Surface Chemical Studies on Silicon Carbide Suspensions in the Presence of Poly (Ethylene Glycol) and Chitosan

Abstract

The changes in the surface chemical properties of SiC suspensions consequent to the addition of polyethylene glycol (PEG) and chitosan, both individually and in the presence of each other were studied. The adsorption densities of PEG and chitosan for SiCwere found to be higher at pH 2-3 and 7-7.5 respectively. The adsorption behaviour in the combined presence of PEG and chitosan was akin to those observed for the individual systems. The isoelectric point (i.e.p.) of SiC was found to be located at pH 3. The addition of chitosan shifted the i.e.p. towards more alkaline pH values, in proportion with the concentration of chitosan added, with a concomitant change in the zeta potentials to less electronegative or more electropositive values. On the contrary, only a marginal change in the electrokineticbehaviour of SiC suspension was found after PEG addition. The favourable pH regimes were established to be 2-6 and 9-11, for the enhanced stability of SiC suspension with the optimum dosage of chitosan. The electrokinetic and dispersion characteristics of the SiC-chitosan system were only slightly altered by the addition of PEG. FTIR spectral investigations provided evidence in support of the proposed hydrogen bonding forces of interaction between SiC and PEG or chitosan.