Synthesis and small angle X-ray scattering (SAXS) characterization of silica spheres covered with gel-like particles formed by means of solvent evaporation

Gutsche, Alexander; Guo, Xiaoai; Dingenouts, N.; Nirschl, Hermann

doi:10.1016/j.powtec.2015.03.037

Cited by 16 publications

(13 citation statements)

References 38 publications

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“…The straight line in the low q region was fitted by the least squares power law and the correlation coefficient R 2 (inset) was higher than 0.99. First of all, according to the obtained SAXS profiles, the fractal characteristics of all related samples belonged to the mass fractal ( D m ) . While, as shown in Table (inset in Figure A), the D m value gradually decreased with the increasing polarity of used solvents, from 2.85 for pure ZZnBMMs, to 2.79 by petroleum ether, 2.72 by CH 2 Cl 2 , 2.64 by CH 3 OH, and 2.65 by DMSO, respectively, indicating that the mesoporous surfaces of the washed ZZnBMMs gradually became rough, which may be due to the Z leaching during the washing.…”

Section: Resultsmentioning

confidence: 90%

Stability of Immobilization of Bipyridine‐proline on Zn‐Modified Bimodal Mesoporous Silicas and Recyclable Catalytic Performance in Asymmetric Aldol Reaction

et al. 2019

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The organic-inorganic mesoporous materials (ZZnBMMs) were successfully synthesized by Zn-grafting into the surface of bimodal mesoporous silicas (BMMs) via covalent bond, and then immobilization of (2 S,2'S)-N,N'-([2,2'-bipyridine]-3,3'-diyl) bis(pyrrolidine-2-carboxamide) (Z) onto the Zn-modified BMMs through coordination method. The influences of washed parameters such as various solvents (petroleum ether, CH 2 Cl 2 , CH 3 OH, or DMSO) and pretreated temperature on the structural stability of obtained ZZnBMMs were investigated thoroughly, which were extensively characterized by means of XRD patterns, UV-vis and FT-IR spectra, N 2 sorption isotherms, SEM images, and SAXS patterns. The results showed that petroleum ether could be acted as optimum solvent for washing ZZnBMMs when pre-treated temperature was around 20°C. The SAXS patterns evidently demonstrated that ZZnBMMs before and after washing presented the fractal features, suggesting their surface roughness and structural irregularities, in which, the mass fractal (D m ) values were gradually decreased along with not only the increased polarity of used solvents (petroleum ether, CH 2 Cl 2 , CH 3 OH, and DMSO), but also enhanced washing temperature of from 20-60°C and prolonged time of from 4-168 hrs. Furthermore, the ZZnBMMs as a heterogeneous catalyst for asymmetric aldol reaction exhibited the recycled (at least 6 times) catalytic performances with high efficiency (around 92.1% yield) and good selectivity (up to 68% ee).

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Section: Resultsmentioning

confidence: 90%

Stability of Immobilization of Bipyridine‐proline on Zn‐Modified Bimodal Mesoporous Silicas and Recyclable Catalytic Performance in Asymmetric Aldol Reaction

et al. 2019

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“…The SAXS spectra were fitted using the equation of fractal particles, as shown in Eq. [3] (Gutsche et al, 2015; László et al, 1998).

I (h) = I_{0} h^{- \dot{a}}

where I 0 is a constant, and α is a fractal with dimensions ranging from 0 to 4.…”

Section: Methodsmentioning

confidence: 99%

“…The SAXS spectra were fitted using the equation of fractal particles, as shown in Eq. [3] (Gutsche et al, 2015;László et al, 1998).…”

