Toxic Effect of Fly Ash on Biological Environment

Kozhukhova, N. I.; Lebedev, M S; Vasilenko, Marina; Гончарова, Е. Н.

doi:10.1088/1755-1315/272/2/022065

Cited by 5 publications

(3 citation statements)

References 7 publications

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“…Given that fly ash is a residual material, an environmental study has been carried out to characterize the product more completely in order to make a better evaluation about its possible uses as construction materials. In particular, the influence of low-calcium fly ash products on life activities of flora and fauna has already been investigated ( Kozhukhova et al, 2019 ), observing a negative effect onto the ecosystem due to release of the ions such as Na + , Cl – , and SO 3 2– as well as CaO. Nevertheless, the use of fly ash as a major component in geopolymer binders assumes the physical–chemical encapsulation with consequent prevention of the release of toxic cations and ions into the environment ( Kozhukhova et al, 2015 ).…”

Section: Discussionmentioning

confidence: 99%

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C

et al. 2022

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Alkali-activated foams (AAFs) are inorganic porous materials that can be obtained at temperatures well below 100°C with the use of inorganic wastes as aluminosilicate precursors. In this case, fly ash derived from a Slovenian power plant has been investigated. Despite the environmental benefits per se, due to saving of energy and virgin materials, when using waste materials, it is of extreme importance to also evaluate the potential leaching of heavy metal cations from the alkali-activated foams. This article presents an environmental study of a porous geopolymer derived from this particular fly ash, with respect to the leachability of potentially hazardous elements, its environmental toxicity as determined by biological testing, and the environmental impact of its production. In particular, attention was focused to investigate whether or not 1,000°C-fired alkali-activated fly ash and metakaolin-based foams, cured at 70°C, are environmentally friendlier options compared to unfired ones, and attempts to explain the rationale of the results were done. Eventually, the firing process at 1,000°C, apart from improving technical performance, could reinforce heavy metal cation entrapment within the aluminosilicate matrix. Since technical performance was also modified by addition of different types of activators (K-based or Na-based), as well as by partial replacement of fly ash with metakaolin, a life cycle assessment (LCA) analysis was performed to quantify the effect of these additions and processes (curing at 70°C and firing at 1,000°C) in terms of global warming potential. Selected samples were also evaluated in terms of leaching of potentially deleterious elements as well as for the immobilization effect of firing. The leaching test indicated that none of the alkali-activated material is classified as hazardous, not even the as-received fly ash as component of new AAF. All of the alkali-activated foams do meet the requirements for an inertness. The highest impact on bacterial colonies was found in samples that did not undergo firing procedures, i.e., those that were cured at 70°C, which induced the reduction of bacterial Enterococcus faecalis viability. The second family of bacteria tested, Escherichia coli, appeared more resistant to the alkaline environment (pH = 10–12) generated by the unfired AAMs. Cell viability recorded the lowest value for unfired alkali-activated materials produced from fly ash and K-based activators. Its reticulation is only partial, with the leachate solution appearing to be characterized with the most alkaline pH and with the highest ionic conductivity, i.e., highest number of soluble ions. By LCA, it has been shown that 1) changing K-based activators to Na-based activators increases environmental impact of the alkali-activated foams by 1%–4% in terms of most of the impact categories (taking into account the production stage). However, in terms of impact on abiotic depletion of elements and impact on ozone layer depletion, the increase is relatively more significant (11% and 18%, respectively); 2) replacing some parts of fly ash with metakaolin also results in relatively higher environmental footprint (increase of around 1%–4%, while the impact on abiotic depletion of elements increases by 14%); and finally, 3) firing at 1,000°C contributes significantly to the environmental footprint of alkali-activated foams. In such a case, the footprint increases by around one third, compared to the footprint of alkali-activated foams produced at 70°C. A combination of LCA and leaching/toxicity behavior analysis presents relevant combinations, which can provide information about long-term environmental impact of newly developed waste-based materials.

