Research Of Micro-molecular Dextran By Clean Technology And Kinetics

Preparation of molecular dextran is currently due to the high production costs, processing difficulties, product uniformity after poor reasons, micro-molecular dextran is not in domestic industrial production, but due to micro-molecular dextran with large market share, in particular micro-molecular dextran average molecular weight of 5000-7500, so need a cleaner that can be applied to industrial production technologyThis article mainly adopts clean technology of the sub-critical water and the sub-critical water/CO2, using water as reaction media, through electricity from the water out of the H+ and carbonated ionization out of H+ as catalyst, catalytic degradation dextran 20, prepared the clean pollution and molecular weight distribution of uniform micro-molecular dextran. Through the research of Kinetics which proved the feasibility for the preparation of micro-molecular dextran by the two kinds of green technology method.Optimized the preparation of micro-molecular dextran by the technology of sub-critical water, through the single factor experiment and orthogonal experiment, showed that this technique influence dextran hydrolysis of secondary factors as: temperature> time> solid-liquid ratio> stirring speed, and the conclusion that the optimum conditions for the preparation of micro-molecular dextran in the sub-critical water as:the reaction temperature was 170℃, the reaction time was 1.5 h, the reaction solid-liquid ratio was 0.6 and the stirring speed was 300 r/min, the molecular weight (Mw) of micro-molecular dextran was 6132 and the molecular weight distribution width was 1.67. Then through the kinetices research in the sub-critical water hydrolysis dextran20 for preparation micro-molecular, and got the level of kinetics was one, and the equation was 1/Mw, t= 1.2*1016t e-184.7/8.314T+0.056,the Ea was 184.7KJ/mol.At last, optimized the preparation of micro-molecular dextran by the technology of sub-critical water/CO2, through the single factor experiment and orthogonal experiment, showed that this technique influence dextran hydrolysis of secondary factors as:temperature> time> solid-liquid ratio> pressure CO2> stirring speed, and the conclusion for the preparation of micro-molecular dextran in the sub-critical water/CO2 as:the temperature was 160℃, the reaction time was 1.5 h, the reaction pressure CO2 was 2.5 MPa, the reaction solid-liquid ratio was 0.6 and the stirring speed was 300 r/min, the molecular weight (Mw) of micro-molecular dextran was 5247 and the molecular weight distribution width was 1.57. Then through the kinetices research in the sub-critical water/CO2 hydrolysis dextran20 for preparation micro-molecular, and got the level of kinetics was one, and the equation was 1/Mw,t=1.8*1016t e-182.8/8.314T+0.056, the Ea was 182.8 KJ/mol.