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Ionothermal Synthesis Of Fe3O4 Magnetic Nanoparticles And Their Application In Heterogeneous Fenton-like Reaction

Posted on:2017-01-19Degree:MasterType:Thesis
Country:ChinaCandidate:S L XieFull Text:PDF
GTID:2311330512962389Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
With the rapid development of printing and dyeing industries,the dye pollutants have become an important issue for environment remediation.In recent years,the peroxidase-like activity of Fe3O4 magnetic nanoparticle?MNPs?has been explored for organic wastewater treatment via heterogeneous Fenton-like oxidation process.However,ionothermal synthesis of Fe3O4 MNPs with high catalytic activity and good recyclability has been rarely reported.In this thesis,Fe3O4 MNPs of ca.10.4 nm were first synthesized by oxidative precipitation-combined ionothermal method.Its synthesis and catalytic conditions were optimized for catalytic degradation of Rhodamine B?RhB?aqueous solution as simulated dye wastewater.Then Cu-doped Fe3O4 MNPs was synthesized by a similar method with the addition of a copper source to further improve the catalytic performance of Fe3O4 MNPs.The main results and conclusions are as follows:?1?The solubility of different alkali and iron sources in choline chloride/urea deep eutectic solvent?DES?were investigated.The results showed that KOH was a suitable alkali source and that Fe SO4×7H2O,FeCl2×4H2O and FeCl3×6H2O are suitable iron sources for ionothermal synthesis of Fe3O4 owing to their high solubility in the DES at 80 oC.Then ionothermal synthesis of Fe3O4 MNPs combined with oxidation precipitation,co-precipitation or reduction precipitation,were respectively optimized.The obtained products were characterized by XRD,SEM,VSM,FTIR,iron content analysis,etc.Only irregular Fe3O4 particles with micrometer size were obtained so far by reduction precipitation in the DES.In contrast,Fe3O4 MNPs of ca.10 nm were successfully synthesized by oxidation precipitation or co-precipitation in the DES.The Fe3O4 MNPs have larger saturated magnetization,smaller remanence and coercive force,and are suitable for the application in magnetic separation.?2?The activity of five Fe3O4 particles prepared by different methods,including oxidation precipitation,co-precipitation and reduction precipitation in the DES,hydrothermal and solvothermal syntheses,was assessed for catalytic degradation of RhB in the solution with H2O2.Meanwhile,the influence of various factors on the catalytic degradation of RhB,the mechanism of catalytic degradation and the recyclability of the catalyst were studied.The results showed that Fe3O4 MNPsprepared by oxidation precipitation-combined ionothermal synthesis?denoted as OP-DES-Fe3O4?exhibited the highest catalytic activity.Under the conditions of 0.01mmol/L of RhB solution,0.5 g/L of OP-DES-Fe3O4,pre-adsorption for 15 min,40mmol/L of H2O2,and reaction time for 2 h at 55 oC and pH 6.4,the decolorization rate of RhB solution was 97.8%,the reaction rate was 0.0293 min-1,the reaction activation energy was 52.25 kJ/mol,and the COD removal rate was 66.3%.The degradation of RhB on Fe3O4 was mainly caused by ×OH radicals generated by the decomposition of H2O2,and the reaction rate is related to the surface active sites.OP-DES-Fe3O4 has good stability and recyclability.After being used six times,it still had higher catalytic activity?i.e.,the decolorization rate was 98.8% and the reaction rate was 0.037 min-1?.?3?In order to further improve the catalytic performance of Fe3O4,Cu-doped Fe3O4 MNPs?denoted as Cu-Fe3O4-n,where n is the tenth of the nominal molar ratio of Fe/Cu?were prepared by oxidation precipitation-combined ionothermal synthesis with the addition of a copper source.The products and the chemical state of Cu were characterized by XRD,VSM,XPS and so on.In addition,the effect of various factors?including some environmental factors?on catalytic properties of Cu-Fe3O4-2 and its recyclability were investigated.The results showed that Cu-Fe3O4-2 had pure cubic inverse spinel structure and that copper existed in the form of Cu2+.Under the conditions of 0.01 mmol/L of RhB,40 mmol/L of H2O2,0.5 g/L of Cu-Fe3O4-2 and pre-adsorption for 15 min,the decolorization rate of RhB solution was 95.2% and the reaction rate was 0.0247 min-1 after 2 h at 25 oC and pH 6.4.Cu-Fe3O4-2 has good catalytic recyclability.After being used four times,its catalytic performance had no significant decrease?the decolorization rate was 94%,and the reaction rate was0.0218 min-1?.However,there was slight decline of the catalytic performance of Cu-Fe3O4-2 on the degradation of RhB in the simulated soil system?the decolorization and reaction rates were 94% and 0.0224 min-1,respectively?.
Keywords/Search Tags:Ionothermal, Fe3O4, Rhodamine B, Fenton reaction, Cu-Fe3O4
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