Direct determination of chemical oxygen demand by anodic decomposition of organic compounds at a diamond electrode

Takeshi Kondo, Yusuke Tamura, Masaki Hoshino, Takeshi Watanabe, Tatsuo Aikawa, Makoto Yuasa, Yasuaki Einaga

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Chemical oxygen demand (COD) was measured directly with a simple electrochemical method using a boron-doped diamond (BDD) electrode. By applying a highly positive potential (+2.5 V vs Ag/AgCl) to an aqueous electrolyte containing potassium hydrogen phthalate, glucose, and lactic acid or sodium dodecylbenzenesulfonate using a BDD electrode, an anodic current corresponding to the electrolytic decomposition of these organic compounds was observed. No such current was seen on glassy carbon or platinum electrodes due to a significant background current caused by the oxygen evolution reaction. The electric charge for the anodic current observed at the BDD electrode was found to be consistent with the theoretical charge required for the electrolytic decomposition of the organic compounds to CO2 and was used to calculate COD. This analysis was performed by a simple I-t measurement at constant potential using a BDD electrode, and no calibration was needed. This new simple indicator, "ECOD" (electrochemical oxygen demand), will be useful for continuous monitoring of industrial wastewater with low protein concentrations and on-site instant analysis of natural water with a BDD electrode-based portable ECOD meter.

Original languageEnglish
Pages (from-to)8066-8072
Number of pages7
JournalAnalytical chemistry
Issue number16
Publication statusPublished - 2014 Aug 19


ASJC Scopus subject areas

  • Analytical Chemistry

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