The effect of a catecholate chelator as a redox agent in Fenton-based reactions on degradation of lignin-model substrates and on COD removal from effluent of an ECF kraft pulp mill
We evaluated the effect of a catecholate chelator as a redox agent in Fenton-based reactions (known as chelator-mediated Fenton reaction—CMFR), in the presence of three different transition metals ions (Fe 2+, Fe 3+ and Cu 2+) by determining the oxidative capability of CMFR towards lignin-model subs...
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Veröffentlicht in: | Journal of hazardous materials 2007-03, Vol.141 (1), p.273-279 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We evaluated the effect of a catecholate chelator as a redox agent in Fenton-based reactions (known as chelator-mediated Fenton reaction—CMFR), in the presence of three different transition metals ions (Fe
2+, Fe
3+ and Cu
2+) by determining the oxidative capability of CMFR towards lignin-model substrates. The potential application of mediated Fenton-based reactions as a novel process to treat pulp mill effluent was evaluated and monitored by chemical oxygen demand (COD) and total phenol removals from a combination of the effluents generated during an ECF bleaching stage. The catecholate chelator 3,4-dihydroxiphenilacetic acid (DOPAC) reduced both Fe
3+ and Cu
2+, in addition, the maximum Cu
2+ reduction activity was reached in a shorter time than for Fe
3+ reduction, however, the highest metal reduction activity was observed with Fe
3+. When DOPAC was added to Fenton-based reactions (Fe
3+/H
2O
2, Fe
2+/H
2O
2, Cu
2+/H
2O
2) an increase in oxidative activities of these reactions were found as they resulted in great degradation improvement of the lignin-model substrates azure B, phenol red and syringaldazine. The same increase in oxidative capability of Fenton-based reactions in the presence of DOPAC was observed after effluent treatment, expressed by the increase in COD removal, namely, an increase in the range of about 70% in COD removal when Fe
2+ or Fe
3+ was the catalytic metal and about 25% for Cu
2+. However CMFR lead to an increase in total phenol content. As COD removal by CMFR system using Fe
3+ and Fe
2+ was not significantly different and that Fe
3+ ions promoted lesser increase in total phenol content, Fe
3+ was chosen for experimental optimization. At optimum conditions, 75% of COD and 30% of total phenol removal were achieved. |
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ISSN: | 0304-3894 1873-3336 |
DOI: | 10.1016/j.jhazmat.2006.06.134 |