Multi-walled carbon nanotube coupled β-Cyclodextrin/PANI hybrid photocatalyst for advance oxidative degradation of crystal violet

Abstract

Here we report a material β-CD/PANI/MWCNTs prepared through oxidative free radical polymerization of aniline (C6H5NH2) monomer in the presence of β-CD and MWCNTs. Indigenous analytical techniques like SEM, TEM, XRD, XPS, UV–vis, and FTIR were analyzed for the characterization of the material. The principle utility of the material was extrapolated towards the visible light-mediated photodegradation of crystal violet (CV) dye. The optimized values of process variables like radiation time 120 min, pH of the dye solution as pH 5, photocatalyst dose as 15 mg, and the concentration of CV as 135 mg L−1 were taken form RSM-CCD model at 298 K temperature. The desirability of the experiment was found to be D = 0.95 with qe, exp = 179.25 mg g−1 (93.54%) and qe, cal = 184.76 mg g−1 (95.39%) of CV degradation. The bandgap energy (Eg) of the material using Tauc's plot was found to be 3.2 eV. Benzoic acid (BA) as a trapping agent decreases the photodegradation capacity drastically suggesting the major role of •OH− radical as reactive oxidant (RO) for the CV degradation. The rate-determining step, as suggested by the pseudo-first-order model in heterogeneous catalysis, follows the adsorption of CV molecule on β-CD/PANI/MWCNTs surface and thereby their dissipation through reactive OH• radicals. The values of first-order rate constants (K1) having values of 0.014, 0.015, 0.016, 0.018 and 0.019 min−1 and a t1/2 values of 49.5, 46.2, 43.3, 38.5 and 36.5 min were calculated for 30, 60, 90, 120 and 135 mg L−1 of CV with 15 mg of photocatalyst.