A Study On Removal Of Hexavalent Chromium、Methyl Orange And Trichloroethylene In Water By Nanoscale Zero-valent Iron

Nanoscale zero-valent iron(n ZVI) has been used to remediate many pollutants in recent years, but there are still some challenges in the application due to its lack of stability and easy aggregation. To address these issues,n ZVI supported on bentonite and bimetal were synthesized B-Fe, B-Fe/Ni, B-Fe/Pd and used them for removal of Cr(VI), methyl orange(MO) and TCE in aqueous.The SEM and TEM images showed that the presence of bentonite is a good stabilizer. The XRD and TEM showed that n ZVI had good dispersion on bentonite and was present as a core-shell structure. TEM images showed that the size of most n ZVI was below 70 nm and almost B-Fe nanoparticles about 40-50 nm. The particles size of B-Fe/Ni was smaller than B-Fe, with average size of 30 nm.B-Fe had an excellent reductive capacity to Cr(VI), in less than five minutes, 50%of Cr(VI) has been removed. However, the efficiency is also affected by other factors in the environment. The effect of HA and initial p H on Cr(VI) removal was investigated. The results showed that HA had a inhibiting effect on reaction and smaller p H was helpful for Cr(VI) removal.In this study, a series of synthesized bentonite supported nanoscale bimetals were proposed for the decoloration of methyl orange, taking into account different materials, the initial concentration of MO, initial p H and different Ni loading. The results showed that B-Fe/Ni and B-Fe/Pd performed effectively for the decoloration of MO. After 20 min reaction, MO was degraded nearly all by B-Fe/Pd(97.3%) and B-Fe/Ni(94.5%). Moreover, the removal rates followed modified pseudo-first order kinetic equations. Thus, the observed removal rate constants(kobs) were 0.005/min,0.046/min, 0.121/min and 0.258/min for n ZVI 、 B-Fe 、 B-Fe/Ni and B-Fe/Pd respectively.The degradation of TCE by B-Fe/Ni showed that B-Fe/Ni had a higher removalefficiency than n ZVI and B-Fe. After 4 hours, almost 85.83% of TCE was degraded by B-Fe/Ni, and after 5h, almost 77% of TCE was degraded by Fe-Ni..In conclusion, in this paper we synthesized a series of bentonite supported nanoscale bimetals, which can be used in a potential application for environmental remediation, the batch experiments demonstrated that B-Fe/Ni had an excellent stability and better activity, and it could remove Cr(VI)、MO and TCE in aqueous.