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
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摘要: 锑矿开采和含锑化合物的应用在一定程度上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. ③Sb(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. ④XRD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.Abstract: Antimony ore exploitation and antimonial compounds application have worsened the antimony pollution in the environment to a certain extent, and posed risks to human health and the ecosystem. In order to allevivate this issue, the study adopts the liquid phase reduction method to prepare the zeolite-supported nanoscale zero-valent iron (Z-ZVI) composite material, thus probing into its effect of removing Sb(Ⅲ) and Sb(Ⅴ). The study utilizes the scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to characterize the composite material before and after the reaction, and explores the impact of different material ratios, initial pH values of solution and inorganic anions on the adsorption efficiency for Sb(Ⅲ) and Sb(Ⅴ). The results show that: (1) With high specific surface area (54.54 m2/g) and reactive activation, Z-ZVI can effectively adsorb and reduce high-valent antimony. (2) Under the condition that the pH value of Z-ZVI equals to 7 and 1.0 g/L, the adsorption efficiency for 20 mg/L of Sb(Ⅲ) and Sb(Ⅴ) reaches 88% and 62% respectively after four hours of reaction, and the adsorption process fits the pseudo-second order kinetic equation and Freundlich isothermal adsorption model. (3) The removal rate of Sb (Ⅲ) is not greatly affected by changes in pH value, but the removal rate of Sb(Ⅴ) decreases as the initial pH value increases, and the final pH value of solution after reaction goes up compared with the initial pH value. (4) XRD and XPS characterizations find that the process of removing Sb produces adsorption and reduction effects concurrently, and the oxidation of Fe0 is accompanied by the reduction of high-valent antimony. The antimonial iron oxides are finally generated which fix antimony. (5) In the simulated groundwater adsorption and desorption experiments with relatively low antimony pollution, the removal rate of Sb(Ⅲ) and Sb(Ⅴ) can reach up to 96%, the concentration of antimony after adsorption 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 reference value for practical application of such materials in groundwater remediation.
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Key words:
- nanoscale zero-valent iron /
- zeolite /
- antimony /
- adsorption
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