Removal of heavy metals from mine waters by natural zeolites.
Removal of heavy metals from mine waters by natural zeolites.
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DOI：
10.1021/es048482s
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发表时间：
2005-05
影响因子：
11.4
通讯作者：
U. Wingenfelder;C. Hansen;G. Furrer;R. Schulin
中科院分区：
文献类型：
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作者：
U. Wingenfelder;C. Hansen;G. Furrer;R. Schulin
在这项研究中，我们研究了天然沸石对合成矿井水中的铁、铅、镉和锌的去除。重点研究了沸石对几个相互竞争的阳离子的行为。铅在中性和酸性溶液中都能被有效去除，而锌和镉的吸收随着低pH和高铁浓度的升高而降低。随着溶液中钙浓度的增加，锌和镉的去除能力变差，而铅的去除几乎没有变化。沸石在酸性溶液中是稳定的。只有在pH 2.0以下才能观察到崩解。在沸石存在和不存在的情况下，对合成酸性矿井水进行了正反滴定，以模拟加入中和剂引起的pH升高和随后与酸性水混合而引起的再酸化的影响。中和过程中pH的升高会导致水合氧化铁的析出，并降低溶解金属的浓度。沸石的加入进一步降低了溶液中铅的浓度，但对溶液中锌和镉的浓度没有影响。在溶液的再酸化过程中，有沸石存在时，铅的再活化作用弱于无沸石时。铁、镉和锌的固定化没有显著差异。PH升高时金属的固定以及随后的酸化引起的再活化可以用一个地化平衡形态模型来描述，该模型考虑了金属在水合三氧化二铁上的络合作用、沸石表面的离子交换以及溶解和沉淀过程。
In this study, we investigated the removal of Fe, Pb, Cd, and Zn from synthetic mine waters by a natural zeolite. The emphasis was given to the zeolite's behavior toward a few cations in competition with each other. Pb was removed efficiently from neutral as well as from acidic solutions, whereas the uptake of Zn and Cd decreased with low pH and high iron concentrations. With increasing Ca concentrations in solution, elimination of Zn and Cd became poorer while removal of Pb remained virtually unchanged. The zeolite was stable in acidic solutions. Disintegration was only observed below pH 2.0. Forward- and back-titration of synthetic acidic mine water were carried out in the presence and absence of zeolite to simulate the effects of a pH increase by addition of neutralizing agents and a re-acidification which can be caused by subsequent mixing with acidic water. The pH increase during neutralization causes precipitation of hydrous ferric oxides and decreased dissolved metal concentrations. Zeolite addition further diminished Pb concentrations but did not have an effect on Zn and Cd concentrations in solution. During re-acidification of the solution, remobilization of Pb was weaker in the presence than in the absence of zeolite. No substantial differences were observed for Fe, Cd, and Zn immobilization. The immobilization of the metals during pH increase and the subsequent remobilization caused by re-acidification can be well described by a geochemical equilibrium speciation model that accounts for metal complexation at hydrous ferric oxides, for ion exchange on the zeolite surfaces, as well as for dissolution and precipitation processes.