Preparation of α-Fe2O3–TiO2/fly ash cenospheres photocatalyst and its mechanism of photocatalytic degradation

this work reveals a green combustion route for the synthesis of tio 2 , fe 2 o 3 and tio 2 -fe 2 o 3 nanocomposites as photocatalysts for decolorization of titan Yellow (tY) and Methyl orange (Mo) dyes at room temperature in aqueous solution concentration of 20 ppm under UV-light irradiation. We observed that the tio 2 -fe 2 o 3 nanocomposite shows superior photocatalytic activity for tY dye compared to pure tio 2 and fe 2 o 3 . Rate constant (k) values of tio 2 , fe 2 o 3 and tio 2 -fe 2 o 3 for tY and Mo are 0.0194, 0.0159, 0.04396 and 0.00931, 0.00772 0.0119 kmin −1 respectively. the surface area and pore volume of tio 2 -fe 2 o 3 nanocomposite were found to be 71.56 m 2 /g and 0.076 cm 3 /g, respectively as revealed by Bet studies. from the Barrett-Joyner-Halenda (BJH) plot, the mean pore diameter of tio 2fe 2 o 3 nanoparticles was found to be 2.43 nm. Further, the TiO 2 -fe 2 o 3 nanocomposite showed good electrochemical behavior as an electrode material for supercapacitors when compared to pure tio 2 and fe 2 o 3 nanoparticles resulted in stable electrochemical performance with nearly 100% coulombic efficiency at a scan rate of 10 mV/s for 1000 cycles. Interestingly, the novelty of this work is that the designed supercapacitors showed stable electrochemical performance even at 1000 th cycle, which might be useful for rechargeable supercapacitor applications. the electrochemical properties of the nanocomposites were compared by the data obtained by cyclic voltammograms, charge-discharge tests and electrochemical impedance spectroscopic studies. these results demonstrated that the tio 2fe 2 o 3 nanocomposite showed stable performance compared to tio 2 and fe 2 o 3 nanoparticles at current density of 5 Ag −1 .Recently electrochemical studies have gained significant attention due to energy and environment related issues. Since the discovery of TiO 2 and its applications as photo-anode for battery, splitting of water, supercapacitor, dye removal etc 1 ., many different metal oxides and electrodes have been explored to enhance the energy conversion efficiency. Amongst a variety of semiconductor metal oxides, hematite (α-Fe 2 O 3 ) was found to be a good anode material for supercapacitor application, which could be attributed to its high solar-to-hydrogen efficiency, encouraging optical band gap (~2 eV), outstanding chemical strength as well as ease of availability in the nature. However, α-Fe 2 O 3 exhibits low experimental performance compared with the theoretical values, which is possibly due to poor conducting and oxygen evolution properties in addition to short whole diffusion length. To overcome these problems, various synthetic methods have been tried in the recent past, to improve the experimental performance of α-Fe 2 O 3 .But, solution-based combustion method is a simple, low cost, energy saving, easy to control the surface morphology and particle size 2 . In addition, the materials prepared in this method are organic solvent free as we used water as solvent 3-5 .

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“…Fe 2 O 3 nanoparticles ability to remove MO dye was found to be 38.67% as shown in Fig. 8 [33][34][35][36] .…”

Section: Decolorization Of Titan Yellow (Ty) Andmentioning

confidence: 93%

Enhanced photocatalytic and electrochemical performance of TiO2-Fe2O3 nanocomposite: Its applications in dye decolorization and as supercapacitors

Kumar¹,

Abebe

Nagaswarupa

et al. 2020

Sci Rep

117

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“…The importance can be reflected in the following two aspects. On one hand, the holes on the catalyst surface can capture the electrons from the H 2 O molecule to form the active hydroxyl radical ( • OH) by , and • OH can subsequently react with Hg 0 to form HgO by . On the other hand, the photoexcited electrons and photoexcited holes from the irradiation of UV can convert the adsorbed H 2 O molecule into H + and OH – () .…”

Section: Effect Of External Fields and Ultraviolet Lightmentioning

confidence: 99%

“…The MF also shows a promotional effect on Hg 0 removal by fly ash . UV light is also widely applied in photocatalytic oxidation of Hg 0 over different photocatalysts due to its advantages of high catalytic oxidation efficiency and no secondary pollution. − As for the photocatalytic oxidation, fly ash had been widely applied as substrate for various photocatalysts for helping the separation and recycle of spent photocatalysts. − In addition to the application as substrate, it was found the removal of Hg 0 using fly ash was enhanced in the presence of the UV light at 150 °C . In summary, when fly ash was applied as the adsorbent and catalyst for Hg 0 removal, all the EF, MF, and UV affected the adsorption and oxidation of Hg 0 using fly ash to different extents, while relevant studies about the effects and mechanisms of EF, MF, and UV on Hg 0 removal by fly ash are still limited.…”

