Selective adsorption of fluoride from drinking water using NiAl-layered metal oxide film electrode

Selective adsorption and regeneration of adsorbents are great challenges for fluoride removal in drinking water. In this study, a NiAl-layered metal oxide (NiAl-LMO) electrode was successfully prepared and used as an electro-adsorption electrode. With its structural memory effect for anions and high specific capacitance of 575 F.g(-1), the NiAl-LMO electrode exhibits capacitive deionization performance. The maximum adsorption capacity of F- by the electrode reached 49.28 mg/g, which was 4 times that of Cl- and 2 times that of SO42-, respectively. The good selectivity for F- electrosorption was ascribed to the high electronegativity of F- and the complexation between F- and hydroxyl aluminum groups. The electrode material has good stability and can be regenerated easily by applying a reverse voltage. After 10 cycles, the F- adsorption rate by the NiAl-LMO electrode was 94. 4% of the initial adsorption rate. The applied voltage enhanced the selectivity of F- adsorption by the NiAI-LMO electrode, and this electrosorption process was mainly dominated by electrical double layer adsorption. Under the conditions of 1.0 V and pH 7, the electrode showed a maximum adsorption efficiency of 73.5%. (C) 2018 Elsevier Inc. All rights reserved.