1, 3-Dinitrobenzene reductive degradation by alkaline ascorbic acid – Reaction mechanisms, degradation pathways and reagent optimization. (January 2017)

• Record Type: Journal Article
• Authors: Ciou, Chiya; Liang, Chenju
• Is Part Of: Chemosphere. Volume 166(2017)
• Page Start: 482
• Page End: 488
• Publication Date: 2017-01
• Subjects: Nitroaromatic compound -- Explosive -- In situ chemical reduction (ISCR) -- Vitamin C -- Soil and groundwater remediation; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2016.09.103
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Nitro-aromatic compounds (NACs) such as 1, 3-dinitrobenzene (1, 3-DNB) contain the nitrogroup (-NO2 ), in which the N with a +III oxidation state accepts electrons. Water soluble ascorbic acid (AsA) at elevated pH produces electron transfer and governs the electron-donating pathway. The influence of the NaOH/AsA molar ratio on the degradation of 1, 3-DNB was investigated. Using 0.21–2 M NaOH and 20–100 mM AsA, nearly complete 1, 3-DNB removals (90–100%) were achieved within 0.5 h. On the basis of intermediates identified using GC/MS, the reduction pathways of 1, 3-DNB can be categorized into step-by-step electron transfer, and condensation routes. A higher NaOH/AsA molar ratio would result in relatively higher AsA decomposition, promote the condensation route into the formation of azo- and azoxy-compounds, and ultimately reduce 1, 3-DNB to 1, 3-phenylenediamine. Contaminated soil flushing using 500 mM NaOH/100 mM AsA revealed that 1, 3-DNB was completely degraded within 2 h. Based on these test results, the alkaline AsA treatment method is a potential remediation process for NACs contaminated soils. Graphical abstract: Highlights: AsA at elevated pH produces electron transfer and governs the electron donating pathway. The alkaline AsA reductive reaction is an effective method for the destruction of 1, 3-DNB. The reduction mechanisms include step-by-step electron transfer and condensation routes. Higher NaOH/AsA ratios promote the condensation route and govern the electron release from AsA. Eventually, 1, 3-DNB was reduced to 1, 3-phenylenediamine by the alkaline AsA reductive process.