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

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.

A novel carbon nanotube–magnesium oxide composite with excellent recyclability to efficiently activate peroxymonosulfate for Rhodamine B degradation

“…Advanced oxidation processes (AOPs), based on the generation of highly reactive oxygen species [e.g., hydroxyl radical ( Á OH), superoxide anion radical (O 2 Á-), sulfate radical (SO 4 Á-), and singlet oxygen ( 1 O 2 )], have attracted much attention because it can achieve complete mineralization and degradation of organic pollutants instead of simple separation [2][3][4].…”

“…Generally, activating PMS to produce reactive oxygen species requires energy input in the form of light [6], heat [7] and ultrasound [8] [as presented in Eq. 1], or catalytic reaction from catalysts [4,9], and so on. Among the developed activation methods, transitional metal-containing catalysts (e.g., M = Ag, Fe, Mn, Co, and V) were considered as promising routes without energy inputs [as presented in Eq.…”

“…Although transition metal-containing catalysts have achieved good degradation efficiency, their practical applications are limited because of the secondary pollution of dissolved transition metals in the process [12,13]. In order to solve these problems, some researchers have used various porous supporters to load transition metal oxides, which can actually enhance the catalytic performance and reduce the leaching rate of transition metal ions [4,14,15]. Besides, various eco-friendly and metalfree heterogeneous catalysts with high catalytic performance for PMS appear in people's field of vision [16,17].…”

High-Efficiency Catalysis of Peroxymonosulfate by MgO for the Degradation of Organic Pollutants

“…Through extensive research on the removal of various organic pollutants, many treatment methods have been developed, such as physical methods (adsorption, coagulation, and membrane separation), chemical methods (ozone oxidation, electrochemical and wet oxidation, and advanced catalytic oxidation), and biological methods (aerobic biological treatment, anaerobic biological treatment, and anaerobic-aerobic combined biological treatment) [5][6][7]. Among these methods, advanced oxidation process (AOP) is considered to be the most promising method because of its high removal efficiency and wide range of applications [8].…”

“…Liu's group catalyzed PMS by supporting Fe 3 O 4 nanoparticles and nanoflower-like MnO 2 layer by layer on the surface of porous diatomite or silica nanofiber. The high specific area of the core-shell nanocomposites made it easier for PMS and organic pollutants to contact with the catalysts, and the synergistic effect between MnO 2 and Fe 3 O 4 increased the activation performance of the catalysts [8,19,20]. Huang's group reported iron-copper bimetal doped mesoporous g-Al 2 O 3 catalyzed PMS to effectively degrade 4-chlorophenol, finding that the Al-O-Fe and Al-O-Cu bonds formed by Fe and Cu doping into the framework of g-Al 2 O 3 were the key structures for high activity of the catalyst [21].…”