The influence of thermodynamic parameters on alkaline activator of geopolymers and structure of geopolymers

Ivanović, Milan; Nenadović, Snežana; Pavlović, Vera P.; Radović, Ivona R.; Kijevčanin, Mirjana Lj.; Pavlović, Vladimir B.; Kljajević, Ljiljana

doi:10.20450/mjcce.2021.2127

Cited by 7 publications

(12 citation statements)

References 30 publications

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“…In previous work by Ivanovic et al [ 30 ], velocity of sound values shows a small increase with increasing temperature for solutions with lower NaOH concentration, which may be an indicator of increased ion mobility in solution. Since the changes during heating of the alkaline activator are in the range of 15–60 °C below 2.0% when it comes to density and refractive index, and since the velocity of sounds is slightly above 3.0%, this indicates the thermodynamic stability of the activator leading to dissolution of the initial aluminosilicate types and creation of a new Na–aluminosilicate gel structure of geopolymer samples.…”

Section: Resultsmentioning

confidence: 77%

“…Ivanovic et al examined the thermodynamic parameters (viscosity, density, refractive index, velocity of sound) of the alkaline activator and examined the influence on the synthesis of geopolymers [ 30 ]. It was confirmed that, with the knowledge of thermodynamic parameters, there is a better understanding of the first phase of gel formation of geopolymer structure.…”

Section: Introductionmentioning

confidence: 99%

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Structural and Chemical Properties of Geopolymer Gels Incorporated with Neodymium and Samarium

Nenadović

Kljajević

Ivanović

et al. 2021

Gels

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The present work was focused on doping of 1% and 5% both of Nd2O3 and Sm2O3 in geopolymer gels. One of the main goals was to determine the influence of the behavior of Nd and Sm as dopants and structural nanoparticles changes of the final geopolymer formed. It is shown that the disorder formed by alkali activation of metakaolin can accommodate the rare earth cations Nd3+ and Sm3+ into their aluminosilicate framework structure. The main geopolymerization product identified in gels is Al-rich (Na)-AS-H gel comprising Al and Si in tetrahedral coordination. Na+ ions were balancing the negative charge resulting from Al3+ in tetrahedral coordination. The changes in the structures of the final product (geopolymer/Nd2O3; Sm2O3), has been characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analysis with energy dispersive spectrometry (EDS). Nucleation at the seed surfaces leads to the formation of phase-separated gels from rare earth phase early in the reaction process. It is confirmed that Nd and Sm have been shown to form unstable hydroxides Nd(OH)3 and Sm(OH)3 that are in equilibrium with the corresponding oxides.

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Section: Resultsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Structural and Chemical Properties of Geopolymer Gels Incorporated with Neodymium and Samarium

Nenadović

Kljajević

Ivanović

et al. 2021

Gels

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“…The characteristics for all the samples are the vibration bands with a maximum of ~3450 cm −1 and bands at 1635 cm −1 , which are attributed to stretching vibrations and the deformation of physically adsorbed water molecules (H-O-H) on the surface. The presented spectra in Figure 5 of all samples show a strong peak at approximately 1000 cm −1 , which is associated with the Si-O-Si asymmetric stretching vibration and fingerprints of polymerization [ 26 ]. In the part of the spectrum corresponding to wave numbers at 1000–1200 cm −1 , there are two broad bands: the Si-O-Si stretching vibration and the Si-O and Si (Al)-O stretching vibration.…”

Section: Resultsmentioning

confidence: 99%

“…The vibrational band with a maximum at approximately 1050 cm −1 is assigned to Si-O stretching of tetrahedra, in which Si is surrounded by three oxygen bridges and one non-bonding oxygen. The structure Si-O-X (X = Al, Si), the building blocks of geopolymers, and the shift of vibrational bands corresponding to the Si-O-X bond stretching toward the lower wavenumbers indicate the lengthening of the O-X bond of this structure and the reduction in the bond angle [ 26 ].…”

