| Abstract
| - Response surface methodology (RSM) was used for controlling molecular weight (MW) and degreeof deacetylation (DOD) of chitosan in chemical processing. In a reduced model, MW of chitosan isy = 1736166.406 − 250.745X1X2 − 265.452X2X3, with R 2 = 0.86, and DOD of chitosan is y = 30.6069+ 0.3396X1 + 0.4948X2 + 0.0094X32, with R 2 = 0.89. MW of chitosan depends on the crossproductof temperature and NaOH concentration and the crossproduct of NaOH concentration and time, andDOD depends linearly on temperature and NaOH concentration, and quadratically on time. Chitosanwas widely depolymerized in a range from 1,100 kDa to 100 kDa and deacetylated from 67.3 to95.7% by NaOH alkaline treatment. MW and DOD of chitosan were drastically decreased andincreased, respectively, with increase of temperature, reaction time, and NaOH concentration.Furthermore, the rate of MW decrease and DOD increase of chitosan gradually decreased withprolonged reaction time. Keywords: Chitosan; response surface methodology; molecular weight; degree of deacetylation
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