A preliminary study of the release of platinum and palladium from metallic particles in the surface environment by organic acids: relevance to weathering of particles from vehicle exhaust catalysts
A preliminary study of the release of platinum and palladium from metallic particles in the surface environment by organic acids: relevance to weathering of particles from vehicle exhaust catalysts
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有机酸从表面环境中金属颗粒中释放铂和钯的初步研究：与汽车尾气催化剂颗粒风化的相关性
作者：
J. Bowles;A. Giże
对天然矿床中铂族矿物风化作用的研究表明，铂族元素（PGE）在适当条件下可被活化，并有足够的溶解度进入溶液。虽然无机化学提供了可行的机制，在红土遇到的极端条件下，它似乎可能是PGE-有机复合物提供了一个更令人信服的解释的表观溶解度。进行的实验工作，以说明有机过程和反应时间尺度检查各种反应，包括铂和钯箔和腐殖酸和富里酸溶液之间的反应。这些反应似乎与汽车尾气催化剂排出的PGE颗粒与自然环境之间可能发生的反应有关。实验工作在室温下暴露于金属箔约一年的腐殖酸溶液中产生高达195 μ/l的Pt和102 μ/l的Pd。实验条件可以比较，在路边排水与铂族元素颗粒和腐烂的植被。对汽车尾气催化剂排出的颗粒中PGE可能对健康产生的影响的考虑集中在吸入颗粒或通过皮肤吸收。现在还应调查从饮用水或使用含PGE水生产的食物中摄入的PGE。由于腐烂植物产生的有机化合物种类繁多，PGE有机产品的身份尚不清楚，因此无法估计其毒性。
Abstract Studies of the weathering of platinum-group minerals in natural deposits have indicated that the platinum-group elements (PGE) can be mobilized under appropriate conditions and have sufficient solubility to move into solution. Although inorganic chemistry provides feasible mechanisms under the extreme conditions encountered in laterites it appears likely that PGE-organic complexes offer a more convincing explanation of the apparent solubility. Experimental work undertaken to illustrate the organic processes and the reaction timescale examined various reactions including those between Pt and Pd foils and humic and fulvic acid solutions. These reactions appear pertinent to those that may occur between the PGE particles ejected by vehicle exhaust catalysts and the natural environment. The experimental work produced up to 195 μ/1 Pt and 102 μ/1 Pd in humic acid solutions exposed to the metal foils for about a year at room temperature. The experimental conditions can be compared to those encountered in roadside drainage supplied with PGE particles and decaying vegetation. Consideration of the possible health effects of the PGE from the particles ejected by vehicle exhaust catalysts has centred on inhalation of the particles or absorption through the skin. Intake from drinking water or from food produced using PGE-bearing water should now also be investigated. Due to the variety of organic compounds produced by decaying vegetation the identity of the PGE-organic products is not yet known so their toxicity cannot be estimated.