Abstract

VALLADARES, Noe; VASQUEZ-MEDRANO, Ruben; PRATO-GARCIA, Dorian  and  IBANEZ, Jorge G.. Electrochemical Oxidation of Bentazon at Boron-doped Diamond Anodes: Implications of Operating Conditions in Energy Usage and Process Greenness. J. Mex. Chem. Soc [online]. 2023, vol.67, n.4, pp.518-535.  Epub Apr 26, 2024. ISSN 1870-249X.  https://doi.org/10.29356/jmcs.v67i4.1997.

We studied the mineralization of the herbicide bentazon (Bn) through advanced electro-oxidation using a non-divided modified Diachem® cell. The treatment system consisted of an array of three boron-doped diamond (BDD) electrodes: cathode-anode-cathode. The chosen variables of interest were current density (j = 0.5, 1.0, and 1.5 mA cm-2), the initial Bn concentration (10, 50, and 100 mg L-1), and the volumetric flow (v = 280, 500, and 750 mL min-1). In all cases, a 0.04 M Na2SO4 and 0.05 M NaHSO4 (pH ~ 2) solution was used as the supporting electrolyte. Results indicate that, at low current densities, up to 86 % of the Bn present in the solution can be removed (j = 1.0 mA cm-2 and v = 500 mL min-1); however, additional increases in j (from 1.0 to 1.5 mA cm-2) slightly increase (2-3 %) the removal efficiency but increase 55 % the carbon footprint and the treatment cost. Likewise, increases in the volumetric flow from 500 to 750 mL min-1 marginally affect the elimination of Bn and the removal of total organic carbon (TOC) in 1% and 4 %, respectively. The highest efficiencies for TOC (68 %) and COD (82 %) removals were obtained with the following operational conditions: j = 1.0 mA cm-2 and v = 750 mL min-1. Values obtained for the instantaneous current efficiency (ICE) showed an exponential reduction, suggesting that mass transfer influences importantly the efficiency of the process.

Keywords : Bentazon; boron-doped diamond; electrochemical oxidation; process greenness; sustainable energy mix.