Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich, Zurich 8092, Switzerland.
Environ Sci Technol. 2012 Apr 3;46(7):3882-90. doi: 10.1021/es204496d. Epub 2012 Mar 19.
Natural Organic Matter (NOM) is a major sorbent for organic pollutants in soils and sediments. While sorption under oxic conditions has been well investigated, possible changes in the sorption capacity of a given NOM induced by reduction have not yet been studied. Reduction of quinones to hydroquinones, the major redox active moieties in NOM, increases the number of H-donor moieties and thus may affect sorption. This work compares the sorption of four nonionic organic pollutants of different polarities (naphthalene, acetophenone, quinoline, and 2-naphthol), and of the organocation paraquat to unreduced and electrochemically reduced Leonardite Humic Acid (LHA). The redox states of reduced and unreduced LHA in all sorption experiments were stable, as demonstrated by a spectrophotometric 2,6-dichlorophenol indophenol reduction assay. The sorption isotherms of the nonionic pollutants were highly linear, while paraquat sorption was strongly concentration dependent. LHA reduction did not result in significant changes in the sorption of all tested compounds, not even of the cationic paraquat at pH 7, 9, and 11. This work provides the first evidence that changes in NOM redox state do not largely affect organic pollutant sorption, suggesting that current sorption models are applicable both to unreduced and to reduced soil and sediment NOM.
天然有机物 (NOM) 是土壤和沉积物中有机污染物的主要吸附剂。虽然在氧化条件下的吸附已经得到了很好的研究，但还原条件下给定 NOM 吸附能力的可能变化尚未得到研究。醌类物质还原为氢醌类物质是 NOM 中的主要氧化还原活性部分，增加了 H 供体部分的数量，因此可能会影响吸附。本工作比较了四种不同极性的非离子有机污染物（萘、苯乙酮、喹啉和 2-萘酚）以及有机阳离子对苯二铵在未还原和电化学还原的莱纳德特腐殖酸 (LHA) 上的吸附。所有吸附实验中，还原和未还原 LHA 的氧化还原状态都很稳定，这可以通过分光光度法 2,6-二氯苯酚靛酚还原测定来证明。非离子污染物的吸附等温线高度线性，而对苯二铵的吸附则强烈依赖于浓度。LHA 的还原并没有导致所有测试化合物的吸附发生显著变化，即使在 pH 值为 7、9 和 11 时，对阳离子对苯二铵也没有影响。本工作首次提供了证据表明，NOM 氧化还原状态的变化不会显著影响有机污染物的吸附，这表明当前的吸附模型既适用于未还原的也适用于还原的土壤和沉积物 NOM。
