In this work the adsorption and kinetics studies of methyl orange (MO) on polymer of intrinsic microporosity (PIM 1) was investigated. The results showed that adsorption of MO increases with temperature, suggesting the endothermic nature of sorption process. The adsorption data was found well fitted to the Langmuir model as compared to Freundlich and Temkin models. The kinetics data was described by first order, second order, pseudo first order, pseudo second order, Elovich equation, film diffusion and particle diffusion models. The kinetic data confirmed that the adsorption of methyl orange on PIM-1 follows particle and film diffusion models along with Lagergren pseudo first order and Elovich equations, indicating the sorption as a mixed diffusional process. The activation energy values for the particle and film diffusion processes were 13.09 k J/mol and 13.12 k J/mol respectively whereas, it was 14.11k J/mol according to pseudo first order equation. The low value of activation energy (less than 42 k J/mol) indicates that the adsorption of MO on PIM-1 is diffusional and physical in nature. The values of thermodynamic parameters ensure that the adsorption was endothermic and non-spontaneous with increase in entropy.

Muhammad Shakeel, Khalid Mehmood, Muhammad Waseem, Wajid Rehman, Khizar Hussain Shah and Mohsan Nawaz