Abstract The kinetics of electroreduction of Cr(III) ions in a deep eutectic solvent, ethaline (an eutectic mixture of ethylene glycol and choline chloride), and water-ethaline mixtures on a glassy carbon electrode was investigated by means of cyclic voltammetry technique. The electrochemical reduction of chromium (III) ions to chromium (II) soluble ions was shown to proceed irreversibly. Some kinetics parameters (standard electrochemical rate constants, transfer coefficients and activation energy for charge transfer) as well as transport properties (diffusion coefficients and activation energy for diffusion) were calculated and discussed as a function of extra water content (10, 15 and 20 wt%) at the temperatures of 313, 323, 333 and 343 K. An increase in water content in the fluid results in both higher values of diffusion coefficients of Cr(III) ions and a reduction of activation energy of diffusion mass transfer. However, the introduction of water into ethaline causes the deceleration of charge transfer (i.e. a decrease in standard rate constants and an increase in activation energy of electron transfer) which may be due to the changes in Cr(III) speciation in solution (the reduction of the fraction of chlorinated complexes with increasing water content).

中文翻译：

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Cr(III) 离子在基于低共熔溶剂（乙醇）的溶液中放电的动力学：加水的影响

摘要 通过循环伏安法研究了在深共晶溶剂、乙炔（乙二醇和氯化胆碱的共晶混合物）和水-乙炔混合物中Cr(III)离子在玻碳电极上的电还原动力学。铬 (III) 离子向铬 (II) 可溶性离子的电化学还原显示不可逆地进行。计算并讨论了一些动力学参数（标准电化学速率常数、转移系数和电荷转移活化能）以及传输特性（扩散系数和扩散活化能）作为额外水含量（10、15 和 20 重量％）的函数。 %) 在 313、323、333 和 343 K 的温度下。流体中水含量的增加导致 Cr(III) 离子扩散系数值的升高和扩散传质活化能的降低。然而，将水引入乙醇会导致电荷转移减速（即标准速率常数降低和电子转移活化能增加），这可能是由于溶液中 Cr(III) 形态的变化（还原随着含水量的增加，氯化络合物的比例）。