硫化纳米铁对模拟地下水中Cr(Ⅵ)的去除效果及影响因素

doi:10.13278/j.cnki.jjuese.20180029

摘要/Abstract

摘要： 硫化纳米铁（S-nZVI）是一种具有壳核结构的新型纳米铁（nZVI）改性材料，在多种污染物的去除上表现出超越nZVI的反应活性。本文采用两步合成法制备了S-nZVI，并采用透射电镜-能量色散X射线（TEM-EDX）、X射线衍射（XRD）和X射线光电子能谱分析（XPS）方法对S-nZVI和nZVI进行表征，探讨了不同硫铁摩尔比（n（S）/n（Fe））、初始pH值、试剂投加量和地下水化学成分对nZVI及S-nZVI去除Cr（Ⅵ）的影响。结果表明：S-nZVI具有明显的壳核结构，其Fe⁰核外层包覆着非晶的硫化亚铁和多硫化物；S-nZVI去除Cr（Ⅵ）的最佳n（S）/n（Fe）为0.14；增加S-nZVI投加量会提高其对Cr（Ⅵ）的去除率，投加量相同时，S-nZVI对Cr（Ⅵ）的去除率显著高于nZVI；提高初始pH值时，S-nZVI和nZVI对Cr（Ⅵ）的去除率均逐渐降低，但在相同pH值条件下，S-nZVI对Cr（Ⅵ）的去除率和去除速率始终高于nZVI，尤其是在pH=5时，S-nZVI仍能去除100%的Cr（Ⅵ），而nZVI只能去除85%；K⁺、Na⁺、Ca²⁺、Mg²⁺、SO₄^2-、NO₃^-和Cl^-对S-nZVI和nZVI去除Cr（Ⅵ）均有促进作用，但对S-nZVI体系的促进作用更强；HCO₃^-的存在会使溶液的pH值升高从而抑制S-nZVI和nZVI对Cr（Ⅵ）的去除，对nZVI的抑制作用强于S-nZVI。总体来说，S-nZVI对Cr（Ⅵ）的去除率在不同pH值和多种地下水化学组分影响条件下均高于nZVI，因此具有更广泛的应用前景。

关键词: Cr(Ⅵ), 硫化纳米铁, 硫铁摩尔比, pH, 地下水化学组分

Abstract: Sulfidated nanoscale zerovalent iron (S-nZVI) is a new nZVI modified material with core-shell structure, and exhibits a higher reactivity towards various contaminants than nZVI. In this study, S-nZVI was synthesized by a two-step method. S-nZVI and nZVI were investigated by transmission electron microscope-energy dispersive X-ray spectroscopy (TEM-EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of n(S)/n(Fe), initial pH, reagent dosage and groundwater chemical composition on Cr(Ⅵ) removal by nZVI and S-nZVI were evaluated. The results showed that S-nZVI has obvious core-shell structure, and the core of Fe⁰ is coated with amorphous ferrous sulfide and polysulfide. The optimum n(S)/n(Fe) was 0.14 for the reaction between S-nZVI and Cr(Ⅵ). The increased dosage of S-nZVI enhanced Cr(Ⅵ) removal efficiency. With the same dosage, the Cr (VI) removal efficiency by S-nZVI was significantly higher than that by nZVI. When pH increased, the Cr(Ⅵ) removal efficiency by both S-nZVI and nZVI decreased gradually. But the efficiency and removal rate by S-nZVI were always higher than by nZVI under the same pH. Especially at pH=5, S-nZVI removed 100% of Cr(Ⅵ), whereas nZVI removed 85%. K⁺, Na⁺, Ca²⁺, Mg²⁺, SO₄^2-, NO₃^-, and Cl^- promoted Cr(Ⅵ) removal by both S-nZVI and nZVI, but more effectively in S-nZVI system. The presence of HCO₃^- increased the solution pH, and thus inhibited Cr(Ⅵ) removal more stronger in nZVI than S-nZVI systems. S-nZVI shows a higher efficiency of Cr(Ⅵ) removal than nZVI under the influence of various pH and groundwater chemical components, so it has a broader application prospect.

Key words: Cr(Ⅵ), S-nZVI, n(S)/n(Fe), pH, chemical composition of ground water

中图分类号:

X523

洪梅, 韩旭, 王蔷, 刘璐, 史玉玺. 硫化纳米铁对模拟地下水中Cr(Ⅵ)的去除效果及影响因素[J]. 吉林大学学报(地球科学版), 2018, 48(6): 1821-1830.

Hong Mei, Han Xu, Wang Qiang, Liu Lu, Shi Yuxi. Removal Effect and Influencing Factors of Cr(Ⅵ) in Simulated Groundwater by Sulfidated Nanoscale Zerovalent Iron[J]. Journal of Jilin University(Earth Science Edition), 2018, 48(6): 1821-1830.

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