Removal of sulfadiazine antibiotic using carbon-based adsorbents: A comprehensive review on influencing factors, adsorption models and mechanisms.

The widespread use of the sulfadiazine antibiotic leads to a significant environmental challenge, e.g., promoting antimicrobial resistance and ecotoxicity. This work comprehensively reviewed the adsorptive removal of sulfadiazine from water using carbon-based adsorbents, including biochar, activated carbon, carbon nanotubes, and carbon-based composites. The sulfadiazine adsorption mechanisms, such as electrostatic interactions, ion exchange, complexation, hydrogen bonding, π-π stacking, and pore-filling were comprehensively discussed. Electrostatic interactions and hydrogen bonding were main mechanisms for sulfadiazine adsorption and heavily influenced by pH and surface functional groups. The effect of pH, temperature, ionic strength, and initial concentration on sulfadiazine adsorption performance was evaluated. Almost sulfadiazine adsorption kinetic studies were best described with pseudo-second-order model while isotherm studies were best described with Langmuir and Freundlich models. Remarkably, among carbon-based composites, bamboo-derived ZnCl2-activated carbon delignified with NaClO2 and acetic acid, and then modified with FeCl3/FeCl2 attained a surface area of 1389 m2/g and an exceptionally high sulfadiazine adsorption capacity of 645.08 mg/g. Moreover, magnetic nickel-incorporated carbon nanofiber composite could be reused for 5 cycles and was easily generable using ethanol as an eluting solvent. However, several limitation aspects of laboratory scale, continuous adsorption, and verification of adsorption mechanisms still remain, and should be addressed in future works.