The influence of the chitosan adsorption on the stability of SnO2 suspensions

The influence of the polyssacharide CS on the zeta potential variation of a SnO2 aqueous suspension has been systematically studied. The maximum potential obtained for the suspension was about 30 mV, which is high enough to stabilize the suspension. No significant effects on the zeta potential variation were identified when the molecular weight of CS was raised. Kinetics experiments have also been carried out and the potential of the suspension was stabilized about 10 s after the addition of the polymer. A new procedure was proposed for obtaining the adsorption isotherm curve, studying its relation with potential variation in increasing CS concentration. The method avoids some inconveniences of experimental procedures and the results obtained were very reasonable. The interaction of the CS with the surface was studied by FTIR and indicates that the most probable interaction is the formation of hydrogen bonds between the polymer and the surface hydroxyl groups. A deflocculating curve of a suspension of SnO2 as a function of CS concentration is also presented, indicating that at about 1.5 mg of CS/g of SnO2 the viscosity falls to zero. (C) 2002 Elsevier Science Ltd. All rights reserved.