on their point of zero charge and their phosphate adsorption capacity were investigated. All three samples consist of nanosized particles with cubic spinel structure and ferromagnetic properties, which allows them to be easily separated from aqueous effluents using a magnet. According to the batch experiments, the adsorption isotherms and the adsorption kinetics for these mesoporous materials are well fitted with the nonlinear Langmuir model and the nonlinear pseudo-second-order model, respectively. Among them, CuFe2O4 powder showed the best phosphate adsorption performance with the maximum P adsorption capacity of 27.49 mgP g-1, which can be assigned to the highest surface area and the high pH value at its point of zero charge.