Catalytic activity of magnetite fish-scales and tea-waste as heterogeneous photo-Fenton catalysts for removal of methyl orange through Cu(Ⅱ) adsorption

Abstract

In this study, magnetite fish scales and tea waste (MFS and MTW) were first used to adsorb Cu(Ⅱ) cations (Cu-MFS and Cu-MTW) and were then applied as heterogeneous photo-Fenton catalysts to degrade methyl orange (MO) from an aqueous solution. The morphological and structural properties of the fabricated catalysts were characterized via SEM, XRD, EDX/MAP, VSM, BET and FTIR techniques. The effects of pH, catalyst dosage, initial concentration of MO, and the initial concentration of H2O2 on the degradation efficiency of MO were investigated. The degradation efficiency of MO through the use of MFS, Cu-MFS, MTW, and Cu-MTW in the photo-Fenton process was achieved 82.6%, 97.2%, 89.1%, and 96.9%, respectively, under optimum condition (pH of 3, 0.2 g/L of MFS and Cu-MFS and 0.4 g/L of MTW and Cu-MTW, an H2O2 concentration of 0.5 mM within 200 min). Additionally, the rate of degradation reactions followed the first-order kinetics. Catalytic action was assigned to the formation of hydroxyl radicals (OH•) via the reaction between H2O2 and Fe(II) and Cu(II) on the surface of Cu-MFS and Cu-MTW during the photo-Fenton process. Furthermore, not only did Cu-MFS and Cu-MTW exhibit negligible iron and copper leaching, but they also indicated long-term stability after three consecutive cycles.