Ultrasonic Degradation of Dextran in Aqueous Solution

An ultrasonic device with frequency of 20 kHz was used to investigate the effect of different operational parameters such as ultrasonic power, temperature and initial molecular weight on dextran degradation. Results show that the molecular weight of dextran can be controlled by ultrasonic treatment. Higher the ultrasonic power and lower the temperature could increase the degradation rate (R-ij). The initial molecular weight plays an important role in R-ij at the initial stage of dextran degradation (within 20 minutes). A smilar limiting molecular weight (Mw approximate to 8.7x10(4)) was obtained after 2 hours ultrasonic treatment for four different initial molecular weight dextrans, suggesting that the limiting molecular weight is independent on the initial molecular weight of dextran. Ultrasonic treatment can be used as a safe, simple and effective method to control the molecular weight of dextran.