Oxidative Decolorization of Acid Azo Dyes by a Mn Oxide Containing Waste
Oxidative Decolorization of Acid Azo Dyes by a Mn Oxide Containing Waste
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DOI：
10.1021/es902305e
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发表时间：
2010-02-01
影响因子：
11.4
通讯作者：
Johnson, Karen. L.
中科院分区：
文献类型：
--
作者：
Clarke, Catherine E.;Kielar, Filip;Johnson, Karen. L.
在卡拉哈里锰矿区产生的含锰氧化物的尾矿已显示出氧化分解酸性偶氮染料酸性橙子（AO）7、酸性红88、酸性红151和酸性黄36，但不分解酸性黄9。尾矿中总的可还原锰含量为33%，其中3%是对苯二酚可提取的，因此易于还原。尾矿中Mn的净氧化态为3+。脱色的AO 7的锰尾矿的增加，随着pH值的降低。脱色机制是在AO 7的羟基上启动，并通过连续的电子转移从染料分子到氧化物表面，导致偶氮键的不对称裂解进行。反应产物经鉴定为1，2-萘醌、4-羟基苯磺酸盐和1，2-萘醌与苯磺酸根的偶联产物。初步计算出AO 7：W（III）反应的化学计量比为1：3。该反应显示出持久性，在染料补充60天后仍观察到95%的脱色。未观察到1，2-萘醌和4-羟基苯磺酸盐的进一步分解，因此认为这些化合物是AO 7- Mn尾矿反应的最终反应产物。
A Mn oxide containing mine tailings, generated in the Kalahari Mn fields, has been shown to oxidatively breakdown acid azo dyes acid orange (AO) 7, acid red 88, acid red 151 and acid yellow 36 but not acid yellow 9. The total reducible Mn content of the tailings is 33%, of which 3% is hydroquinone extractable and thus easily reducible. The net oxidation state of the Mn within the tailings is 3+. Decolorization of AO 7 by the Mn tailings increases with decreasing pH. The decolorization mechanism is initiated on the hydroxyl group of AO 7 and proceeds via successive electron transfers from the dye molecule to the oxide surface resulting in the asymmetric cleavage of the azo bond. The reaction products have been identified as 1,2-naphthoquinone, 4-hydroxybenzenesulfonate, and coupling products involving 1,2-naphthoquinone and benzenesulfonate radicals. The AO 7: W(III) reaction stoichiometry has been tentatively calculated to be 1:3. The reaction shows longevity with 95% decolorization still observed after 60 days of dye replenishment Further breakdown of 1,2-naphthoquinone and 4-hydroxybenzenesulfonate was not observed, thus these compounds are considered to be the terminal reaction products of the AO 7- Mn tailings reaction.