Effect of Hydrogen Peroxide Treatment of Rubber Leaf Powder in Removing Pb(II) Ions

Abstract

The low concentration of hydrogen peroxide treatment of rubber leaf powder (HPRL) was studied to determine its effect on the Pb(II) adsorption capacity from aqueous solution. Oxidation process increased the amount of carboxylic groups which serve as the active site for the adsorption of Pb(II) ions. The amount of Pb(II) adsorbed was influenced by physicochemical parameters such as pH, adsorbent dosage, shaking rate, initial Pb(II) concentration, contact time, and temperature. It was found that the amount of Pb(II) adsorbed increased with increasing pH, shaking rate, initial Pb(II) concentration, and contact time but decreased with increasing the adsorbent dosage and temperature. The kinetic data was analyzed using two kinetic models (pseudo-first-order and pseudo-second-order models), and the adsorption of Pb(II) ions fitted well with pseudo-second-order model. Isotherm study was evaluated based on Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models, and the adsorption of Pb(II) followed Langmuir isotherm model with the monolayer adsorption capacity of 52.6 mg/g at pH 4. The equilibrium time was achieved within 90 min and the adsorption process was found to be exothermic process. The E (kJ/mol) value calculated from D-R model suggested that adsorption of Pb(II) by HPRL involved chemical adsorption.