Synthesis of novel Bi2O3–montmorillonite nanocomposite with enhanced photocatalytic performance in dye degradation

• Bi2O3–montmorillonite nanocomposites synthesized by intercalation method.
• Bi2O3–montmorillonite is a potentially suitable catalyst for photodegradation of CR under visible light irradiation.
• Bi2O3–montmorillonite nanocomposites with high mineralization efficiency, high stability and recyclability act as potential material for the photodegradation of CR.

Novel Bi2O3–montmorillonite nanocomposite photocatalyst was synthesized and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Effect of Bi2O3 intercalation with montmorillonite clay on photocatalytic performance of Bi2O3–montmorillonite under visible light irradiation was systematically investigated. The results indicate that Bi2O3–montmorillonite shows enhanced adsorption and photocatalytic performance for Congo red (CR) removal under visible light irradiation. Higher rate of light absorption and lower rate electron–hole pair recombination are responsible for the increase in photocatalytic efficiency. Adsorption of CR on Bi2O3–montmorillonite follows pseudo-second-order kinetics and the adsorption isotherm follows Freundlich isotherm. The monolayer capacity was observed to be 500 mg g−1. The maximum percentage removal achieved upto 86.4% at pH 9 for 2 g L−1 photocatalyst dose. Photocatalytic degradation of CR by Bi2O3–montmorillonite proceeds via advanced oxidative process.