Characterization of barley straw biochar produced in various temperatures and its effect on lead and cadmium removal from aqueous solutions

Conversion of agricultural wastes into a carbon rich material (i.e. biochar) using pyrolysis process could be an appropriate approach for their management. This study was carried out to convert barley straw to biochar in different temperatures (300, 400 and 500°C) and to investigate the potential of the produced biochar as a sorbent of heavy metals (Pb and Cd). Considering the pretest results of Pb and Cd sorption, the biochar produced at 500°C (BS500) was selected to find effect of pH, the sorbent dose, the initial concentration of Pb and Cd and the contact time on metal removal efficiency. The results showed that the optimum conditions of adsorption were pH = 6, the sorbent dose 1 g/L and the contact time of 45 min. The adsorption kinetics and isotherms had the best fit to the pseudo‐second order and Langmuir models, respectively.