scholarly journals Coal Fly Ash Ceramics: Preparation, Characterization, and Use in the Hydrolysis of Sucrose

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Ricardo Pires dos Santos ◽  
Jorge Martins ◽  
Carlos Gadelha ◽  
Benildo Cavada ◽  
Alessandro Victor Albertini ◽  
...  
Keyword(s):  
Fly Ash ◽  
Surface Area ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Coal Ash ◽  
Mineralogical Composition ◽  
Degree Of Hydrolysis ◽  
High Degree ◽  
Hydrolysis Of

Coal ash is a byproduct of mineral coal combustion in thermal power plants. This residue is responsible for many environmental problems because it pollutes soil, water, and air. Thus, it is important to find ways to reuse it. In this study, coal fly ash, obtained from the Presidente Médici Thermal Power Plant, was utilized in the preparation of ceramic supports for the immobilization of the enzyme invertase and subsequent hydrolysis of sucrose. Coal fly ash supports were prepared at several compaction pressures (63.66–318.30 MPa) and sintered at 1200°C for 4 h. Mineralogical composition (by X-ray diffraction) and surface area were studied. The ceramic prepared with 318.30 MPa presented the highest surface area (35 m2/g) and amount of immobilized enzyme per g of support (76.6 mg/g). In assays involving sucrose inversion, it showed a high degree of hydrolysis (around 81%) even after nine reuses and 30 days’ storage. Therefore, coal fly ash ceramics were demonstrated to be a promising biotechnological alternative as an immobilization support for the hydrolysis of sucrose.

scholarly journals Composition and Morphology Characteristics of Magnetic Fractions of Coal Fly Ash Wastes Processed in High-Temperature Exposure in Thermal Power Plants

2019 ◽  
Vol 9 (9) ◽  
pp. 1964 ◽  
Author(s):  
Dinh-Hieu Vu ◽  
Hoang-Bac Bui ◽  
Bahareh Kalantar ◽  
Xuan-Nam Bui ◽  
Dinh-An Nguyen ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Combustion Process ◽  
Mineralogical Composition ◽  
Striking Difference ◽  
Thermal Power Plants ◽  
Power Stations ◽  
Magnetic Components

Coal-fired power stations are one of the primary sources of power generation in the world. This will produce considerable amounts of fly ash from these power stations each year. To highlight the potential environmental hazards of these materials, this study is carried out to evaluate the characterization of fly ashes produced in thermal power plants in northern Vietnam. Fly ash was firstly fractionated according to size, and the fractions were characterized. Then, each of these fractions was analyzed with regard to their mineralogical features, morphological and physicochemical properties. The analytical results indicate a striking difference in terms of the characteristics of particles. It was found that magnetic fractions are composed of magnetite hematite and, to a lower rate, mullite, and quartz. Chemical analyses indicate that the non-magnetic components mainly consist of quartz and mullite as their primary mineral phases. As the main conclusion of this research, it is found that the magnetic and non-magnetic components differ in terms of shape, carbon content and mineralogical composition. In addition, it was found that magnetic components can be characterized as more spheroidal components compared to non-magnetic ones. This comprehensive characterization not only offers a certain guideline regarding the uses of different ash fractions but it will also provide valuable information on this common combustion process.

scholarly journals CONVERSION OF COAL FLY ASH TO ZEOLITE-BASED IRON OXIDE MAGNETIC NANOCOPOSITES BY MODIFIED FUSION-HYDROTHERMAL SYNTHESIS

2020 ◽  
pp. 30-35
Author(s):  
Silviya Boycheva ◽  
Denitza Zgureva
Keyword(s):  
Magnetic Properties ◽  
Iron Oxide ◽  
Fly Ash ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Coal Ash ◽  
Low Temperature Processing ◽  
Oxide Phases ◽  
Stage Synthesis

