Abstract
In this study, infused tea leaves as a low-cost adsorbent have been used in the removal of the Pb2+, Fe2+ and Cd2+ 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 Pb2+ and Fe2+ and at pH 6 for Cd2+. 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 Pb2+ > Cd2+ > Fe2+ with the adsorption capacities of 26.32 mg·gǃ, 14.29 mg·gǃ and 12.38 mg·gǃ respectively. The adsorption process followed the pseudo-second order reaction and the corresponding rate constant were found to be 4.30 × 10Dž g·mgǃ·minǃ, 1.75 × 10ǃ g·mgǃ·minǃ and 1.45 × 10DŽ g·mgǃ·minǃ for Pb2+, Fe2+ and Cd2+ ions respectively.
Highlights
The rapid growth of the manufacturing industries such as chemicals, foods, motor vehicles, paper, electronics, etc., have caused a lot of pollutions in the world especially in developing countries such as China, India, Brazil as well as Malaysia
The maximum removal of metal ions was observed at pH 5 for Pb2+ and Fe2+ ions, and at pH 6 for Cd2+
The present study shows that infused tea leaves like the most other natural absorbents are able to remove Cd2+, Pb2+ and Fe2+ ions from aqueous solutions
Summary
The rapid growth of the manufacturing industries such as chemicals, foods, motor vehicles, paper, electronics, etc., have caused a lot of pollutions in the world especially in developing countries such as China, India, Brazil as well as Malaysia. The environmental pollution by heavy metals such as Cd, Zn, Fe, Ni, and Pb has become one of the many serious pollution issues These heavy metals are often discharged into the environment by a number of industrial and domestic wastewater processes [1]-[3]. The release of large quantities of these heavy metals into the natural environment has resulted in a number of environmental problems because of their non-biodegradability and persistence characteristics [4]-[7]. Various treatment methods, such as chemical precipitation and coagulation, ion exchange, reduction, osmosis and reverse osmosis, membrane filtration, and electrolytic technologies have been used for the removal of heavy metal contaminants in industrial effluents [12]-[14]. Special attention has been paid on the use of natural adsorbents as an alternative to replace the conventional methods mentioned above, mainly due to environmental and economic reasons [15] [16]
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