scholarly journals Hybrid Geopolymers from Fly Ash and Polysiloxanes

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3510 ◽  
Author(s):  
Giuseppina Roviello ◽  
Laura Ricciotti ◽  
Antonio Jacopo Molino ◽  
Costantino Menna ◽  
Claudio Ferone ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Hybrid Materials ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Synthetic Strategy ◽  
Thermoelectric Power Plants ◽  
First Time ◽  
By Products

The preparation and characterization of innovative organic-inorganic hybrid geopolymers, obtained by valorizing coal fly ash generated from thermoelectric power plants, is reported for the first time. These hybrid materials are prepared by simultaneously reacting fly ash and dimethylsiloxane oligomers at 25 °C in a strongly alkaline environment. Despite their lower density, the obtained materials are characterized by highly improved mechanical properties when compared to the unmodified geopolymer obtained without the use of polysiloxanes, hence confirming the effectiveness of the applied synthetic strategy which specifically aims at obtaining hybrid materials with better mechanical properties in respect to conventional ones. This study is an example of the production of new materials by reusing and valorizing waste raw resources and by-products, thus representing a possible contribution towards the circular economy.

scholarly journals Hybrid Fly Ash-Based Geopolymeric Foams: Microstructural, Thermal and Mechanical Properties

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2919 ◽  
Author(s):  
Giuseppina Roviello ◽  
Laura Ricciotti ◽  
Antonio Jacopo Molino ◽  
Costantino Menna ◽  
Claudio Ferone ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Circular Economy ◽  
Coal Fly Ash ◽  
Silicate Solution ◽  
Thermal And Mechanical Properties ◽  
Blowing Agent ◽  
Materials Used

This research investigates the preparation and characterization of new organic–inorganic geopolymeric foams obtained by simultaneously reacting coal fly ash and an alkali silicate solution with polysiloxane oligomers. Foaming was realized in situ using Si0 as a blowing agent. Samples with density ranging from 0.3 to 0.7 g/cm3 that show good mechanical properties (with compressive strength up to ≈5 MPa for a density of 0.7 g/cm3) along with thermal performances (λ = 0.145 ± 0.001 W/m·K for the foamed sample with density 0.330 g/cm3) comparable to commercial lightweight materials used in the field of thermal insulation were prepared. Since these foams were obtained by valorizing waste byproducts, they could be considered as low environmental impact materials and, hence, with promising perspectives towards the circular economy.

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 Synthesis of Geopolymers from Mechanically Activated Coal Fly Ash and Improvement of Their Mechanical Properties

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 791
Author(s):  
Mitsuaki Matsuoka ◽  
Kaho Yokoyama ◽  
Kohei Okura ◽  
Norihiro Murayama ◽  
Masato Ueda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Mechanical Activation ◽  
Power Plants ◽  
Raw Materials ◽  
Coal Fly Ash ◽  
Fine Powder ◽  
Acid Resistance ◽  
Curing Conditions ◽  
Long Time

Coal fly ash is a spherical fine powder by-product discharged from coal-fired power plants. When coal fly ash is used as raw materials for the synthesis of geopolymers, there are practical problems associated with the stable surface of the particles that do not allow the production of geopolymers with sufficient strength. A long-time is also required for the curing. In this study, we aim to promote the curing reaction of geopolymers by activating the surface of coal fly ash particles. By mechanically activating the surface of coal fly ash particles using an attrition-type mill, the dissolution of Si4+ and Al3+ in coal fly ash is promoted, and the acceleration of the reaction taking place during curing is also anticipated. The surface morphology and crystal phase of coal fly ash particles change with the use of an attrition-type mill. The mechanical activation results in improvement of the compressive strength and the acid resistance under milder curing conditions by the densification of the hardened body. Thus, it is clearly shown that mechanical activation is effective for the production of geopolymers with beneficial mechanical properties under milder curing conditions.

scholarly journals Development and mechanical properties of low fired bricks from drinking water sludge and fly ash