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Section: Discussionmentioning

confidence: 99%

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C

et al. 2022

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“…Geopolymer concrete (GPC) has the advantages of environmental protection and energy savings, as well as mechanical properties close to or better than OPC concrete (OPCC) [ 16 , 17 , 18 , 19 , 20 ]. Besides, GPC will show higher temperature resistance on some structures, compared to OPCC [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Nano-SiO2 Reinforced Geopolymer Concrete under the Coupling Effect of a Wet–Thermal and Chloride Salt Environment

Jin

Zhang

et al. 2022

Polymers

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In this study, the mechanical behaviors of nano-SiO2 reinforced geopolymer concrete (NS-GPC) under the coupling effect of a wet–thermal and chloride salt environment were investigated through a series of basic experiments, and a simulation on the coupling effect of a wet–thermal and chloride salt environment and SEM test were also included. During the experiments for the coupling effect of the wet–thermal and chloride salt environment, an environment simulation test chamber was utilized to simulate the wet–thermal and chloride salt environment, in which the parameters of relative humidity, temperature, mass fraction of NaCl solution and action time were set as 100%, 45 °C, 5% and 60 d, respectively. The content of nano-SiO2 (NS) particles added in geopolymer concrete (GPC) were 0, 0.5%, 1.0%, 1.5% and 2.0%. The result indicated that the mechanical properties of NS reinforced GPC decreased under the coupling effect of the wet–thermal and chloride salt environment compared to the control group in the natural environment. When the NS content was 1.5%, the cube and splitting tensile strength, elastic modulus and impact toughness of GPC under the coupling environment of wet–thermal and chloride salt were decreased by 9.7%, 9.8%, 19.2% and 44.4%, respectively, relative to that of the GPC under the natural environment. The addition of NS improved the mechanical properties of GPC under the coupling effect of the wet–thermal and chloride salt environment. Compared to the control group without NS, the maximum increment in cube compressive strength, splitting tensile strength and elastic modulus of NS–GPC under the coupling effect of the wet–thermal and chloride salt environment due to the incorporation of NS reached 25.8%, 9.6% and 17.2%, respectively. Specifically, 1.5% content of NS increased the impact toughness, impact numbers of initial crack and the ultimate failure of GPC by 122.3%, 109% and 109.5%, respectively.

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“…However, lately, some studies highlighted the environmental impact of geopolymers and their main components. The production of industrial materials, such as fly ash used in the production of geopolymer material, showed a lower rate of toxicity when compared to the production of OPC [248,249]. The use of optimization techniques for producing geopolymer materials has not been extensively studied yet.…”

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confidence: 99%

Scientometric Analysis of Global Research on the Utilization of Geopolymer Composites in Construction Applications

et al. 2023

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This study conducts a scientometric review on the use of geopolymer mortar and composites in different construction applications. It aims to analyze the findings of past research and reveal the research constituents, development trends, and knowledge gaps. The Scopus database was employed to retrieve the relevant publications, while Bibliometrix was used to conduct the statistical analyses. Results revealed a steady and gradual increase in the number of publications after 2013, as the annual growth rate increased from 23.9% to 45.2% between the timeframes 2003–2013 and 2014–2022, respectively. The analysis highlighted that many authors collaborated on different construction applications of geopolymers regardless of geographic location. Meanwhile, Construction and Building Materials, China, and Universiti Malaysia Perlis were found to be the predominant journal, country, and institution, respectively. The scientometric analysis showed that the most frequently investigated applications for geopolymer mortars and composites were fire resistance, corrosion protection, and repair. Research gaps highlighted that other applications are not as well investigated despite the promising performance of the geopolymer composites, including 3D printing, heavy metals absorption, environmental protection, and underwater applications. Future research is required to assess the use of other alumina and silica-rich binders in geopolymers while also exploring their lifecycle assessment and economic impact.

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Toxic Effect of Fly Ash on Biological Environment

Cited by 5 publications

References 7 publications

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C

Mechanical Properties of Nano-SiO2 Reinforced Geopolymer Concrete under the Coupling Effect of a Wet–Thermal and Chloride Salt Environment

Scientometric Analysis of Global Research on the Utilization of Geopolymer Composites in Construction Applications

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