New chitosan-biochar composite derived from agricultural waste for removing sulfamethoxazole antibiotics in water

This study aims to develop a new chitosan-biochar composite derived from agricultural waste for removing sulfamethoxazole (SMX) antibiotics in water. Biochar was prepared from orange peel (OB) and spent coffee grounds (SCB). To fabricate chitosan-biochar composites, chitosan and biochar were crosslinked with glutaraldehyde. Results showed that pH, adsorbent dosage, time, temperature, and initial concentrations have a significant impact on the SMX adsorption. The adsorption data was better described by Langmuir (with good regression) than Freundlich model. The highest adsorption capacity (Qmax) of SMX on OB, SCB, CTS-OB, and CTS-SCB were 3.49, 7.65, 7.24, and 14.73 mg/g, respectively. The Freundlich constant (KF) values for adsorption capacity were 1.66, 1.91, 2.57, and 5.57 (mg1-nLn/g), respectively, for OB, SCB, CTS-OB, and CTS-SCB. Ion exchange, π bonding, hydrogen bonding and pore filling, were proposed as dominant mechanisms of SMX removal process.