零价铁脱除水中六价铬的实验研究

Removal of Chromium (Ⅵ) with Zero Valent Iron:an Experimental Research

目的观察零价铁(ZVI)对水中Cr(Ⅵ)的脱除效果以及影响Cr(Ⅵ)脱除的主要因素。方法将一定量ZVI加入盛有50 ml含Cr(Ⅵ)溶液的磨口锥形瓶中,观察在Cr(Ⅵ)初始浓度为5、10、20、30 mg/L,温度分别为5、15、25、35℃,pH值为2、4、6,ZVI用量为0.25、0.5、0.75、1.0、1.25、1.50 g以及Cl-、NO3-、SO42-、CO32-、PO43-等阴离子存在条件下对脱除率的影响。结果零价铁可有效脱除溶液中Cr(Ⅵ),5 min内脱除率即可达90%以上,可满足GB 5749—2006《生活饮用水卫生标准》中Cr(Ⅵ)限值标准(≤0.05 mg/L)的要求,其最佳反应条件是温度25℃、pH=2、ZVI用量1.0 g。结论零价铁能快速除去水中Cr(Ⅵ),溶液pH值、Cr(Ⅵ)初始浓度、温度等是影响Cr(Ⅵ)脱除的主要因素。

Objective To observe the removal of Cr（Ⅵ） and effects of some factors in solution on Cr（Ⅵ） with zero valent iron （ZVI）. Methods A certain amount ZVI were added in a 50 ml solution with Cr （Ⅵ）, the effects on removal ratio were observed when the initial Cr （Ⅵ） concentration was 5,10,20 and 30 mg/ L, temperatures was 5,15,25 and 35 ℃,the ZVI dosage was 0.25, 0.5, 0.75, 1.0, 1.25 and 1.50 g and anions such as Cl^-, NO3^-, SO4^2-, CO3^2- and PO4^3-.The removal ratio of Cr （Ⅵ） was evaluated by Cr （Ⅵ） concentration difference pre and post-treatment with ZVI. Results Cr（Ⅵ） could be removed effectively with ZVI and removal ratio of Cr （Ⅵ） could reach over 90% in 5 min, the Cr （Ⅵ） concentration of the solution could meet the requirement of GB5749-2006 Sanitary Standard for Drinking Water Quality [ Cr （Ⅵ） concentration ≤ 0.05 mg/L]. The best reaction conditions was 35 ℃, pH=2, dosage of ZVI =1.0 g. Conclusion Cr （Ⅵ） can he removed by ZVI in solution, the removal ratio can be impacted by some factors such as pH value, Cr （Ⅵ） initial concentration, temperature.