Utilization of Infused Tea Leaves (<i>Camellia sinensis</i>) for the Removal of Pb²⁺, Fe²⁺ and Cd²⁺ Ions from Aqueous Solution: Equilibrium and Kinetic Studies

Abstract

In this study, infused tea leaves as a low-cost adsorbent have been used in the removal of the Pb 2+ , Fe 2+ and Cd 2+ ions from aqueous solution. The adsorption study was carried out in a batch process and the effects of parameters such as initial pH, adsorbent dose, contact time and initial metal ion concentration were investigated. Experimental results showed that the maximum adsorption of metal ions occurred at pH 5 for Pb 2+ and Fe 2+ and at pH 6 for Cd 2+ . Adsorption of metal ions increased with increasing adsorbent concentration and contact time. The isothermal data for the adsorption of metal ions by infused tea leaves were found to fit well with the Langmuir equations. Based on the experimental data of the Langmuir isotherm model, the maximum adsorption capacities of the metal ions onto the infused tea leaves were found in the order of Pb 2+ > Cd 2+ > Fe 2+ with the adsorption capacities of 26.32 mg &#183 g &#45 1 , 14.29 mg &#183 g &#45 1 and 12.38 mg &#183 g &#45 1 respectively. The adsorption process followed the pseudo-second order reaction and the corresponding rate constant were found to be 4.30 × 10 &#45 3 g &#183 mg &#45 1 &#183 min &#45 1 , 1.75 × 10 &#45 1 g &#183 mg &#45 1 &#183 min &#45 1 and 1.45 × 10 &#45 2 g &#183 mg &#45 1 &#183 min &#45 1 for Pb 2+ , Fe 2+ and Cd 2+ ions respectively.