Remediation of 1,2-dichlorobenzene contaminated soil by activated persulfate using green synthesized nanoscale zero valent iron: activation mechanism and degradation pathways

• Published in: Journal of soils and sediments Vol. 22; no. 4; pp. 1135 - 1144
• Main Authors: Yan, Jingchun, Hu, Linchao, Gao, Weiguo, Yang, Lei, Qian, Linbo, Han, Lu, Chen, Mengfang
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2022; Springer Nature B.V
• Subjects: Acetone; Biodegradation; Chlorophenol; Deionization; Dichlorobenzene; Dominant species; Earth and Environmental Science; Electron paramagnetic resonance; Electron spin resonance; Environ Risk Assess; Environment; Environmental factors; Environmental Physics; Free radicals; Gas chromatography; Glass; Hexanes; Intermediates; Iron; Organic carbon; Organic soils; pH effects; Pollutants; Remediation; Removal; Room temperature; Sec 2 • Global Change; Sediment pollution; Slurries; Soil; Soil contamination; Soil degradation; Soil investigations; Soil pollution; Soil remediation; Soil Science & Conservation; Soils; Sulphates; Sustainable Land Use • Research Article; Synthesis; Tea; Total organic carbon; Soil remediation; Nanoscale zero valent iron; 1,2-Dichlorobenzene; Persulfate
• ISSN: 1439-0108; 1614-7480
• DOI: 10.1007/s11368-021-03116-5

Purpose The method using persulfate (PS) activation is effective for the remediation of organic pollutants contaminated soil. This study aims to evaluate the possibility of the application of green synthesized nanoscale zero valent iron (nZVI) activating PS for 1,2-dichlorobenzene (1,2-DCB) degradation in soil, investigate the effect of environmental factors such as nZVI dosage, PS concentration, and initial pH on 1,2-DCB removal efficiency and interpret the activation mechanism of nZVI for PS and degradation pathways of 1,2-DCB in soil. Materials and methods The contaminated soil was added to a brown bottle of 250 mL and dispersed in deionized water with a volume ratio of 1:5. Specified concentration of PS and nZVI were added to the bottle to initiate the degradation reaction. The bottle was placed on a reciprocating shaker at room temperature of 25 ºC. Control experiments containing PS or nZVI were also performed under the same reaction conditions. At desired time intervals, the well-mixed suspension of 10 mL slurry was transferred into 50 mL glass vials and centrifuged. 20 mL organic solvent with a volumetric ratio of hexane to acetone of 1:1 was added to 50 mL glass vials after the supernatant was discarded. 1,2-DCB and its degradation intermediates were analyzed by Gas Chromatograph-Mass Spectrometer (GC-MS) through extract. Results and discussion The maximum degradation efficiency of 97.3% with total organic carbon (TOC) removal of 61.3% for 1,2-DCB was achieved under the reaction conditions of initial 1,2-DCB concentration of 28.6 mg kg −1 in soil, 67.2 mg L −1 nZVI, 1.2 mmol L −1 PS and pH 7.5. Electron paramagnetic resonance (EPR) test indicated that SO 4 • − and •OH radicals were the dominant species being responsible for the degradation of 1,2-DCB. In addition, the GC-MS analysis showed that 3,4-dichlorophenol and o -chlorophenol were the primary intermediates, and the degradation pathways of 1,2-DCB were proposed subsequently. Conclusions nZVI was successfully synthesized through green processes based on extracted tea polyphenol, and utilized for the remediation of 1,2-DCB contaminated soil by activated PS. The generated free radicals were responsible for the efficient degradation of 1,2-DCB with high TOC removal. The findings might have significant implications for the remediation of 1,2-DCB contaminated soil utilizing the nZVI/PS system. Graphical abstract