Mixed metal oxide and boron-doped diamond anodes for the treatment of 1-butyl-3-methylimidazolium chloride in single- and dual-flow configuration

Abstract

The treatment of 1-butyl-3-methylimidazolium chloride (BMImCl) has been studied under different anodes (Ti-Pt-SnO2-Sb2O5, MMO, and boron-doped diamond, BBD) and configurations (single-flow and dual-flow cell‒SFC and DFC, respectively) using MMO and BBD alone or combined. In terms of BMImCl removal and mineralization, BDD overperforms MMO in SFC configuration at any current density, becoming less costly when operated at the highest current density (100 mA cm‒2 in the range 25 to 100 mA cm‒2) due to the reduced anode costs despite the higher electricity consumption. Nonetheless, attention must be given to the formation of chlorates and perchlorate in significant concentrations. In DFC configuration, the performances do not surpass those of BDD with the same overall current density in terms of BMImCl oxidation/mineralization, requiring higher volumetric charges than BDD in comparable conditions. The study also includes a preliminary economic analysis to compare the fixed capital costs, mainly coming from the required electrode area, as well as the operating costs, from the electricity demand, for the different SFC and DFC configurations.