Ultrasonic Effect Structural Change In The Nature Of Sodium Aluminate

By several kinds of advanced techniques and DFT Quantum Chemical calcultions, the mechanism of the precipitation process under ultrasound in sodium aluminate solutions have been researched for the first time. In order to investigate the formations of radicals and their characters under ultrasound in solutions, EPR, UV-absorption spectrum, fluorescence photographic technique and fluorescence spectrum have been applied. At the same time, by Raman spectrum and Raman quantitative analytic technique, the changes of the structures of species have been acquired under ultrasound in sodium aluminate solutions. Quantum Chemical calculations and statistic thermodynamics theories have been used for the transformation disciplinarian of species in solutions and possible mechanism for the nucleation of gibbsite under ultrasound. Conclusions are obtained as follow:1. By the technique of radical capturing and EPR, the radicals (OH and -H) are identified in sodium aluminate solutions, which has been treated with ultrasound. In addition, experimental results also indicate that water molecule can be splitted into radicals under ultrasound when the power of ultrasound reaches its threshold value, the formations of radicals are influenced with different ultrasound power, treating time and concentration of solutions.2. The amount of hydroxyl radicals produced by ultrasonic cavitations can been calculated indirectly by the value of absorbency of alizarin violet solutions in U-V absorption spectrum, as well as fluorescence photographic technique and fluorescence spectrum.3. The structures of different species have been systematically studied under ultrasound in sodium alminate solutions by Raman spectra and Raman quantitative analysis. The results indicate that the concentration of monomer alimunate ions Al(OH)4- are decreasing, but that of dimmer ions (OH)3A1-(OH)2-A1(OH)32- are increasing.4. The total energies, geometrical equilibrium, vibrational frequencies of species in solutions have been calculated at the DFT/BLPY level. The solvent effects of species have also been acquired by COMSO and the additory static model. Based on the calculated results and experiments, the transformations among species have been researched by thermodynamics, and a possible mechanism of the nucleation of gibbsite has also been presented.