Controlled preparation of cerium oxide loaded slag-based geopolymer microspheres (CeO@SGMs) for the adsorptive removal and solidification of F from acidic waste-water.

A new cerium oxide loaded slag-based geopolymer microspheres (CeO@SGMs) was prepared by a two-step i.e. dispersion-suspension-solidification and in-situ co-precipitation method. The optimal parameters for the preparation of 0.02CeO@SGMs were slag (30 g), 1.7 M water glass (12.86 g), water (8 g) and 0.02 mol/L of Ce. 0.02CeO@SGMs was characterized by SEM, XRD, BET, EDX, FTIR, XPS and PSD techniques. The leaching concentration of Ca (95.65 mg/L) was only 1/5 of the SGMs at pH 2 after the modification of CeO. Adsorption data fitted well with Freundlich isotherm model suggesting multilayer adsorption mechanism with a maximum adsorption capacity for F by 0.02CeO@SGMs of 121.77 mg/g at 298 K. The negative values of thermodynamic parameters (ΔH and ΔS) indicated the exothermic nature of the adsorption process with reduced chaos of the whole system. 0.02CeO@SGMs exhibited excellent dynamic adsorption performance at 4 mL/min F solution flow rate. The influence of various co-existing anions on adsorption of F over 0.02CeO@SGMs followed an order of: Cl ≈ NO < SO < PO. Attributed to the facile preparation process, cost-effectiveness and environmental friendliness, the newly designed 0.02CeO@SGMs can be deemed of promising industrial applications for the abatement of F from wastewater.