Preparation Of Nano-TiO₂ And Surface Coating Of It

Nano-TiO2 whose crystal size is from 8nm to 30nm is prepared by using homogeneous precipitation method using TiOSO4 as precursor and CO(NH2)2 as precipitator. The factors including of reaction temperature and time, TiOSO4/CO(NH2)2, [TiO2+], calcination temperature and time which have effect on production rate, crystal size and crystalline phase of nano-TiO2 are studied by XRD, TEM and DTA-TG Experimental results show that production rates of nano-TiO2 are increased with accretion of reaction temperature, TiOSO4/CO(NH2)2, reaction time and reduced with decreasing of [TiO2+]; Crystal size is largen with reaction temperature, [TiO2+], calcinations temperature and time. Crystalline phase of nano-TiO2 is transformed from amorphism to anatase, subsequently to rutile with accretion of calcinations temperature. Optimum reaction conditions are choiced by orthogonal experiments, which are that eaction temperature was 90 C, [TiO2+] is 0.8mol/l, reactiontime was 4h, TiOSO4/CO(NH2)2 was 1:3. Crystal shape changing is studied by DTA. Results which is in consistent with XRD show that crystalline phase of nano-TiO2 which is prepared in optimum reaction condition is transformed from amorphism to anatase in 470 C, from anatase to rutile in 830 C.It is researched on SiO2-coated for TiO2 and nano-TiO2 that has been prepared in optimum reaction conditions. Characters of SiO2-coated nano-TiO2, including of crystal size, shape, mechanism,chemical bond combining and surface composing, are studied by TEM, XPS, XRF. Optimum reaction conditions are gained. For TiO2, they are that reaction temperature was 85 C, reaction time was 5h, concentration of Na2SiO4 was 0.5mol/l, pH was 9.5, concentration of TiO2 was 200g/l; For nano-TiO2, reaction temperature was 90 C, reaction time was 1h, concentration of Na2SiO4 was 0.5mol/l, pH was 9.5, concentration of TiO2was 100g/l.