Study On The Degradation Of Chlorinated Organic Pollutants By Carbon Supported Iron-based Composites

Degradation of chlorinated organic compounds with iron nanoparticles is a new method which has been widely used.Nano bimetal can be formed through doping another catalytic metal with iron,when used in remediation,the catalytic metal can promote the corrosion of iron.Then the chlorinated organic compounds will be degraded by the reaction of catalytic hydrogenation.It can improve the degradation efficiency and the utilization rate of iron nanoparticles.Then the time of remediation will be shorten.Recently,among these modification methods of iron-based material,loading iron-based material on soluble starch can significantly improve the degradation efficiency of chlorinated organic compounds.Thus,this modification is really promising,meanwhile,it will not pollute environment.In the first study,Zero-valent iron（ZVI）-Ni and ZVI-Ni-Cu nanoparticles were supported on the starch through chemical reduction by using NaBH₄ as a reductant,respectively.The two composites were characterized by XRD,SEM,BET and XRF.The degradation efficiencies of trichloroethylene（TCE）and trichloromethane（CHCl3）by ZVI,ZVI-Ni,starch/ZVI,starch/ZVI-Ni and starch/ZVI-Ni-Cu were studied and compared.The effects of starch/ZVI-Ni-Cu on the degradation efficiencies of TCE and CHCl3 were also proposed.The results showed that the degradation efficiency can be enhanced by adding bi-metals or tri-metals.The decreasing orders of degradation efficiencies are as follows: starch/ZVI-Ni-Cu>> starch/ZVI-Ni> starch/ZVI>ZVI-Ni>ZVI.The starch/ZVI-Ni-Cu can completely degrade CHCl3 and TCE in48 hours.Due to the addition of starch,the composites not only overcome ordinary nanomaterials’ drawback of easy aggregation,but also improve the oxidation resistance.Meanwhile,the composite is much more stable and reliable.The needed reaction time for composite to degrade CHCl3 and TCE is 48 hours.In the second study,starch/ZVI-Ni prepared by the combination of traditional reduction and green method showed high degradation efficiency of2,4-dichlorophenol.Compared the degradation efficiency with the efficiency of ZVI-Ni prepared by traditional reduction and ZVI-Ni prepared by combinationmethod,the results showed that the degradation efficiency can be enhanced by improvement of material preparation.The decreasing orders of degradation efficiencies are as follows: starch/ZVI-Ni >ZVI-Ni prepared under the protection of tea polyphenols>ZVI-Ni prepared without the protection of tea polyphenols.It indicates that the improvement of preparation method and the addition of starch can significantly improve the degradation efficiency of iron-based material.