Research On Synthesis Of Titanium Dioixde Nanoparticles By Detonation Method

Detonation method is a synthesis technique for preparing nanomaterials under high temperature and high pressure by detonating the mixed explosives composed of explosive and the precursors,such as inorganic salts,organic salts,metal powders and containing water oxides.It possesses the particular features of simple operation,high-controlling accuracy, high efficiency,low costs and more energy-saving.Firstly,this paper summarized the research and application developments of TiO₂ nanoparticles from the physicochemical properties,preparation and applications.Secondly,according to the flaws of the presented synthesis methods for preparing TiO₂ nanoparticles and the fact that the output of TiO₂ nanoparticles at present can not meet the market demand in future,a conclusion that exploring new methods for synthesizing TiO₂ nanoparticles is still one of the key research fields is drawn.Finally in view of the specialty and novelty of detonation synthesis method in synthesizing nanomaterials,the detail research on preparing TiO₂ nanoparticles by detonation method was carried out from the following aspects.1.Using titanyl sulfate as the TiO₂ source,the experiments for synthesizing TiO₂ nanoparticles were carried out by detonating the mixed explosives composed of the TiO₂ precursor,ammonium nitrate(NH₄NO₃)and cyclortrimethylenetrinitramine(RDX),the structures and properties of the as-prepared TiO₂ nanoparticles were also characterized, meanwhile in combination with detonation theory and experimental measurement,detonation parameters,such as detonation heat,detonation temperature were calculated,and detonation velocity was also measured.Synthesis process was optimized on the basis of the discussion about the feasibility of experiments and affecting factors,such as the density of the mixed explosives,RDX content,water content and detonation parameters.2.The morphologies and dimensions of the as-prepared TiO₂ nanoparticles were studied during the processes of thermal treatment and removing impurities via oxidation method by chromic anhydride(CrO₃)and concentrated nitric acid(HNO₃),and the growth kinetics behaviours of the TiO₂ nanoparticles during thermal treatment were also studied.The photocatalytic degradation experiments of methyl orange in aqueous solution were carried out and affecting factors on the degradation rate,such as initial concentration of solution, environment temperature,TiO₂ consumption,mean particle size,phase composition, ultrasonic vibration,alkalinity acidity of solution,illumination intensity and illumination time were also studied in detail.3.The influence of detonation on microstmctures of the phosphor nanoparticles and TiO₂ nanoparticles prepared by detonation method were carried out systematically via X-ray diffraction measurements,and the basic law of the influence of detonation on the microstructures of nanoparticles was demonstrated.The research showed that many affecting factors,such as synthesis process,synthesis method,explosive content,detonation temperature and subsequent thermal treatment process could influence the microstructures of the nanoparticles.A conclusion that the particle size of nano-crystalline was the most direct reflection of lattice distortion degree was drawn and the reasons for the lattice distortion were also given during detonation process.4.Nucleation and growth behaviours of TiO₂ nanoparticles during detonation process were discussed using detonation theory.Phase transition behaviours of the TiO₂ nanoparticles during detonation process under high temperature and high pressure were studied according to the corresponding relationship between detonation parameters,phase composition and traditional phase transition process.The relationship between the melting pointing of TiO₂ nanoparticles and the grain effect was also shown via thermodynamics theory.Based on reasonable assumptions,the heat chansfer behaviours of nanosized TiO₂ precursor and micron-scale agglomerates of TiO₂ precursor were discussed during detonation process. Using titanyl sulfate as the TiO₂ source,synthesis mechanism for preparing TiO₂ nanoparticles by detonation method was also given preliminarily.