Section: Characterization Of Biocharsmentioning

confidence: 99%

Roles of Phosphoric Acid in Biochar Formation: Synchronously Improving Carbon Retention and Sorption Capacity

et al. 2017

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Pretreatment of biomass with phosphoric acid (HPO) for biochar production was expected to improve carbon (C) retention, porosity structure, and the sorption ability of biochar. This study investigated the interaction of phosphorus with the C structure to elucidate the mechanisms by which HPO simultaneously captured C and created micropores. Sawdust was soaked in diluted HPO and dried for pyrolytic biochar generation at 350, 500, and 650°C. Results showed that HPO pretreatment resulted in 70 to 80% of biomass C retention in biochar, compared with only about 50% remaining without pretreatment. The specific surface area and total pore volume of the HPO-pretreated biochar were 930 m g and 0.558 cm g, respectively, compared with <51.0 m g and 0.046 cm g in the untreated biochar. The volume of micropores (<10 nm) increased from 59.0% to 78.4-81.9%. The presence of HPO shifted the decomposition temperature to a lower value and decreased the energy required for biomass decomposition. Micropore formation was via the insertion of P-O-P into the C lattice, leading to swelling and amplification of amorphous form and lattice defect of the C structure, as evidenced by Raman spectrum and small-angle X-ray scattering analysis. The crosslinking of P-O-P and C bonds resulted in greater biomass C retention in biochar. This biochar-phosphorus composite had a much higher sorption ability for Pb than the unmodified biochar, which was possibly dominated by phosphate precipitation and surface adsorption. This study provided a simple method to improve biochar properties and explored the multiple benefits of HPO in biomass pyrolysis.

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“…which characterizes the width of the size distribution. In the scattering vector q region, the scattering intensity I(q) can be characterized by the so-called power law [37]:…”

Section: Saxs Analysesmentioning

confidence: 99%

“…From the log I(q) versus log q curves and slopes of linear region (at large values of scattering vector q), the values of the exponent P can be measured. In order to study particle surface characteristics like roughness, the surface-fractal dimension or d s (d s = 6 − P) is often used [36,37]. This is in particular useful for ideal two-phase structure with smooth surfaces and sharp boundaries.…”

Section: Saxs Analysesmentioning

confidence: 99%

Towards Multi-Functional SiO2@YAG:Ce Core–Shell Optical Nanoparticles for Solid State Lighting Applications

et al. 2020

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This paper aims to investigate the synthesis, structure, and optical properties of SiO2@YAG:Ce core–shell optical nanoparticles for solid state lighting applications. YAG:Ce phosphor is a key part in white light emitting diodes (LEDs), with its main functionality being the generation of yellow light. Generated yellow light from phosphor will be combined with blue light, emitted from chip, resulting in the generation of white light. Generated light in LEDs will often be scattered by SiO2 nanoparticles. SiO2 nanoparticles are often distributed within the optical window, aiming for a more homogeneous light output. The main idea in this research is to combine these functionalities in one core–shell particle, with its core being SiO2 and its shell being phosphor. In this study core–shell nanoparticles with different Ce3+ concentrations were synthesized by a sol–gel method. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), small angle X-ray scattering (SAXS) analysis, high resolution transmission electron macroscopy (HRTEM), Fourier transform infrared (FTIR), and photoluminescence spectroscopy. Luminescence characteristics of SiO2@YAG:Ce core–shell particles were compared with that of SiO2/YAG:Ce mixture composite, which is now used in commercial LEDs. Obtained results showed that core–shell nanoparticles have comparatively much better optical properties, compared to SiO2/YAG:Ce mixture composite and can therefore be potentially used in LEDs.

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Synthesis and small angle X-ray scattering (SAXS) characterization of silica spheres covered with gel-like particles formed by means of solvent evaporation

Cited by 16 publications

References 38 publications

Stability of Immobilization of Bipyridine‐proline on Zn‐Modified Bimodal Mesoporous Silicas and Recyclable Catalytic Performance in Asymmetric Aldol Reaction

Stability of Immobilization of Bipyridine‐proline on Zn‐Modified Bimodal Mesoporous Silicas and Recyclable Catalytic Performance in Asymmetric Aldol Reaction

Roles of Phosphoric Acid in Biochar Formation: Synchronously Improving Carbon Retention and Sorption Capacity

Towards Multi-Functional SiO2@YAG:Ce Core–Shell Optical Nanoparticles for Solid State Lighting Applications

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