Electrochemical degradation of bisphenol A using a flow reactor with a boron-doped diamond anode

Constant current electrolyses are performed in a filter-press reactor using a boron-doped diamond (Nb/BDD) anode to investigate the effect of volumetric flow rate, temperature, pH, current density, and NaCl addition on the chemical oxygen demand (COD) abatement of a 150 mg L−1 bisphenol A (BPA) solution. Only the volumetric flow rate, temperature, and current density significantly affect the COD abatement. However, at 25 °C, NaCl addition significantly increases the COD abatement rate at 30 mA cm−2, but no effect is observed at 6.5 mA cm−2; under optimized hydrodynamic conditions, the best condition in terms of current efficiency and energy consumption occurs at 6.5 mA cm−2 and 7.0 L min−1, in the absence of NaCl, when only 1.7 A h L−1 is needed to attain a 90% COD abatement. When comparative electrolyses are carried out at 25 °C and 30 mA cm−2 using Nb/BDD, Ti–Pt/β-PbO2, and TiO2–RuO2 anodes, the Nb/BDD anode always presents the best performance, in the absence or presence of NaCl. The oxidation performance attained with the Nb/BDD anode using the filter-press reactor is significantly better than those previously reported in the literature for the degradation of BPA using conventional electrochemical cells.

► Use of the flow reactor significantly enhances the degradation of bisphenol A. ► Solution COD abatement is attained with low average molar electric energy consumption. ► Mass-transport control leads to pH-independent COD abatement rates. ► BDD stands out as best-performing anode when compared to Ti–Pt/β-PbO2 and TiO2–RuO2.