缓冲药剂对高铁酸盐的稳定性研究

Study on Stability of Ferrate(VI)under the Effect of the Buffering Agent

目的为延长高铁酸盐的保存时间,筛选出对高铁酸盐起到最佳稳定作用的添加剂,并确定碱液的最佳浓度和与高铁酸盐的体积比以及缓冲药剂组分的最佳物质的量比和添加量.方法将高铁酸盐溶液与不同浓度NaOH溶液、缓冲药剂混合,低温避光保存,定时测其吸光度,比较分解速率.结果NaOH溶液与Na2FeO4混合,浓度越高,体积比越大,Na2FeO4分解率越低.添加碳酸盐缓冲药剂时,n(NaHCO3)∶n(NaOH)为2∶1,且以高铁酸盐浓度的100倍浓度添加效果最好,磷酸盐缓冲药剂稳定效果次之,除50倍浓度的硼酸盐缓冲药剂外,其他浓度的硼酸盐药剂都会加速高铁酸盐的分解.结论高浓度碱液可抑制高铁酸盐的分解,碳酸盐缓冲药剂对高铁酸盐能起到一定的稳定作用,为高铁酸盐的长时间稳定保存提供了有效的试验依据.

In order to extend the preservation time of the ferrate salts, the paper selects the additive with the best stabilizing effect to the ferrate salts, and determines the best consistency and volume ratio of the alkaline solution, as well as the components＇ best molar ratio and dosage of the buffering agents. The method of the study is that the ferrate salts were mixed with different consistencies of the NaOH solutions and the buffering agents, preserving with low-temperature in dark place and the decompositions of the ferrate salts were compared by the absorbance. The results show that decomposition of the fen＇ate salt was lower under the condition that the alkaline solution＇s consistency was higher and the volume fraction was higher. The best molar ratio of NaHCO3 and NaOH and the consistency were 2：1 and 100 times of the ferrate solution＇s separately when the carbonate buffering agent was added. The stable effect of the phosphate buffering agent is good as well. Other concentrations of borate buffering agent all could accelerate the decomposition of ferrate salts besides 50 times of the ferrate solution＇s. Therefore the high concentration of the alkaline solution can inhibit the decomposition of ferrate salts, and the carbonate buffering agent has a certain stable effect on the ferrate salts. These conclusions provide an effective basis for preserving ferrate salts stably for a long time.