Experimental Study On Degradation Of Volatile Chlorinated Hydrocarbons By Different Supported Nano Zero-valent Iron In Aqueous Phase/Soil

The nano scale nano zero-valent iron(ZVI) particles have the small sizes, the large surface areas and high surface reactivity. The treatment method of nano ZVI is a new in situ remediation technology which can be rapidly removed the pollutants in short term. In order to enhance the reactivity of nano ZVI particles, surface modification of nano ZVI particles was performed. Synthesis of nano ZVI, Sodium Bentonite supported nano ZVI, OMMT supported nano ZVI and polymer coated nano ZVI particles were achieved by liquid phase reduction, deposition and emulsion polymerization in ethanol/water system. These different supported nano ZVI particles were characterized by XRD, TEM, SEM to study their existence and properties, which were also used to transform TCE and1,2-EDC.The results showed that the nano ZVI particles with the size of less than100nm had spherical structure. The surface area of nano ZVI particles was40times higher than ZVI particles. It was found that the the dispersion of freshly synthesized polymer coated nano ZVI particles was remarkably improved in TCE.The OMMT supported nano ZVI had the fastest dechlorination rate in the aqueous phase. TCE and1,2-EDC concentration were lowered by76.27%and44.38%in6hours. The speed of TCE andl,2-EDC removal by different supported nZVI was OMMT supported nano ZVI> Sodium Bentonite supported nano ZVI> nano ZVI> polymer coated nano ZVI particles. The pseudo-first order reaction law fit the reduction of TCE and1,2-EDC. The effects of some factors were discussed,such as initial pH, initial concentration of TCE or1,2-EDC, pollutant type, and so on.In the research,60%～80%of TCE sorbed in soil was degraded by different supported nano ZVI particles in200h, The OMMT supported nano ZVI had the fastest dechlorination rate. The speed of TCE and1,2-EDC removal by different supported nZVI was OMMT supported nano ZVI> Sodium Bentonite supported nano ZVI> polymer coated nano ZVI> nano ZVI particles. The linear fit of the apparent reaction constant for TCE using different supported nZVI declined from0.0067h"’to 5.0036h-1in soil.