Activation of persulfate by TiO۲-Fe۳O۴ nanocomposite for reactive red ۱۹۸ degradation along with modeling and optimization approach

Background: Recently, sulfate radical-based photocatalytic processes have attracted significant interests because of unique advantages in pollutants purification. In this study, TiO۲-Fe۳O۴ nanocomposites in the presence of persulfate and under ultraviolet light-emitting diode (UV-LED) irradiation were applied for reactive red ۱۹۸ removal with a focus on the main operating parameters such as pH, persulfate molar concentration, irradiation time, and catalyst dosages in different initial concentrations. Methods: The nanoparticles were synthesized by co-precipitation technique. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR) analysis were used to evaluate TiO۲- Fe۳O۴ nanocomposites. The response surface methodology (RSM) was employed for modeling and optimization. The kinetics and mechanisms of decolorization by sulfate and hydroxyl radicals were investigated. The mineralization of dye was evaluated using total organic carbon (TOC) analysis. Results: Modeling and optimization through RSM showed that the maximum decolorization of reactive red ۱۹۸ is accursed an initial concentration of ۱۰-۵۰ mg/L was reached under UV-LED irradiation of ۶۲-۸۵ min, persulfate concentration = ۰.۸-۱ mM, ۰.۱۹-۰.۳ g/L TiO۲-Fe۳O۴ nanocomposites concentration, and pH = ۳. The kinetics of process was in agreement with pseudo-first order. The mineralization of reactive red ۱۹۸ during the optimum conditions was determined at about ۶۱.۱% and ۴۹.۶%, meanwhile, the decolorization efficiency in the same conditions was approximately ۹۸.۱% and ۸۷.۶%, respectively. Conclusion: The use of TiO۲-Fe۳O۴ nanocomposites under UV-LED irradiation in the presence of persulfate can be used as an efficient and promising method for dye removal from textile wastewater.

Keywords:

Reactive red ۱۹۸ , Nanocomposites , Titanium dioxide , Wastewater