Adsorption of Pb2+ in Wastewater Using Adsorbent Derived from Grapefruit Peel

The adsorbent was prepared from Grapefruit peel by activation with ZnCl2. Grapefruit peel adsorbent (GPA) was employed to be as adsorbent to remove Pb(Ⅱ) in wastewater. The affecting factors on the adsorption of Pb(Ⅱ)from aqueous solution with GPA, such as solution pH, contact time, GPA dosage, initial Pb(Ⅱ) concentration, and reaction temperature were investigated. Adsorption kinetics and adsorption mechanism were investigated also. The results showed that the factors mentioned above have remarkably influence on adsorption of Pb(Ⅱ) ions onto GPA. The suitable conditions for the adsorption conditions were as following: solution pH, 5.3~6.5; contact time, 1.5 hours; GPA dosage, 10 g/L; initial Pb(Ⅱ) ion concentration, 100 mg/L; temperature, 30°C. Under the suitable conditions, the removal rate of Pb(Ⅱ) was more than 90% and the sorption capacities of the GPA for Pb(Ⅱ) were 12.73mg/g. Adsorption kinetics of Pb(Ⅱ) ions onto GPA obeyed pseudo-second-order equation. The isothermal adsorption can be described well by Langmuir, Freundlich and Temkin models, and the Freundlich model was the best.