Redox-mediated electrochemical separation of boron ions

Abstract

Boron contamination of various water sources has been increasing in recent years and is receiving worldwide attention for its negative effects on the environment, wildlife, and humans; therefore, its removal is of utmost importance. Considering dwindling water sources and the possibility of the world population soon experiencing water scarcity, effective and innovative technologies must be developed to remove boron ions from water sources. The aim of the present study was to assess a sustainable separation process for the removal of boron ions using an electrochemical flow cell with symmetric redox-active polyvinyl ferrocene (PVF) functionalized carbon nanotube (CNT) electrodes using real-time measurements of the boron adsorption performance in continuous-flow mode while varying the flow rate, cell voltage, and boron concentration. A Box–Behnken experimental design (BBD) was used to improve boron adsorption. The adsorption isotherms, kinetics, and thermodynamics were investigated to further describe the adsorption process. The high R² value, calculated using a linear and nonlinear procedure, demonstrated that the Langmuir isotherm and pseudo-first order models fit quite well. The maximum adsorption of 60.61 mg/g was observed. The thermodynamic results illustrated that the adsorption of boron ions onto the PVF/CNT electrodes was spontaneous and endothermic under continuous flow mode.