Substantial and rapid phosphorous adsorption by calcium modified mesoporous silicon micropheres

Abstract

Water deterioration and eutrophication caused by phosphorus (P) contamination necessitates P removal from polluted water, and has been a research focus since the second half of last century. In this study, novel mesoporous micropheres based on silicon and calcium (Ca) was prepared as an adsorbent by direct pyrolysis to enrich and remove P. The maximum adsorption capacities of the prepared adsorbents were 356.34 and 496.73 mg g−1 P−PO43− for potassium phosphate (K3PO4) and potassium dihydrogen phosphate (KH2PO4) solutions, respectively, and adsorption equilibrium was attained rapidly in less than 30 min. The Langmuir isotherm and pseudo-second-order kinetic model adequately fit the adsorption process for K3PO4 solution, while the Langmuir isotherm and pseudo-first-order kinetic appropriately fit the KH2PO4 solution. The adsorption of P was due to the reaction between Ca2+ and PO43−, forming different phosphates. Addition of interfering ions had no significant effect on the adsorption ability of the prepared adsorbents. The proposed adsorbent was successfully applied to remove P from real wastewater. Notably, this new Ca-modified mesoporous silicon micropheres is an excellent adsorbent for treating wastewater containing low P content, providing an effective approach for facile preparation of P adsorbents and exhibiting promising P removal from wastewater.