磁黄铁矿对铼的还原固定及其影响因素研究

On the reduction-immobilization function of rhenium and its influential factors via pyrrhotite

利用非放射性的高铼酸根离子（Re O-4）模拟放射性的高锝酸根离子（Tc O-4）的化学行为,研究天然磁黄铁矿还原固定地下水中高锝酸根离子的机理。结果表明：磁黄铁矿可以较好地处理水溶液中的铼,其80 d对初始浓度为5×10-5mol/L的Re O-4处理率可达97%,处理效果随反应时间延长、投加量增大而增强,磁黄铁矿对高铼酸根的去除符合准一级反应动力学方程,室温下,其准一级速率常数（kobs）为0.046 3 d-1;温度越高,磁黄铁矿对铼的处理效果越好,在80℃下效果最好,7 d内就可以完全处理Re（Ⅶ）;p H值对磁黄铁矿处理铼的效果有明显影响,p H=1.02时24 h就可以完全去除铼离子,但在p H值为3~8.5时对反应速率影响不大。

The aim of this paper is to explore the feasibility of pyrrhotite as a media for pertechnetate removal from the sewage.To facilitate our experimental work,we have adopted perrhenate as an analogue to pertechnetate,while conducting the batch kinetic tests to analyze and determine the kinetic reduction regulations. In doing so,we have investigated the effects of the various parameters concerned,such as the reducing time,the initial p H,the temperature and the coexistent ions. In our work,we have also used scanning electronic microscope（ SEM） and X-ray diffraction（ XRD） to trace the surface morphology and determine the composition of the pyrrhotite in its natural state. The results of our experimental work prove that the reductively removal rate of perrhenate（ 5 × 10- 5mol / L） can be made up as high as 97% in a period of 80 days. The experimental facts we have gained tell us that the Re（ Ⅶ） removal rate tends to increase with the increase of the dosage of pyrrhotite and the reaction time. At the same time,the experimental results we have found out imply that it is possible to improve the ionic strength of the system and facilitate the experiment by adding 0. 1 mol / L Na Cl to the experiment,which proves to have some certain positive effects on the reduction of Re（ Ⅶ）. What is more,the pseudo-first-order kinetic model we have proposed turns to be able to help to interpret the kinetic data（ R2= 0. 9675） in a form of a pseudo first order rate constant（ kobs） of 0. 046 3 d- 1at room temperature（ 25 ℃） and p H =5. 2. Besides, the temperature proves to have a predominant effect on the removal of pertechnetate. For example,when the temperature is higher than 55 ℃,it would be possible to speed up the removing rate of Re（ Ⅶ） with the increase of temperature.The results of the aforementioned experiment have shown that the natural pyrrhotite is endowed with the capability to reductively remove perrhenate（ 100 mg / L） from the sewage within 7 days at 80℃ at a superior rate of 98%. At the same time,the p H value also proves to have an obvious influence on the removal rate of perrhenate,which can be removed within 24 hours at p H = 1 absolutely with the p H values from 3 to 8. 5,though it is not obvious with the change of removal rate.