Impact of Peroxymonocarbonate on the Transformation of Organic Contaminants during Hydrogen Peroxide in Situ Chemical Oxidation

Abstract

Under the conditions employed when in situ chemical oxidation is used for contaminant remediation, high concentrations of H2O2 (e.g., up to ∼10 M) are typically present. Using 13C NMR, we show that in carbonate-rich systems, these high concentrations of H2O2 result in a reaction with HCO3 – to produce peroxymonocarbonate (HCO4 –). After formation, HCO4 – reacts with phenol to produce di- and trihydroxyl phenols. HCO4 – 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 HCO4 – is a potentially important but previously unrecognized oxidative species generated during H2O2 in situ chemical oxidation that selectively reacts with electron-rich organic compounds. Under conditions in which HO· formation is inefficient (e.g., relatively high concentration of HCO3 –, low total Fe and Mn concentrations), the fraction of the phenolic compounds that is transformed by HCO4 – 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 HCO4 – as a means of accelerating rates of contaminant removal.

Simple Catalytic Approach for Removal of Analytical Interferences Caused by Hydrogen Peroxide in a Standard Chemical Oxygen Demand Test

“…This small decrease may indicate that the competing reaction pathway (A in Fig. 1) made only a small contribution to COD oxidation, as proposed by Yang et al (2019), because HCO -4 reacts with electronrich compounds, such as organic sulfides (Richardson et al 2000), amines (Balagam and Richardson 2008), and alkenes (Yao and Richardson 2000), which may exist in untreated wastewater. In untreated leachate, this fraction seemed to be higher than in the other wastewaters examined, resulting in the highest SD, which could be neglected, however, due to the much higher COD value of the leachate.…”

“…This method was applied and verified for municipal secondary effluents with COD values of ∼35 mg=L and H 2 O 2 concentrations of 5-50 mmol=L. Yang et al (2019) investigated the impact of bicarbonates on the transformation of organic contaminants using H 2 O 2 . Peroxymonocarbonate (HCO − 4 ) was identified as an oxidative species by Carbon-13 nuclear magnetic resonance ( 13 C-NMR) analysis; the proposed decomposition reaction of H 2 O 2 by bicarbonate is shown in Eq.…”

“…(3) (Truzzi et al 2019). A higher H 2 O 2 concentration promotes HCO − 4 decomposition through the reaction pathway (C) along with the self-decomposition pathway (B), which both generate oxygen gas as a final product (Yang et al 2019).…”

Unexpected Role of Nitrite in Promoting Transformation of Sulfonamide Antibiotics by Peracetic Acid: Reactive Nitrogen Species Contribution and Harmful Disinfection Byproduct Formation Potential

“…Several natural anions in water also affect PAA disinfection and oxidation. For instance, bicarbonate (HCO 3 – ) can promote the decomposition of PAA and may produce the secondary oxidant peroxymonocarbonate (HCO 4 – ) . Moreover, PAA may oxidize the halide to produce hypohalous acids (e.g., HOCl and HOBr), which can further oxidize dissolved organic matter to potentially generate halogenated DBPs .…”

“…For instance, bicarbonate (HCO 3 − ) can promote the decomposition of PAA and may produce the secondary oxidant peroxymonocarbonate (HCO 4 − ). 19 Moreover, PAA may oxidize the halide to produce hypohalous acids (e.g., HOCl and HOBr), which can further oxidize dissolved organic matter to potentially generate halogenated DBPs. 20 However, very little or undetectable amounts of halogenated DBPs are generated because the reaction rate constants between PAA and halogen ions are relatively low (k PAA,Cl − = 1.47 × 10 −5 M −1 s −1 and k PAA,Br − = 0.24 M −1 s −1 ), and the coexistence of H 2 O 2 in PAA solution can eliminate the generated hypohalous acids.…”