Reductive decolorization of azo dyes via in situ generation of green tea extract-iron chelate
In this study, rapid decolorization of azo dyes was achieved by in situ-generated green tea extract-iron (GTE-Fe) chelate for the first time. When changing reaction conditions from the aerobic condition to the anaerobic condition, the decolorization efficiencies of two azo dyes, i.e., acid orange 7 (AO7) and acid black 1 (AB1), increased from 46.38 and 83.17 to 90.13 and 95.37%, respectively. The recalcitrant AO7 was then selected as the targeting pollutant in subsequent optimization and mechanism studies. Experimental evidences showed that the initial concentrations of AO7, Fe(III), and GTE are the key factors to optimize the decolorization efficiency. Further characterization studies by spectroscopic analysis, including FESEM, FTIR, and XPS, suggested that the major mechanism of AO7 decolorization is the nucleophilic attack of the oxygen in green tea polyphenols (GTP), and this attack could be facilitated by the organometal chelation. This study provided an efficient and environmental friendly strategy to decolorize azo dyes via in situ generation of the GTE-Fe chelate, as well as its mechanistic insights, shedding lights on in situ remediation of azo dye pollution.
KeywordsGreen tea extract-iron chelate Decolorization Azo dye Green tea polyphenols In situ generation
This study was supported by the Guangzhou Science and Technology Program general project (201804010141).
- Beamson G, Briggs D (1992) High resolution XPS of organic polymers. WileyGoogle Scholar
- Hider RC, Liu ZD, Khodr HH (2001) Metal chelation of polyphenols, Methods Enzymol Elsevier, pp. 190–203Google Scholar
- Moulton MC, Braydich-Stolle LK, Nadagouda MN, Kunzelman S, Hussain SM, Varma RS (2010) Synthesis, characterization and biocompatibility of “green” synthesized silver nanoparticles using tea polyphenols. Nano 2:763–770Google Scholar
- Rathod J, Dhebar S, Archana G (2017) Efficient approach to enhance whole cell azo dye decolorization by heterologous overexpression of Enterococcus sp. L2 azoreductase (azoA) and Mycobacterium vaccae formate dehydrogenase (fdh) in different bacterial systems. Int Biodeter Biodegr. Int. Biodeter. Biodegr 124:91–100CrossRefGoogle Scholar
- Serafini M, Ghiselli A, Ferroluzzi A (1996) In vivo antioxidant effect of green and black tea in man. Eur J Clin Nutr 50:28Google Scholar