Simultaneous Sorption of Ciprofloxacin and Amoxicillin on Chitosan Composites from Aqueous Solutions: Kinetics and Isotherms

Abstract

The occurrence of pharmaceutical compounds, particularly antibiotics, in treated water has posed a significant toxic health risk to humans, fauna, and flora. This is ascribed to the inability of conventional wastewater treatment plants to completely eradicate these contaminants of environmental concern during treatment. Despite the effectiveness of the solid-liquid adsorption process in the removal of antibiotics and other pharmaceutical compounds (PCs), studies on simultaneous adsorption of PCs are scanty. As such, the present work is focusing on investigating the simultaneous sorption of ciprofloxacin and amoxicillin on chitosan carbon nanotubes (CCNT) composites. The model adsorbent demonstrated affinity in the order amoxicillin > ciprofloxacin for the binary sorption system. The observed high affinity in terms of amoxicillin was ascribed to the hydrophobic nature of amoxicillin (logKow = 0.87) compared to ciprofloxacin (logKow = 0.28). It is worth noting that the solution pH demonstrated to have a significant effect on the speciation distribution of the model contaminants. Moreover, the nonlinear pseudo-first-order kinetic model best fitted the data for single adsorption (R 2 ≥ 0.948) and the Extended Langmuir isotherm model (R 2 ≥ 0.903) was the selected model to predict the simultaneous sorption of ciprofloxacin and amoxicillin on CCNT from aqueous solution. As such, CCNT demonstrated to be an effective adsorbent for the simultaneous sorption of antibiotics from aqueous solutions.