Application of the Modified Biochar from Sewage Sludge for Removal of Pb(II) from Aqueous Solution: Kinetics, Equilibrium and Thermodynamic Studies

An adsorbent Modified Biochar (MB) made from sewage sludge was characterized with FT-IR spectra and SEM image. The effects of contact time, solution temperature, pH and initial concentration on the adsorption performance Pb(II) onto MB was investigated in a batch adsorption experiment. Results showed that MB had great adsorption capacity, due to the existence of hydroxyl, carboxyl, ether, alcohol and amino groups. As the contact time prolonged, the adsorption quantity of MB increased sharply first and then tended to the balance. The adsorption capacity increased slightly with the temperature increase. The effect of pH on the absorbability of MB was non-linear, and the maximum adsorption capacity was obtained when the pH was approximately 6. The adsorption capacity increased abruptly first and then become slowly with the initial concentration increase. Compared with the pseudo-first-order, the pseudo-second-order kinetic models were more suitable to test the kinetic experimental data. Equilibrium data were analyzed using the Langmuir and Freundlich isotherm models and it was found to correspond to the Langmuir isotherm model better.