Metal powders as foaming agents in fly ash based geopolymer synthesis and their impact on the structure depending on the Na /Al ratio

Kränzlein, E.; Pöllmann, Herbert; Krcmar, Wolfgang

doi:10.1016/j.cemconcomp.2018.02.009

Cited by 60 publications

(23 citation statements)

References 16 publications

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“…These materials might also ensure performance and environmental advantages over common insulating materials (e.g. polystyrene and polyurethane foams) since they possess much higher thermal stability [16] and may be produced using mainly/solely industrial wastes as solid precursors [17,18] instead of nonrenewable fossil fuels. One particularly interesting approach to produce lightweight AAM is through the use of lightweight aggregates, especially if natural aggregates [19] are employed, instead of synthetic or non-renewable aggregates [20,21].…”

Section: Introductionmentioning

confidence: 99%

Multifunctional cork – alkali-activated fly ash composites: A sustainable material to enhance buildings’ energy and acoustic performance

Novais

Carvalheiras

Senff

et al. 2020

Energy and Buildings

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This work evaluates, for the first time, the possibility of producing multifunctional alkali-activated composites combining ultra-low density, low thermal conductivity, high acoustic absorption, and good moisture buffering capacity. The composites were prepared using cork as a lightweight aggregate. This novel material might promote energy savings and tackle the CO 2 emissions of the building sector, while simultaneously improve the comfort for inhabitants (e.g. humidity levels regulation and sound pollution reduction). The composites apparent density (as low as 168 kg/m 3 ) and thermal conductivity (as low as 68 mW/m K) are amongst the lowest ever reported for alkali-activated materials (AAM) composites and foams, while their sound absorption ability is comparable to the best performing AAM foams reported to date, but in addition these eco-friendly composites also show good ability to passively adjust the humidity levels inside buildings. The multifunctional properties shown by the cork -AAM composites set them apart from other conventional building materials and might contribute to the global sustainability of the construction sector.

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Section: Introductionmentioning

confidence: 99%

Multifunctional cork – alkali-activated fly ash composites: A sustainable material to enhance buildings’ energy and acoustic performance

Novais

Carvalheiras

Senff

et al. 2020

Energy and Buildings

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“… 6 , 8 Highly porous geopolymer foams are a recent addition to the group of inorganic foams. 9 Pores are commonly introduced into the geopolymers by the incorporation of a blowing agent (e.g., H 2 O 2 or metallic Al powder) during synthesis, 10 , 11 but other methods exist, such as mechanical foaming, 12 sacrificial templating, 13 freeze-casting, 14 additive manufacturing, 15 and emulsion templating. 16 …”

Section: Introductionmentioning

confidence: 99%

Surface Modification of Cured Inorganic Foams with Cationic Cellulose Nanocrystals and Their Use as Reactive Filter Media for Anionic Dye Removal

Selkälä

Suopajärvi

Sirviö

et al. 2020

ACS Appl. Mater. Interfaces

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In this work, a surface cationized inorganic–organic hybrid foam was produced from porous geopolymer (GP) and cellulose nanocrystals (CNCs). GPs were synthesized from alkali-activated metakaolin using H 2 O 2 as a blowing agent and hexadecyltrimethylammonium bromide (CTAB) as a surfactant. These highly porous GPs were combined at pH 7.5 with cationic CNCs that had been synthesized from dissolving pulp through periodate oxidation followed by cationization in a deep eutectic solvent. The GP-CNC hybrid foams were employed as reactive filters in the removal of the anionic dye, methyl orange (MO; 5–10 mg/L, pH 7). The effects of a mild acid wash and thermal treatments on the structure, properties, and adsorption capacity of the GPs with CNCs and MO were investigated. The CNCs aligned as films and filaments on the surfaces of the neutralized GPs and the addition of CNCs improved MO removal by up to 84% compared with the reference sample. In addition, CTAB was found to disrupt the attachment of CNCs on the pores and improve adsorption of MO in the GPs with and without CNCs.

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“…Some attempts have been made to produce geopolymer using different types of foaming agent such as metal powder (aluminium powder), hydrogen peroxide (H 2 O 2 ), and sodium hypochlorite [ 39 , 40 , 41 ]. Amorphization by mechanical alloying also can improve the porosity of the geopolymer adsorbent [ 42 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Aluminium Powder on Kaolin-Based Geopolymer Characteristic and Removal of Cu2+

et al. 2021

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This current work focuses on the synthesis of geopolymer-based adsorbent which uses kaolin as a source material, mixed with alkali solution consisting of 10M NaOH and Na2SiO3 as well as aluminium powder as a foaming agent. The experimental range for the aluminium powder was between 0.6, 0.8, 1.0 and 1.2wt%. The structure, properties and characterization of the geopolymer were examined using X-Ray Diffraction (XRD), Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Adsorption capacity and porosity were analysed based on various percentages of aluminium powder added. The results indicate that the use of aluminium powder exhibited a better pore size distribution and higher porosity, suggesting a better heavy metal removal. The maximum adsorption capacity of Cu2+ approached approximately 98%. The findings indicate that 0.8% aluminium powder was the optimal aluminium powder content for geopolymer adsorbent. The removal efficiency was affected by pH, adsorbent dosage and contact time. The optimum removal capacity of Cu2+ was obtained at pH 6 with 1.5 g geopolymer adsorbent and 4 h contact time. Therefore, it can be concluded that the increase in porosity increases the adsorption of Cu2+.

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Metal powders as foaming agents in fly ash based geopolymer synthesis and their impact on the structure depending on the Na /Al ratio

Cited by 60 publications

References 16 publications

Multifunctional cork – alkali-activated fly ash composites: A sustainable material to enhance buildings’ energy and acoustic performance

Multifunctional cork – alkali-activated fly ash composites: A sustainable material to enhance buildings’ energy and acoustic performance

Surface Modification of Cured Inorganic Foams with Cationic Cellulose Nanocrystals and Their Use as Reactive Filter Media for Anionic Dye Removal

Effect of Aluminium Powder on Kaolin-Based Geopolymer Characteristic and Removal of Cu2+

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