Adsorption of Lead and Arsenic Ions from Aqueous Solution by Activated Carbon Prepared from Tamarix Leaves

Lead and arsenic are regarded as the significant heavy metal ions which have a great contribution in the pollution of industrial wastewaters. In this research, the adsorption of Pb (II) and As (III) ions from the aqueous solution was studied using activated carbon prepared from Tamarix leaves as a new adsorbent. The adsorbent was characterized by Brunauer, Emmett, and Teller (BET), X-ray fluorescence spectrometer (XRF), scanning electron microscope (SEM), energy dispersive X-ray and mapping (EDX/Map), X-ray diffraction (XRD), and Raman techniques. Batch experiments were designed to investigate the significance of adsorption parameters including pH, adsorbent dosage, time, temperature, and initial concentration on Pb and As ions removal efficiencies. The experiments indicated that the highest adsorption efficiencies were 97.86% for lead and 96.18% for arsenic ions in pH values of 6 for Pb and 7 for As, adsorbent dosage of 3 g/L and initial concentration of 10 mg/L for both of them, and contact time of 60 min and 40 min for Pb and As ions, respectively. Additionally, the results of adsorption kinetics showed that the pseudo second-order model was more effective for the description of adsorption mechanism of both metals compared to the pseudo first-order model. The equilibrium behavior of arsenic and lead ions were described well by Langmuir and Freundlich models, respectively. In addition, thermodynamic studies showed that the current adsorption processes were exothermic and spontaneous. Based on the results, the prepared adsorbent can be considered as a good adsorbent for the removal of Pb and As ions from aqueous solutions.