Adsorption and electrokinetic studies on alumina suspensions using poly(viny1 alcohol)

The adsorption of poly(vinyl alcohol) (PVA) of molecular weight 25,000 onto alumina was studied as a function of pH. The adsorption isotherms were also determined. The adsorption density increases with increasing pH, while the isotherms are rounded and of the low affinity type. Electrokinetic studies indicate that the electrophoretic mobilities are reduced in magnitude in proportion to the PVA concentration, without any shift in isoelectric-point (iep). This resembles the influence of an indifferent electrolyte. The calculated values of the free energy of adsorption between alumina and PVA are suggestive of hydrogen bonding. FTIR spectro-scopic data provide additional evidence in support of hydrogen bonding.