Coal fly ash generated in Thermal Power Plants is utilized for synthesis of zeolites due to its aluminosilicate composition. The highest degree of zeolitization of coal ash in a particular zeolite phase is achieved by double-stage synthesis involving successive alkaline melting and hydrothermal activation of the reaction mixtures, while the uniform distribution of the iron oxides transferred from the raw coal ash is ensured by ultrasonic treatment. However, the applied melting step results in the oxidation of the magnetic iron oxide phases to non-magnetic ones, which results in the loss of magnetic properties of the resulting materials. The present investigation focuses on an improved double- stage synthesis procedure by the addition of raw coal ash containing magnetite between high temperature and low temperature processing. In this way, the magnetic phase is retained in the final product and the magnetic properties of the zeolites are preserved, which is important for their application in the adsorption of pollutants from wastewater.

scholarly journals Processing of high-grade zeolite nanocomposites from solid fuel combustion by-products as critical raw materials substitutes

2020 ◽  
Vol 7 ◽  
pp. 22
Author(s):  
Silviya Boycheva ◽  
Denitza Zgureva ◽  
Hristina Lazarova ◽  
Katerina Lazarova ◽  
Cyril Popov ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Raw Materials ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Coal Ash ◽  
High Grade ◽  
Fly Ash Zeolite ◽  
By Products ◽  
Critical Raw Materials

High-grade zeolite nanocomposites are synthesized utilizing solid by-products from combustion of coal for energy production in Thermal Power Plants applying alkaline aging, hydrothermal and fusion-hydrothermal activation procedures. The obtained coal ash zeolites were studied with respect to their chemical and phase composition, morphology, surface parameters and thermal properties. It was found that they are distinguished in nanocrystalline morphology and significant content of iron oxide nanoparticles (γ-Fe2O3, α-Fe2O3, γ-Fe3O4) and doping elements (Cu, Co, Mn, V, W, etc.) transferred from the raw coal ash, and therefore they are assumed as nanocomposites. Coal fly ash zeolite nanocomposites are characterized by a mixed micro-mesoporous texture, significant concentration of acidic Brønsted centers due to their high surface insaturation, high chemical and thermal stabilty. This unique combination of compositional and textural properties predetermines the application of these materials as catalysts for thermal oxidation processes, anticorrosion barrier coatings, carbon capture adsorbents, matrices for hosting functional groups, detergents etc. Examples for coal fly ash zeolite applications for substitution of critical raw materials in practice are provided.

scholarly journals Preparation of Synthetic Zeolites from Coal Fly Ash by Hydrothermal Synthesis

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1267
Author(s):  
David Längauer ◽  
Vladimír Čablík ◽  
Slavomír Hredzák ◽  
Anton Zubrik ◽  
Marek Matik ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Product Analysis ◽  
Coal Combustion Products ◽  
X Ray ◽  
Wide Range ◽  
Silica Alumina

Large amounts of coal combustion products (as solid products of thermal power plants) with different chemical and physical properties cause serious environmental problems. Even though coal fly ash is a coal combustion product, it has a wide range of applications (e.g., in construction, metallurgy, chemical production, reclamation etc.). One of its potential uses is in zeolitization to obtain a higher added value of the product. The aim of this paper is to produce a material with sufficient textural properties used, for example, for environmental purposes (an adsorbent) and/or storage material. In practice, the coal fly ash (No. 1 and No. 2) from Czech power plants was firstly characterized in detail (X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), particle size measurement, and textural analysis), and then it was hydrothermally treated to synthetize zeolites. Different concentrations of NaOH, LiCl, Al2O3, and aqueous glass; different temperature effects (90–120 °C); and different process lengths (6–48 h) were studied. Furthermore, most of the experiments were supplemented with a crystallization phase that was run for 16 h at 50 °C. After qualitative product analysis (SEM-EDX, XRD, and textural analytics), quantitative XRD evaluation with an internal standard was used for zeolitization process evaluation. Sodalite (SOD), phillipsite (PHI), chabazite (CHA), faujasite-Na (FAU-Na), and faujasite-Ca (FAU-Ca) were obtained as the zeolite phases. The content of these zeolite phases ranged from 2.09 to 43.79%. The best conditions for the zeolite phase formation were as follows: 4 M NaOH, 4 mL 10% LiCl, liquid/solid ratio of 30:1, silica/alumina ratio change from 2:1 to 1:1, temperature of 120 °C, process time of 24 h, and a crystallization phase for 16 h at 50 °C.

