纳米铁系物对三价砷的吸附机理与性能

Mechanism and Performance of Adsorption for As(Ⅲ) by Applied with Nanoscale Iron Materials

利用实验室条件下制备的纳米零价铁(NZVI)、纳米FeOOH和纳米Fe_3O_4,研究不同环境因素条件下各纳米铁系物对As(Ⅲ)的吸附性能。通过扫描电镜和X射线衍射扫描三种铁系物的微观结构,并分析模拟吸附动力学和吸附等温线。批试验的结果显示:当pH值为6,As(Ⅲ)的初始浓度为0.5 mg/L,2 h内NZVI对溶液中As(Ⅲ)的去除率高达99%,最大吸附量为5.99 mg/g;纳米FeOOH的最佳吸附条件为pH值为5,As(Ⅲ)初始浓度1 mg/L,4 h内的去除率可达92%;纳米Fe_3O_4的最佳吸附条件为pH值为7,As(Ⅲ)初始浓度为1 mg/L,24 h的最终去除率为60%。共存离子影响试验表明,对三种纳米铁系物吸附作用影响最大的均是溶液中的磷酸根。对吸附机理进行研究,结果表明:三种纳米铁系物吸附As(Ⅲ)的过程符合伪二级动力学模型,NZVI和纳米FeOOH的吸附等温数据符合Freundlich模型,纳米Fe_3O_4的吸附等温模型更加符合Langmuir等温模型。

Effects of different environmental factors on adsorption properties of nanoscale zero-valent iron （ NZVI）, nanoscale iron carbonyl and nanoscale ferroferric oxide on As （ Ⅲ ） were studied. Microstructures of three kinds of iron were scanned by electron microscope and X-ray diffraction. Then kinetic equation and adsorption isotherm of this adsorption process were analyzed. Results of batch experiments showed that,when pH value was 6,initial concentration of As（ Ⅲ ） was 0. 5 mg/L,the removal rate of NZVI on As （ Ⅲ ） was 99% in 2 hours,and the maximum adsorption capacity was 5. 99 mg/g. When pH value was 5,initial concentration of As （Ⅲ） was 1 mg/L,the adsorption of nanoscale iron carbonyl on As（ Ⅲ） had the best effect,the removal rate reached to 92% in 4 hours. When pH value was 7,initial concentration of As（Ⅲ ） was 1 mg/L,the adsorption of nanoscale ferroferric oxide on As（ Ⅲ ） had the best effect,the final removal rate reached to 60% in 24 hours. In addition, the biggest influence on adsorption of three kinds of nanoscale iron was the phosphate radical in the solution. At last, adsorption mechanism was studied, results showed that adsorption process of three kinds of iron content on As（ Ⅲ ） were in line with two order kinetic model. Meanwhile,adsorption isotherm data of NZVI and nanoscale iron carbonyl were in accordance with the Freundlich model, adsorption process of nanoscale ferroferric oxide was more in line with the Langmuir model.