Enhanced decolorization of azo dye solution by cadmium sulfide/multi-walled carbon nanotubes/polymer composite in combination with hydrogen peroxide under simulated solar light irradiation

Cadmium sulfide/multi-walled carbon nanotubes/polymer nanocomposite (CdS/MWCNTs/polymer) was fabricated via a facile precipitation process by depositing nanocrystalline CdS on carbon nanotubes/crosslinked chitosan nanocomposite and characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). Under simulated solar light irradiation, a combination of CdS/MWCNTs/polymer and H2O2 was found to be highly efficient for photocatalytic decolorization of a soluble azo dye, methyl orange (MO), even at neutral pH values. 99.9% of MO solution was successfully decolorized after 90 min under simulated solar light irradiation with 15 mg L−1 of initial MO concentration, 1.0 mM of H2O2 concentration and 0.70 g L−1 of photocatalyst dosage. Experimental results also indicated that the photocatalytic decolorization of methyl orange solution was strongly influenced by operational parameters and followed a simplified Langmuir–Hinshelwood (L–H) kinetic model with high R2 values. When the CdS/MWCNTs/polymer–H2O2 system was reused for the 5th time, the decolorization efficiency was still about 88.0% after 90 min under simulated solar light irradiation. As a result, the CdS/MWCNTs/polymer–H2O2 will potentially provide cheaper and cleaner means for the effective treatment of dyeing effluents since it increased substantially the efficiency of dye decolorization and could take full advantage of economical solar light.