Study of equilibrium and thermodynamic adsorption of α-picoline, β-picoline, and γ-picoline by Jordanian zeolites: Phillipsite and faujasite

In the present study the ability of phillipsite and faujasite to remove α-picoline, β-picoline, and γ-picoline from aqueous solution in the broad range of concentrations (1–500 mg L−1) was investigated. Adsorption equilibrium was carried out at different initial concentrations, sorbent concentrations, and temperatures. Brunauer–Emmett–Teller (BET), the Harkins–Jura, the Smith, and the Halsey equations were applied to the experimental data. The data fitted the BET model best. The overall adsorption of α-, β-, and γ-picoline on phillipsite and faujasite followed the order: faujasiteα-picoline < phillipsiteα-picoline < faujasiteβ-picoline < phillipsiteβ-picoline < faujasiteγ-picoline < phillipsiteγ-picoline. The values of change in Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were calculated. Thermodynamic study revealed that the adsorption of picolines onto phillipsite and faujasite was an exothermic process. Isosteric heat of adsorption was found to decrease with the increase in surface loading.