绿茶还原制备纳米铁对模拟地下水中Cr(Ⅵ)的去除效果

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。

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

Nano2iro n pr oduced by reductio n w ith g reen tea extr act ( GT2NIP) has g ood r emo val efficiency of hexav alent chromi2 um in w ater. It is ex pected that the remov al of hexav alent chr omium from gr oundw ater can be achieved in situ by injecting GT2 NIP into the aquifer; but this has not been verified yet. In this paper, we pr epar ed nano- ir on by reductio n w ith g reen tea ex2 tr act, measured its reductio n effect o n hex av alent chromium in w ater, and then used sand co lumn to study its remo val efficiency on hex avalent chromium in simulated g ro undw ater. The GT2NIP w e made w ere spherical and unifo rm in size, w ith a diameter of 10220 nm and g ood dispersion stability in w ater. They consisted o f 551 6% Fe2+ and 441 4% Fe3+ . When GT2NIP concent ratio n was 120 g/ L, after 1 h of r eact ion, the remo val rate of Cr( VI) w it h an initial concent ratio n o f 100 mg / L reached 9628% . In the co lumn test, GT2NIP could pass thro ug h the sand column, with an aver age outflow per centage o f 681 6% . When a Cr( ? ) so lu2 tion of 100 mg/ L was injected into t he sand co lumn, the concentrat ion of Cr 3+ w as abo ut 01 20 mg / L, and the concentr ation of Cr 6+ in the effluent was 01 10201 25 mg / L; that is, the to tal remo val r ate o f hex avalent chromium by GT2 NIP w as more than 99% .