Silver nanoparticles anchored TiO₂ nanotubes prepared using saponin extract as heterogeneous and recyclable catalysts for reduction of dyes

In the present study, we made an effort to synthesize silver nanoparticles anchored onto TiO₂ nanotubes using saponin extracted from Simarouba glauca oil seed meal. Obtained silver anchored TiO₂ nanotubes (Ag-TiO₂) were characterized using spectroscopic, microscopic and X‐ray diffraction techniques and used as catalysts for reduction of nitrophenol (NP), Methylene blue (MB), Methyl orange (MO) and Congo red (CR). The reduction reactions were carried out in aqueous medium in presence of NaBH₄ at room temperature. Progress of the catalytic reaction was observed by decolorization of the dye solution and monitored by recording UV–Vis spectra. It was observed that Ag-TiO₂ nanotubes emerged as an effective catalyst in reducing the dyes in the time range of 2–7 min with pseudo first-order kinetics and also effective in the simultaneous reduction of all dyes in 12 min. In addition, the catalyst showed a good recovery yield with unaffected catalytic efficiency up to ten cycles.