Single and multicomponent adsorption of amoxicillin, ciprofloxacin, and sulfamethoxazole on chitosan-carbon nanotubes hydrogel beads from aqueous solutions: Kinetics, isotherms, and thermodynamic parameters

Abstract

The removal of antibiotics in water receiving bodies is an integral part in eradicating antimicrobial resistance which has become a major threat to public health. Solid-liquid adsorption has demonstrated to be an effective technique in the removal of antibiotics from aqueous environments. Herein, chitosan-carbon nanotube (chitosan-CNT) hydrogel beads were synthesised for the adsorption of amoxicillin (AMX), ciprofloxacin (CIP) and sulfamethoxazole (SMX) from aqueous solution. Adsorption kinetics, isotherms and thermodynamic parameters were systematically investigated at a solution pH of 7. Single adsorption kinetics findings suggest that experimental data for AMX, CIP and SMX was better fitted by the nonlinear pseudo-first order model with calculated maximum adsorption capacities of 23.1 mg.g−1, 23.7 mg.g−1 and 25.17 mg.g−1, respectively. Moreover, findings from the Weber-Morris kinetic model suggest that multiple processes were limiting the overall adsorption rate of AMX, CIP and SMX on chitosan-CNT. Adsorption isotherm results indicated that single adsorption experimental data was better fitted by the nonlinear Freundlich isotherm model, while binary and ternary system experimental data were better fitted by the nonlinear competitive extended Sips adsorption isotherm models. Moreover, results for binary and ternary adsorption showed that multicomponent adsorption systems exhibited both antagonistic and synergistic adsorption of AMX, CIP and SMX. From the thermodynamics fundings, it was evident that the adsorption of AMX, CIP and SMX from solution is an endothermic process governed by both physical and chemical adsorption mechanisms. Based on the findings of the current study, it was concluded that chitosan-CNT has potential as a green technology for the removal of antibiotics from solution.