Preparation Of Soluble Chitosan By Mechanochemistry Process

Chitosan is prepared by mechanical chemistry way in this paper, by using scanning electron microscopy(SEM), X-ray diffraction (XRD)and infrared spectra(IR), TGA and other analytic- al methods, water-soluble chitosan produced by chemical mechanical is studied and its impact factor also is analyzed. Different mechanical activating time and size of shrimp shell have eff- ects on soluble content, which have been examined respectively. The results indicate that the mechanical-chemical process causes remarkable impact on changing molecular structure, among which stirring time,quantity of shrimp shell ground at a time are the most obvious factors effecting water-soluble of chitosan. The crystal structure of chitin in shrimp shell is destroyed in mechanical-chemical process and changed from chitin to chitosan in a short time, taken off the acetyl group. The results are summarized as follows: from soluble content data ground in a different time, we can see that the longer the grinding time, mechanical activation acts more intensely, so that water-soluble substances more. Grinding 1 min, 2min, 4min, 6min, 8min, 10min respectively, from the figure we also can obtain that at six minute there is a significant turning point, the soluble content is 23.4%, before six minute the soluble content increases significantly, after six minute, the soluble content increases slowly. From the infrared absorption spectrometry, the crystallization which can dissolve in water has two symmetrical peaks in 3446 cm-1, 3429cm-1, according to analysis, it is N-H in the asymmetric and symmetric stretching of NH2, thus we can conclude that the crystalline material is chitosan which has been taken off the acetyl group. After the planetary ball mill grinding, mechanical chemical reaction happens, the acetyl group taken off. From SEM analysis, after a strong mechanical polishing, the crystalline substance appears yellow, of which containing substances such as chitosan and some of the soluble protein and calcium type substances. Combining XRD analysis it can be drawn that the crystallization material contains soluble calcium type substances. Taking insoluble and soluble material in muffle furnace in high temperature for some hours, residual material appears spherical shape from the SEM, which takes further evidence of chemical mechanical role fiercely, compare of the crystalline material of the remnants with a standard card, we found material for CaO, and the insoluble residues in the XRD patterns did not reflect this point, so we need further study. Similarly, from TG-DTG analysis we can prove that peak temperature of the decomposition of calcium carbonate is 697.99οC, advance of the nano-calcium carbonate decomposition temperature about 37.01οC. Thus it proves that crystals contain tiny uniform water-soluble calcium substances.