Feasibility study on a new pomelo peel derived biochar for tetracycline antibiotics removal in swine wastewater

Removal of tetracycline antibiotics (TCs) by biochar adsorption is emerging as a cost-effective and environmentally friendly strategy. This study developed a novel pomelo peel derived biochar, which was prepared at 400 °C (BC-400) and 600 °C (BC-600) under nitrogen conditions. To enhance the adsorption capacity, BC-400 was further activated by KOH at 600 °C with a KOH: BC-400 ratio of 4:1. The activated biochar (BC-KOH) displayed a much larger surface area (2457.37 m2/g) and total pore volume (1.14 cm3/g) than BC-400 and BC-600. High adsorption capacity of BC-KOH was achieved for removing tetracycline (476.19 mg/g), oxytetracycline (407.5 mg/g) and chlortetracycline (555.56 mg/g) simultaneously at 313.15 K, which was comparable with other biochars derived from agricultural wastes reported previously. The adsorption data could be fitted by the pseudo-second-order kinetic model and Langmuir isotherm model successfully. The initial solution pH indicated the potential influence of TCs adsorption capacity on BC-KOH. These results suggest that pore filling, electrostatic interaction and π-π interactions between the adsorbent and adsorbate may constitute the main adsorption mechanism. BC-KOH can be used as a potential adsorbent for removing TCs from swine wastewater effectively, cheaply and in an environmentally friendly way.