Alkali activated cedar wood as an efficient adsorbent for Pb2+ removal from aqueous solutions: Optimization, kinetic and thermodynamic study

In the present study, activated carbon prepared from cedar wood was synthesized, via NaOH activation, and optimized to be used as the adsorbent for Pb2+ removal from aqueous solutions in a batch process mode. The physicochemical properties of the synthesized adsorbent were examined by SEM, FTIR and BET analysis. In order to determine the optimum operational conditions, the effects of different parameters including pH, adsorbent dosage, contact time, temperature, and initial Pb2+concentration on the adsorptive performance of synthesized samples were also investigated. According to the obtained results, the highest Pb2+ ion adsorption capacity (971.9 mg/g) took place at the optimum operational condition of pH=4, adsorbent dosage of 0.025 g/L, contact time of 60 minutes, 300 ppm of Pb2+ and 30 ℃. The results showed that among Langmuir, Freundlich, and Temkin isotherms, the obtained data were fitted the best with the Freundlich model. Additionally, the process of Pb2+ adsorption was consistent with the pseudo-second-order kinetics model, indicating that chemical adsorption was the dominant mechanism of adsorption. Finally, according to the calculated thermodynamic parameters, i.e., ∆H°, 〖∆S〗^° & 〖∆G〗^°, Pb2+ adsorption on activated cedar wood can be considered as an exothermic and spontaneous process.