Geopolymers with a high percentage of bottom ash for solidification/immobilization of different toxic metals

Santa, Rozineide A. Antunes Boca; Soares, Cíntia; Riella, Humberto Gracher

doi:10.1016/j.jhazmat.2016.06.059

Cited by 90 publications

(22 citation statements)

References 21 publications

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“…As described above in the FTIR analysis, a variety of carbonates, aluminosilicate hydroxy compounds and other substances may show ion exchange and molecular polymerization activity in the reaction system under the hydration of cement‐based mineral polymers. Previous studies 28,34 also exhibited similar expressions. This characteristic of cement could be used for heavy metals and other harmful substances in solid waste solidification disposal.…”

Section: Resultssupporting

confidence: 73%

Cement solidification/stabilization of the toxicants from spent commercial SCR catalyst

Kong

Bao

et al. 2020

J of Chemical Tech & Biotech

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BACKGROUNDThe present work focuses on a harmless treatment of hazardous substances in spent commercial selective catalytic reduction (SCR) catalyst by using cement as a binder. The spent V2O5‐WO3/TiO2 SCR catalysts were ground and mixed with the cement to prepare the solidified products, according to a simple method in this study. The solidified products were subsequently submitted to a characterization process based on inductively coupled plasma mass spectrometry (ICP‐MS), X‐ray diffraction (XRD), X‐ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and N2 adsorption–desorption analysis. The leaching characteristics of hazardous substances, such as V, As, Cr and Pb, in solidified products were studied and the effects of mixed ratio between deactivated SCR catalyst and cement on leaching characteristics of hazardous substances were investigated.RESULTSThe experimental results showed that the cement was effective in immobilizing hazardous substances (V, As, Cr and Pb) present in the spent catalyst. When the cement hardened with 50% spent catalyst addition, the solidified products exhibited extremely low leaching concentrations of V, As, Cr and Pb, which are 0.6, 1.3, 2.3 mg L−1 and 16.5 μg L−1, respectively.CONCLUSIONThe leaching toxicity of hazardous substances is far lower than that of the National Standard of China and European regulations. The characterization analysis revealed that the active silicate sand hydroxyl compounds play an important role in immobilizing hazardous substances in spent SCR catalyst. The cement solidification method was expected to achieve the harmless treatment on spent SCR catalyst for the first time. © 2020 Society of Chemical Industry (SCI)

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Section: Resultssupporting

confidence: 73%

Cement solidification/stabilization of the toxicants from spent commercial SCR catalyst

Kong

Bao

et al. 2020

J of Chemical Tech & Biotech

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“…Geopolymers have been paid more attention by researchers and industry. A great amount of research focuses on the possibility of using for the synthesis of geopolymers fly ash [ 2 ], red mud [ 3 ], biomass ash [ 4 ], heavy metal waste [ 5 ], and recycled glass [ 6 ]. Geopolymer materials are gaining ground due to their excellent properties and sustainable.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Dudek

Sitarz

2020

Materials

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The inorganic structure formed at the stage of setting of the geopolymer binder ensures high durability of the material under high-temperature conditions. However, changes in the microstructure of the material are observed. The purpose of the study was to analyze changes in the structure of geopolymer mortar after exposure to high temperatures T = 200, 400, 600, 800, and 1000 °C. Mortars with a binder based solely on fly ash (FA) and mixed in the 1:1 ratio with a binder containing fly ash and ground granulated blast-furnace slag (GGBFS) were tested. The descriptions of their microstructures were prepared based on digital microscope observations, scanning electron microscope (SEM) observations, EDS (energy dispersive spectroscopy) analysis, and mercury intrusion porosimetry (MIP) porosity test results. Changes in the material due to high temperature were observed. The differences in the microstructure of the samples are also visible in the materials that were not exposed to temperature, which was influenced by the composition of the materials. Porosity increases with increasing annealing temperature. The distribution of individual pores also changes. In both materials, the proportion of pores larger than 1000 nm increases with the temperature increase. Moreover, the number of cracks and their width also increases, reaching 20 µm in the case of GGBFS. Furthermore, the color of geopolymers has changed. The obtained results extend the current state of knowledge in the field of changes in the microstructure of geopolymers subjected to high temperature.

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“…They are obtained from a chemical reaction between a binding component (the source of aluminosilicates) and an alkaline activator, usually a blend of caustic alkalis or alkaline salts. For their synthesis, raw materials such as metakaolin, calcined clays, or industrial wastes, such as fly ash or slags, have been used (Boca Santa et al, 2016;Borges et al, 2016;Logesh Kumar and Revathi, 2016;Boca Santa et al, 2017;Bai et al, 2019). Bottom ashes from municipal solid waste incineration can also have an application in these materials because they can be alkali activated when mixed with metakaolin (Lancellotti et al, 2013;Lancellotti et al, 2014;Lancellotti et al, 2015;Silva et al, 2017;Wongsa et al, 2017;Huang et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Alkali-Activated Binders From Waste Incinerator Bottom Ashes and Metakaolin Reinforced by Recycled Carbon Fiber Composites

et al. 2020

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In view of creating low-impact materials for the building industry, the fostering of alkaliactivated binder gains high importance. Metakaolin can successfully be activated with alkalis at room temperature, but the contemporary use of wastes to create mixed binders can further increase the environmental benefits. Bottom ashes obtained from the incineration of municipal solid wastes have been tentatively mixed in different amounts to develop matrix with acceptable mechanical properties, which still can be cured at room temperature. Moreover, scraps obtained from the production of epoxy/carbon fiber composites are employed as a reinforcing phase. No chemical or physical treatments have been used to modify the epoxy/carbon fiber wastes, apart from size reduction, thus minimizing the overall economic and energy impact of the process. The workability, physical and mechanical properties, microstructure, and porosity of the obtained materials are investigated. Up to a 50 weight percent of bottom ashes from municipal solid waste incineration can be mixed with metakaolin. Fibers still embedded in the epoxy matrix disclose a fair interaction with the matrix, thus managing to increase flexural strength, toughness, and dimensional stability without decreasing the compressive strength.

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Geopolymers with a high percentage of bottom ash for solidification/immobilization of different toxic metals

Cited by 90 publications

References 21 publications

Cement solidification/stabilization of the toxicants from spent commercial SCR catalyst

Cement solidification/stabilization of the toxicants from spent commercial SCR catalyst

Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Alkali-Activated Binders From Waste Incinerator Bottom Ashes and Metakaolin Reinforced by Recycled Carbon Fiber Composites

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