K L University, India
"The potential of using Grewia Orbiculata leaf powder as a new adsorbent for the removal of lead from aqueous solutions was investigated. Batch adsorption experiments were performed to find out the effective lead removal at different metal ion concentrations, adsorbent size and dosage. Adsorption of Pb2+ ion was strongly affected by pH. The Grewia Orbiculata L. exhibited the highest lead adsorption capacity at pH 6.1. Isotherms for the adsorption of lead on Grewia Orbiculata L. were evaluated with the Langmuir, Freundlich, Temkin and Dubinin- Radushkevich adsorption isotherm models. The equilibrium data fitted well to the Langmuir and Freundlich isotherm models. At pH 6.1, the maximum lead adsorption capacity of Grewia Orbiculata L. estimated with the Langmuir model at different temperature levels, ranges from 303K to 318K were increased from 22.39 mg g−1 to 30.08 mg g−1 adsorbent. Thermodynamic parameters such as ∆G, ∆H, and ∆S were evaluated by applying the van’t Hoff equation. The thermodynamics of Pb(II) on Grewia Orbiculata L. indicates the spontaneity at low temperatures and exothermic nature of adsorption."