Fabrication of Green Synthesized SnO₂–ZnO/Bentonite Nanocomposite for Photocatalytic Degradation of Organic Dyes

This paper proposes a simple and environmentally friendly method for the green synthesis of SnO₂–ZnO/bentonite nanocomposite in the presence of Acroptilon repens flower extract as a reducing and stabilizing agent. The synthesized nanocomposite was characterized using various techniques to investigate their structural properties and morphology. The photocatalytic degradation of the organic dye, eriochrome black-T (EBT) under solar irradiation and in the presence of synthesized nanocomposite was investigated. The results indicated that the nanoparticles were well immobilized onto bentonite as a support with minimum agglomeration. Moreover, the results of photocatalytic reactions showed that SnO₂–ZnO/bentonite nanocomposite could remove the dyes in just 2.5 h and the degradation efficiencies approached 100% indicating the excellent performance of the catalyst. The kinetic study revealed that degradation of EBT in presence of the SnO₂–ZnO/bentonite nanocomposite obeys first-order kinetics with the rate constant of 1.75 × 10^–2 min⁻¹. Furthermore, the biosynthesized nanocomposite exhibited a stable performance and high tolerance to the reaction conditions and was reused in three cycles with negligible loss of activity.