Removal of strontium by in situ electrochemical synthesis of Zn–Al LDHs using a bidirectional pulse method

Abstract

In this study, in situ electrochemical synthesis of Zn–Al-LDHs with a bidirectional pulse power supply was applied to remove Sr²⁺ from the simulated liquid radioactive waste from nuclear power plants. The removal rate of Sr²⁺ can reach up to 99.26% under the optimal conditions of the bidirectional pulse power supply: a current density of 57 mA cm⁻² (Zn electrode), a reversal time of 25 s, a frequency of 1000 Hz, a duty ratio of 80%, and a Zn/Al current ratio of 2 : 1. The Sr²⁺ adsorption behavior was also investigated. Adsorption kinetics studies suggested that the adsorption process followed the Lagergren pseudo-second-order kinetic model with good correlation. The adsorption process, preferably fitting the Langmuir isotherm model, suggested the monolayer adsorption of Sr²⁺ on Zn–Al-LDHs. Thermodynamic parameters revealed that the electrolysis process and the aging process were endothermic and exothermic, respectively.