Ultrasensitive QCM sensor development for monitoring of methyl orange dye in aqueous phase based on novel cross-linked chitosan/PVA/GO/Ce-ZnO nanocomposite film

Abstract

In this study, chitosan/polyvinyl alcohol (CS/PVA) nanocomposite hydrogels were produced using the solution casting method due to their non-toxic and biocompatible nature. The best composition was chosen and cross-linked with glutaraldehyde, after which a certain amount of graphene oxide nanosheets (GO NS) and cerium doped zinc oxide nanoparticles (Ce-ZnO NPs) were added to develop nanocomposite hydrogel films (NCs). X-ray diffractometer (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), N2 adsorption–desorption isotherm, Raman spectroscopy, and thermogravimetric analyzer (TGA/DTG) were used to characterize the films. The synthesized composites were also evaluated for sensitivity towards methyl orange (MO) dye based on the quartz crystal microbalance (QCM) technique at different pH of MO solution. XRD results revealed that all films whether CS film or the blend CS/PVA/GO and CS/PVA/GO/Ce-ZnO films exhibited good crystallinity. The SEM images depicted the surface morphology of films, which clarified the adding effect of GO NS and Ce-ZnO NPs on the surface morphology of CS/PVA films. While the EDS analysis demonstrated the elemental composition of CS/PVA/GO/Ce-ZnO film. In the same context, the TEM images emphasized the results obtained by the SEM examination and showed no phase separation of the polymers. Whereas AFM showed an increase in surface roughness with adding of GO NS, while was decreased in the case of Ce-ZnO NPs addition. Surface area and pore size distribution results revealed significant differences due to the addition of GO NS and Ce-ZnO NPs to the CS/PVA matrix. The chemical structure of all films was investigated using the Raman shift and their thermal behaviours were also analysed. Finally, the results of QCM sensor-based prepared films showed that the inclusion of GO NS and Ce-ZnO NPs boosted the monitoring performance of sensor films towards MO dye. Furthermore, the sensors-based nanocomposite films presented the same monitoring attitude for MO at different pH.