纳米零价铁颗粒除磷反应机理  

Mechanism of phosphorus removal by nanoscale zero-valent iron( NZVI)

作　　者：张颖纯[1] 王伟[1] 

机构地区：[1]同济大学环境科学与工程学院,上海200092

出　　处：《环境工程学报》2015年第5期2041-2047,共7页Chinese Journal of Environmental Engineering

基　　金：国家自然科学基金资助项目(21277102)

摘　　要：从溶液化学与固相表征两方面对纳米零价铁(NZVI)去除水中磷酸根(PO3-4)的机理进行初步探究。分别研究不同初始p H值、溶解氧(DO)对NZVI除磷效果的影响,结果表明,酸性环境(p H为3.0~7.0)有利于NZVI除磷,且初始p H值越低,磷去除率越高;好氧环境较厌氧环境更利于磷的去除,DO>8.0 mg/L时对磷酸根的去除率是厌氧条件(DO<0.1 mg/L)下的2倍。采用Na OH对反应后含磷NZVI进行解析,发现磷解析率不到30%,说明吸附并非NZVI除磷惟一作用机理。微米铁、NZVI和Ca(OH)2等7种不同去除材料中以Ca(OH)2的共沉淀作用去除率最大(99.9%),NZVI次之(87.2%),表明NZVI除磷机理中还存在共沉淀作用。采用多种固相表征手段对NZVI除磷前后进行分析:扫描电子显微镜(SEM)显示反应后出现不规则颗粒;X射线衍射(XRD)表明Fe3(PO4)2是主要反应产物;X射线光电子能谱(XPS)分析未发现磷被还原成低价态。研究表明,NZVI可有效去除水中磷酸根,主要去除机理包括:NZVI对磷酸根的吸附作用、NZVI在水中腐蚀产生的Fe2+离子对磷酸根的化学沉淀作用及铁氢氧化物与磷酸根的共沉淀作用。The mechanisms of aqueous phosphate( PO3-4) by iron nanoparticles( NZVI) were explored from two aspects: the solution chemistry analyses and solid phase characterization. Different initial p H and dissolved oxygen( DO) were investigated respectively. We found that the removal efficiency was much higher under the acidic conditions( p H 3. 0 ~ 7. 0),and the lower the initial p H,the higher the efficiency. The dissolved oxygen could also increase the efficiency and the efficiency under aerobic condition( DO > 8. 0 mg / L) was twice as it( DO > 8. 0 mg / L) under anaerobic condition( DO < 0. 1 mg / L). The phosphate on the reacted nanoparticles could be partially desorbed( < 30%) by Na OH,indicating that adsorption is not the only removal mechanism involved. The mechanism of coprecipitation was proved by seven different materials,among which Ca( OH)2had the highest removal efficiency of 99. 9% and NZVI was the second efficient material(87. 2%). Characterization techniques were further conducted of NZVI before and after phosphate removal. Irregular particles were found in the reacted nanoparticles by scanning electron microscopy( SEM). Fe3(PO4)2was confirmed as the main reaction product by X-ray diffraction( XRD) analysis. No low valence state of phosphorous was identified by X-ray photoelectron spectrometer( XPS). As conclusion,We found three underlying removal mechanisms of phosphorus by NZVI: adsorption,chemical precipitation( corrosion product( Fe2 +) of NZVI) and coprecipitation(iron hydroxides)

关 键 词：纳米零价铁 磷酸根 化学沉淀 共沉淀 吸附 

分 类 号：X703[环境科学与工程—环境工程]