Biosorption of lead from aqueous solution by Ficus religiosa leaves: batch and column study

The biosorption of lead by Ficus religiosa leaves (FRLs) in powder and immobilized form was investigated. Batch experiments were conducted to determine the biosorption capacity, equilibrium time, optimal pH and temperature. The maximum biosorption capacity of lead was 37.45 mg g(-1) at optimal pH of 4. The temperature change in the range of 20-40 degrees C affected the biosorption capacity and the maximum removal was observed at 25 degrees C. The thermodynamics parameters were determined from experimental data. The Langmuir and Freundlich models were used to explain the equilibrium data. The Langmuir model showed better fit of data with correlation coefficient of 0.97. The kinetics of biosorption followed pseudo second order model. For continuous biosorption experiments, FRLs biomass was immobilized in polysulfone matrix. Breakthrough curves were analyzed at different flow rates, pH and bed depth. Bed depth service time (BDST) and the Thomas models were used to describe the experimental data. A solution of 0.05 M HNO(3) did well to elute lead from biomass. The release of Ca, Mg and Na ions during lead biosorption revealed that ion exchange was the major removal mechanism.