杭锦土负载硫化零价铁的研制及除磷性能

Preparation of Hangjin clay-supported sulfidated zero-valent iron and its performance on phosphate removal

  • 摘要: 以具有较大比表面积和良好吸附性能的天然杭锦土为载体制备杭锦土负载硫化零价铁(HJ@S-nZVI)。优化铁负载比、硫铁摩尔比(S/Fe)以及陈化时间等制备条件,利用扫描电子显微镜(SEM)、能量色散光谱(energy dispersive spectroscopy,EDS)、X射线光电子能谱(XPS)及比表面积(specific surface area,SSA)等手段对HJ@S-nZVI进行综合表征分析。考察投加量、初始pH以及共存离子等因素对HJ@S-nZVI去除磷酸盐效果的影响,并结合吸附等温线和吸附动力学研究其吸附性能和吸附机理。结果表明:HJ@S-nZVI的优化制备条件为铁负载比为0.25,S/Fe为0.01,陈化时间为10 d;SEM、EDS和元素分布图分析表明,硫化零价铁以球状颗粒形式成功负载于杭锦土表面,XPS表明HJ@S-nZVI表面铁的主要存在形态为FeS和FeOOH等;投加量、初始pH和SiO3 2−共存对HJ@S-nZVI去除磷酸盐的效果影响较大,而SO4 2−、CO3 2−和Cl共存对磷酸盐的去除效果无明显竞争影响;HJ@S-nZVI对磷酸盐的吸附过程符合Freundlich等温模型(R2=0.992),不同初始浓度下,准二级动力学模型可较好地描述磷酸盐的去除过程(R2>0.995)。

     

    Abstract: Natural Hangjin clay with large specific surface area and excellent adsorption properties was used as a carrier to synthesize Hangjin clay-supported sulfidated zero-valent iron (HJ@S-nZVI). Preparation conditions such as the iron loading ratio, the molar ratio of sulfide iron (S/Fe) and the aging time were optimized. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and specific surface area (SSA) and other methods were utilized to comprehensively characterize and analyze the characteristics of HJ@S-nZVI. The effects of the dosage, initial pH, and co-existing ions on the phosphate removal efficiency were investigated, and the adsorption performance and adsorption mechanism of phosphate removal by HJ@S-nZVI were studied based on the adsorption isotherms and adsorption kinetics. The results showed that the optimized preparation conditions of HJ@S-nZVI were: iron loading ratio was 0.25, S/Fe was 0.01, and aging time was 10 d. SEM, EDS and element distribution map analysis manifested that sulfidated zero-valent iron was successfully loaded on the surface of Hangjin clay in the form of spherical particles. XPS analysis showed that the main existing forms of iron on the surface of HJ@S-nZVI were FeS and FeOOH. The dosage, initial pH and SiO3 2− had a greater influence on phosphate removal, while SO4 2−, CO3 2− and Cl had no obvious competitive influence. The adsorption process of phosphate by HJ@S-nZVI conformed to Freundlich isotherm model (R2=0.992). Under different initial concentrations, the quasi-second-order kinetic model could better describe the phosphate removal process(R2>0.995).

     

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