有机膨润土负载纳米零价铁还原-类芬顿氧化降解2,4-二氯苯酚

目前,虽然有很多关于纳米零价铁(NZVI)通过吸附、还原和氧化作用去除各种污染物的报道,但关于如何联合这些方法来提高污染物的去除率仍然不是很清楚。本实验研究了联合有机膨润土DK1(十六烷基三甲基铵盐改性,d(001)=2.2 nm)吸附、NZVI还原、类芬顿氧化作用来去除溶液中2,4-二氯苯酚(2,4-DCP)的方法。在反应前30分钟,有机膨润土DK1负载NZVI(NZVI/DK1)通过吸附还原作用去除溶液中2,4-DCP,2,4-DCP和COD的去除率分别为16.1%和7.8%,说明了吸附还原作用对2,4-DCP的去除效果是有限的。接着向溶液中滴加适量的H2O2,在5 min内2,4-DCP的去除率由16.1%提高到了99%以上,COD的去除率达到了64.1%,这可能是由于NZVI腐蚀形成铁的氧化物缓慢释放出Fe2+和Fe3+,增强了芬顿反应对2,4-DCP和降解产物的氧化去除效果。通过SEM,EDS,UV-Vis和GC-MS等分析方法佐证了上面的结果。最后提出了联合吸附、还原和Fenton氧化去除2,4-DCP的机制。

Combination of reduction and heterogeneous Fenton oxidation for removal of 2,4-DCP from aqueous solution using organobentonite-nanoscale zerovalent iron

There are many reports on the nano-scale zero-valent iron (NZVI) for removal of various contaminants by adsorptive, reductive and oxidative process. However, combination of these processes to improve the removal efficiency of contaminants are still unclear. In this work, the removal of 2, 4-dichlorophenol (2, 4-DCP) combines the advantages of the adsorption by organobentonite,NZVI reduction. Organobentonite supported NZVI (NZVI/DK1) was used to remove 2,4-DCP, where 16.1% of 2,4-DCP and 7.8% of chemical oxygen demand (COD) were removed by the adsorption and reduction process at first 30 min, respectively, indicating the effectiveness of these processes for 2,4-DCP removal was limited. In contrast, the removal efficiency of 2, 4-DCP increased significantly from 16.1% to 99% within 5 min, and total COD removal also reached 64.1% after added subsequently H2O2 to this system, suggesting that Fe2+ and Fe3+ were leached by corrosion of NZVI to iron oxide, then Fenton-like oxidation of 2, 4-DCP and other degradation products was enhanced. These results were confirmed by scanning electron microscopy (SEM), EDS, UV-Vis and GC-MS analysis. Finally, the degradation mechanism by combination of adsorption, reduction and oxidation of 2, 4-DCP was proposed.