Response surface methodology approach for optimization of removal of strontium by in-situ electrochemical synthesis of monohydric phosphate intercalated layered double hydroxides

In this study, in-situ electrochemical synthesis of monohydric phosphate intercalated layered double hydroxides (LDHs) was used to remove Sr 2+ from the simulated liquid radioactive wastes. The optimum reaction conditions were obtained by response surface methodology (RSM). The removal of Sr 2+ can reach up to 99.30% and the adsorption capacity of Zn–Al–LDHs–HPO 4 toward Sr 2+ was 6.01 mg/g under optimal conditions. With Sr 2+ being removed mainly by multilayer chemisorption, the adsorption kinetics followed Lagergren pseudo-second-order kinetic model, and the adsorption isotherms followed Freundlich model. Thermodynamic studies of adsorption showed that the adsorption of Sr 2+ to LDHs was a spontaneous and endothermic process. This method of LDHs synthesis simplifies the operational steps and is a promising treatment method because of its low energy consumption, high efficiency and small solid waste volume. This study provides an innovative idea for the treatment of strontium-containing liquid radioactive wastes from nuclear power plants. Graphical abstract