Electroactivity Variable Valence NiFe Layered Double Hydroxyde for Cl <sup>−</sup> Removal through Electrically Switched Ion Exchange
Xiaoyang Guo, Xiaowei An, Peifen Wang, Tianyun Wang, Zhenkun Li, Xuli Ma, Xiao Du, Xiaogang Hao
Abstract
Abstract NiFe layered double hydroxide (LDH) films with different Ni/Fe molar ratios were successfully prepared on carbon paper (CP) by the potentiostatic method and were used for the removal of chloride ions (Cl − ) by electrically switched ion exchange (ESIX) technology. The results showed that the Ni/Fe ratios had a significant effect on the adsorption performance of LDH for Cl − . The prepared NiFe LDH film with Ni/Fe molar ratio of 1 : 1 showed the best Cl − ESIX performance and the maximum adsorption capacity could reach 43.8 mg ⋅ g −1 at 1.4 V (vs. SCE) in 20 ppm Cl − solution. The excellent adsorption performance of LDH for Cl − was mainly due to the coupling of the interlayer anion exchange mechanism and the electroactivity‐variable valence mechanism. In addition, the Cl − regeneration rate remained above 95 % during five repeated adsorption/desorption experiments, and the charging capacity was still about 96 % of the initial capacity even after 1000 CV cycles. Therefore, the NiFe LDH film could be a promising electroactive material for the removal of Cl − from aqueous solution.