Facile strategy for the synthesis of non-covalently bonded and para-toluene sulfonic acid-functionalized fibrous polyaniline@graphene-PVC nanocomposite for the removal of Congo red

This paper reports a simple route for the generation of fibrous polyvinyl chloride (PVC) and graphene (GN) fibers (GN-PVC). The prepared fibrous GN-PVC was functionalized further with para-toluene sulfonic acid (pTSA) and polyaniline (Pani) to obtain pTSA-Pani@GN-PVC fibers with high functionality. The resulting fibers were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, UV-vis diffuse absorbance spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction. The synthesized fibers were used for the adsorption of Congo red (CR) dye from aqueous solutions at different solution pH, initial dye concentrations and temperatures. Langmuir, Freundlich and Temkin isotherm models were applied to determine the interaction between the synthesized fibers and CR. The adsorption efficacy of the pTSA-Pani@GN-PVC composite fiber for the removal of CR was 4.43 and 2.51 times higher than that of the PVC and GN-PVC fibers, respectively. Thermodynamic studies showed that the adsorption of CR onto all the fibers was exothermic in nature and that the spontaneity decreased with increasing solution temperature.