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Abstract
The efficiency of lead removal from aqueous solution using non-modified and nitric acid-modified charred carbon has been investigated. The charred carbon was obtained through the direct pyrolysis of used cigarette filters, one of the world’s largest solid wastes. The effects of lead solution’s pH, adsorbent dosage, initial lead concentration, and contact time on lead uptake from water by the two carbons were studied. It was revealed that the maximum lead uptake from water was at optimum pH values of 5 and 4 for non-modified and surface modified carbons, respectively. However, the effect of adsorbent dosage was almost identical for both carbons with an optimum value of 0.1 g. The equilibrium was reached after almost 24 h of contact time for both types of carbons. The adsorption data were fitted by the Freundlich and Langmuir adsorption isotherm models. The adsorption for both carbons was best explained by Freundlich adsorption isotherm. The kinetics of the adsorption were also investigated. Pseudo-second-order kinetic model could successfully fit the kinetic data implying the chemisorption adsorption mechanism being dominant for both carbons. At an initial lead concentration of 600 mg/l, the removal efficiency was measured to be 66 and 74.5 mg/g for non-modified and HNO3-modified carbons, respectively.