废水中的砷是最具毒性的环境污染物之一.为了更好地利用纳米零价铁(Nanoscale Zero-Valent Iron,NZVI)修复水体污染,本文进行了浮石负载NZVI去除水相中As(Ⅴ)的研究.利用环境扫描电镜(SEM)和透射电子显微镜(TEM)对浮石负载纳米零价铁(P-NZVI)的形态和粒度进行表征分析,根据批试验和间歇试验探究反应条件对去除效果的影响,并通过对照P-NZVI与As(Ⅴ)溶液反应前后的样品的X射线光电子能谱(XPS),结合XPS Fe2p和XPS As3d窄轨道图谱,探讨P-NZVI对水相中As(Ⅴ)的去除机理.研究结果表明,制备所得NZVI颗粒平均粒径30.6 nm,分散在浮石表面.利用BET-N2法检测得到P-NZVI的比表面积为32.2 m2·g-1(NZVI含量0.28 g,质量比7.7％).P-NZVI对As(Ⅴ)的去除率随初始pH值、反应温度、As(Ⅴ)初始质量浓度的升高而降低,反应符合准一级和准二级动力学方程.初始As(Ⅴ)浓度为100 mg·L-1时,P-NZVI的平衡时吸附量为35.7 mg·g-1.P-NZVI对As(Ⅴ)的去除机理包括吸附、沉淀和共沉淀作用.
Nanoscale zero-valent Iron (NZVI) was successfully coated onto pumice support (P-NZVI).It was used for the removal of arsenic (Ⅴ),which is one of the most toxic waste-water pollutants.P-NZVI characterization by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that NZVI was dispersed on pumice.NZVI particles were nearly spherical in shape with a mean diameter of 30.6 nm,which demonstrated that pumice was effective in preventing NZVI particles from agglomerating.P-NZVI with a 7.7％ NZVI mass fraction had a specific surface area (SBET) of 32.2 m2·g-1.The influence of experimental factors on As (Ⅴ)removal was investigated by batch experiments.The results showed that As (Ⅴ) was removed by P-NZVI adsorption rapidly with high removal rate (more than 99％) over a wide range of pH (3.10-12.54) and concentrations (20-100 mg· L-1).The removal mechanism of As (Ⅴ) by P-NZVI was investigated by comparing the X-ray photo-electron spectroscopic intensity (including XPS Fe2p and XPS As3d) of the samples before and after reacting with P-NZVI.Our results indicated that P-NZVI might be an effective material for both in situ and ex situ remediation of As(Ⅴ).
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