Metal-based mesoporous materials and their application as catalysts for the degradation of methyl orange azo dye

Abstract

Cobalt, manganese and copper heterogeneous catalysts were prepared using MCM-41 and SBA-16 mesoporous supports. The synthesized materials were characterized by X-ray diffraction, chemical analysis, N2 sorptometry, vibrational spectroscopy and transmission electron microscopy. Their catalytic activity was studied in the oxidative degradation of methyl orange (MO) in aqueous solution, at pH 6, using persulfate (PS) anion as oxidant at 30°C. The level of degradation of the dye was monitored by UV–vis spectroscopy and Total Organic Carbon (TOC) analysis. The synthesized materials showed high activity, being the most effective catalysts those based on Co and Cu, achieving an efficient dye decolorization of >95% until 2h of reaction. After 24h of reaction a high degree of mineralization was achieved (>70%). Radical quenching studies showed that sulfate radicals are the main species formed by the catalyst/PS interaction. The supported catalysts exhibited stable performance during the reusability test, reaching an activity greater than 90% up to the fifth evaluated cycle of reuse for copper and cobalt based catalysts.