A comparative study on dark adsorption of dyes using mesoporous MCM-41 catalyst

Abstract

Mobil composition of matter N. 41 (MCM-41) was investigated as a catalyst for the adsorption of methyl orange (MO) and setazol black (SB) under dark conditions. The MCM-41 catalyst was prepared via modified sol-gel method and fresh and spent catalysts were characterized by X-ray diffraction, scanning electron microscope, and Fourier-transform infrared spectroscopy. To examine the optimum conditions of dye adsorption, the catalyst dosage (0.2-1 g/L), contact time (5-240 min), and dye concentration (10-100 mg/L) were identified. The best performance showed that over 99.5% of methyl orange was removed in 60 min (concentration of dye = 20 mg/L, adsorbent dosage = 0.2 g/L, temperature = 22 degrees C). In case of SB, MCM-41 catalyst removed SB up to 95% under 60 min in 20 mg/L dye concentration. The MCM-41 catalyst was found to be more effective in removing MO through rather than SB with the help of the generation of reactive oxygen species. The spent catalysts characterization results concluded that the dark adsorption did not affect and announce a serious disorder on the pore structure of MCM-4. Consequently, the prepared MCM-41 presented a high catalytic efficiency and can be used especially for textile industry wastewater treatment applications at dark atmosphere in an energy-saving profile with no need of light irradiation.