Enhancing biochar sorption properties through self-templating strategy and ultrasonic fore-modified pre-treatment: Characteristic, kinetic and mechanism studies

Abstract

The traditional anaerobic sewage treatment facilities are unsuitable for the widely uncontrolled spread of antibiotic residues in hospital or on livestock farm, which have raised the risk levels of high concentrations of antibiotic residues leakages and seriously threatened the aquatic ecology safeties. Thus, to develop an effective adsorbent with safe, low cost, and high firmly adsorptive capacity are imminent required. In this investigated, a self-templating hydrothermal alkali fore-modified & ultrasonic treatment was developed to achieve the highly adsorptive capacity and low desorption rate of biochar. As expected, the prepared biochar adsorbents present plenty of surface functional groups and micro pores. The BET value is raised up 1452 cm2·g−1 for biochar treated by the associated alkali fore-modified and ultrasonic treatment (UFB), whereas it is only 415.8 cm2·g−1 for the biochar treated by traditional carbonization (AC) and 1205 cm2·g−1 for the biochar by further hydrothermal alkali fore-modification (FB). Congruously, UFB exhibits the removal abilities of 397.70 mg·g−1 of levofloxacin (LEV) and 320.99 mg·g−1 of chlorotetracycline (CTC), 3.5–6.3 times absorbability towards familiar antibiotics than traditional biochar. Moreover, the corresponding the lowest desorption of 1.30 mg·g−1 (LEV) and 0.43 mg·g−1 (CTC) mg·g−1 by UFB have been confirmed. Meanwhile, Furthermore, both the adsorption and desorption mechanisms have been addressed by kinetic studies, pore width distributions, XPS and FTIR surveys. It is proposed the fore-modified treatment is more helpful for carbon functionalization while the ultrasonic treatment dedicates to the largely microporous structures. Consequently, the adsorption's capacity and stability of UFB adsorbents is large promoted due to its more micro- and meso-porous structure through a jointly hydrothermal alkali fore-modified and ultrasonic treatment. The present investigation will provide a novel alternative preparation strategy of the highly efficient adsorbent for emergency medical wastewater treatment.