Synthesis of a MnO2/Fe3O4/diatomite nanocomposite as an efficient heterogeneous Fenton-like catalyst for methylene blue degradation.

Zishun Li,Xuekun Tang,Yueyang Xu,Kun Liu,Qian Peng,Jing Huang,Minlin Ao

doi:10.3762/bjnano.9.185

Abstract

Heterogeneous Fenton-like catalysts with the activation of peroxymonosulfate (PMS), which offer the advantages of fast reaction rate, wide functional pH range and cost efficiency, have attracted great interest in wastewater treatment. In this study, a novel magnetic MnO2/Fe3O4/diatomite nanocomposite is synthesized and then used as heterogeneous Fenton-like catalyst to degrade the organic pollutant methylene blue (MB) with the activation of PMS. The characterization results show that the Fe3O4 nanoparticles and nanoflower-like MnO2 are evenly distributed layer-by-layer on the surface of diatomite, which can be readily magnetically separated from the solution. The as-prepared catalyst, compared with other Fenton-like catalysts, shows a superb MB degradation rate of nearly 100% in 45 min in the pH range of 4 to 8 and temperature range of 25 to 55 °C. Moreover, the nanocomposite shows a good mineralization rate of about 60% in 60 min and great recyclability with a recycle efficiency of 86.78% after five runs for MB. The probable mechanism of this catalytic system is also proposed as a synergistic effect between MnO2 and Fe3O4.

Highlights

Organic contaminants are widely distributed in water and soil due to the excessive emissions of industrial processes, which causes a great threat to the ecosystem as well as to human health [1,2,3]
Most of the organic pollutants are toxic and can not be degraded spontaneously, various methods focusing on the removal of organic pollutant, including adsorption, photocatalysis and advanced oxidation processes, have been extensively studied over the past decades [2,4,5]
The original characteristic peaks of magnetite are weakened. This indicates that the nano-MnO2 covering on the Fe3O4/diatomite is of low crystallinity or amorphous

Summary

Introduction

Organic contaminants are widely distributed in water and soil due to the excessive emissions of industrial processes, which causes a great threat to the ecosystem as well as to human health [1,2,3]. In order to solve the problem, loading the catalysts on appropriate carriers to form a core–shell composite is the most effective strategy [14] Through this strategy, catalysts with controllable particle size, better dispersion and decreased agglomeration are easy to be synthesized and are expected to significantly increase the contact between active sites and contaminants. We propose a novel nanocomposite of magnetic MnO2/ Fe3O4/diatomite as an efficient heterogeneous Fenton-like catalyst for PMS activation. Dried Fe3O4/diatomite was added into 70 mL water and stirred vigorously for 30 min with subsequent ultrasound dispersion for 5 min, followed by dissolving 0.35 g KMnO4 into the mixture. The MnO2/Fe3O4/diatomite nanocomposite was obtained after washing with water and drying in vacuum at 60 °C

Characterization methods

Results and Discussion

Evaluation of catalytic performance

Conclusion