Investigation of silica polymorphs stratified in siliceous geode using FTIR and XRD methods

Awadh, Salih Muhammad; Yaseen‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬, Zaher Mundher

doi:10.1016/j.matchemphys.2019.02.048

Cited by 47 publications

(25 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…One characteristic of this transition is a significant inflexion point at 1245 cm −1 [34,35]. Opal-C can be identified by the absorption appearing at 480, 620, 675, 800 and 1110 cm −1 , especially the intense bands at about 630 cm −1 [5][6][7]. The infrared spectra of our samples are obviously different from those of opal-C, and more similar to the spectra of opal-A and opal-CT.…”

Section: Ftir Spectroscopymentioning

confidence: 65%

See 1 more Smart Citation

Crystallinity and Play-of-Colour in Gem Opal with Digit Patterns from Wegel Tena, Ethiopia

Zhao

Bai

2020

Minerals

View full text Add to dashboard Cite

A typical feature of Wegel Tena opal is the "digit pattern". This pattern consists of two parts, columns and matrix, with different colours, transparency or play-of-colour effect, which is still unexplained. This study aims at investigating the various parts of the digit pattern using different spectroscopic methods, and scanning and transmission electron microscopy (SEM and TEM). The band at 780 cm−1 on the Fourier transform infrared (FTIR) spectrum is correlated to the symmetric stretching vibration of Si–O. The bands at 1085, 895, 785 and 3600 cm−1 on Raman spectra indicate that Wegel Tena opal is opal-CT. Comparison of the relative intensity of the Raman signals around 360 cm−1 indicates that the microcrystalline opal on the top of the sample contains a higher amount of tridymite-like structural units, and the tridymite-type regions in the matrix contain a higher degree of structural defects. Silica spheres in the columns tend to be smaller and better ordered than in the matrix. The diameter of the silica spheres (d = 80–500 nm) or agglomerates (d = 200–580 nm) in Wegel Tena opal satisfies the conditions of diffraction of visible light, and the thickness of the silica layer (h = 120–200 nm) satisfies the conditions for film interference.

show abstract

Section: Ftir Spectroscopymentioning

confidence: 65%

“…Other techniques, such as infrared spectroscopy [5][6][7] and Raman spectroscopy [8][9][10][11][12][13][14], have also been used to distinguish different types of opal. Furthermore, Raman spectroscopy has been considered a method to distinguish the complex structural relationships between different types of opal [4,8,10,13].…”

Section: Introductionmentioning

confidence: 99%

Crystallinity and Play-of-Colour in Gem Opal with Digit Patterns from Wegel Tena, Ethiopia

Zhao

Bai

2020

Minerals

View full text Add to dashboard Cite

show abstract

“…Bands located between 1000cm -1 and 1200cm -1 commonly observe antisymmetric bonds which represent the existence of silica in the intended materials (Portaccio et al, 2011). This is as well supported by much research which has reported nearly close absorbance bands assigned as Si-O-Si chain stretching, i.e., 1064cm -1 by Portaccio et al (2011), 1086cm -1 by Awadh and Yaseen (2019), and between 1040cm -1 and 1100cm -1 by Osman and Sapawe (2020b). From the spectra, observable peaks of Si-O-Si do not arise at lower temperatures as indicated by the curves of EFB400, PKS400 and DC400 around the said band range.…”

Section: Ftir Spectroscopymentioning

confidence: 62%

“…This corresponds to the symmetric stretching of Si-O-Si chain, thus again, depicting the presence of silica compounds in the samples. Portaccio et al (2011), Yuvakkumar et al (2014 and Awadh and Yaseen (2019) have observed respective peak bands of 787cm -1 (Portaccio et al, 2011), 795cm -1 (Yuvakkumar et al, 2014), and 790cm -1 (Awadh & Yaseen, 2019) related to symmetrical Si-O-Si vibrations. Similar to asymmetric Si-O-Si FTIR spectra, these bands are only obvious for samples exposed to high temperatures, no less than 500°C.…”

