Adsorption of cationic polyacrylamide (C-PAM) on expanded perlite

The adsorption of cationic polyacrylamide (C-PAM) onto expanded perlite (EP) from aqueous solutions was investigated as a function of some parameters such as pH, ionic strength, and temperature. The adsorption of C-PAM was increased with increasing pH and temperature and with decreasing ionic strength. The Langmuir isotherm model fitted the isotherm data better than the Freundlich model. The electrophorotic mobility of EP dispersions was measured in aqueous solutions of NaCl and at different C-PAM concentrations and pH. The thermodynamic parameters Gibbs free energy, enthalpy, and entropy were evaluated. The dimensionless separation factor (RL) revealed that EP can be used for adsorption of C-PAM from aqueous solutions. The pseudo first-order kinetics equation best fitted the experimental data.