Influential biosorption of lead ions from aqueous solution using sand leek (Allium scorodoprasum L.) biomass: kinetic and isotherm study

Abstract In this study, a zero-cost, naturally effective adsorbent, sand leek ( Allium scorodoprasum L.), was used for the effective removal of lead ions from an aqueous solution. This natural adsorbent was characterized by FT-IR, SEM–EDX, and PZC analyses. Batch studies were conducted at one factor at a time to explore maximum removal efficiency in terms of pH, initial lead(II) ion concentration, contact time, adsorbent dosage, and temperature for efficient adsorption. The maximum lead(II) ion uptake capacity for SAC was obtained at pH 4.5, initial lead(II) ion concentration at 1000 mg/L, operation time of 1440 min, adsorbent dosage of 10 g, and temperature of 25 °C. The adsorption data were well-fitted by the Freundlich isotherm model, with an R 2 value of 1.000, indicating a good fit. The kinetic study revealed that the adsorption of lead(II) ions followed a pseudo-first-order kinetic model, with an R 2 value of 0.9746. Furthermore, the thermodynamic parameters including Gibbs-free energy change (Δ G °), enthalpy change (Δ H °), and entropy change (Δ S °) were calculated to demonstrate that the adsorption of lead(II) ions onto natural adsorbent was endothermic and spontaneous.