The Preparation Of Chitosan/hydrotalcite Composite And Its Application

Composite of polymer and inorganic nanometer material is an important part of the nanometer science and technology, which is also one of the important methods for preparation of new composite materials. A new organic-inorganic composite material can be obtained by fixing organic and inorganic materials using physical and chemical means. The performance of the composite material will be better because of every component acting synergistically. For hydrotalcite inorganic material has good compatibility with sodium dodecyl sulfate, composite material of hydrotalcite and sodium dodecyl sulfate, which is formed when sodium dodecyl sulfate enter hydrotalcite layer board through solution intercalation, has superior performances. But to starch, cellulose and chitosan, kinds of materials which are big molecular weight, difficult to dissolve and can not enter hydrotalcite layer board, it’s difficult to form stable-uniform composite material with hydrotalcite. Therefore, the application of chitosan is serious limited in polymer field. Based on this situation, this article attempts to prepar one of stable performance of chitosan/hydrotalcite composite. Concrete experimental content and experimental results are as follows:Firstly,based on the method of urea coprecipitation to prepare hydrotalcite(LDHs), the paper prepared a new organic-inorganic hybrid material(CMCS/LDHs) composed of carboxymethyl chitosan and hydrotalcite successfully by dripping into the certain amount of carboxymethyl chitosan(CMCS) solution slowly before heating. The structure and composition of the CMCS/LDHs composite materials were determined by FT- IR, XRD and SEM to make sure that carboxymethyl chitosan adhered in hydrotalcite uniformly and does not affect the crystal phase structure of the hydrotalcite. The Cu2+ adsorption experiments showed that the adsorption performance of different batches of CMCS/LDHs is stable, and the preparation method of CMCS/LDHs has good repeatability.Secondly, using the composite(CMCS/LDHs) as the carrier of immobilized papain to prepar biological catalyst(P-CMCS/LDHs). The optimal conditions obtained were as follows: 3mL glutaraldehyde solution with its concentration is 8%; 0.1 g CMCS/LDHs as carrier; 3 m L 1 mg/mL of papain solution; activation time 2 h; reaction temperature 25°C; reaction time 10 h.Thirdly, the enzyme activity, enzyme activity recovery and storage stability of P-CMCS/LDHs is simultaneously estimated and compared. The experimental results show that the enzyme activity is 25.7μg·mL-1·min-1, and the enzyme activity recovery rate was 52.3%. P-CMCS/LDHs shows good catalytic stability in the process of using The residual activity of P-CMCS/LDHs was 90% after after 4 cycles. P-CMCS/LDHs can be wet storage in a short period of time, it is better dry storage at 4°C if there is needed to long time storage.Finally, we discussed the performance of the catalytic degradation of P-CMCS/LDHs on casein. The main research includes the most appropriate pH and temperature, pH and temperature stability, Michaelis constant. Besides, through experiments of the resistance of P-CMCS/LDHs to organic solvent(acetonitrile ethanol and toluene) and Cu2+, our work found out that the papain had greater resistance to Cu2+ than the free papain but no to these three solvents. It means that the range application of the papain immobilized on the CMCS/LDHs will be widen.