Section: Ftir Spectroscopymentioning

confidence: 97%

Characteristics of calcined palm oil pastes for biosilica extraction as a function of calcination temperatures

Samat¹,

Jaman²,

Saree³

et al. 2021

JART

View full text Add to dashboard Cite

Palm oil production in Malaysia has increased over the years. As the consequence of high production of palm oil, surplus quantities of palm oil biomass wastes such as empty fruit bunches (EFB), palm kernel shell (PKS), and oil palm decanter cake (DC) are generated. Generally, these wastes are used as fuel to generate steam for boilers, which end up as ash. As several agricultural wastes are well-known to be rich in silica content, this study aims to investigate the bio-silica content of EFB, PKS and DC and their characteristics when calcined at various calcination temperatures from 400°C to 800°C. Several analyses were conducted such as weight loss, color, BET, SEM and FTIR. The results have shown that all samples favorably exhibited silica at higher temperatures, i.e., 800°C. Color analysis depicted that combustible elements were mostly removed at 800°C, leaving non-combusted silica in the waste ash. Weight loss analysis presented that EFB achieved the highest weight loss at 99.05%, followed by PKS at 95.65% and DC at 83.95%. This led to a relatively high amount or purity of silica in the sample. BET analysis showed highest surface area, 20.087m2/g (PKS) and the lowest is 9.492m2/g (DC) at 800°C which verified the high porosity of samples for further absorption applications. The presence of silica was also significantly observed in 800°C FTIR spectra for all waste samples. Overall, it is concluded that EFB, PKS, and DC are highly potential wastes to contribute to the production of bio-silica, which thus can be an option to overcome waste disposal issues in palm oil industries.

show abstract

“…35-1974] [48]. Figure 7b suggests that the raw Dt consists mainly of silica (SiO2) [49] with a little kaolin (Al2Si2O5(OH)42H2O) [50], cristobalite [51], and montmorillonite [52]. The diffraction broad-bands observed in range of 18-32° may be attributed to the amorphous SiO2 [53].…”

Section: Int J Environ Res Public Health 2020 17 429 7 Of 14mentioning

confidence: 99%

Adsorption of As(V) from Aqueous Solution on Chitosan-Modified Diatomite

Yang

Gong

Huang

et al. 2020

IJERPH

View full text Add to dashboard Cite

A novel chitosan (CS)-modified diatomite (Dt) was prepared by a simple mixture in the mass ratio to remove As(V) from aqueous solution in this research. The CS-modified Dt adsorbent was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD) analysis. The parameters to influence the adsorption of As(V) ion were studied under such conditions as kinetics, adsorption isotherm, and pH effect. The results revealed that adsorption of As(V) was initially rapid and the equilibrium time was reached after 40 min. The optimal value of the pH was 5.0 for better adsorption. The equilibrium data were well fitted to the Langmuir isotherm compared to the Freundlich isotherm, and exhibited the highest capacity and removal efficiency of 94.3% under an initial As(V) concentration of 5 mg/L. The kinetic data were well described by the pseudo-second-order model. In addition, 0.1 M NaOH has the best desorption efficiency of As(V) adsorbed on CS-modified Dt, and the removal efficiency of As(V) was still higher than 90% when after six adsorption-desorption cycles. These results showed that the CS-modified Dt could be considered as a potential adsorbent for the removal of As(V) in aqueous solution.

show abstract

Investigation of silica polymorphs stratified in siliceous geode using FTIR and XRD methods

Cited by 47 publications

References 11 publications

Crystallinity and Play-of-Colour in Gem Opal with Digit Patterns from Wegel Tena, Ethiopia

Crystallinity and Play-of-Colour in Gem Opal with Digit Patterns from Wegel Tena, Ethiopia

Characteristics of calcined palm oil pastes for biosilica extraction as a function of calcination temperatures

Adsorption of As(V) from Aqueous Solution on Chitosan-Modified Diatomite

Contact Info

Product

Resources

About