The Preparation Of Dialdehyde Modified Rice Starch And Its Application In The Leather Tanning

The thesis take the rice starch as the research object, the preparation of the rice of Dialdehyde starch and acid degradation of Dialdehyde Starch for preparation of leather tanning reagent were studied, and explore the degradation product with similar state, different molecular weight for the leather tanning. The main research content includes the following aspects:(1) The rice of Dialdehyde Starch is prepared by the oxidization of rice starch with sodium periodate. The best optimum process is discovered through the single factor experiment and orthogonal experiment. The conditions are as follows: reaction temperature 35℃、reaction time 4h、reaction p H 3.5、0.3mol/L Na IO4 and the molar ratio of sodium periodate and the original rice starch was 1.1:1.(2) The best conditions of the lactic acid, hydrochloric acid about the mixed acid degradation were as follows: the mole ratio of lactic acid and hydrochloric acid 3:1, the degradation temperature 60℃(4h), 70℃(3h), liquid-solid ratio 5:1, the concentration of H+ is 0.0126 mol/L. The degradation product is stable, milky white, molecular weight around 2300.(3) The best conditions of the lactic acid, Sulfuric acid about the mixed acid degradation were as follows: the mole ratio of lactic acid and Sulfuric acid 1:1, the degradation temperature 60℃(4h), 70℃(2h), liquid-solid ratio 5:1, the concentration of H+ is 0.0126 mol/L. The degradation product is stable, milky white, molecular weight around 2500.(4) The best conditions of high temperature and high pressure hydrothermal degradation were as follows: a. lactic acid 0.625%, the degradation temperature 90℃(2h), liquid-solid ratio 4:1. The degradation product is stable, milky white, molecular weight around 2100. b. lactic acid 0.625%, the degradation temperature 100℃(45min), liquid-solid ratio 4:1. The degradation product is stable, milky white, molecular weight around 2000.(5) This article preliminarily explores the influence about the aldehyde content for the degradation: with the increase of the aldehyde content, it is difficult to clear the impurity iodine, so that the degradation product is unstable and mixed color, shall not apply to the application process; 30% aldehyde content is advisable.(6) The influence about the degradation product with similar state, different molecular weight for the leather tanning: with the decrease of the molecular weight, there were no significant differences in leather retanning process for the degradation products, but with the decrease of the molecular weight, the thickening rate increase significantly of raw hides in the tanning process.