改性净水污泥负载纳米零价铁去除水中的Cr(Ⅵ)

Removal of Cr(Ⅵ)in Wastewater by Modified Waterworks Sludge Supported Nanoscale Zero-valent Iron

以净水污泥为原材料,通过高温煅烧和盐酸活化制备得到改性净水污泥。利用液相还原法,以NaBH4为还原剂还原Fe3+合成改性净水污泥负载纳米零价铁(MWS-nZVI)吸附剂,将其用于去除水中的Cr(Ⅵ);并将MWS-nZVI与净水污泥负载纳米零价铁(WS-nZVI)作对比,考察了溶液pH值、吸附剂投加量和Cr(Ⅵ)初始浓度对吸附效果的影响;另外,采用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)等表征手段,分析吸附材料的物理特性和化学组成。结果表明,MWS-n ZVI对Cr(Ⅵ)具有良好的去除效果,当投加量为0.3 g/L、pH值为2、Cr(Ⅵ)初始浓度为20 mg/L、反应时间为3.5 h时,对Cr(Ⅵ)的最大吸附量可达到26.0mg/g。表征结果显示,MWS-n ZVI的比表面积较大,且对纳米零价铁的负载效果更好。通过拟合发现,Freundlich吸附等温方程更适合模拟MWS-nZVI对Cr(Ⅵ)的去除过程。

Modified waterworks sludge was prepared by high temperature heat treatment and hydrochloric acid activation.The modified waterworks sludge supported nanoscale zero-valent iron(MWS-nZVI)was prepared by reduction of Fe3+with NaBH4 through liquid phase chemical reduction method,and the adsorbent was applied for the removal of Cr(Ⅵ)in wastewater.The adsorption performance of MWS-nZVI was compared with that of waterworks sludge supported nanoscale zero-valent iron(WS-nZVI),and the effects of pH,adsorbent dosage and initial concentration on adsorption of Cr(Ⅵ)were evaluated.Physical properties and chemical composition of the adsorbent were analyzed by different kinds of characterization methods(SEM,XPS and FTIR).The results indicated that MWSnZVI had a good removal efficiency on Cr(Ⅵ).When the dosage was 0.3 g/L,pH value was 2,initial concentration of Cr(Ⅵ)was 20 mg/L and reaction time was 3.5 h,the maximum adsorption capacity was 26.0 mg/g.The characterization results showed that MWS-nZVI had a large specific surface area and a better loading effect on nanoscale zero-valent iron.The Freundlich adsorption isotherm equation was more suitable to simulate the removal process of Cr(Ⅵ)by MWS-nZVI.