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

Abstract

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 X-ray 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 × 10−8 - 2 × 10−7 M with a limit of detection (LOD) of 1.07 × 10−8 M for copper ions. The results indicated satisfactory adsorption and successful detection of Cu2+ at trace concentrations.

Keywords

• Colorimetric chemosensor
• Cu (II)-Imprinted polymer
• Naked-eye detection
• Nanofiber
• PVA/Chitosan
• Adsorption