A new method for removal of hydrogen peroxide interference in the analysis of chemical oxygen demand

Tingting Wu, James D. Englehardt

Research output: Contribution to journalArticle

61 Scopus citations

Abstract

Many advanced oxidation processes involve addition of hydrogen peroxide (H 2O 2) with the aim of generating hydroxyl radicals to oxidize organic contaminants in water. However, chemical oxygen demand, a common measure of gross residual organic contamination, is subject to interference from residual H 2O 2 in the treated water. A new method, involving catalytic decomposition of H 2O 2 with addition of heat and sodium carbonate (Na2CO3), is proposed in this work to address this problem. The method is demonstrated experimentally, and modeled kinetically. Results for 5 mM H 2O 2 in deionized (DI) water included reduction to below the COD detection limit after 60 min heating (90°C) with addition of 20 g/L Na2CO3 concentrated solution, whereas 900 min were required in treated municipal wastewater. An approximate second order rate constant of 11.331 M -1min -1 at Na 2CO 3 dosage of 20 g/L was found for the tested wastewater. However, kinetic modeling indicated a two-step reaction mechanism, with formation of peroxocarbonate (CO 4 2-) and ultimate decomposition to H 2O and O 2 in pure H 2O 2 solution. A similar mechanism is apparent in wastewater at high catalyst concentrations, whereas at low Na 2CO 3 addition rates, the catalytic effects of other constituents appear important.

Original languageEnglish (US)
Pages (from-to)2291-2298
Number of pages8
JournalEnvironmental Science and Technology
Volume46
Issue number4
DOIs
StatePublished - Feb 21 2012

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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