Abstract
This paper reports a comparative study of the electrochemical performance of in situ hydrogen peroxide electrogeneration on gas diffusion electrodes modified by organic redox catalysts 2-ethylanthraquinone, 2-terc-butylanthraquinone and azobenzene in medium of 0.1 mol L-1 H2SO4 plus 0.1 mol L-1 K2SO4, pH = 1. Hydrogen peroxide generation proved strongly dependent on the applied potential and on the concentration of added catalysts. Electrode modifications led to a significant increase in H2O2 yield (30%) reaching 850 mg L-1, and the overpotential for oxygen reduction shifted to less negative values (400 mV vs Ag/AgCl for electrodes modified by quinones and 300 mV vs Ag/AgCl for electrodes modified by azobenzene) compared to noncatalyzed gas diffusion electrodes, resulting in reduced energy consumption of 596.5 to 232.4 kWh kg-1. The results indicated that the best electrode for H2O2 electrogeneration is the gas diffusion electrode modified with 10% of 2-ethylanthraquinone, offering the best cost to benefit ratio.
Highlights
Hydrogen peroxide is a widely used reagent in processes as bleaching in the textile, pulp and paper industries, food processing, and pharmaceuticals.[1,2,3,4,5] In wastewater treatment, hydrogen peroxide can oxidize organic pollutants to CO, offering numerous advantages in terms of treatment rate, cost and availability in comparison to traditional biodegradation methods.[6]
To study the electrochemical behavior of electrodes, linear voltammograms were recorded in the cathode region in a medium of 0.1 mol L-1 H2SO4 plus 0.1 mol L-1 K2SO4
The (LVO2 - LVN2) curves were obtained by subtracting linear voltammetries (LV) current values recorded with O2 from those recorded with N2
Summary
Hydrogen peroxide is a widely used reagent in processes as bleaching in the textile, pulp and paper industries, food processing, and pharmaceuticals.[1,2,3,4,5] In wastewater treatment, hydrogen peroxide can oxidize organic pollutants to CO , offering numerous advantages in terms of treatment rate, cost and availability in comparison to traditional biodegradation methods.[6] Electrochemical technology can be an efficient means of hydrogen peroxide electrosynthesis. Much interest has focused on the modification of electrodes with organic catalysts for hydrogen peroxide electrosynthesis. Investigations with catalysts of the anthraquinone class to help hydrogen peroxide production have become common (see Table 1). The O2 reduction reaction mechanism on the surface of anthraquinonemodified electrodes is represented by reactions:[8,9]
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