Catalytic degradation of methylene blue in aqueous solution using cobalt oxide kaolin nanocomposite

Abstract

Textile dye pollution of water is becoming a major cause of pollution in the environment and a threat to aquatic ecology. In this work, a kaolin-cobalt oxide nanocomposite was used to catalyze the degradation of methylene blue (MB) dye in an aqueous solution. The composite was prepared by oxidizing cobalt ions adsorbed onto readily available, inexpensive, and easily pretreated kaolin surfaces, forming kaolin-supported cobalt oxide nanoparticles. By using ultraviolet-visible spectroscopy, scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller, Transmission emission spectroscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy, the synthesized materials’ morphology, structure, surface area, and ion interaction were all examined. The characterization results demonstrated that cobalt oxide-NPs were successfully growing on the surface of kaolin. MB dye was used as a model dye in batch tests to better understand the catalytic degradation performance of the prepared catalyst. The significance of cobalt oxide nanoparticles and the strong catalytic activity of the produced cobalt oxide nanoparticles/kaolin composite toward MB dye degradation were validated by the catalytic oxidation experiments. The degradation results showed that removing MB dye from an aqueous solution could be successfully enhanced by increasing the cobalt oxide NP content on the kaolin surface through repeated cycles. The pseudo-first-order kinetic model fits the kinetic analysis of the catalyst’s MB dye degradation. After five reuse cycles, over 96% removal efficiency persisted, indicating the remarkable resilience and reusability of the composite. To sum up, the kaolin composite supported by cobalt oxide nanoparticles was discovered to be a promising catalyst with exceptional catalytic activity to degrade a model dye, MB, concentration of 50 ppm from the aqueous solution in the presence of NaOCl by above 99% catalytic removal efficiency in 12 min at operating temperature of 45 °C with the oxidation rate constant, koxd, of 0.38 min− 1.