Pyrolysis condition affected sulfamethazine sorption by tea waste biochars

Sulfamethazine (SMT) as a veterinary drug has been detected frequently in the environment. In this study, six biochars produced from tea waste (TW) at 300 and 700 °C with or without N2 and steam activation were characterized and evaluated for SMT sorption in water. The sorption of SMT was interpreted as a function of biochar production condition, SMT concentration, pH and physicochemical characteristics of biochar. Distribution coefficient data showed high sorption of SMT at low pH (∼3) and the highest sorption density of 33.81 mg g−1 was achieved by the steam activated biochar produced at 700 °C. The steam activation process increased the adsorption capacity by increasing the surface area of the biochar. The π–π electron donor–acceptor interaction, cation–π interaction and cation exchange at low pH were the primary mechanisms governing SMT retention by biochars. Overall, steam activated tea waste biochar could be a promising remedy of SMT removal from water.