Abstract

Chitosan is a natural substance that has many applications in the fields of pharmacy and medicine. Because it hashigh molecular weight and does not dissolved easily in a neutral pH solution, then there is an effort todepolymerize chitosan into low molecular weight chitosan and oligomers. Nowdays, one of the methods used todegrade biomass is hydrothermal. Hydrotermal is one method of biomass degradation and polymers that is quiteeffective and environmentally friendly. Because chitosan has strong hydrogen bonds in addition to highmolecular weight, it is necessary to treat chitosan by sonication before subjected to hydrothermal process. Thisstudy will compare degrading chitosan by only hydrothermal process and also sonication–hydrothermalprocesses. The hydrothermal of chitosan was carried out using a stainless steel tube reactor of 4-mL capacity at200 °C for 4 s under pressures of 25 MPa for both of hydrothermal systems. For sonication– hydrothermalprocesses, chitosan was treated with sonication at 40 oC for 30 and 120 min before subjected to hydrothermalprocess. After hydrothermal, chitosan was characterized by viscosimetry and HPLC to determine molecularwight and also the dissolved product. Based on the product yield of the process, the sonication (40 °C,120 mins,1 %)-hydrothermal process (200 °C, 4 mins) was the best process on this study and gave lactose yield as much as90 %.

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