Biological removal of Lead from aqueous solutions using low-cost biosorbents

Background: Lead is widely known as one of the most hazardous substances that causes adverse long-term effects on human health and environment. In this research, the biosorption capacity of tea waste in aqueous solution containing Lead ions was studied. Also important parameters (e.g. pH, initial concentration and contact time on the biosorption) were investigated. In order to evaluate the adsorption capacity of tea waste, the experimental data were fitted to the Langmuir and Freundlich isotherm models. Materials and Methods: All the chemicals used were of analytical grade. Biosorption experiments were carried out in rotary shaker at 25 ◦C. The samples were analyzed by spectroscopy. Results: The results showed that the optimal pH value for adsorption was 4.5 which was decreased with increasing and decreasing of pH. The biosorption was relatively quick and the equilibrium time 2 hours. The biosorption kinetics studies showed that more than 95% of biosorption was completed within 1 hour. The maximum removal efficiency (98%) obtained on using 4 g/l tea waste in aqueous solution containing Lead (100 ppm) ions at optimal pH. According to results, Freundlish model was the best isotherm model for biosorption. The best isotherm model was Freundlish model. Conclusion: The results showed that tea waste is a good and new low- cost biosorbent for removing lead ions from aqueous solution with no chemical or physical pre-treatment. Considering the high adsorption value (the maximum biosorption 142 mg g-1), tea waste could be considered as an effective biosorbent to remove lead ions from industrial wastewater due to inexpensive, abundance and readily availability in Iran.