Preparationandapplication Of Inorganic Hollow Particles Using Water-Soluble Inorganic Salt And Anionic Polymer Astemplates

Inorganic hollow particles are widely used in energy,environment,catalysis,biomedicine and nanomaterials because of theirspecial performance,such as large specific surface area,good dispersion and low density.At present,Polymerparticlesare the most common themplates used for the preparation of inorganic hollow microspheres in the related reports,which were removed by calcining or dissolution of organic solvent after deposition of the shell materials.In this paper,the preparation of hollow inorganic particles using water-soluble inorganic salt particles as templates and their properties and applications were studied.The main research contents are as follows:1.Na2SO4/SiO2 and Na2SO4/TiO2 core-shell composite particles were prepared by sol-gel method using 1000 mesh industrial Na2SO4 particles as templates.Hollow SiO2 and hollow TiO2 particles were obtained by removing template core with water dissolution.Thencoated TiO2 and CeO2 on the surface of the hollow SiO2 particles to fabricate the double-shell hollow SiO2/TiO2 and hollow SiO2/CeO2 particles.The effects of addition of water,ammonia,precursor,template and reaction conditions on the morphology and properties of hollow particles were investigated.The adsorption performance of hollow SiO2 particles on Rhodamine B and the photocatalytic performance of hollow TiO2 particles and double-shell hollow particles on Rhodamine B also were studied.The results showed that:(1)hollow particles and double shell hollow particles can be prepared successfully by using the method.The shell structure is obvious,the particle size is about 10 m,and the dispersion is good.(2)By adjusting the amount of water,ammonia and precursor and changing the reaction conditions,the coating of shell materials can be effectively adjusted.The surface morphology of hollow particles can be controlled by changing the amount of ammonia.By increasing the amount of precursor,the shell of hollow particles becomes thicker.The shell thickness of hollow SiO2 shell is controllable in a wide range(25 nm-332 nm).(3)Hollow SiO2 particles have a good adsorption effect on Rhodamine B.The photocatalytic degradation effect of double-shell hollow SiO2/TiO2 particles on Rhodamine B was significantly better than that of hollow TiO2 particles and solid TiO2 particles.2.Na2SO4nanoparticles prepared by microemulsion method and local saturation method have regular morphology and smooth surface.Hollow SiO2 and hollow TiO2 nanoparticles with different shapes were preparedby using the as-prepared Na2SO4 nanoparticles as templates.The size and shape of Na2SO4nanoparticles are regulated by adjusting the amount of Na2B4O7·10H2O,surfactant,propylene triol and the type of alcohol reagent.The shapes ofNa2SO4 nanoparticles are spherical,ellipsoidal,dendritic,stick and prismatic.Theresearch results showed that:(1)the effect of polyethylene glycol(PEG)on the morphology of Na2SO4 particles was better than that of sodium dodecyl benzene sulfonate(SDBS)in microemulsion method.With the increase of Na2B4O7·10H2O and PEG,the size of the prepared Na2SO4nanoparticles decreased,the shape changed,and the size can be controlled in the range of 700 nm-5 μm.(2)In the local saturation method,the size of Na2SO4nanoparticles decreases with the increase of the content of propylene triol and the carbon chain in the alcohol reagent,which the size can be controlled in the range of 450 nm-2μm.(3)The shell thinkness of hollow SiO2 particles prepared by dendritic Na2SO4nanoparticles can be controlled within the range of 85nm-225nm by changing the amount of TEOS.(4)Na2SO4 nanoparticles prepared by microemulsion method can undergo phase transition at 53 ℃,but the phase transition properties of the particles after silica encapsulation do not change.3.The above method is extended to other water-soluble inorganic salt templates.Na2HPO4/SiO2 and MgSO4/SiO2 composite microspheres were prepared using Na2HPO4 and MgSO4 water-soluble inorganic salt particles withabout 10 μm as the template under the appropriate ratio of water,ammonia and TEOS.The templates were removed with water to further obtain hollow SiO2 particles.The shell thickness of hollow SiO2 particles prepared using Na2HPO4particles as templatescan be adjusted in the range of 98 nm-148 nm.4.Copolymer nanospheres of styrene and acrylic acid(P(St-co-AA))were prepared by soapless emulsion polymerization.The size of the polymer spheres was adjusted by changing the amount of acrylic acid(AA)and initiator potassium persulfate(KPS).The emulsion without centrifugation and other means of treatment was directly used in the reaction to prepare hollow SiO2 particles.The effects of content of ammonia,TEOS and emulsion on the morphology of hollow particles were investigated.The results showed that:(1)with the increase of the amount of AA or initiator,the size of the polymer nanospheresdecreases.(2)The surface roughness of P(St-co-AA)/SiO2 composite microspheres can be regulated by changingammonia,and the wall thickness of hollow microspheres can be controlled at 5nm-20nm by changing the amount of TEOS.(3)The particle size of the template and the carboxyl group on the template surface will affect the coating of silica,thus affecting the wall thickness of the hollow ball.