scholarly journals Zeolite Synthesis from Brazilian Coal Fly Ash for Removal of Zn2+ and Cd2+ from Water

2011 ◽  
Vol 356-360 ◽  
pp. 1900-1908 ◽  
Author(s):  
Juliana De Carvalho Izidoro ◽  
Denise Alves Fungaro ◽  
Shao Bin Wang
Keyword(s):  
Fly Ash ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Metal Ion ◽  
Raw Materials ◽  
Coal Fly Ash ◽  
Mineralogical Composition ◽  
Batch Process ◽  
Metal Ion Removal

A Brazilian fly ash sample (CM1) was used to synthesize zeolites by hydrothermal treatment. Products and raw materials were characterized in terms of real density (Helium Pycnometry), specific surface area (BET method), morphological analysis (SEM), chemical composition (XRF) and mineralogical composition (XRD). The zeolites (ZM1) from fly ash were used for metal ion removal from water. Results indicated that hydroxy-sodalite zeolite could be synthesized from fly ash sample. The zeolite presented higher specific surface area and lower SiO2/Al2O3ratio than the ash precursor. The adsorption showed that cadmium is more preferentially adsorbed on ZM1 than zinc. The adsorption equilibrium time for both Zn2+and Cd2+was 20 hours in a batch process. The adsorption isotherms were better fitted by the Langmuir model and the highest percentages of removal using ZM1 were obtained at pH 6 and 5 and doses of 15 and 18 g L-1for Zn2+and Cd2+, respectively. Thermodynamic studies indicated that adsorption of Zn2+and Cd2+by ZM1 was a spontaneous, endothermic process and presented an increase of disorder at the interface solid/solution.

POSSIBLE USE OF FLY ASH IN CERAMIC INDUSTRIES: AN INNOVATIVE METHOD TO REDUCE ENVIRONMENTAL POLLUTION

2013 ◽  
Vol 22 ◽  
pp. 99-102 ◽  
Author(s):  
GAYATRI SHARMA ◽  
S. K. MEHLA ◽  
TARUN BHATNAGAR ◽  
ANNU BAJAJ
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Fine Particles ◽  
Thermal Power ◽  
Coal Ash ◽  
Natural Soil ◽  
Thermal Power Plants ◽  
Silica Alumina ◽  
Near Future ◽  
Land Water

The process of coal combustion results in coal ash, 80% of which is very fine in nature & is thus known as fly ash. Presently, in India, about 120 coal based thermal power plants are producing about 90-120 million tons of fly ash every year. With increase in demand of power energy, more and more thermal power plants are expected to commission in near future and it is expected that fly ash generation will be 225 million tons by 2017. Disposal of fly ash requires large quantity of land, water and energy and its fine particles, if not disposed properly, by virtue of their weightless, can become air born and adversely affect the entire Environment. These earth elements primarily consist of silica, alumina & iron etc. and its physicochemical parameters are closely resembles with volcanic ash, natural soil etc. These properties, therefore, makes it suitable for use in ceramic industries and helps in saving the environment and resources.

