Efficient removal of the ciprofloxacin drug using an electrospun Co/Al-layered double hydroxide-embedded chitosan/polyvinylidene fluoride nanofiber membrane

Abstract

The contamination of water by antibiotics due to the persistence and bioaccumulation of pharmaceutical compounds such as ciprofloxacin (CIP) is an environmental issue of great concern. This study focused on developing multifunctional nanofiber membranes by incorporating an Al/Co-layered double hydroxide (Co/Al-LDH) into a chitosan/polyvinylidene fluoride (CS/PVDF) matrix via the electrospinning technique for the efficient removal of CIP from water. The hybrid membrane synergized the high anion exchange and redox properties of Co/Al-LDH, the functionality brought about by the amino and hydroxyl groups in chitosan, and the stability provided by polyvinylidene fluoride. This led to the development of Co/Al-LDH–CS/PVDF with many active sites for adsorption by means of hydrogen bonding, electrostatic attraction, metal-ligand coordination, and fluorine-related interactions. Its full characterization via FT-IR, BET, XRD, SEM-EDX, XPS and 2D correlation FT-IR analyses validated the successful integration of Co/Al-LDH into the polymeric nanofibers and elucidated the adsorption mechanisms at the molecular level. Batch studies revealed a very high maximum adsorption capacity of 352.6 mg g⁻¹ with rapid equilibrium at 40 min, pH-sensitive performance with the optimum pH of 6 and the adsorption being endothermic and spontaneous in nature. The isotherms and kinetic studies revealed that the adsorption process was predominantly monolayer chemisorption with a secondary contribution from multilayer interactions. Furthermore, response surface methodology (RSM) was actively employed for optimizing the operational parameters for practical applications. These membranes also have stability and the potential for reusability, as well as multifunctional biomedical applications. This shows that the Co/Al-LDH–CS/PVDF nanofiber membrane can be used effectively as a large-scale and sustainable adsorbent for treating pharmaceutical wastewater.