Possible applications of coal fly ash in wastewater treatment.

Ash based nanocomposites for photocatalytic degradation of textile dye pollutants: A review

Fly ash is readily available and cheaply generated as 47a by-product of the combustion of organic matter. A tremendous amount of fly ash is generated worldwide, and its disposal has imposed 47a severe environmental concern. Its good adsorption capacities attracted several researchers to study the use of fly ash as 47a support for photocatalysts for the degradation of contaminants from wastewater. Undoubtedly the photocatalysts supported on fly ash have represented excellent degradation efficiencies due to the synergistic effect of adsorption and photocatalytic capacity. The utilization of fly ash as 47a precursor has solved the problem of disposal and added value to the waste by-product. Various preparation techniques for fly ash-based nanocomposites such as the sol-gel method, hydrothermal method, solvothermal method, precipitation and co-precipitation, modified metalorganic decomposition, electrospinning, incipient impregnation, and wet chemical synthesis, along with 47a brief study of their characterization using scanning electron microscopy, X-ray diffraction technique and Fourier transform infrared (FTIR) spectroscopy, and the mechanism of photodegradation of dyes have been discussed in this paper. The literature shows that SiO2, TiO2, and Al2O3 present in fly ash play an essential role in the photodegradation of dyes. Factors affecting the degradation of dyes, their kinetic studies, and methods to enhance photodegradation efficiency have also been discussed.

Fly ash–based nanocomposites: a potential material for effective photocatalytic degradation/elimination of emerging organic pollutants from aqueous stream

Recycled cyanobacteria ashes for sono-enhanced photo-Fenton wastewater decontamination

Combined Adsorption/Photocatalytic dye removal by copper-titania-fly ash composite

The novel valorization of lignite combustion fly ashes in the development of ceramic substrates modified with ΤiΟ2 photocatalyst, with environmental benefits, was investigated. Disc-shaped compacts from fly ashes (either calcareous or siliceous) were sintered (1000 °C, 2 h), then coated with TiO2 slurry, and further thermally treated (400 and 500 °C, 1 h) to acquire TiO2 consistency onto the ceramic substrate. The ceramic microstructures were examined by XRD and SEM-EDAX. Their photocatalytic activity was examined in aqueous solutions of two organic dyes, methylene blue and methyl orange using visible and UV irradiation, with encouraging results. A synergistic effect between ash ceramic substrates and ΤiΟ2 enhances the properties of the final activated product. Pores occurring on the non-activated ash surface are to some extent covered by TiO2. As a result, the photocatalytic activity, rather than simple dye adsorption onto the surface of the coated substrates, is promoted leading to efficient dye decolorization. Higher dye removal is achieved in the case of methylene blue under cool daylight compared to methyl orange under UV (blacklight and blacklight blue). A major advantage of the process is the immobilization of TiO2 onto a cheap porous substrate, which can provide an alternative for the photocatalytic treatment of industrial effluents.

M. Volioti

Papers

Synthesis and characterization of lignite fly ash ceramic substrates coated with TiO 2 slurry, and evaluation in environmental applications