Photocatalytic degradation of RB dye by CdS-decorated nanocomposites based on polyaniline and hydrolyzed pectin: Isotherm and kinetic

Abstract

In this work a grafted copolymer of polyaniline (PANi) and hydrolyzed pectin (HPEc) (HPEc-g-PANi) and its nanocomposites with CdS and modified CdS (mCdS) nanoparticles (CdS@HPEc-g-PANi and mCdS@HPEc-g-PANi) were prepared by heterogeneous chemical copolymerization and were characterized by different analyses of FTIR, 1HNMR, Raman and UV/vis for structural, XRD, SEM, TEM and EDX-map for morphological, EDX for elemental and TGA, DSC and DMTA for thermo-mechanical characterizations. The SEM images demonstrated a nanocauliflower, nanorod and nanospherical-like growth for the copolymer and nanocomposites respectively. An uniform distribution and more homogeneous morphology for mCdS@HPEc-g-PANi due to better dispersion of CdS nanaoparticles was approved by the SEM analyses. The XRD patterns showed good crystallinity of the CdS nanostructures in mCdS@HPEc-g-PANi owing to better dispersion of the CdS nanoparticles. The TEM and elemental mapping images indicated the contribution of CdS nanoparticles in the nanocomposites. The electrical conductivity was assayed to study the effect of electrical conductivity of the polymeric matrix on photodegradation of dye. The samples were investigated in terms of the adsorption and photocatalytic activity of RB dye and adsorption isotherms and kinetic. Higher dye removal efficiency was attained for the nanocomposites compared to the copolymer owing to photocatalytic activity of CdS nanoparticles. Due to the efficient charge transfer between PANi and CdS in mCdS@HPEc-g-PANi, a proficient dye removal (up to 86%) was obtained for the mCdS@HPEc-g-PANi, which it is consistent with its high electrical conductivity (up to 2.86 × 10−2 S cm−1) as compared to other samples. The adsorption studies confirmed more conformity of the samples with Freundlich isotherm and pseudo-second-order kinetic model. Our research work, displays that by designing polymeric nanocomposites of CdS nanoparticles, the photocatalytic degradation activity for RB dye can be effectively enhanced.