Amino-functionalized magnetic zirconium alginate beads for phosphate removal and recovery from aqueous solutions

Amino-functionalized magnetic zirconium alginate beads with an interpenetrating network (Fe₃O₄/PAM/SA–Zr) were prepared, characterized, and then tested as a novel biomass adsorbent for phosphate removal and recovery. The hydrogel beads exhibited outstanding thermostability and possessed a magnetic response. The effects of the pH, dosage, initial phosphate concentration, interference ions, and temperature on the removal of phosphate were investigated. The kinetics, isotherms, and thermodynamics of the adsorption were studied. Notably, the adsorption of phosphate was endothermic, feasible, and spontaneous with a maximum uptake capacity of 42.23 mg-P/g at an optimized pH of 2.0. The phosphate could be desorbed effectively with a 0.2 mol/L NaOH solution, and the adsorbent exhibited a good reusability. The possible adsorption mechanisms were verified by zeta potential, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses. Continuous phosphate-adsorption tests were conducted in a fixed-bed columns packed with Fe₃O₄/PAM/SA–Zr, and the breakthrough curves were predicted by the Adams–Bohart, Thomas, and Yoon–Nelson models, respectively. The suitability of the hydrogel beads for the treatment of real wastewater was also tested. These hydrogel beads should be a promising adsorbent for phosphate removal and recovery from aqueous solutions, with the advantages of a high uptake capacity, good reusability, and easy magnetic separation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46897.