纳米零价铁去除磷酸盐机理研究

纳米零价铁(nanoscale zero-valent iron,nZVI)颗粒具有独特核-壳结构,使其具有较强氧化还原特性,比表面积大和表面活性高等特点,因此被广泛用于不同环境介质中多种污染物的去除修复。本研究采用传统的液相化学还原法合成nZVI颗粒并用于去除水溶液中的磷酸盐。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射仪(XRD)表征nZVI颗粒的性质。实验研究了nZVI投加量、PO3-4初始浓度、溶液初始pH值对nZVI去除PO3-4效率的影响及微米零价铁(micro-ZVI)和nZVI去除PO3-4的对比。实验结果表明,当PO3-4初始浓度为20mg/L时,随着nZVI投加量从200mg/L增加到1000mg/L,PO3-4去除效率从32.94%上升到90.17%;当nZVI投加量为600mg/L时,随着PO3-4初始浓度从10mg/L增加到100mg/L,PO3-4去除效率从87.33%下降到45.77%;当nZVI投加量为600mg/L且PO3-4初始浓度为20mg/L,溶液pH分别为3和4时,PO3-4去除效率分别为83.63%和92.36%;nZVI和mZVI投加量均为600mg/L且PO3-4初始浓度为10mg/L,nZVI的PO3-4去除率(87.33%)是mZVI(8.86%)的9.86倍。研究结果表明,nZVI能够高效去除水体中的磷酸盐,主要去除机理是吸附和化学沉淀的双重作用。

Study on Aqueous Phosphate Removal Mechanism by Nanoscale Zero-Valent Iron

Nanoscale zero-valent iron （nZVI） particles have been widely used for the remediation of a variety-of contaminants due to its unique core-shell structure which result in characteristics of stronger redox properties,high surface areas and high surface reactivity-.In this study,nanoscale zero-valent iron （NZVI） was synthesized by conventional liquid-phase chemical reduction methods and then characterized by transmission electron microscopy （TEM）,scanning electron microscopy （SEM） and X-ray diffraction （XRD）.Batch experiments of aqueous phosphate removal using nZVI particles were conducted.The effect of various factors such as nZVI dosage,initial PO43-concentration,and pH on phosphate removal was studied.Batch studies of aqueous phosphate removal using micro-ZVI （mZVI） were also conducted in comparison to nZVI.The results showed that when the initial phosphate concentration was 20mg/L,the phosphate removal efficiency increased from 32.94％ to 90.17％ as the dosage of nanoscale iron particles increased from 200mg/L to 1000mg/L.When the nZVI dosage is 600mg/L,the phosphate removal efficiency decreased from 87.33％ to 45.77％ as the initial phosphate concentration increased from 10mg/L to 100mg/L When the nZVI dosage is 600mg/L,the initial phosphate concentration is 20mg/L,and pH is 3 and 4,the phosphate removal efficiencies are 83.63％ and 92.36％,respectively.When the nZVI and mZVI dosages are both 600mg/L,and the initial phosphate concentration is 10mg/L,the efficiency of phosphate removal by nZVI （87.33％） was found 9.86 times higher than mZVI（8.86％）.Based on experimental results,it was concluded that high phosphate removal efficiency could be achieved using nZVI particles through adsorption and chemical precipitation samutaneously.