电化学合成法制备高铁酸盐的研究进展

Research progress on preparation of potassium ferrate by electrosynthesis

高铁酸盐是公认的"绿色"化学试剂,但制备成本过高大大限制了它的应用。电解法制备高铁酸盐以其工艺简单,原料消耗少而成为最可能商业化生产的方法。本文从电解槽结构、阳极材料组成、电解液的组成和浓度、电流密度、电解时间等各个方面阐述了影响电流效率和高铁酸盐产品浓度的因素。阳极室体积减小、电流密度和电解时间适当增加,可使Na2FeO4产品的浓度加大。阳极材料比表面积大,含有碳、硅的铸铁比纯铁活性高。新发展起来的惰性阳极法值得深入研究。电解液组分为氢氧化钠,浓度约为14mol/L时电流效率较高,电解液中添加适当的氧化剂或腐蚀性离子有助于减少阳极钝化和稳定高铁酸根离子。交直流叠加的加电方式有利于缓解阳极钝化现象。文章指出,未来需要设计新型合理的电解槽结构和研发新的生产工艺,降低电耗和电解液浓度,提高电流效率,最终达到长时间连续生产高浓度高铁酸盐的目的。

Ferrate is a recognized “green” chemical reagent,but high cost of potassium ferrate preparation greatly restricted its applications. Electrosynthesis method could become commercial technology of potassium ferrate preparation for its simple process and low consumption of raw materials. This paper reviewed the influencing factors of current efficiency and ferrate concentration from the view of electrolyzer structure,anode material composition,the component and concentration of electrolyte,current density,and the time of electrolysis. Small volume of anode chamber, appropriate increase of current density and electrolysis time can produce high concentration of ferrate. Anode materials containing carbon and silicon,and large surface area,such as cast iron,have higher activity than pure iron. Inert electrode developed in research may be worth of further investigation. Using sodium hydroxide as electrolyte at the concentration of 14mol/L,higher current efficiency can be obtained. Adding certain types of oxidants and corrosive ions in the electrolyte could help to alleviate the passivation and stable the ferrate. Employing alternating-current superimposed on direct-current can ease passivation of anode. Future research should focus on new electrolyzer structure and new process to reduce power consumption and electrolyte concentration,to achieve the final goal of continuous high concentration of potassium ferrate.