Coal Fly Ash as a Dual Site Material for Cr(VI) Adsorption: Comparation between Single Site and Dual Site Isotherm Models

2015 ◽  
Vol 1101 ◽  
pp. 149-152
Author(s):  
Widi Astuti ◽  
Triastuti Sulistyaningsih ◽  
Dewi Selvia Fardhyanti
Keyword(s):  
Fly Ash ◽  
Active Sites ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Single Site ◽  
Unburned Carbon ◽  
Isotherm Models ◽  
Equilibrium Data ◽  
Dual Site

The major problem in coal-based thermal power plants is related to solid waste called coal fly ash (CFA). CFA is mainly composed of some oxides including SiO2, Al2O3 having active site and unburned carbon as a mesopore that enables it to act as a dual site adsorbent for heavy metals including Cr (VI). To get different characters of dual site, CFA was treated by sulfuric acid (H2SO4) at different concentrations, temperatures and reaction time. Furthermore, treated CFA were used as an adsorbent to adsorb Cr (VI) in aqueous solutions. Equilibrium data were evaluated by single site and dual site isotherm models. It can be concluded, although unburned carbon contributes on the Cr (VI) adsorption, the existence of unburned carbon decreases the amount of Cr (VI) adsorbed because unburned carbon can plug active sites where dominant adsorption occurs. However, dual site isotherm model yielded excellent fit with equilibrium data.

scholarly journals Recent Advances in Methods for Recovery of Cenospheres from Fly Ash and Their Emerging Applications in Ceramics, Composites, Polymers and Environmental Cleanup

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1067
Author(s):  
Virendra Kumar Yadav ◽  
Krishna Kumar Yadav ◽  
Vineet Tirth ◽  
Ashok Jangid ◽  
G. Gnanamoorthy ◽  
...  
Keyword(s):  
Fly Ash ◽  
Mechanical Strength ◽  
Power Plants ◽  
Agricultural Land ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Value Added ◽  
Thermal Power Plants ◽  
Environmental Cleanup ◽  
High Mechanical Strength

Coal fly ash (CFA) is a major global pollutant produced by thermal power plants during the generation of electricity. A significant amount of coal fly ash is dumped every year in the near vicinity of the thermal power plants, resulting in the spoilage of agricultural land. CFA has numerous value-added structural elements, such as cenospheres, plerospheres, ferrospheres, and carbon particles. Cenospheres are spherical-shaped solid-filled particles, formed during the combustion of coal in thermal power plants. They are lightweight, have high mechanical strength, and are rich in Al-Si particles. Due to cenospheres’ low weight and high mechanical strength, they are widely used as ceramic/nanoceramics material, fireproofing material, and in nanocomposites. They are also used directly, or after functionalization, as an adsorbent for environmental cleanup—especially for the removal of organic and inorganic contaminants from wastewater. By utilizing this waste material as an adsorbent, the whole process becomes economical and eco-friendly. In this review, we have highlighted the latest advances in the cenospheres recovery from fly ash and their application in ceramics and wastewater treatment.

scholarly journals Dissolution kinetics of South African coal fly ash and the development of a semi-empirical model to predict dissolution

2015 ◽  
Vol 21 (2) ◽  
pp. 319-330 ◽  
Author(s):  
Lawrence Koech ◽  
Ray Everson ◽  
Hein Neomagus ◽  
Hilary Rutto
Keyword(s):  
Fly Ash ◽  
Surface Area ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Dissolution Kinetics ◽  
Product Layer ◽  
Bet Surface Area ◽  
X Ray ◽  
Shrinking Core ◽  
Coal Power Plants

Wet flue gas desulphurization (FGD) is a crucial technology which can be used to abate the emission of sulphur dioxide in coal power plants. The dissolution of coal fly ash in adipic acid is investigated by varying acid concentration (0.05-0.15M), particle size (45- 150?m), pH (5.5-7.0), temperature (318-363K) and solid to liquid ratio (5-15 wt %.) over a period of 60 minutes which is a crucial step in wet (FGD). Characterization of the sorbent was done using X-ray fluorescence (XRF), X-ray diffraction (XRD), Furrier transform infrared (FTIR), scanning electron microscope (SEM) and Branauer-Emmett-Teller (BET) surface area. BET surface area results showed an increase in the specific surface area and SEM observation indicated a porous structure was formed after dissolution. The experimental data was analyzed using the shrinking core model and the diffusion through the product layer was found to be the rate limiting step. The activation energy for the process was calculated to be 10.64kJ/mol.

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