纳米零价铁颗粒去除As(III)和As(V)的动力学过程及性能研究

本研究系统分析了不同初始砷浓度和不同nZVI投加量等条件下，nZVI去除As（III）和As（V）的动力学过程和除砷性能.结果表明，nZVI可快速有效地去除As（III）和As（V），除砷过程均符合准二级动力学模型，且As（III）的去除速率明显快于As（V）.在砷浓度为5 mg·L^-1时，As（III）去除速率常数达最大值0.30 g·mg^-1·min^-1，为As（V）去除速率（0.034 g·mg^-1·min^-1）的8.8倍.Weber-Morris粒子内扩散模型拟合结果表明，nZVI除砷速率是由外扩散和颗粒内扩散共同控制的.分析反应平衡时砷浓度测定结果，发现不同砷浓度条件下nZVI对As（III）的去除量为As（V）的1.5~2.6倍，nZVI对砷的去除量随初始砷浓度增加而降低，随nZVI投加量增加而增加.砷浓度为50.0 mg·L^-1时，As（III）和As（V）去除量达到最高，分别为152.14 mg·g^-1和62.02 mg·g^-1，均高于传统（羟基）氧化铁对As（III）和As（V）的去除量.因此，nZVI可高效去除水中As（III）和As（V），且用于修复以As（III）污染为主的地下水更具有优势.

Investigation of kinetic processes and performance of As(III) and As(V) removal by nano-zero-valent iron particles

To analyze the kinetics and evaluate the performance of As(III) and As(V) removal by nano-zero-valent iron (nZVI), a batch experiment was conducted with different initial concentrations of arsenic (As) and nZVI dosages. The results showed that both As(III) and As(V) were rapidly and effectively removed by nZVI, and the removal processes were in accordance with the pseudo-secondary kinetic model. The removal rate of As(III) by nZVI was significantly higher than that of As(V), and achieved the maximum of 0.30 g·mg^-1·min^-1 at the As concentration of 5 mg·L^-1, 8.8 times higher than the removal rate of As(V) (0.034 g·mg^-1·min^-1). Based on the curve fitting by Weber-Morris intraparticle diffusion model, the removal rate of As by nZVI was controlled by both external and intraparticle diffusion. Additionally, it was also observed that the removal capacity of As(III) was 1.5~2.6 times hihger than that of As(V) with different initial As concentrations, whereas the removal of As decreased with the increase of initial arsenic concentration and increased with the increased nZVI dosage. The maximum removal capacities of As(III) and As(V) by nZVI were 152.14 mg·g^-1 and 62.02 mg·g^-1 at the initial As concentration of 50 mg·L^-1, respectively, which was much higher than that of by (hydroxy)iron oxide. Accordingly, nZVI can be an alternative for the remediation of As contaminated groundwater, especially for coping with the As(III) dominated groundwater pollution.