低共熔溶剂中铬的阳极造液及阴极电沉积工艺研究

发布时间：2018-03-12 10:31

本文选题：低共熔溶剂　切入点：铬粉　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：本论文主要研究了在新型离子液体即低共熔溶剂(deep eutectic solvents,DESs)体系中,电解铬的阴极沉积、阳极溶解和同时电解的工艺条件,并对低共熔溶剂的性质,铬电化学反应的机理进行了探究。本论文首先对低共熔溶剂的电化学性质进行了分析,分别测定其熔点Tf、电导率σ、粘度η、电化学窗口等性质,分析表明,低共熔溶剂的电导率与粘度与氢键供体的性质有关,氯化胆碱与乙二醇制备的DESs电导率最高,σ=17.72m S/cm,其电化学窗口为3.36 V,最适用于电沉积体系。通过阴极沉积的工艺试验中发现,草酸与氯化铵共同做添加剂时,铬沉积效果不如单独使用好,温度对沉积过程影响显著,其主要原因是电导率受温度的影响较大。阴极沉积最优工艺条件为:反应温度353 K,电流密度450 A/m2,电解时间1 h,搅拌速率300 rpm,阴极电流效率为14.01%。在阳极溶解铬锭的试验中发现,酸类添加剂的阳极电流效率要比碱类添加剂高很多,阳极溶解受温度的影响最大,且搅拌速率对槽压和电流效率的影响也较大。该工艺所得到的最高的阳极电流效率为73.94%。该体系在同时电解时,只有温度和阴极电流密度的影响具有显著性,该工艺的阴阳极电流效率分别达到16.94%和70.23%。本论文在低共熔溶剂中成功对同时电解铬工艺进行了探索性的研究,阳极电流效率基本均在70%以上。通过循环伏安曲线确定了铬还原为不存在前置反应的不可逆过程,并通过不同温度下的稳态极化曲线求出反应的活化能、阴阳极传递系数、反应级数等参数。确定了反应的活化能为14.446 k J/mol,并且铬的反应为扩散控制。并分别对阴阳极测定其极化曲线,通过对阳极极化曲线的分析发现,升高温度可以减弱阳极钝化,即促进阳极溶解的进行。
[Abstract]:This paper mainly studies the model in ionic liquid eutectic solvents (deep eutectic solvents, DESs) system, the cathode electrolytic chromium deposition, anodic dissolution and electrolysis process conditions at the same time, and the properties of eutectic solvents, the electrochemical reaction mechanism of chromium was discussed. Firstly, electrochemical properties the eutectic solvents were analyzed, the melting point of Tf, were measured by conductivity sigma, viscosity, electrochemical window properties analysis showed that the eutectic solvent viscosity and conductivity and hydrogen bond donor properties, choline chloride and ethylene glycol prepared DESs highest conductivity Sigma =17.72m S/cm, the electrochemical window 3.36 V, the most suitable for the electro deposition system. Through the process test found in the cathodic deposition, oxalic acid and ammonium chloride as common additives, as chromium deposition effect alone, the effect of temperature on the deposition process was the main The reason is greatly influenced by the temperature. The conductivity of the cathode deposition of optimal process conditions: reaction temperature 353 K, current density of 450 A/m2, electrolytic time is 1 h, stirring rate of 300 rpm, the cathodic current efficiency of 14.01%. found in the test of anodic dissolution of chromium ingot in acid additive anode current efficiency is much higher than the base class additive, anode dissolution is affected by temperature, and the effect of stirring speed on the cell voltage and current efficiency is higher. By this process the highest anode current efficiency of 73.94%. system in the simultaneous electrolysis, affecting only temperature and cathodic current density was significant, the process of cathode and anode current efficiency respectively. 16.94% and 70.23%. in this paper, the eutectic solvents and success of electrolytic chromium process was studied, the anode current efficiency was above 70%. Determined by cyclic voltammetry There is no pre chromium reduction reaction irreversible process, and by steady-state polarization curves at different temperatures and the activation energy of the reaction, anode transfer coefficient, reaction parameters were determined. The reaction activation energy of 14.446 K J/mol, and the reaction of chromium is diffusion controlled. And the determination of the Yin and Yang the polarization curve, through the analysis of the anodic polarization curve, increasing temperature can weaken the anodic passivation, which accelerate the anodic dissolution.

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ153

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