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首页> 外文期刊>Marine Chemistry >Particle-water interactions of platinum group elements under estuarine conditions
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Particle-water interactions of platinum group elements under estuarine conditions

机译：河口条件下铂族元素的颗粒-水相互作用

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Particle-water interactions of selected platinum group elements (PGE) have been studied as a function of pH (between 5 and 10), salinity, and concentrations of Cl~- and Ca~(2+). Rhodium(Ⅲ), Pd(Ⅱ) and Pt(Ⅳ) were added to water samples and sediment suspensions and, following a period of equilibration and subsequent phase separation, filtrates and HCl-digested filters were analysed by ICP-MS. PGE removal from the aqueous phase to the particulate phase appeared to proceed via both coagulation of organic/colloidal associations and adsorption to estuarine sediment particles. In river water, removal of Rh increased and Pt decreased with increasing pH, whereas Pd was not detected in the particulate phase throughout much of the pH range studied. In end-member estuarine water (salinity=28), removal of Rh and Pt increased with increasing pH, but removal of Pd was relatively insensitive to pH. Conditional particulate-aqueous distribution coefficients, K_(D~S) (mL g~(-1)), were on the order of a few hundred (Pd and Pt) to several thousand (Rh) along the estuarine gradient. Increasing salinity and Cl~- concentration were accompanied by an increase in K_D for Rh and Pd, and a reduction in K_D for Pt, while increasing Ca~(2+) concentration resulted in an increase in K_D for all PGE. Experimental observations were qualitatively interpreted in terms of what is known about the aqueous speciation of PGE. Thus, Rh data were consistent with the adsorption of cationic species of the form: [RhCl_(6-x)(H_2O)_x]~(x-3), where x=0 to 6; although in river water complexation by additional (e.g. organic) ligands may have also occurred. Speciation of Pd was predicted to be dominated by organic complexes under all experimental conditions, consistent with its stabilisation in solution in freshwater and apparent salting out and/or coagulation in the presence of dissolved ions. The presence of hydroxychloride complexes of Pt(Ⅳ), whose ligand number (and negative charge) increases with increasing chlorinity, could explain most of the experimental observations for this element.
机译：研究了所选铂族元素（PGE）的颗粒-水相互作用与pH（5至10），盐度以及Cl〜-和Ca〜（2+）浓度的关系。将铑（Ⅲ），钯（Ⅱ）和铂（Ⅳ）添加到水样和沉积物悬浮液中，经过一段时间的平衡和随后的相分离，通过ICP-MS分析滤液和HCl消化的过滤器。通过有机/胶体缔合的凝结和对河口沉积物颗粒的吸附，PGE从水相到颗粒相的去除似乎都在进行。在河水中，随着pH值的增加，Rh的去除增加而Pt减少，而在整个研究的pH范围内，颗粒相中均未检测到Pd。在最终成员河口水（盐度= 28）中，Rh和Pt的去除随pH值的增加而增加，但Pd的去除对pH值相对不敏感。沿河口梯度，条件性颗粒水分配系数K_（D〜S）（mL g〜（-1））约为几百（Pd和Pt）至几千（Rh）。盐度和Cl〜-浓度的增加伴随着Rh和Pd的K_D升高，Pt的K_D降低，而Ca〜（2+）浓度的增加导致所有PGE的K_D升高。根据对PGE的水形态学的了解，定性地解释了实验观察结果。因此，Rh数据与以下形式的阳离子物质的吸附一致：[RhCl_（6-x）（H_2O）_x]〜（x-3），其中x = 0至6；尽管在河水中也可能发生了其他（例如有机）配体的络合。预测Pd的形态在所有实验条件下均以有机络合物为主，这与它在淡水中的溶液稳定以及在存在溶解离子的情况下明显盐析和/或凝结相一致。 Pt（Ⅳ）的羟基氯化物配合物的存在（其配体数（和负电荷）随氯的增加而增加）可以解释该元素的大多数实验观察结果。

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