氯化胆碱添加剂对[Bmim]Cl-AlCl3离子液体体系电解精炼铝的影响

研究了AlCl3摩尔分数为0.667的[Bmim]Cl-AlCl3离子液体体系中氯化胆碱(ChCl)添加剂对体系电导率及电解精炼铝的影响. 结果表明,当ChCl浓度小于8 mmol/L时,体系的电导率随ChCl浓度增加而显著提高,但ChCl浓度进一步增加体系的电导率逐渐降低. 添加少量ChCl后,阴极还原峰电位正移,还原峰电流逐渐降低. 在温度373 K和电流密度50 A/m2条件下添加5 mmol/L ChCl进行恒电流电解,电解过程的槽电压显著降低,阴极电流效率显著提高(接近100%),直流电耗仅为0.611 kW×h/kg,只有纯离子液体体系电解铝的50%,且在低碳钢基体上得到的铝沉积层光滑致密、晶粒细化.

Effects of Additive Choline Chloride on Electrolysis of Aluminum from [Bmim]Cl-AlCl3 Ionic Liquid System

The effects of additive choline chloride (ChCl) on electrical conductivity of [Bmim]Cl-AlCl3 ionic liquid (molar fraction of AlCl3 was 0.667) system and electrorefining of aluminum in the system were investigated. The results indicated that electrical conductivity of the system increased obviously with increasing the concentration of ChCl (CChCl) when CChCl was less than 8 mmol/L. However, electrical conductivity decreased with further increasing CChCl. The peak potential shifted positively and the peak current decreased in the presence of ChCl. Constant current electrolysis experiments at 373 K of temperature and 50 A/m2 of current density indicated that the cell voltage decreased significantly, the current efficiency enhanced (nearly 100%), and the energy consumption was 0.611 kW×h/kg which was only 50% of the pure ionic liquid system when the concentration of ChCl was 5 mmol/L. Moreover, the deposit obtained on alloy steel was well-adherent, dense and fine-grained.