Section: Resultsmentioning

confidence: 99%

Design of PEI and Amine Modified Metakaolin-Brushite Hybrid Polymeric Composite Materials for CO2 Capturing

et al. 2023

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In this paper, the properties of organic-inorganic hybrid polymer materials, which were synthesized from an aluminosilicate inorganic matrix with the addition of brushite and aminosilane grafted on one side and PEI covalently bonded composites on the other side, were examined. The synthesized organic-inorganic hybrid polymers were examined in terms of a structural, morphological, thermo-gravimetric, and adsorption-desorption analysis and also as potential CO2 capturers. The structural and phase properties as well as the percentage contents of the crystalline and amorphous phase were determined by the X-ray diffraction method. The higher content of the amorphous phase in the structure of hybrid polymers was proven in metakaolin and metakaolin-brushite hybrid samples with the addition of amino silane and with 1,000,000 PEI in a structure. The DRIFT method showed the main band changes with the addition of an organic phase and inorganic matrix. Microstructural studies with the EDS analysis showed a uniform distribution of organic and inorganic phases in the hybrid geopolymers. The thermo-gravimetric analysis showed that organic compounds are successfully bonded to inorganic polymer matrix, while adsorption-desorption analysis confirmed that the organic phase completely covered the surface of the inorganic matrix. The CO2 adsorption experiments showed that the amine-modified composites have the higher capture capacity, which is 0.685 mmol·g−1 for the GM10 sample and 0.581 mmol·g−1 for the BGM10 sample, with 1,000,000 PEI in the structure.

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“…Geopolymer manufacture is one of the effective methods for creating a rapidly inorganic ionic conductor [25]. Furthermore, the thermodynamic properties of the mixture alkali activator (density, viscosity, speed of sound) are conducive to easier arrangement of engineering processes [26]. Afterwards, geopolymers have a number of advantages: heat and acid/alkaline resistance, immense strength, and beneficial solidification of toxic waste [27].…”

Section: Introductionmentioning

confidence: 99%

The Study of Cu(II) Adsorption onto Synthetically Modified Geopolymers

et al. 2023

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The study of Cu(II) from aqueous solutions using the adsorption process on synthetically modified geopolymers was performed under static conditions. Three geopolymers (based on metaphase of Serbian clay, metaphase of German clay and metaphase of German clay plus 10% of carbon cloth) were used. The geopolymers were made by condensing a mixture of metaphases and alkali activator solution at a fixed ratio at room temperature and then at a temperature of 60 °C in a dry oven. Then, the geopolymer samples were pre-crashed to a fixed-radius size. Their properties were characterized by X-ray diffractometry (XRD), Diffuse Reflectance Infrared Fourier Transform (DRIFT) analysis and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). Adsorption experiments were carried out under batch process as a function of the dose, concentration of metal, and contact time. The uptake of Cu(II) was rapid, and it increased with increasing metal concentration. The sorption percentage decreased with increasing concentration of Cu(II). The equilibrium adsorption capacity of geopolymers was measured and extrapolated using more isotherms. The data fit very well the linear Langmuir isotherm model. The pseudo-second-order kinetic model can well describe the adsorption behavior of Cu(II) ions with geopolymers samples. These results show that used geopolymers hold great potential to remove Cu(II) from industrial wastewater.

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The influence of thermodynamic parameters on alkaline activator of geopolymers and structure of geopolymers

Cited by 7 publications

References 30 publications

Structural and Chemical Properties of Geopolymer Gels Incorporated with Neodymium and Samarium

Structural and Chemical Properties of Geopolymer Gels Incorporated with Neodymium and Samarium

Design of PEI and Amine Modified Metakaolin-Brushite Hybrid Polymeric Composite Materials for CO2 Capturing

The Study of Cu(II) Adsorption onto Synthetically Modified Geopolymers

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