Ultrasound degradation of xanthan polymer in aqueous solution: Its scission mechanism and the effect of NaCl incorporation
Document Type
Article
Publication Date
1-1-2017
Abstract
Degradation of xanthan polymer in aqueous solution by ultrasonic irradiation was investigated. The effects of selected variables i.e. sonication intensity, irradiation time, concentration of xanthan gum and molar concentration of NaCl in solution were studied. Combined approach of full factorial design and conventional one-factor-at-a-time was applied to obtain optimum degradation at sonication power intensity of 11.5 W cm−2, irradiation time 120 min and 0.1 g L−1 xanthan in a salt-free solution. Molecular weight reduction of xanthan gum under sonication was described by an exponential decay function with higher rate constant for polymer degradation in the salt free solution. The limiting molecular weight where fragments no longer undergo scission was determined from the function. The incorporation of NaCl in xanthan solution resulted in a lower limiting molecular weight. The ultrasound-mediated degradation of aqueous xanthan polymer chain agreed with a random scission model. Side chain of xanthan polymer is proposed to be the primary site of scission action.
Keywords
Xanthan gum, Ultrasound, Chain scission, Molecular weight, Ionic strength
Divisions
InstituteofBiologicalSciences
Funders
University of Malaya. Research grants PG057/2013A, FP020-2013A, RG330-15AFR and RP031C-15AET
Publication Title
Ultrasonics Sonochemistry
Volume
39
Publisher
Elsevier