Highly selective and sensitive colorimetric chemosensor using PVA/chitosan ion-imprinted nanofibers for copper ion detection and removal

Herein, a highly efficient colorimetric chemosensor incorporating ion-imprinted electrospun nanofiber was developed for the removal and detection of Cu2+ ions. In this regard, PVA/chitosan composites were used as the polymeric matrix, and 1-(2-pyridylazo)-2-naphthol was employed for complex formation. The prepared naked-eye sensor was characterized using Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, and Xray diffraction analysis, revealing the morphological, structural, and molecular properties of the sensor. The results showed that the colorimetric chemosensor based on copper-imprinted nanofiber (Cu-INF) possesses higher selectivity for Cu2+ compared to interference ions. The selectivity coefficient (k) and relative selectivity coefficient (K ') indicated the selective behavior of Cu-INF in the adsorption of Cu2+ in binary systems including Cu2+/Co2+, Cu2+/Ni2+, and Cu2+/Zn2+. Furthermore, the ion-imprinted nanofiber was used for the preconcentration of copper ions, demonstrating a high adsorption capacity of 128.205 mg g- 1 for Cu2+. The equilibrium adsorption isotherm and adsorption kinetics of Cu2+ on Cu-INF followed the Freundlich adsorption isotherm and a pseudo-second-order model, respectively. The developed sensor exhibited a linear detection range of 5 x 10- 8 - 2 x 10- 7 M with a limit of detection (LOD) of 1.07 x 10- 8 M for copper ions. The results indicated satisfactory adsorption and successful detection of Cu2+ at trace concentrations.