Adsorption of Pb(II) from aqueous solutions by wheat straw biochar

This work focuses on the preparation of biochar and the study of the adsorption properties of lead ions on it in water. CS (carbon wheat straw) was obtained by carbonizing 60 min at 300 degrees C. Batch experiments were conducted to study the effects of initial pH value, contact time, adsorbent dose, initial concentration and temperature on the adsorption properties. Pseudo first order and pseudo second order models were used to study the kinetics of the process, and results showed adsorption of Pb2+ by CS followed pseudo second order kinetic model. The Langmuir isotherm model provided the best correlation for Pb2+ adsorption, indicating that the adsorption was chemical monolayer adsorption. The adsorption capacity q(m) was increased with increasing temperature, reached 149.701 mg/g for CS and 44.663 mg/g for NS (natural straw), at 35 degrees C, respectively, showing the adsorption was exothermic. It was concluded that the adsorption capacity of CS is 3.3 times of that of NS which means that the carbonization of wheat straw was of certain value in the treatment of lead ions in wastewater.