Preparation of sustainable of eco-friendly MWCNT-geopolymer composites with superior sulfate resistance

Khater, H. M.; El-Nagar, Abdeen M.

doi:10.1007/s42114-020-00170-4

Cited by 25 publications

(9 citation statements)

References 37 publications

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“…The bands in the range of 463-484 cm −1 possibly were due to the bending vibrations of Fe-O [2]. As Khater states, this band could also be relevant to (Si-O-Si and O-Si-O) bending vibration due to quartz [14].…”

Section: Infrared Spectroscopymentioning

confidence: 95%

“…Due to the low reactivity of red mud, the flexural strength of the geopolymer is reduced. For this purpose, the carbon nanotube (CNT) reinforcing phase is used to improve the mechanical properties of the geopolymer [8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…The researchers elaborated on this issue that the compressive and flexural strength were augmented up to 32% and 28%, respectively, as the carbon nanotubes were added about 0.5% [13]. Khater et al [14] used MWCNT to the production of sulfate resistance geopolymer composite. The results displayed that the addition of MWCNT increased the sulfate resistance [14].…”

Section: Introductionmentioning

confidence: 99%

“…Khater et al [14] used MWCNT to the production of sulfate resistance geopolymer composite. The results displayed that the addition of MWCNT increased the sulfate resistance [14].…”

Section: Introductionmentioning

confidence: 99%

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Metakaolin-red mud/carbon nanotubes geopolymer nanocomposite: mechanical properties and structural studies

Ahmadi

Khalaj

Najafi

et al. 2022

Mater. Res. Express

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In this research, the mechanical properties and structural studies of the geopolymer nanocomposite of metakaolin-red mud/carbon nanotubes were investigated. The geopolymer was designed by using metakaolin and red mud as aluminosilicate sources. Red mud replaced between 10 to 30% of the metakaolin. The mass ratio of the solid material and activator liquid was optimized in 1.5:1. Afterward, 1, 2, and 3 wt. % multi-wall carbon nanotubes (MWCNTs) were dispersed in a polycarboxylate-based superplasticizer and were added to the geopolymer, which was mixed homogeneously. Geopolymer nanocomposites were characterized by XRD, FTIR, SEM, compressive and flexural strength measurements. The results indicated that the compressive and flexural strengths of the samples increased with curing time. The addition of red mud decreased the compressive and flexural strength of the geopolymer samples due to less reactivity and presence of a non-reactive impurity in red mud. By adding 2% MWCNTs, the compressive and flexural strengths increased to 37.05% and 36.06%, respectively, owing to the crack-bridging mechanism and filling of the cavities and porosity. FTIR spectra demonstrated the growth of the asymmetric stretching vibrations of T–O–Si (T: Si or Al) at approximately 995.85-1083.55 cm-1, confirming the realization of the geopolymerization process in the structure.

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Section: Infrared Spectroscopymentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Khater et al [14] used MWCNT to the production of sulfate resistance geopolymer composite. The results displayed that the addition of MWCNT increased the sulfate resistance [14].…”

Section: Introductionmentioning

confidence: 99%

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Metakaolin-red mud/carbon nanotubes geopolymer nanocomposite: mechanical properties and structural studies

Ahmadi

Khalaj

Najafi

et al. 2022

Mater. Res. Express

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“…Recently, metal-free nanocarbons such as carbon nanotubes, graphene, carbon black, etc., and their composites have been widely used in the fields of catalysis, electrochemistry, and environmental remediation. − In this regard, the use of nonmetallic nanocarbons as the catalyst in this reaction has also attracted extensive attention. Because of the excellent physical/chemical properties and easy-to-control surface electronic properties, nanocarbons are widely used as the catalysts for the oxidative activation of methane, , dehydrogenation (ODH) of hydrocarbons, , hydrogenation of nitrobenzene, hydroxylation of benzene, selective oxidations, , and so on.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Huang

Bai

Feng

et al. 2022

ACS Sustainable Chem. Eng.

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The catalytic synthesis of lactones from alkanes is a novel strategy from the viewpoint of environmentally benign technology. In this work, we propose a new protocol of using a typical alkane (cyclohexane, CyH) as a substrate to produce lactone (ε-caprolactone, ε-CL) in the presence of carbon nanotubes (CNTs) and aldehydes. The results demonstrated that CNTs could be used as an efficient catalyst for the production of ε-CL. Nitrogen doping would greatly enhance the activity, with 26.2% conversion of CyH and 87% selectivity of ε-CL. The specific N dopants served as complex active sites for improving the catalytic efficiency of NCNTs with an optimum content of N (3.38 atom %). Further investigations revealed that the ratio of pyridine N/ quaternary N probably played a significant role in the facilitation of this reaction, which displayed a linear relationship with the specific activity of NCNTs. A mechanistic study demonstrated that the activation of benzaldehyde for the production of carbonyl radicals was considered as the initial reaction, which activated CyH molecules to produce alkyl radicals, thus promoting the oxidation of CyH. The intermediate product CyO was found to be the main precursor of ε-CL, and during the reaction, cyclohexanol (Cy−OH) would likely be transformed into CyO.

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Effect of multi‐walled carbon nanotubes on rheological behavior and electrical conductivity of poly(ethylene‐co‐vinyl acetate)/acrylonitrile‐butadiene rubber/multi‐walled carbon nanotubes nanocomposites

Razavi‐Nouri

Salavati

2022

Polymer Composites

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In this work, the effect of multi‐walled carbon nanotubes (MWCNTs) on electrical conductivity and rheological behavior of poly(ethylene‐co‐vinyl acetate) (EVA)/acrylonitrile‐butadiene rubber (NBR) blends containing 0 to 7 wt% MWCNTs are investigated. The theoretical calculations according to the interfacial free energy of the components revealed that the nanofillers had a tendency to locate in NBR domains. However, the rheological, electrical, and morphological studies indicated that the majority of the MWCNTs remained in the EVA phase. Shear creep measurements of the molten materials showed that the creep stability improved steadily with the increase in MWCNTs content. The creep behaviors of the materials, except EVA, were analogous to the Burgers model prediction and all four parameters of the model increased in value with the increase in the nanofillers content in comparison with those of the unfilled blend. The rheological studies indicated that the damping factor (tanδ) for the materials containing small amounts of the nanofillers reached a maximum and subsequently decreased with rising temperature. However, for the materials having 1 wt% MWCNTs and higher, the tanδ values were smaller at the highest temperature (200°C) than those of the lowest temperature (100°C) investigated in this work. The electrical percolation threshold was also found to take place at about 2.80 wt% MWCNTs loading.

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Preparation of sustainable of eco-friendly MWCNT-geopolymer composites with superior sulfate resistance

Cited by 25 publications

References 37 publications

Metakaolin-red mud/carbon nanotubes geopolymer nanocomposite: mechanical properties and structural studies

Metakaolin-red mud/carbon nanotubes geopolymer nanocomposite: mechanical properties and structural studies

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Effect of multi‐walled carbon nanotubes on rheological behavior and electrical conductivity of poly(ethylene‐co‐vinyl acetate)/acrylonitrile‐butadiene rubber/multi‐walled carbon nanotubes nanocomposites

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