Adsorption behavior of carboxymethyl starch on titanium dioxide surfaces

The adsorption of carboxymethyl starch (CMS) on titanium dioxide surface from aqueous solution of electrolyte was investigated by adsorption and electrokinetics mobility measurements. Zeta potential measurements showed that the addition of CMS resulted in a shift of isoelectric point to the more acidic region, indicating the adsorption of CMS from the aqueous solution onto titanium dioxide surface. The positively charged and hydrophilic surface sites of titanium dioxide favor the adsorption of CMS molecules. The adsorption capacity of CMS on titanium dioxide surface was found to be controlled by the number of functional group on CMS that promotes surface charge CMS adsorption in agreement with Langmuir isotherm. For the adsorption of CMS, the pseudo-second-order kinetics of chemical reaction provides the best correlation of the experimental data.