Section: Introductionmentioning

confidence: 96%

Mercury Removal Based on Adsorption and Oxidation by Fly Ash: A Review

Liu

Zhao

et al. 2020

Energy Fuels

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Mercury (Hg), in particular elemental mercury (Hg0) captured from coal-fired power plants, has attracted much attention because of its severe harm to human health and environment. Hg0 can be removed using the technology of adsorbent injection, and one of the promising adsorbents is fly ash. To evaluate the effect of complex multifactors of fly ash on Hg0 removal performance, this review summarizes, analyzes, and evaluates the quantitative effects of fly ash compositions, physical parameters, flue gas components, and modification reagents. The effects of electric field (EF), magnetic field (MF), and ultraviolet (UV) light on Hg0 removal using fly ash are also introduced. Unburned carbon (UBC) and Fe2O3 are two reactive components in fly ash for Hg0 oxidation. Physical parameters including higher specific surface area, larger total pore volume, and wider distribution of pores with well-developed micropores are beneficial for Hg0 retention, and no consistent relationship between particle size and Hg0 retention using fly ash has been obtained. While gas phase components including HCl, NO, and O2 promote the removal of Hg0 using fly ash, no agreement about the effects of SO2 and H2O vapor on Hg0 removal has been reached. The promotion of halogen-modified fly ash on Hg0 removal may be explained by the Langmuir–Hinshelwood mechanism, the Mars–Maessen mechanism, as well as the Eley–Ridel mechanism. The contribution of metal-modified fly ash to Hg0 removal is attributed to the oxidation ability of metal oxides as well as metal positive ions. EF, MF, and UV light enhance the oxidation of Hg0 using fly ash to different degrees. The promotion of EF may be attributed to the formation of more Cl, O, and OH radicals by a series of electron-induced reactions. The enhancement of MF is simultaneously attributed to the energy-level splitting of Hg0 as well as the magnetochemistry effect of magnetic materials in fly ash. The function of fly ash on the photocatalytic oxidation of Hg0 under the UV light has been verified, while relevant studies are still limited. More studies are still needed on the relationship between surface functional groups and carbon types, the control of Hg0 secondary emission from the spent fly ash, the development of fly ash-based products, the compromise between fly ash modification cost and Hg0 removal efficiency, and the effective and economical coremoval of Hg0, NO x , and SO x using fly ash. In particular, the promotional effects of EF, MF, and UV light on Hg0 removal necessitate extensive studies on their underlining mechanisms. This review resolves the existing controversies on the Hg0 removal mechanism and promotes the development of fly ash on Hg0 removal from coal combustion.

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“…Bismuth tungstate (Bi 2 WO 6 ), with suitable band gap and intrinsic structure, has captured considerable attention for its photocatalytic effect on pollutant decomposition under visible light irradiation [189] . However, the practical application of Bi 2 WO 6 is limited by its low photocarriers separation efficiency.…”

Section: The New Promising Semiconductors In Photo-degradation Of Dyesmentioning

confidence: 99%

Advances in Photo-catalytic Materials for Environmental Applications

Ra¹

2016

Res. Rev. J Mat. Sci

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INTRODUCTIONOver two thirds of Earth's surface is covered by water; less than a third is taken up by land. As Earth's population continues to grow, people are putting ever-increasing pressure on the planet's water resources. In a sense, our oceans, rivers, and other inland waters are being "squeezed" by human activities-not so they take up less room, but so their quality is reduced. Poorer water quality means water pollution. We know that pollution is a human problem because it is a relatively recent development in the planet's history: before the 19 th century Industrial Revolution, people lived more in harmony with their immediate environment. As industrialization has spread around the globe, so the problem of pollution has spread with it. When Earth's population was much smaller, no one believed pollution would ever present a serious problem. It was once popularly believed that the oceans were far too big to pollute. Today, with around 7 billion people on the planet, it has become apparent that there are limits. Pollution is one of the signs that humans have exceeded those limits.Water pollution can be defined in many ways. Usually, it means one or more substances have built up in water to such an extent that they cause problems for animals or people. Water pollution almost always means that some damage has been done to an ocean, river, lake, or other water source. A 1969 United Nations report defined ocean pollution as: "The introduction by man, directly or indirectly, of substances or energy into the marine environment (including estuaries) resulting in such deleterious effects as harm to living resources, hazards to human health, hindrance to marine activities, including fishing, impairment of quality for use of sea water and reduction of amenities."Most water pollution doesn't begin in the water itself. Take the oceans: around 80 percent of ocean pollution enters our seas from the land. Virtually any human activity can have an effect on the quality of our water environment. When farmers fertilize the fields, the chemicals they use are gradually washed by rain into the groundwater or surface waters nearby. Sometimes the causes of water pollution are quite surprising. Chemicals released by smokestacks (chimneys) can enter the atmosphere and then fall back to earth as rain, entering seas, rivers, and lakes and causing water pollution. That's called atmospheric deposition. Water pollution has many different causes like: Sewage, Nutrients, Chemical waste, radioactive waste, Oil pollution, Plastics and Alien species. The common pollutants include toxic organic compounds like chlorinated and non-chlorinated aliphatic and aromatic compounds, dyes, inorganic compounds like heavy metals, noxious gases like NO x , SO x , CO and NH 3 , and pathogens like bacteria, fungi and viruses. ABSTRACTThe growth of industry worldwide has extremely increased the generation and accumulation of waste by products. This has caused severe environmental problems that have become a major concern. Because of this, photo-catalytic polluta...

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Preparation of α-Fe2O3–TiO2/fly ash cenospheres photocatalyst and its mechanism of photocatalytic degradation

Cited by 30 publications

References 32 publications

Enhanced photocatalytic and electrochemical performance of TiO2-Fe2O3 nanocomposite: Its applications in dye decolorization and as supercapacitors

Enhanced photocatalytic and electrochemical performance of TiO2-Fe2O3 nanocomposite: Its applications in dye decolorization and as supercapacitors

Mercury Removal Based on Adsorption and Oxidation by Fly Ash: A Review

Advances in Photo-catalytic Materials for Environmental Applications

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