Preparation and characterization of NZVI–MCM-48 mesoporous molecular sieves and its mechanism for treatment of methylene blue wastewater

Abstract

The nanoscale zero valent iron (NZVI) and ordered mesoporous molecular sieve Mobil Composition of Matter No. 48 (MCM-48) composite material (NZVI–MCM-48) were prepared by the hydrothermal treatment at 120°C for 36 h and then drying at 100°C of synthetic solution with a mole ratio of silica, cobalt, cetyltrimethylammonium bromide (CTAB), sodium hydroxide, sodium fluoride, and water is l:0.01:0.65:0.5:0.1:71 to get the NZVI–MCM-48 raw powder which was then treated by roasting in a nitrogen atmosphere to release the surfactant and by high temperature carbonization and reduction. The existence of NZVI in the composite material and its orderliness, form, and element composition were analyzed by characterization means such as X-ray diffractometer (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The orthogonal degradation experiment for treating methylene blue (MB) wastewater by the composite material led to a 853 mg/g decolorization rate of MB and a 821 mg/g chemical oxygen demand (COD) removal rate under the optimal conditions including an initial concentration of wastewater of 10 mg/L, an initial pH of 6, a concentration of the added sample of 0.8 g/L, and a reaction time of 60 min. The degradation mechanism for MB wastewater is also discussed.

Keywords:

• NZVI–MCM-48 mesoporous molecular sieve
• Hydrothermal synthesis
• Methylene blue
• Degradation mechanism

Acknowledgment

The authors greatly acknowledge the Foundation of Shanghai Science and Technology Commission (No. 071605122) for financial support.