Low Valent Aluminum as a Product of Anodic Oxidation in Aqueous Solution
Low Valent Aluminum as a Product of Anodic Oxidation in Aqueous Solution
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DOI：
10.1021/ja01584a011
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发表时间：
1956-02
影响因子：
15
通讯作者：
E. Raijola;A. Davidson
中科院分区：
文献类型：
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作者：
E. Raijola;A. Davidson
在铝阳极和铂阴极之间的各种水溶液的电解中，铝以显著低于3的初始平均价数阳极溶解，并且在阳极处放出氢。在氧化剂溶液中，化合价数低于卤化物溶液，放出的氢量也较少。在电解氯化铝-硝酸铝混合物时，得到了最低的化合价，为1.67。在分开的电池中用各种氧化剂进行的实验揭示了阳极电解液中存在除氢以外的还原产物。通过流动的电解质，表明在某些情况下，主还原剂可以从一个容器转移到另一个容器。所有这些事实都可以用铝的一次阳极氧化部分地变成单正态来解释。大约在世纪以前，Wohler和Buff首次观察到活性铝阳极的反常行为，他们指出，在纯度相当低的铝电极之间电解氯化钠水溶液时，不仅在阳极放出氢，而且铝的溶解对应于130%的电流效率，假设氧化成三价阳离子。这些作者特别拒绝了铝的价态低于3的明显解释。为了解释氢在铝阳极上的析出（他称之为“反向电解”的一个例子），Turrentine，3假设了单正性或双正性铝的存在，或者两者都存在;然而，他没有直接测定电流效率。直到Mazzitelli用纯铝阳极重复了Wohler和Buff的实验，并在一次电解中获得了1.95的表观价数，才对这种明显的反常现象进行了系统的研究。与此同时，其他工作人员也证明了在
In the electrolysis, between an aluminum anode and a platinum cathode, of various aqueous solutions, aluminum dissolves anodically with an initial mean valence number significantly lower than 3, and hydrogen is evolved at the anode. In solu-tions of oxidizing agents the valence number is lower than in halide solutions, and the amount of hydrogen given off is smaller. The lowest valence number observed, 1.67, was attained in the electrolysis of an aluminum chloride-aluminum nitrate mix-ture. Experiments with various oxidants in a divided cell revealed the presence in the anolyte of reduction products other than hydrogen. By means of a flowing electrolyte it was shown that in some instances the primary reducing agent can be transferred from one vessel to another. All of these facts maybe interpreted in terms of primary anodic oxidation of alumi-num partly to the unipositive state.The anomalous behavior of an active aluminum anode was first observed almost a century ago by Wohler and Buff, 2 who noted, during the electroly-sis of an aqueous sodiumchloride solution between aluminum electrodes of rather low purity, not only that hydrogen was evolved at the anode, but also that the dissolution of aluminum corresponded, on the assumption of oxidation to the tripositive ion, to a current efficiency of 130%. These authors specifically rejected the obvious explanation of a valence state of aluminum lower than 3. Turren-tine, 3 in order to account for the evolution of hydro-gen at an aluminum anode—termed by him an ex-ample of “reversed electrolysis”—postulated the existence of unipositive or dipositive aluminum, or both; he, however, made no direct determination of current efficiency. There appearsto have been no systematic investigation of this apparent anom-aly until Mazzitelli4 repeated the experiments of Wohler and Buff with an anode ofpure aluminum, and obtained in one electrolysis an apparent valence number of 1.95. Meanwhile, other workers dem-onstrated the occurrence of parallel phenomena in