Prediction and optimization of adsorption properties for Cs+on NiSiO@NiAlFe LDHs hollow spheres from aqueous solution: Kinetics, isotherms, and BBD model

Abstract

In this work, novel NiSiO@NiAlFe layered double hydroxides (LDHs) hollow spheres were prepared by hydrothermal method. It was worth noting that LDHs’ grafting towards NiSiO hollow spheres could avoid the LDHs’ aggregation, and thus enhanced the material’s adsorption capacity. Furthermore, adsorption kinetics, adsorption isotherms, and Box-Behnken Design (BBD) model were conducted. Results indicated that NiSiO@NiAlFe LDHs hollow spheres had sufficient adsorption capability towards Cs+. The adsorption kinetics satisfied the pseudo-second-order adsorption model, Temkin model and Langmuir isotherm model. The adsorption process was efficient at the alkaline condition (pH = 10). The adsorption kinetics indicated that the adsorption process could reach the equilibrium in only 20 min. The maximum adsorption capacity of Cs+ towards NiSiO@NiAlFe LDHs hollow spheres was estimated to be 61.5 mg g−1. Moreover, the adsorption thermodynamics indicated that the adsorption process was exothermal, feasible and spontaneous. Thus, NiSiO@NiAlFe LDHs hollow spheres presented a broad potential for treating cesium containing wastewater.