Kinetics and Equilibrium Studies of Adsorption of Anionic Dyes Using Acid-Treated Palm Shell

This study investigates the potential uses of palm shell, pretreated with sulfuric acid (APSP) for the adsorption of AOII, DSB, and AV7. The effects of different system variables like adsorbent dosage, pH, contact time, and temperature were studied. Optimum pH values for all the three dyes were determined as 1.0. Equilibrium was achieved within 30 min. Langmuir I, II, III, IV and Freundlich isotherm models were applied to describe the equilibrium isotherms at different temperatures, and the langmuir model was found to agree very well with the experimental data. The maximum adsorption capacity was found to be 2180.05 mg/g, 1199.99 mg/g, and 243.9 mg/g for AOII, DSB, and AV7, respectively. Thermodynamic parameters such as change in free energy (Delta G(0)), enthalpy (Delta H-0), and entropy (Delta S-0) were also determined. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to fit the experimental data. The pseudo-second-order equation was able to fit well and provide a realistic description of the adsorption kinetics.