Process Study On Preparation And Surface Modification Of Nanometer Alumina

The properties, applications and research situation, and preparation method ofnanometer alumina at home and abroad has been presented in this paper. The theoreticalfoundation of nanometer particles of liquid-phase precipitation reaction was reviewed;especially theoretical analysis of preventing agglomeration mechanism in preparing nanometer particles was focused on. Furthermore, the feasibility and superiority of microwave drying method to prepare nanometer oxide has been analyzed based on the principle of microwave drying theory. In addition, the necessity and possibility of surface modification of nanometer alumina has been discussed.The process of both preparation of nanometer alumina in direct precipitation method(DPM) using sodium carbonate and aluminum chloride as materials and its surface modification has been deeply investigated. In the experimental section for preparation of nanometer alumina, a series of single-factor experiments has been firstly designed to do research on the preparation technology of nanometer alumina in order to study the effect of different factors in nanometer alumina preparation process; then the optimal preparation conditions have been obtained through multi-factor orthogonal experiment. On the other hand, in the experimental section for surface modification of nanometer alumina, both the mono-factor and multi-factor orthogonal method have been used to achieve selection of optimal surface modification processing conditions as sodium laurate was chosen as the modifying addition. Different surface modification technologies have also been practiced with triethanolamine to get an optimum process course.The experimental results are shown the following as follows:(1) Using a two-part microwave-drying method to dry nanometer alumina can significantly improve the drying rate and the energy utilization efficiency. It is a new efficient way to dry nanometer oxide.(2)The process of preparing nanometer alumina using the direct precipitation method with sodium carbonate and aluminum chloride as materials is possible. The optimal process conditions for preparation of nanometer alumina are: the reaction time is 25 min, the reaction temperature is 40 , and the concentration of sodium carbonate and that of aluminum chloride are 1.0 mol/1 and 0.4 mol/1, respectively; The optimum drop style was chosen; The calcination temperature and time are 500℃ and 1.5h. Under this optimal condition mentioned above, the average diameter of the nanometer alumina is 8.7nm.(3) Nanometer alumina turns to hydrophobic after surface modification with sodium laurate. The optimum conditions of surface modification are: temperature is 30℃ , the pH is 4, the concentration of modifying agent is 3.0g/L; modification time is 70min. The hydrophobic is about 0.53 under the above processing condition.(4) Nanometer alumina can be well dispersed in ethanol through modification with triethanolamine in mechanical chemical modification method. A new bond was produced between nanometer alumina and triethanolamine.