凹凸棒负载非晶态零价铁去除水体中的Cr(Ⅵ)

Removal of Cr (Ⅵ) in aqueous solution by amorphous zero-valent iron supported on attapulgite

以非晶零价铁(AZVI)为核心,采用液相还原法将AZVI负载到凹凸棒(ATP)表面制备凹凸棒负载非晶态零价铁复合材料(ATP-AZVI),考察其对Cr(Ⅵ)的去除特性;并通过扫描电子显微镜、原子力显微镜、X射线衍射仪和比表面积分析仪等手段对复合材料进行表征,验证负载的可靠性及去除Cr(Ⅵ)机理。结果表明:非晶态零价铁分散在凹凸棒的表面,团聚效应得到缓解,相比于晶态零价铁负载凹凸棒复合材料(ATP-ZVI),ATP-AZVI的比表面积更大、亲水性能更好。ATP-AZVI对Cr(Ⅵ)有很好的去除效果,反应30min即可去除97.4%的Cr(Ⅵ),试验也证明AZVI负载凹凸棒适用性很强。去除机理研究表明,ATP减缓了AZVI的团聚,加快了电子传递,Cr(Ⅵ)被还原成Cr(Ⅲ)后与Fe(Ⅲ)沉淀在材料表面,从而达到去除的目的。

Amorphous zero-valent iron(AZVI) was loaded on the surface of attapulgite(ATP) by liquid phase reduction method to prepare ATP-loaded AZVI composite(ATP-AZVI). We investigated the removal characteristics of Cr(Ⅵ) by ATP-AZVI, and characterized the composite materials by means of scanning electron microscope(SEM), atomic force microscope(AFM), X-ray diffraction(XRD) and N2 adsorption-desorption measurement(BET) to verify the reliability of loading and the mechanism of Cr(Ⅵ) removal. The results show that the AZVI is dispersed on the surface of the attapulgite, and the agglomeration effect is relieved. Compared with the crystalline zero-valent iron loaded ATP composite(ATP-ZVI), ATP-AZVI has a larger specific surface area and better hydrophilic property. ATP-AZVI has good removal effect on Cr(Ⅵ), 97.4% of Cr(Ⅵ) can be removed after 30 min of reaction, and experiments proves that AZVI-loaded attapulgite has strong applicability. The removal mechanism study shows that ATP slows the agglomeration of AZVI and accelerates the electron transfer. Cr(Ⅵ) is reduced to Cr(Ⅲ) and then precipitates with Fe(Ⅲ) on the surface of the material, thus achieving the purpose of removal.