Insights into the impacts of chloride ions on the oxidation of 2,4-dinitrotoluene using ferrous activated persulfate: Removal efficiency, reaction mechanism, transformation pathway, and toxicity assessment

Xiaodong Li; Jialun Shen; Zongquan Sun; Wenwen Zhang; Fujun Ma; Qingbao Gu

doi:10.1016/j.chemosphere.2023.137887

Insights into the impacts of chloride ions on the oxidation of 2,4-dinitrotoluene using ferrous activated persulfate: Removal efficiency, reaction mechanism, transformation pathway, and toxicity assessment

Chemosphere. 2023 Mar:317:137887. doi: 10.1016/j.chemosphere.2023.137887. Epub 2023 Jan 16.

Authors

Xiaodong Li¹, Jialun Shen², Zongquan Sun², Wenwen Zhang³, Fujun Ma⁴, Qingbao Gu⁵

Affiliations

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China. Electronic address: lixd1991@sina.com.
² State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
³ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
⁴ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China. Electronic address: mafj@craes.org.cn.
⁵ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China. Electronic address: guqb@craes.org.cn.

PMID: 36657571
DOI: 10.1016/j.chemosphere.2023.137887

Abstract

Persulfate/Fe²⁺-based advanced oxidation processes are widely used to treat water contaminated with 2,4-dinitrotoluene (DNT). However, the oxidation of DNT by persulfate/Fe²⁺ in the presence of the chloride ion (Cl⁻) has not been addressed, and the transformation pathways and toxicities of the intermediate products remain unclear. In this study, the effect of different Cl⁻ concentrations on the oxidation of DNT was investigated by persulfate/Fe²⁺. After the addition of 1.0 mM Cl⁻ and 6 h of oxidation, the removal efficiency of DNT increased by 68.5%. Scavenging experiments and an electron spin resonance analysis suggested that Cl⁻ caused hydroxyl radicals to increase in content in the persulfate/Fe²⁺ system, thus promoting the removal of DNT. Eight intermediate products of DNT were accurately detected using high-resolution mass spectrometry, and the transformation pathways of DNT were proposed, including hydroxylation/oxidation, elimination of the nitro group, and chlorination process. The acute and chronic toxicities of the intermediate products decreased during the oxidation process, but chlorinated by-products posed a higher toxicological risk. This result is vital for the practical application and environmental safety evaluation of persulfate/Fe²⁺-based advanced oxidation.

Keywords: 2,4-Dinitrotoluene; Chlorine ion; Hydroxyl radical; Persulfate; Toxicity assessment; Transformation pathways.

MeSH terms

Chlorides*
Dinitrobenzenes / toxicity
Halogens
Oxidation-Reduction
Sulfates / chemistry
Water Pollutants, Chemical* / chemistry
Water Pollutants, Chemical* / toxicity

Substances

2,4-dinitrotoluene
Chlorides
Dinitrobenzenes
Halogens
Water Pollutants, Chemical
Sulfates