Conventional techniques such as filtration, electro-deposition, chemical oxidation and ionic exchange show important drawbacks, including the high cost and poor elimination of pollutants at low concentrations. Spent chai tea leaves (CT) are proposed as a viable, low-cost, biodegradable, recyclable and efficient material for the removal of heavy metals such as copper, zinc and cobalt from solutions. Batch experiments at room temperature demonstrate a high affinity of CT towards Cu, followed by Zn and Co divalent ions. Initial pH of the solution and salinity greatly affected the process. Results indicate that the adsorption of the metal is maximized at a pH of 5 using 150 mg of CT. Presence of substances like Pb(II) ions surfactants decreased the adsorption due to ion competition. This was confirmed by experiments with metal mixture were copper was better adsorbed even in the presence of cobalt and zinc. Time-dependent test show that an average of 50 min is needed to reach equilibrium. Data was fitted according to Langmuir and Freundlich theories, indicating a qmax of 22.90, 17.69 and 8.39 mg/g for zinc, copper and cobalt ions, respectively. Finally SEM, EDAX and FTIR analyses demonstrated that CT is a good candidate for the removal of heavy metals from contaminated wastewaters.
Buy this Article