Simultaneous removal of fluoride and phosphate in a continuous fixed-bed column filled with magnesia-pullulan composite.

A magnesia-pullulan composite (MgOP) was prepared by chemical sol-gel method and utilized for the simultaneous removal of fluoride and phosphate in a continuous fixed-bed column. A series of dynamic adsorption experiments were conducted to explore the impacts of different factors on the dynamic adsorption of fluoride and phosphate in the single- and binary-adsorbate systems, including bed mass, flow rate, temperature, inlet adsorbate concentration, influent pH and coexisting anions. The results demonstrated that the adsorption capacities of fluoride and phosphate ions were 6.21 and 7.76 mg/g, respectively, at the optimal conditions (i.e., 6 g of bed mass and 0.48 L/h of flow rate), when influent fluoride and phosphate concentrations were fixed at 10 mg/L. An increased bed mass had a negative effect on the simultaneous adsorption of fluoride and phosphate on MgOP. In contrast, increasing the volumetric flow rate facilitated the removal of fluoride and phosphate from an aqueous solution in the binary-adsorbate system. Besides, the MgOP can be effectively regenerated by calcination with high stability. The column adsorption of fluoride and phosphate in the binary-adsorbate system were well described by the Thomas model. In conclusion, the present study provides insight into the simultaneous removal of fluoride and phosphate through adsorption. Image 1 • Fixed-bed of MgOP was feasible for simultaneous fluoride and phosphate removal. • Thomas and Yan models described the simultaneous adsorption of fluoride and phosphate. • Bed mass, flow rate, concentration, pH and temperature effects were invesitgated. • Competitive effects were observed between fluoride and phosphate in MgOP fixed bed. [ABSTRACT FROM AUTHOR]