Removal Of Organic Pollutants By Using Biochar Supported Nanoscale Zerovalent Iron

With large specific surface area and strong reactivity, nanoscale zero valent iron( n-ZVI) can remove organic pollutants effectively. n-ZVI currently is one of the most potential reducing agent. But the aggregation of n-ZVI in application of treating pollutants limited its engineering application. To overcome this, a novel biochar supported nanoscale zero-valent iron( BC-n-ZVI) particles was synthesized by means of liquid phase reduction method. Then study the removing process of methyl orange( MO), trichloroethylene( TCE) and 1,2,4-trichlorobenzene using BC-n ZVI. Finally, to broaden the application range of this material, persulfate activated by BC-n ZVI was studied. The main research contents are described as follows:(1) A novel biochar supported nanoscale zero-valent iron particles was successful synthesized by means of liquid phase reduction method. Characterization results showed that biochar was sheet like and with hydroxyl, carboxyl, carbonyl on the surface,which favor to the supporting of n-ZVI. The particle size of n-ZVI ranges from 30 to 70 nm, and the specific surface area of n-ZVI increased from 20.9 m2/g to 126.6~138.1 m2/g when it was supported by biochar.(2) The results of removing methyl orange using BC-nZVI showed that n-ZVI supported by biochar effectively improve the removing rate of methyl orange, the removal rate was more than 93.26%, the best was up to 98.51% using the biochar supported n-ZVI when the mass ratio of biochar and n-ZVI is of 5:1.(3) Initial concentration of pollutants, dosage of BC-nZVI, initial pH and coexisting anions could influence the removing rate. The removal rate of methyl orange decreased when initial concentration of methyl orange increased. More dose of BC-n ZVI in the reaction can speed up the reaction rate. Increasing the pH value of solution could slow down the reaction rate. To add such as chloride ions, sulfate ions, nitrate ions in the solution will cause competitive adsorption, which lead the removal rate decreased.(4) BC-nZVI could still had high removal rate of methyl orange when putting the BC-n ZVI in natural condition for one month, which indicated that biochar can protect n-ZVI from oxidation to a certain extent.(5) The degradation rate of TCE and 1,2,4-trichlorobenzene were good using BC-n ZVI, the results showed that the reduction process plays a dominant position.(6) To broaden the application range of this material, persulfate activated by BC-n ZVI was studied. Using this compound degradated the TCE, degradation process reach balance in 1 min, the removal rate was up to 99.4% using the biochar supported n-ZVI when the mass ratio of biochar and n-ZVI is of 5:1.