Liu Jie, Huang Kun, Xie Keng, Yang Ying, Liu Huizhou
Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China; Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, 266101, PR China.
Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China.
Water Res. 2016 Apr 15;93:187-194. doi: 10.1016/j.watres.2016.02.025. Epub 2016 Feb 16.
An ecological new approach for photochemical reduction of Cr(VI) in aqueous solution by adding into water-soluble copolymer, polyethylene glycol (PEG), was investigated. Various influences including light intensity, initial solution pH value, PEG molecular weight and initial concentration ratio of PEG to Cr(VI) on photochemical reduction of Cr(VI) were discussed, and a possible reaction mechanism was proposed. Experimental results revealed that Cr(VI) could be reduced to Cr(III) by PEG under sunlight irradiation. The photo-reduction rate of Cr(VI) increased with the decrease of solution pH and PEG molecular weight, but increased with the light intensity. The reduction percentage of Cr(VI) increased with the initial concentration ratio of PEG to Cr(VI). When the initial solution pH value was below 3.0, almost all of Cr(VI) was completely reduced to Cr(III) within 20 min of 50 × 10(3) lux solar irradiation in the presence of PEG. After photo-reduction, PEG and Cr(III) in aqueous solutions could be recovered by adding into a high-concentrated Na2SO4 aqueous solution to induce the formation of a stable PEG-based aqueous biphasic system. By doing so, Na2SO4 in aqueous solution could also be removed. The present work highlights a promising new route for treating the industrial wastewater containing toxic Cr(VI) ions by adding into environmental-friendly PEG for photo-reduction of Cr(VI) to Cr(III), and then salting-out recovery of PEG and removal of Cr(III) in wastewater by adding into another high-salt wastewater, so that the high-salt wastewater could also be treated.
研究了一种通过向水溶性共聚物聚乙二醇（PEG）中添加来光化学还原水溶液中Cr(VI)的生态新方法。讨论了包括光强、初始溶液pH值、PEG分子量以及PEG与Cr(VI)的初始浓度比等各种因素对Cr(VI)光化学还原的影响，并提出了可能的反应机理。实验结果表明，在阳光照射下，PEG可将Cr(VI)还原为Cr(III)。Cr(VI)的光还原速率随溶液pH值和PEG分子量的降低而增加，但随光强的增加而增加。Cr(VI)的还原率随PEG与Cr(VI)的初始浓度比的增加而增加。当初始溶液pH值低于3.0时，在PEG存在下，50×10(3)勒克斯太阳光照20分钟内，几乎所有的Cr(VI)都完全还原为Cr(III)。光还原后，通过向高浓度Na2SO4水溶液中添加以诱导形成稳定的基于PEG的双水相体系，可以回收水溶液中的PEG和Cr(III)。这样做还可以去除水溶液中的Na2SO4。本工作突出了一条有前景的新途径，即通过添加环境友好的PEG将含毒性Cr(VI)离子的工业废水光还原Cr(VI)为Cr(III)，然后通过添加到另一种高盐废水中进行盐析回收PEG并去除废水中的Cr(III)，从而也能处理高盐废水。
