The preparation of a cross-linked cerium (III)-loaded alginate bead adsorbent for the removal of phosphate from wastewater

The aim of this study was to prepare a cross-linked cerium(III)-loaded alginate bead (denoted as SA-Ca-Ce) and to apply it to remove phosphate from aqueous solution. The adsorption behaviors were investigated by the batch experiments at various experimental parameters including contact time, initial phosphate concentration, solution pH, temperature, and coexisting anions. The results showed that the Langmuir model is more suitable than the Freundlich model for well elucidation of the experimental data, and the maximum adsorption capacity is calculated to be 41.39mg/g at 318K. The adsorption of phosphate, which followed pseudo-second-order kinetics, is a chemisorption process. The phosphate adsorption had a slight decrease with the increasing of pH. The coexistence of other anions in solutions has an adverse effect on phosphate adsorption with the extent following the order: HCO3- > SO42- > Cl-. The phosphate adsorption mechanism was also investigated by scanning electron microscopy, Fourier transform infrareds spectroscopy. The electrostatic interactions and Lewis acid ligand were manifested to be two main mechanisms for phosphate adsorption onto SA-Ca-Ce. All the results indicated that the SA-Ca-Ce has a considerable potential for the phosphate removal from contaminated waters.