Fe^0对饮用水中砷的去除效率及影响因素

Factors influencing arsenic-removing efficiency from the drinking water by using Fe^0

研究零价铁(Fe0)的除砷效果,试验考察了Fe0投加量、接触时间、pH值、DO浓度、温度、腐殖质、竞争性阴离子(SO42-,NO3-,SiO23-,H2PO3-,HCO3-)对Fe0除砷效率的影响。结果表明,Fe0(80目)投加量为2g/L,接触时间180min,pH值为6.5,DO值6.5mg/L的条件下,对质量浓度为1mg/L的含砷水样,Fe0对As(Ⅴ)的去除率高达96.5%,而对As(Ⅲ)的去除率只有75.8%。降低水样pH值或提高DO可显著提高Fe0的除砷效率,温度对Fe0除砷影响不大,水体中的腐殖质、磷酸盐、硅酸盐的存在会由于竞争性吸附而导致Fe0除砷效率下降。采用Fe0颗粒去除饮用水中的砷高效、经济,具有良好的应用前景。实际应用中,对于DO值较低的地下含As水,可通过充氧提高Fe0除As效率。当水体中腐殖质、磷酸盐或硅酸盐浓度较高时,应考虑采取相应的预处理措施。

This paper is aimed to present its study results on the factors influencing arsenic-removing efficiency from the drinking water by using Fe^0. For this purpose, we have investigated the effects of such factors, as Fe^0 dosage, contact hours, the solntion＇s pH value, dissolved oxygen （DO） value, temperature and concentrations of humic substances, conlpetltive anions （SO4^2-, NO3^-, SiO3^2-, H2PO3^-, HCO3^- ） through hatch experimemts. The results of our experiments prove that the removing effects can be as high as 95 % of As（ V ） by using Fe^0（80 mesh） with a dosage of 2 g/L at pH 6.5 and DO of 6.5 mg/L after 180 min of mixing, wheleas the previous methods only reached 75.8% of A（ Ⅲ ）. In addition, it proves to be possible to heighten Fe^0＇s removal efficiency of arsenic dramatically by lowering the solution of pH or raising DO content with less reliance on the temperature increase, while the presence of high concentration of humic substanees, phosphate and silicate in the＇ solution would inhibit the arsenic removal for its noticeable adsorption. Thus, the suggested method is highly promising to remove arsenic with Fe^0 from the drinking water for its high efficiency. The method can further be expectantly improved by using oxygen aeration with low DO value plus necessary pretreatment.