title: 1,3-Dinitrobenzene reductive degradation by alkaline ascorbic acid - Reaction mechanisms, degradation pathways and reagent optimization.
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.
authors.affiliation: Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan.
authors.forename: Chiya
authors.initials: C
authors.lastname: Ciou
authors.affiliation: Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan. Electronic address: cliang@nchu.edu.tw.
authors.forename: Chenju
authors.initials: C
authors.lastname: Liang
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry*; D004136:Dinitrobenzenes / Q000737:chemistry*; D004583:Electrons; D052918:Environmental Restoration and Remediation; D006863:Hydrogen-Ion Concentration; D009574:Nitro Compounds / Q000737:chemistry; D010084:Oxidation-Reduction; D010655:Phenylenediamines / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry; D014867:Water; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D004136:Dinitrobenzenes; D009574:Nitro Compounds; D010655:Phenylenediamines; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D014867:Water; D012972:Sodium Hydroxide; C017906:3-dinitrobenzene; C008381:3-phenylenediamine; D001205:Ascorbic Acid
keywords: Explosive; In situ chemical reduction (ISCR); Nitroaromatic compound; Soil and groundwater remediation; Vitamin C