绿茶还原制备纳米铁对模拟地下水中Cr(Ⅵ)的去除效果

Study on the removal efficiency of nano-sized iron particles produced by green tea reduction on Cr(Ⅵ) in simulated groundwater

利用绿茶提取液还原制备的纳米铁(GT-NIP)对水中六价铬具有良好的去除效果的原理,通过向含水层中注入GT-NIP可望实现六价铬在地下水中的原位去除,但尚未得到验证。为此,首先利用绿茶提取液还原法制备纳米铁,然后考察了其对水中六价铬的还原效果,再利用柱试验研究GT-NIP对模拟地下水中六价铬的去除效果。结果表明:利用绿茶提取液制备的纳米铁为圆球形,大小均匀,直径约为10～20nm,且分散性较好,其中Fe2+含量为55.6%,Fe3+含量为44.4%。GT-NIP悬浮液在水中对Cr(Ⅵ)具有良好的降解能力,当GT-NIP浓度为1.0g/L时,反应1h,初始浓度为100mg/L的Cr(Ⅵ)去除率达到96.8%;在柱试验中,GT-NIP可以顺利穿透砂柱,平均出流百分比为68.6%。浓度为100mg/L的Cr(Ⅵ)溶液流过该纳米铁砂柱后,流出液中Cr3+浓度约为0.20mg/L,Cr6+浓度为0.10～0.25mg/L,即六价铬去除率达到99%以上。

Nano-iron produced by reduction with green tea extract(GT-NIP)has good removal efficiency of hexavalent chromium in water.It is expected that the removal of hexavalent chromium from groundwater can be achieved in situ by injecting GTNIP into the aquifer;but this has not been verified yet.In this paper,we prepared nano-iron by reduction with green tea extract,measured its reduction effect on hexavalent chromium in water,and then used sand column to study its removal efficiency on hexavalent chromium in simulated groundwater.The GT-NIP we made were spherical and uniform in size,with a diameter of 10-20 nm and good dispersion stability in water.They consisted of 55.6% Fe2+and 44.4% Fe3+.When GT-NIP concentration was 1-0g/L,after 1h of reaction,the removal rate of Cr(VI)with an initial concentration of 100mg/L reached 96-8%.In the column test,GT-NIP could pass through the sand column,with an average outflow percentage of 68.6%.When a Cr(Ⅵ)solution of 100mg/L was injected into the sand column,the concentration of Cr3+ was about 0.20mg/L,and the concentration of Cr6+in the effluent was 0.10-0.25mg/L;that is,the total removal rate of hexavalent chromium by GT-NIP was more than 99%.