Synthesis Of Magnetic Composite Particles And Their Catalytic And Adsorption Properties

Water is the foundation of all life forms.However,with the continuous development of the industrial economy,the discharge of industrial wastewater continues to increase,and the problem of sewage treatment has become a key issue of concern.Among various pollutants,methylene blue,as a cationic phenothiazine dye,not only easily causes environmental problems,but also affects human health.However,it is difficult for the traditional adsorbent to recycle in the water environment,which is easy to cause secondary pollution.Ferroferric oxide particles have been widely used in many fields because of their magnetic characteristics.As a kind of very important magnetic composite material,it has a huge application prospect in the removal of methylene blue solution in wastewater.However,the exposed ferric oxide magnetic nanoparticles have the disadvantages of being easy to aggregate and poor dispersibility,while the surface coating with amorphous carbon layer and silica can prevent the agglomerate in the solution and enhance the chemical stability.Therefore,we designed two kind of magnetic composite materials to remove the methylene blue in wastewater to protect the environment and human health.1.We reported a facile strategy for the synthesis of dual-functional Fe₃O₄@C-Mo O₂-Ni composites as efficient and recyclable adsorbent to remove methylene blue dye in water and catalysts for reduction of 4-nitrophenol into 4-aminophenol.Firstly,ferromagnetic iron oxide nanoparticles were prepared by coprecipitation method,and Fe₃O₄@RF core-shell composite structure was obtained by resorcinol-formaldehyde polymerization on its surface.The coating layer on magnetic Fe₃O₄ spheres could protect Fe₃O₄ spheres from acidic and oxidative conditions.And the larger Fe₃O₄ core has strong magnetism,which can promote magnetic separation to recover the composites.At the same time,the resorcinol-formaldehyde shell is embedded with nickel nanosheets,followed by the carbonization to convert them into Fe₃O₄@Carbon core-shell particles entrapped high-density Ni tiny particles without using any extra reductant.The carbon layer can be good support for nickel nanoparticles,fixing the position of nickel and preventing agglomeration from affecting the catalytic activity.Adsorption behaviors of Fe₃O₄@C-Mo O₂-Ni magnetic composites for methylene blue and catalytic behaviors for4-nitrophenol are conducted.The effects of adsorption solution p H,adsorption cycle capacity,catalytic time,and catalyst amount on adsorption and catalysis were mainly studied during the experiment.The results confirmed the adsorbed amounts of methylene blue increased with the decreasing of p H value,and were 88.95 mg g^-1 of methylene blue at p H=3.19,showing the character of favorable adsorption by acid;after five times of adsorption-desorption,the methylene blue adsorption capacity only had slightly drop;the Fe₃O₄@C-Mo O₂-Ni composites exhibited efficient catalytic performance for reduction of0.1Mm 4-nitrophenol to 4-aminophenol within 4 min(k=0.8788 min^-1);as the amount of nickel carried on the carbon layer decreases,the longer the time required for catalysis.These experimental data show that the prepared Fe₃O₄@C-Mo O₂-Ni composites not only has strong adsorption capacity for methylene blue but also has efficient catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol.Thus,the prepared Fe₃O₄@C-Mo O₂-Ni composites can be used as both an ideal catalyst and adsorbent for removing methylene blue in sewage.2.Based on the combination of magnetic materials and carbon materials as an adsorbent has a significant effect,we tried to use macromolecular materials and magnetic materials to prepare the following composite materials.A simple method for synthesizing Fe₃O₄-Si O₂-?-CD composite was prepared.This composite can be used as an adsorbent to remove methylene blue by using the inclusion effect of?-cyclodextrin.By epoxidizing?-cyclodextrin,it can be directly combined with hydroxyl groups on Fe₃O₄-Si O₂ magnetic particles under the environment of the nitrogen to directly obtain Fe₃O₄-Si O₂-?-CD composites.Methylene blue with complex structure was selected as a model pollutant,and the adsorption capacity and cycle performance of Fe₃O₄-Si O₂-?-CD were studied.The results confirmed the adsorbed amounts of methylene blue increased with the decreasing of p H value,and were 55.6 mg g^-1 of methylene blue at p H=4?5,showing the character of favorable adsorption by acid;the composites can be successfully recovered and reused for at least five consecutive cycles,with about 90%adsorption performance.The new magnetic adsorbent has the advantages of simple preparation,low cost and easy material recovery and recycling,which is very useful for further research and practical application of the new magnetic adsorbent in sewage treatment.By improving the preparation process of traditional adsorbents and researching their adsorption properties,a solid foundation for the further development and utilization of magnetic adsorbent materials will also produce huge environmental,economical and social benefits.