沸石负载纳米零价铁去除水中Sb(Ⅲ)和Sb(Ⅴ)的研究

Removal of Sb(Ⅲ) and Sb(Ⅴ) in Water by Zeolite-Supported Nanoscale Zero-Valent Iron

锑矿开采和含锑化合物的应用在一定程度上会造成环境锑污染的加重,对人体健康和生态系统带来风险,为缓解这一现象,采用液相还原负载的方式制备沸石负载纳米零价铁(Z-ZVI)复合材料,探究其对Sb(Ⅲ)和Sb(Ⅴ)的去除效果;采用扫描电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)对反应前后复合材料进行表征,并探究不同材料配比、溶液初始pH及无机阴离子对Sb(Ⅲ)和Sb(Ⅴ)吸附效率的影响.结果表明:(1)沸石负载后的纳米零价铁(Z-ZVI)具有较高的比表面积(54.54 m2/g)和反应活性,能够有效吸附、还原高价锑.(2)在pH=7、1.0 g/L Z-ZVI的条件下,反应4 h对20 mg/L Sb(Ⅲ)和Sb(Ⅴ)的吸附率分别达到88%和62%,吸附过程符合准二级动力学方程和Freundlich等温吸附模型.(3)Sb(Ⅲ)的去除率受pH变化的影响不大,但Sb(Ⅴ)的去除率随初始pH的升高而下降,溶液反应终点pH相比初始pH均有所上升.(4)XRD和XPS表征发现,Sb的去除过程中同时存在吸附和还原作用,Fe0氧化过程中伴随着高价锑的还原,最终生成含锑铁氧化物固定锑.(5)在较低锑污染模拟地下水吸附和脱附试验中Sb(Ⅲ)和Sb(Ⅴ)的去除率可达到96%,吸附后锑浓度可降至0.01 mg/L,且脱附量远小于吸附量.研究显示,Z-ZVI材料能够有效去除污染水体中的Sb(Ⅲ)和Sb(Ⅴ),对实际地下水修复应用具有一定参考价值.

Antimony ore mining and antimony compounds application have contributed to a certain degree of antimony pollution in the environment, and posed risks to human health and the ecosystems. In order to alleviate this problem, the zeolite-supported nanoscale zerovalent iron(Z-ZVI) composite material was prepared by liquid phase reduction method, and its removal efficiency of Sb(Ⅲ) and Sb(Ⅴ)was studied. Scanning electron microscope(SEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to characterize the composite material before and after the reaction, and the impact of different material ratios, initial pH values of solution and inorganic anions on the adsorption efficiency for Sb(Ⅲ) and Sb(Ⅴ) was studied. The results show that:(1) Z-ZVI has a high specific surface area(54.54 m~2/g) and reactive activation, it can effectively adsorb and reduce high-valent antimony.(2) Under the conditions of pH=7 and 1.0 g/L Z-ZVI, the adsorption efficiency of 20 mg/L of Sb(Ⅲ) and Sb(Ⅴ) reaches 88% and 62%, respectively after four hours of reaction. The adsorption process conforms to the pseudo-second order kinetic equation and the Freundlich adsorption model.(3) The removal rate of Sb(Ⅲ) is not greatly affected by pH, but the removal rate of Sb(Ⅴ) decreases as the initial pH increases. The final pH value of the solution after the reaction is higher than the initial pH.(4) XRD and XPS characterizations show that Sb adsorption and reduction occur simultaneously during the Sb treatment, and the oxidation of Fe~0 is accompanied by the reduction of high-valent antimony.Antimony-containing iron oxides are finally formed.(5) In the simulated groundwater adsorption and desorption experiments with relatively low antimony concentration, the removal rate of Sb(Ⅲ) and Sb(Ⅴ) can reach up to 96%. After adsorption, the antimony concentration can be reduced to 0.01 mg/L, and the desorption capacity is much less than the adsorption capacity. The study indicates that Z-ZVI materials can effectively remove Sb(Ⅲ) and Sb(Ⅴ) in polluted water, which has certain value for the practical application of the materials in groundwater remediation.