Open AccessImpact of Peroxymonocarbonate on the Transformation of Organic Contaminants during Hydrogen Peroxide in Situ Chemical Oxidation
Author(s) -
Xuejing Yang,
Yanghua Duan,
Jinling Wang,
Hualin Wang,
Honglai Liu,
David L. Sedlak
Publication year - 2019
Publication title -
environmental science and technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.497
H-Index - 58
ISSN - 2328-8930
DOI - 10.1021/acs.estlett.9b00682
Subject(s) - chemistry , hydrogen peroxide , phenol , phenols , substituent , electrophile , in situ , carbonate , chemical transformation , reactivity (psychology) , organic chemistry , photochemistry , catalysis , medicine , alternative medicine , pathology
Under the conditions employed when in situ chemical oxidation is used for contaminant remediation, high concentrations of H 2 O 2 (e.g., up to ~10 M) are typically present. Using 13 C NMR, we show that in carbonate-rich systems, these high concentrations of H 2 O 2 result in a reaction with HCO 3 - to produce peroxymonocarbonate (HCO 4 - ). After formation, HCO 4 - reacts with phenol to produce di- and tri-hydroxyl phenols. HCO 4 - reacts with substituted phenols in a manner consistent with its electrophilic character. Exchanging an electron-donating substituent in the para position of a phenolic compound with an electron-withdrawing group decreased the reaction rate. Results of this study indicate that HCO 4 - is a potentially important but previously unrecognized oxidative species generated during H 2 O 2 in situ Chemical Oxidation (ISCO) that selectively reacts with electron-rich organic compounds. Under conditions in which HO· formation is inefficient (e.g., relatively high concentration of HCO 3 - , low total Fe and Mn concentrations), the fraction of the phenolic compounds that are transformed by HCO 4 - could be similar to or greater than the fraction transformed by HO·. It may be possible to adjust treatment conditions to enhance the formation of HCO 4 - as a means of accelerating rates of contaminant removal.