Preparation Of MFe₂O₄?M=Fe,Cu?/Hyperbranched Polymer Nanoparticles And Their Application In The Degradation Of Dyes Wastewater

The removal of the high concentration of refractory organic pollution in dyeing wastewater was a problem in the field of water treatment.Due to its fast to produce very reactive hydroxyl radica?·OH?,the homogeneous Fenton system was one of the most wasterwater treatment process.But homogeneous Fenton system suitable pH range was too narrow and the Fe²⁺ was easy to form sludge which would cause secondary pollution,making the systems processing costs increased.With the development of Fenton oxidation,using iron oxide as a heterogeneous Fenton system catalyst over hydrogen peroxide has received extensive attention.However,the agglomeration of the iron oxide nanoparticles?Fe₃O₄?leaded to increase the particle size and decrease the degradation efficiency.In order to solve the above problems,in this study,MFe₂O₄?M=Fe,Cu?/hyperbranched polymer nanoparticles were prepared by co-precipitation method due to metal ions adsorption characteristic of lone pair electron in hyperbranched polymer which was as a template,and the MFe₂O₄?M=Fe,Cu?/hyperbranched polymer nanoparticles were used to degrade dyes in wastewater.In this paper,we mainly studied the preparation technology of MFe₂O₄?M=Fe,Cu?/hyperbranched polymer nanoparticles,analyzed the effect of single factor on the particle size,then it was applied in the oxidation and degradation of dyes in waste water over hydrogen peroxide.The details study was as follows.Part one: Study on the synthesis and properties of modified hyperbranched polymers.AB₂ type intermediate monomer was prepared with diethylenetriamine and methyl acrylate as raw materials,then hyperbranched polyamide was synthesized by AB₂ type intermediates monomer with self-polycondensation,and modified by maleic anhydride as modifier,then it was applied in preparation of Fe₃O₄ nanoparticles.The structure of modified hyperbranched polyamide was characterized by FT-IR,NMR and UV,and the particle size of Fe₃O₄ nanoparticles prepared by modified and unmodified hyperbranched polyamide as a template was compared.The analysis of NMR and UV proved that the number of modified hyperbranched polyamide double bond wasiv obviously increased.Compared with the unmodified hyperbranched polyamide,the Fe₃O₄ nanoparticles prepared by modified hyperbranched polyamide as a template had a smaller agglomeration,a smaller particle size,a narrower particle size distribution.The results showed that the preparation of Fe₃O₄ nanoparticles by modified hyperbranched polyamide could effectively reduce the agglomeration of nanoparticles.Part two: Study on the preparation of Fe₃O₄/hyperbranched polymer nanoparticles?Fe₃O₄/HB?and catalytic degradation of dyes wastewater over hydrogen peroxide.The Fe₃O₄/HB nanoparticles were prepared by modified hyperbranched polyamide?HB?as a template.The influence of the preparation factors such as the mole ratio of nFe²⁺ and nFe³⁺,the mass ratio of hyperbranched polymer and ferrous chloride,the adsorption and coordination time and precipitation reaction pH on the particle size of Fe₃O₄ were studied and the preparation conditions of Fe₃O₄/HB nanoparticles were optimized.The particle size of Fe₃O₄ nanoparticles were measured and compared with Fe₃O₄ nanoparticles prepared without hyperbranched polyamide as a template.The structure of Fe₃O₄ nanoparticles was characterized by IR,TEM,XRD and BET,and the catalytic degradation performance of Fe₃O₄/HB nanoparticles was evaluated.The results showed that the Fe₃O₄ nanoparticles exhibited small diameter around116.3 nm,when the ratio of nFe²⁺ and nFe³⁺ was 1?1.8,the ratio of m HB and mFeCl₂ was 7.5?1,the coordination time was 4 h,the reaction pH was about 11.Compared with Fe₃O₄ without hyperbranched polyamide as a template,the nanoparticles had a smaller particle size and better dispersibility.Fe₃O₄/HB nanoparticles were non-crystalline,with a larger specific surface area and a smaller pore size structure.After calcination of nano Fe₃O₄/HB,the nanoparticles showed a needle-tip type,and the crystallization was complete.Fe₃O₄/HB nanoparticles as heterogeneous Fenton catalysts were used to degrade KN-G dye over hydrogen peroxide,under the neutral condition,the dosage of Fe₃O₄/HB was 40 mg/L,the concentration of H₂O₂?30%,w/w%?was8%,the activity of KN-G was 200 mg/L,the degradation rate could reach 85% at 30 min and 96.6% at 60 min.Compared with non-templated Fe₃O₄,the catalytic degradation rate was obviously improved.Compared with the degradation rate of the Fe₃O₄/HB after calcined,the catalytic degradation rate less 10% at 30 min,and the similar effect was achieved at 60 min.The results showed that the modified hyperbranched polyamide as a template could effectivelyv reduce its agglomeration of Fe₃O₄ nanoparticles,its particle size,and improve its catalytic performance.Calcination could make the crystal form more complete and improve the catalytic degradation performance,but the calcination made the preparation process complicated and increased its cost.Part three: Study on the preparation of CuFe₂O₄/Hyperbranched polymer nanoparticles?CuFe₂O₄/HB?and catalytic degradation of dyes wastewater with hydrogen peroxide.The CuFe₂O₄/HB nanoparticles were prepared by modified hyperbranched polyamide as a template and applied to the degradation of dyes wastewater.The influence of the preparation factors including the mass ratio of hyperbranched polymer and copper sulfate,the adsorption and coordination time and precipitation reaction pH on the particle size of CuFe₂O₄ were explored and the preparation CuFe₂O₄/HB nanoparticles were optimized.The structure of CuFe₂O₄ nanoparticles was characterized by FT-IR,TEM,XRD and BET.The effects of pH,temperature,the dosage of catalyst,the amount of hydrogen peroxide,and the initial concentration of dye on the degradation rate of KN-G degradation by CuFe₂O₄/HB nanoparticles over hydrogen peroxide were studied and the degradation stability of CuFe₂O₄/HB nanoparticles was evaluated.The results showed that the CuFe₂O₄ nanoparticles exhibited small diameter around 162.4 nm,when the ratio of mHB and mCuSO₄ was 6.25?1,the coordination time was 4 h,the reaction pH was about 9.CuFe₂O₄/HB nanoparticles were non-crystallinem with a large specific surface area and a smaller pore size structure.CuFe₂O₄/HB nanoparticles as catalysts degraded KN-G dye over hydrogen peroxide,under the neutral condition,the dosage of CuFe₂O₄/HB was 40 mg/L,the concentration of H₂O₂?30%,w/w%?was 8%,the activity of KN-G was 200 mg/L,the degradation rate could reach 98% at 30 min.The degradation rate of CuFe₂O₄ nanoparticles without hyperbranched polyamide as atemplate was only 40%.Compared with the non-templated CuFe₂O₄ nanoparticles and Fe₃O₄/HB nanoparticles,the catalytic effect was obviously improved and was closed to the Fe₃O₄/HB nanoparticles after calcined.The results showed that the preparation cost of the catalyst could be reduced and the catalytic degradation performance of iron oxide nanoparticles could be improved by doping with copper.The results showed that hyperbranched polyamide could effectively control the agglomeration of iron oxide nanoparticles and its doped oxides with copper,decreased theparticle size of iron oxides nanoparticles and improved their dispersion,thereby improved the catalytic degradation efficiency of dyes.