KINETICS OF POLYACRYLAMIDE ADSORPTION AT THE IRON-OXIDE - SOLUTION INTERFACE

The adsorption of polyacrylamide (PAM) onto an iron oxide suspension (hematite) has been carried out with the object of studying the dynamics of the adsorption process. The adsorption experiments were performed at fixed pH and ionic strength of the medium, and various kinetic and adsorption parameters such as surface coverage and rate constants for the adsorption have been evaluated. It has been found that both the adsorption rate and the rate constants for adsorption decrease with increasing pH of the adsorption medium. Also, the effect of the addition of anions like Cl-, SO42- and PO43- on the adsorption behaviour of PAM has been investigated. This reveals that the initial rate of adsorption decreases with increasing salt concentration. An attempt has also been made to observe the effect of urea on the initial rate of adsorption as it is believed to be a compound that competes with PAM for adsorption. The initial rate of adsorption has been found to decrease with increasing molecular weight of PAM.