The Research On Magnetic-Nanometer Composite Photocatalyst Of TiO₂/Fe₃O₄

With the development of our industry,the amount of the industrial waste water has grown. Such as,the total number of waste water is 731 hundred million only in 2006.The environment including many rivers has been polluted by the waste water in different degree, the people's health has effected,so the treatment of industrial waste water has become one of the most impotant problems.This problem has been extensively studied in the last few years and some discoveries has got by rearchers at home and abroad.Recently,the research of photocatalytic technology have evoked tremendous interest.Nanometer TiO₂ photocatalyst has been proved to have outstanding performance due to its highly chemical stability,highly photocatalytic efficiency and no pollution to the environment,so TiO₂ is widely used in many fields including self-cleaning,removing bacterium and breaking down organic pollutants,especially in destroy the industrial waste water.However,the TiO₂ powder can hardly be recycled and circular used,so that the cost of production is too high to be industrialized application.In this paper,magnetic Fe₃O₄ nanoparticles were prepared firstly and then the magneticnanometer composite photocatalysts(TiO₂/Fe₃O₄)by directly depositing TiO₂ onto a magnetic core.TiO₂ acted as the shell and its photocatalytic property was used to destroy organic contaminants,on the other hand,Fe₃O₄ magnetic particles took the role as the core and the magnetic core was used for enhancing the separation property.Compostite photocatalysts powder(TiO₂/Fe₃O₄)could be separated from treated water because of its magnetic property and could be also reused after successful separation to decrease the cost of production.The main results were listed as follows:1)The well-dispersed magnetic Fe₃O₄ particles were prepared by co-precipitation method.In this method,ferric sulfate,ferrous sulfate and ammonia were the main materials. The samples were characterized by XRD,TEM,FT-IR and VSM.The results showed that Fe₃O₄ particles of a face-centered-cubic(FCC)crystalline structure with superparemagnetic behavior and 10nm were prepared.Many factors effected the property of magnetic nanoparticles,such as Fe³⁺to Fe²⁺molar ratio,reaction temperature,reaction time,pH value and so on.The best reaction condition was diacovered by many times trial.2)The TiO₂ were prepared by sol-gel method through TBOT hydrolysis and the solution was light-yellow,homogeneous and transparent.Many factors effected the property of nanoparticles,such as the amount of TBOT,the amount of catalyst,pH value,reaction temperature,reaction time and so on.The best reaction condition was discovered by many times experiment.The TiO₂ powder had crystal structure after heat treatment.The samples were characterized by XRD,TEM,FT-IR and thermal analysis.The results showed TiO₂ nanoparticles with 20nm were prepared and were anatase crystal structure.3)The magnetic- nanometer composite photocatalysts(TiO₂/Fe₃O₄)of a core-shell structure with 30nm were prepared by TiO₂ with anatase crystal structure coated onto the surface of magnetic Fe₃O₄ cores.The particles were superparemagnetic4)Many factors effected the photocatalytic efficiency and they were researched by degrading methyl orange,such as the pH value,the concentration of methyl orange,light source,the amount of photocatalysts and so on.Finally,the photocatalyst powder(TiO₂/Fe₃O₄) were recycled and activated due to its magnetic property,then the powder could be activated and reused again.The results showed that the availability ratio was high.