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

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

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。

There are many reports on the nano-seale zero-valent iron （NZVI） for removal of various con- taminants 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 Fe^2＋ and Fe^3＋ were leached by corrosion of NZVI to i- ron 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 deg- radation mechanism by combination of adsorption, reduction and oxidation of 2, 4-DCP was proposed.