Activation of Fe3O4/bentonite through anchoring of highly dispersed and photo-reduced Cu ions for higher pH fenton-like degradation and effective adsorption of Congo red dye

Abstract

Recently, highly dispersed metal catalysts have gained considerable attention due to active catalytic sites' enhanced exposure for efficient metal-based heterogeneous catalysis. Herein, we report the synthesis of highly dispersed photo-reduced Cu(I) clusters on Fe3O4/bentonite (FB) and amine-modified FB (-N-FB) for efficient Fenton-like catalysis. For that, Cu(II) ions were first chelated by surface heteroatoms of FB (in addition to the ion exchange mechanism), followed by photoinduced reduction to Cu(I). Both products (Cu1-FB and Cu1-N-FB) efficiently degrade Congo red dye while exhibiting high kinetic constants of 0.027 and 0.059 m−1 for Cu1-FB and Cu1-N-FB, respectively. In addition, the investigation of the dye adsorbing capability of the products demonstrated the maximum adsorption capacity of 600 and 610 mg/g for Cu1-FB and Cu1-N-FB, respectively. Results suggested that adsorption followed the Langmuir isotherm model, which operated spontaneously through physical interactions. Both adsorption and degradation reactions were repeated to demonstrate the reusability of the products, which yielded promising results, and the adsorption and degradation mechanisms were proposed with the help of Fourier transform infrared spectroscopy (FTIR) and high-resolution mass spectrometry (HRMS).