Preparation and Characterization of Chitosan-type SO2 Sustained-release Material
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Abstract:
In this study, chitosan-type SO2 sustained-release material (CS-SO2SM) was prepared by metal ion complexation reaction, vulcanization reaction and embedding technology, in order to develop a new SO2 preservative for grapes based on molecular structure. Through single factor experiments, the best metal ion(s) and vulcanizing agent(s) were screened. In combination with the factorial experiment design, the amount of released SO2 and the antibacterial activity were determined by the iodometric method and inhibition zone test, respectively. The preparation process of CS-SO2SM was optimized through taking the SO2 release curve and release days as the main examination indices. Its morphology was observed by the field emission environmental scanning electron microscope-energy spectrometer, and the changes of its functional groups were examined by a Fourier infrared spectrometer. The optimal process conditions: Cu2+ as the metal ion, 0.5 g of dipentamethylenethiuram tetrasulfide (TRA), 0.5 g of sodium pyrosulfite, and preparation duration (with stirring) as 1.5 h. The prepared CS-SO2SM was a dark brown powder which appeared as flocculated clouds under the electron microscope. The characteristic absorption peaks of the main functional groups, -OH, -NH and -CONH showed blue shifts compared with chitosan. The SO2 release curve showed a rise first and then a slow decline. The materials prepared under these conditions had an average diameter of 19.25 mm for the inhibition zone and exhibited the strongest antibacterial effect. The research has shown that CS-SO2SM prepared by coordination reaction, vulcanization reaction and embedding technology is expected to be a new type of SO2 preservative with a certain application prospect.
