Preparation And Photocatalytic Research Of TiO₂ Composite Microspheres

Exploring the energy conservation and environmental protection material is the hot topic all over the world. Usually, half light catalyst materials have the effect of degradation in pollutants. Relative others, titanium（TiO₂） photocatalytic materials have good photocatalytic performance, stable properties, nontoxic, cheap and a great potential in the application and environmental management. However, industrial Ti OB2 B band structure only can absorb ultraviolet part of sunlight. Aiming at some deficiencies, this paper adopted monodisperse porous polystyrene-divinylbenzene（PS-DVB） particles as the template, used the method of static adsorption self-assembly, prepared TiO₂/PS-DVB composite microspheres. Through the nonmetal, metal doped Ti OB2 B and expanded photocatalytic activity of composite microspheres.Firstly, the paper prepared cationic non spherical monodisperse polystyrene-divinyl benzene（PS-DVB） particles via the method of soap-free emulsion polymerization with styrene（St）, divinylbenzene（DVB） and methylacryloyl oxyethyl trimethylammonium chlorideB B（DMC） as the monomer, 2,2’-Azobis（2-methylpropionamidine） dihydrochloride（AIBA） as the initiator, potassium bicarbonate（KHCO₃） as the buffering agent and water as the reaction medium. Investigated the influence of St/DVB ratio, amont of DMC, buffering agent and reaction medium on PS-DVB particle structure, particle size and distribution. It was founded that the average particle size is 174.1 nm, dispersion coefficient is 0.069, Zeta potential is about +42.26 m V of non spherical PS-DVB particles in the optimized process conditions（70℃, 22 g of St, 3 g of DVB, 2.0% of DMC, 0.2% of KHCOB3B）. Then, it prepared porous PS-DVB particle with 704.17 mP²P/g of specific surface area when 3.4 m L of FDA via Friedel-Crafts alkylation’s reaction with dimethoxy methane as the out cross-linking agent. The porous polymer exist large macropore and micropore by nitrogen desorption-adsorption curve and the BJH method.With PS-DVB composite particles as templates and terabutyl titanate（TBOT） as titanium source, an electrostatic self assemble strategy put forward to prepare TiO₂/PS-DVB composite particles and verified the structure and photocatalytic property of the as-prepared composite microspheres via SEM, TEM and Vis DRS. Analysis shows that composite microspheres can realize electric property inversion in 120 min. The composite microspheres show good photocatalytic response and degration when 1 m L/min of ammonium hydroxide adding rate and 0.4 g of TBOT. The methylene blue degration rate is up to 49% to 30 mg/L MB in 120 min.To extend visible light catalytic activity of TiO₂/PS-DVB composite microspheres, N-doped TiO₂/PS-DVB composite microspheres and N, Mo co-doped TiO₂/PS-DVB composite microspheres were prepared using triethylamine and ammonium molybdate as nitrogen source and molybdenum source. The results showed that N changed Ti OB2 B chemical state of Ti and O in the lattice, and had into the Ti OB2 B crystal lattice successfully. N also can improve the absorption spectrum, N-Mo co-doped composite microspheres absorption band edge made them had red shift obviously, and the intensity of light absorption in the ultraviolet visible light area than N-doped composite microspheres had further improved. N-doped composite microspheres showed the better catalytic activity when the ratio of mBTEA B/mBTBOT Bis 2. Methylene blue degradation rate is up to 65% in light 120 min, and co-doped composite microspheres’ degradation rate is 86% when 0.8 g of Mo.