Lead Ion Adsorption on Glutathione-Modified Carbon

This study explores the adsorption of Pb(II) from aqueous solutions using glutathione-modified carbon powder at room temperature. The graphite powder was modified through oxidation followed by surface immobilization of glutathione. The Pb(II) concentration was measured using square wave anodic stripping voltammetry (SWASV). Experiments were conducted with the following varying initial Pb(II) ion concentrations: 20.72 mg L−1, 41.44 mg L−1, 62.16 mg L−1, 82.88 mg L−1, 103.60 mg L−1, and 124.32 mg L−1. The effect of varying the glutathione-modified carbon powder dosage (12.5 mg, 25.0 mg, 50.0 mg, 75.0 mg, and 100.0 mg) on Pb(II) uptake was studied. The adsorption data were modeled using the Freundlich isotherm, resulting in a regression coefficient (R2) of 0.96, which signifies a good fit. The Freundlich constants obtained were KF = 3.54 × 10−5 (adsorption capacity) and n = 1.56 (adsorption intensity). At optimal conditions (10.0 mL of 20.72 mg L−1 Pb(II) solution with 100.0 mg of glutathione-modified carbon powder), the adsorption efficiency was 96.3%. The glutathione-modified carbon powder exhibits a high capacity for adsorbing Pb(II) from aqueous solutions.