硫化纳米零价铁去除水中Cr(Ⅵ)的过程与机制

Process and mechanism of Removal of Cr(Ⅵ)from water by Sulfurized Nano-Zerovalent Iron

以连二亚硫酸钠为硫源,七水合硫酸亚铁为铁源,利用一步硫化法制备硫化纳米零价铁(S-nZVI),并用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等,研究S-nZVI表面形貌及元素化学形态等关键特性;以Cr(Ⅵ)为目标污染物,考察溶液初始pH值、材料投加量和Cr(Ⅵ)的初始浓度对去除效果的影响,分析S-nZVI去除Cr(Ⅵ)的机理。表征结果表明,S-nZVI是Fe(0)和FeS共存的材料,且以Fe(0)为主,其饱和磁场强度为83.5 emu/g。溶液初始pH值、材料投加量能影响S-nZVI对Cr(Ⅵ)的去除。当投加量为0.5 g/L、pH值为2、Cr(Ⅵ)初始浓度为20 mg/L时,在5 min内可以达到反应平衡,去除率可达98%。S-nZVI对Cr(Ⅵ)的去除符合准二级动力学方程,去除机理包括吸附、还原与共沉淀等作用。

Using sodium dithionite as sulfur source and ferrous sulfate heptahydrate as iron source,sulfided nano-zero-valent iron(S-nZVI)was prepared by one-step sulfurization method.X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscope(SEM)and transmission electron microscope(TEM)were used to study the key characteristics of S-nZVI such as surface morphology and element chemical morphology.Taking Cr(Ⅵ)as the target pollutant,the effects of the initial pH value of the solution,the dosage of materials and the initial concentration of Cr(Ⅵ)on the removal effect were investigated,and the mechanism of Cr(Ⅵ)removal by S-nZVI was analyzed.The characterization results show that S-nZVI is a material in which Fe(0)and FeS coexist,and is dominated by Fe(0),and its saturation magnetic field strength is 83.5 emu/g.The initial pH value of the solution and the dosage of materials can affect the removal of Cr(Ⅵ)by S-nZVI.When the dosage is 0.5 g/L,the pH value is 2,and the initial concentration of Cr(Ⅵ)is 20 mg/L,the reaction equilibrium can be reached within 5 minutes,and the removal rate can reach 98%.The removal of Cr(Ⅵ)by S-nZVI conformed to the pseudo-second-order kinetic equation,and the removal mechanism included adsorption,reduction and co-precipitation.