过硫酸盐法处理铁氰废水的研究

A new approach to the treatment of ferricyanide wastewater with persulfate

为实现总氰浓度的达标,采用过硫酸盐热活化和紫外活化处理水中的铁氰化物。考察了反应时间、过硫酸根投加物质的量比及初始pH值对两种活化方式去除铁氰化物中总氰的影响。结果表明,两种活化方式的活化速率和活化过程有所不同。两种活化方式中,反应时间为3 h时总氰浓度均趋于稳定,总氰去除效果均随投加物质的量比增加而减小。热活化中,初始pH值小于10时对反应结果基本没有影响,大于10时呈抑制作用;紫外活化中,初始pH值小于10时无明显影响,大于10时呈促进作用。去除效果对比表明,过硫酸盐紫外活化优于过硫酸盐热活化。

The present paper is aimed at presenting a novel approach to the treatment of ferricyanide sewage with persulfate soas for the method to achieve the standard of the total cyanide concentration. For the said purpose,we have investigated and examined the effects of the reaction time,and the dosage of persulfate and the initial p H value on the removal efficiency of the total cyanide through thermal activiation and ultraviolet activation of the ferriccyanide wastewater. The results of our investigation and exploration tend to demonstrate that the concentration of the total cyanide in the blank control group tends to decrease slowly with the prolongation of the reaction time,though the concentration of the total cyanide content tends to remain stable through 4 h experimentation. Practically speaking,under the control group of different initial p H conditions,the concentration of the total cyanide tends to decrease more obviously under the acidic condition,whereas the total cyanide concentration has been found decreased with the reaction process going on in the two activation modes,though the reduction process might be various. On the other hand,in the thermal activation,the decomposition of persulfate can be done faster than that of the total cyanide,and the decomposition rates of the two components remain consistent in the ultraviolet activation,which implies that in the thermal activation,the dosage of persulfate may have a great influence. Nevertheless,when the molar ratio of persulfate to the total cyanide reaches over 1,the excessive persulfate would become SO-4 scavenger,and the excessive free radicals would also be self-quenched so as to result in the weakening of the oxidation capacity. What is more,when the initial p H value is less than 10,there would be little effect on the reaction. In spite of this,when the initial p H value is over 10,there would come about a negative effect. And,in the ultraviolet activation,when the molar ratio of persulfate to the total cyanide reaches 2. 5,the utilization rate may tend to get decreased. Furthermore,when the initial p H value tends to get less than 10,the status-in-situ remains similar to the thermal activation,with little effect seen on the reaction. And,if the initial p H value tends to get greater than 10,there would appear a positive effect. The removal efficiency of ferricyanide has thus be proven better under the ultraviolet activation as compared with the thermal activation.