2021 ◽  
Vol 880 (1) ◽  
pp. 012042
Author(s):  
Z A Rahman ◽  
A S M Suhaimi ◽  
W M R Idris ◽  
T Lihan
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Drinking Water ◽  
Fly Ash ◽  
Water Absorption ◽  
Raw Material ◽  
Volume Changes ◽  
Fired Bricks ◽  
By Products

Abstract Demand for water and energy supply has dramatically increased the amount of drinking water sludge (DW) and fly ash (FA) annually. These wastes should be properly managed and disposed to protect any potential contamination to surrounding ecosystem. Both by-products can be potentially recycled as raw material for brick development. This study aimed to examine the influence of fly ash content on mechanical properties of drinking water sludge brick at low firing temperature of 500°C. Different ratios of FA content were added to the DWS ranged between 0 and 45%. Brick sample was moulded in 215 mm x 102.5 mm x 65 mm dimension. Samples were air-dried prior to firing at 500°C for 3 hours in a furnace. Basic characterization of DW and FA showed pH of 5.76 and 10.1 with organic contents of 8.42% and 1.14%, respectively. Clay and silt fractions were dominant in DWS while silt more apparent than sand and clay in FA. The volume changes and water absorption of the brick samples decreased with increasing FA content. For the water absorption of the brick increased back as 40% of FA content. The density and compressive strength dropped with the increasing amount of FA. The compressive strength of brick experienced with sulphate attack also decreased with increasing FA content. The results suggested that further study are needed to improve the compressive strength of the studied bricks.

UTILIZATION OF COAL FLY ASH FROM POWER PLANTS - I. ASH CHARACTERIZATION

2008 ◽  
Vol 7 (3) ◽  
pp. 289-293 ◽  
Author(s):  
Maria Harja ◽  
Marinela Barbuta ◽  
Lacramioara Rusu ◽  
Nicolae Apostolescu
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Coal Fly Ash

Synthesis and characterization of coal fly ash supported zinc oxide catalyst for biodiesel production using used cooking oil as feed

2021 ◽  
Vol 170 ◽  
pp. 302-314
Author(s):  
Adeyinka S. Yusuff ◽  
Aman K. Bhonsle ◽  
Jayati Trivedi ◽  
Dinesh P. Bangwal ◽  
Lok P. Singh ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Fly Ash ◽  
Oxide Catalyst ◽  
Coal Fly Ash ◽  
Biodiesel Production ◽  
Synthesis And Characterization ◽  
Cooking Oil ◽  
Used Cooking Oil

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 Extraction and Mass Spectrometric Characterization of Terpenes Recovered from Olive Leaves Using a New Adsorbent-Assisted Supercritical CO2 Process

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1301
Author(s):  
Zully J. Suárez Montenegro ◽  
Gerardo Álvarez-Rivera ◽  
Jose A. Mendiola ◽  
Elena Ibáñez ◽  
Alejandro Cifuentes
Keyword(s):  
Aluminum Oxide ◽  
Silica Gel ◽  
Supercritical Co2 ◽  
Olive Leaves ◽  
Fractionation Process ◽  
Selective Enrichment ◽  
Adsorption Desorption ◽  
First Time ◽  
By Products

This work reports the use of GC-QTOF-MS to obtain a deep characterization of terpenoid compounds recovered from olive leaves, which is one of the largest by-products generated by the olive oil industry. This work includes an innovative supercritical CO2 fractionation process based on the online coupling of supercritical fluid extraction (SFE) and dynamic adsorption/desorption for the selective enrichment of terpenoids in the different olive leaves extracts. The selectivity of different commercial adsorbents such as silica gel, zeolite, and aluminum oxide was evaluated toward the different terpene families present in olive leaves. Operating at 30 MPa and 60 °C, an adsorbent-assisted fractionation was carried out every 20 min for a total time of 120 min. For the first time, GC-QTOF-MS allowed the identification of 40 terpenoids in olive leaves. The GC-QTOF-MS results indicate that silica gel is a suitable adsorbent to partially retain polyunsaturated C10 and C15 terpenes. In addition, aluminum oxide increases C20 recoveries, whereas crystalline zeolites favor C30 terpenes recoveries. The different healthy properties that have been described for terpenoids makes the current SFE-GC-QTOF-MS process especially interesting and suitable for their revalorization.

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