The performance of TiO2/NaY-zeolite nanocomposite in photocatalytic degradation of Microcystin-LR from aqueous solutions: Optimization by response surface methodology (RSM)

Abstract

Background: Microcystin (MC) is a hepatotoxic and carcinogenic toxin that is generated by cyanotoxins which can have adverse effects on the human health. Therefore, it is very important to remove it from the environment. This study was performed to investigate the efficiency of titanium dioxide (TiO2)/NaY-zeolite (T/N-Z) nanocomposite for removal of MC-LR under ultraviolet light. Methods: In the present study, T/N-Z nanocomposite was synthesized using the hydrothermal method. Specification of the photocatalysts was determined by the field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) spectra. The response surface methodology (RSM) was used to survey the effects of operating variables such as pH, contact time, and catalyst dose on the removal of MC-LR. The MC-LR concentration was measured by high-performance liquid chromatography (HPLC). Results: It was revealed that the increase of contact time and catalyst dose had a positive effect on enhancing the removal efficiency of MC-LR, but pH had a negative effect. Finally, the maximum MC-LR removal efficiency was 97.63, which occurred at pH = 5, contact time = 120 min, and catalyst dose = 1.2 g/L. Conclusion: In general, T/N-Z composite in aqueous solutions under the UV light can easily decompose MC-LR and it can also be proposed as an efficient composite for removal of MC-LR from contaminated water.