Effects of Anode Materials and Chloride Ions on Current Efficiency of Electrochemical Oxidation of Carbohydrate Compounds

Abstract

This study interrogated IrO 2 , RuO 2 , IrRuO 2 , Pt, and boron doped diamond for electrochemical oxidation of alginic acid and glucose. Linear sweep voltammetry estimated onset potential of oxygen evolution reaction from 1.03 to 2.60 V NHE in an inverse relation with the current efficiency of free chlorine generation in NaCl solutions, while further oxidation of free chlorine (chlorate ion generation) underestimated the current efficiency on Pt and boron doped diamond. Electrochemical oxidation experiments at 50 mA cm −2 confirmed the free chlorine to be the primary oxidant for chemical oxygen demand degradation on the dimensionally stable anodes since the current efficiency of free chlorine generation (25-35%) was comparable with the current efficiency of chemical oxygen demand degradation. The ClO 3 − generation on Pt was retarded in alginic acid degradation, but effective during glucose degradation due to different reactivity with free chlorine. For boron doped diamond, direct and •OH mediated oxidation were significant (11% for alginic acid and 22% for glucose) and competition among organic pollutants, Cl − , and free chlorine for •OH determined the current efficiency of organic compounds degradation. In a saline water, IrO 2 anode was the most energy-efficient (specific energy consumption for alginic acid: 48 Wh gCOD −1 ) with minimal formation of ClO 3 − .

Enhanced chlorine evolution from dimensionally stable anode by heterojunction with Ti and Bi based mixed metal oxide layers prepared from nanoparticle slurry

“…(5) ) would be far more facile than oxygen atom transfer from higher oxide (Eq. (6) ) [5] . In comparison, the >MO x+1 form would more preferentially mediate OER (Eq.…”

“…Aqueous Cl 2 (commonly noted as free chlorine) is also a famous oxidant for drinking water disinfection and, recently, electrolytic reactive chlorine species (RCS) has been utilized for on-site treatment of saline wastewater as well [5] . Owing to the value consuming nature of environmental technologies, however, the scarcity of Ir and Ru components have substantially constrained a large scale application of the electrochemical chlorination for water treatment.…”