Determining the disordered nanostructure of calcium silicate hydrate (C‐S‐H) from broad X‐ray diffractograms

2021 ◽  
Author(s):  
Felipe Basquiroto de Souza ◽  
Kwesi Sagoe‐Crentsil ◽  
Wenhui Duan
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
X Ray

scholarly journals Performance and adsorption mechanism of a magnetic calcium silicate hydrate composite for phosphate removal and recovery

2018 ◽  
Vol 2017 (2) ◽  
pp. 578-591 ◽  
Author(s):  
Lihong Peng ◽  
Hongliang Dai ◽  
Yifeng Wu ◽  
Zheqin Dai ◽  
Xiang Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Magnetic Separation ◽  
Adsorption Kinetics ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Phosphate Removal ◽  
Separation Technique ◽  
Phosphate Adsorption ◽  
X Ray ◽  
Removal And Recovery

Abstract A novel magnetic calcium silicate hydrate composite (Fe3O4@CSH) was proposed for phosphorus (P) removal and recovery from a synthetic phosphate solution, facilitated by a magnetic separation technique. The Fe3O4@CSH material was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), zeta-potential and magnetic curves. The chemical composition and structure of Fe3O4@CSH and the successful surface loading of hydroxyl functional groups were confirmed. Phosphate adsorption kinetics, isotherm, and thermodynamic experiments showed that adsorption reaches equilibrium at 24 h, with a maximum adsorption capacity of 55.84 mg P/g under optimized experimental conditions. Adsorption kinetics fitted well to the pseudo second-order model, and equilibrium data fit the Freundlich isotherm model. Thermodynamic analysis provided a positive value for ΔH° (129.84 KJ/mol) and confirmed that phosphate adsorption on these materials is endothermic. The P-laden Fe3O4@CSH materials could be rapidly separated from aqueous solution by a magnetic separation technique within 1 min. A removal rate of more than 60% was still obtained after eight adsorption/desorption cycles, demonstrating the excellent reusability of the particles. The results demonstrated that the Fe3O4@CSH materials had high P-adsorption efficiency and were reusable.

scholarly journals Effects of Ca/Si Ratio, Aluminum and Magnesium on the Carbonation Behavior of Calcium Silicate Hydrate

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1268 ◽  
Author(s):  
Jing Li ◽  
Qijun Yu ◽  
Haoliang Huang ◽  
Suhong Yin
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Bond Strength ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
X Ray ◽  
Thermogravimetric Analyzer ◽  
Magnesium Uptake ◽  
Carbonation Resistance ◽  
The Mean

The effects of Ca/Si ratio, aluminum and magnesium on the carbonation behavior of calcium silicate hydrate (C-S-H) were investigated by using X-ray powder diffraction (XRD), nuclear magnetic resonance (NMR) and thermogravimetric analyzer (TGA). The results showed that the Ca/Si ratio, Al/Si ratio and Mg/Si ratio had a significant influence on the structure, carbonation products and carbonation resistance of C-(M)-(A)-S-H. The mean chain length of silicate chains in C-S-H increased as the Ca/Si ratio decreased. Aluminum uptake in C-S-H increased the content of bridging silicate tetrahedron (Q2). A cross-linked structure (Q3) appeared when magnesium uptake in C-S-H. The carbonation product of C-S-H was vaterite if the Ca/Si ratio was lower than 0.87. The carbonation products of C-S-H were vaterite and calcite if the Ca/Si ratio was higher than 1.02. C-M-S-H had more polymerized units, stronger bond strength and better carbonation resistance than C-S-H.

Pozzolanic activity of corn straw leaf ash produced at different temperatures and treated with portlandite solution

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 8708-8727
Author(s):  
Tingye Qi ◽  
Guorui Feng ◽  
Haochen Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Mixing Time ◽  
Pozzolanic Activity ◽  
Mixed Solution ◽  
Corn Straw ◽  
Amorphous Sio2 ◽  
X Ray ◽  
Calcination Temperatures

The effect of calcination temperature on the pozzolanic activity of corn straw leaf ash (CSLA) was evaluated. The CSLA samples calcined at temperatures of 500, 700, and 850 °C were mixed in a portlandite solution for 6 h, and residual samples were obtained. The CSLA and residual samples were analyzed using Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and a contact angle goniometer to determine the vibration bonds, minerals, phase composition, microstructure, Si 2p transformation behavior, and wetting behavior. The conductivity and loss of conductivity with mixing time of the CSLA-portlandite mixed solution was determined. The loss of conductivity of the CSLA prepared at 500 °C was high compared to that of the other calcination temperatures at the same mixing time, which was attributed to the higher amorphous SiO2 content in the CSLA at 500 °C. Calcium silicate hydrate was easily identified in the CSLA residual samples, and some dense small cubic and nearly spherical shaped calcium silicate hydrate particles were found in the CSLA residual samples at 500 °C. Based on the findings, it is recommended that CSLA be calcined at 500 °C using the cement system in view of higher pozzolanic activity but avoiding excessive agglomeration.

Modified xonotlite–type calcium silicate hydrate slabs for fire doors

2018 ◽  
Vol 36 (2) ◽  
pp. 83-96 ◽  
Author(s):  
Rimantas Levinskas ◽  
Irena Lukošiūtė ◽  
Arūnas Baltušnikas ◽  
Algirdas Kuoga ◽  
Aldona Luobikienė ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Solar Furnace ◽  
Liquid Sodium ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Surface Areas ◽  
Back Door

Xonotlite-type calcium silicate hydrate slabs were examined under the thermal shock conditions in a solar furnace at the Plataforma Solar de Almeria which can reach a peak of 300 W/cm2. We have studied the original slabs as well as those modified with a mixture of liquid sodium silicate including montmorillonite as thermal insulation materials for fire doors applications. The slabs were kept at 950°C for 1 h. We performed X-ray diffraction, thermogravimetry and differential scanning calorimetry analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermal conductivity measurements and determined N2 adsorption/desorption isotherms. X-ray diffraction shows that during the thermal shock at 950°C xonotlite is converted to wollastonite. Specific surface areas of xonotlite slabs decrease due to release of crystalline water molecules. It is possible to maintain temperatures of the back door not exceeding 70°C while the front door is subjected to 950°C for 1-h time periods. The standard requires no more than 140°C at the back door.

Compositional Evolution of Calcium Silicate Hydrate (C-S-H) Structures by Total X-Ray Scattering

2011 ◽  
Vol 95 (2) ◽  
pp. 793-798 ◽  
Author(s):  
Sezen Soyer-Uzun ◽  
Sejung Rosie Chae ◽  
Chris J. Benmore ◽  
Hans-Rudolf Wenk ◽  
Paulo J. M. Monteiro
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
X Ray ◽  
Compositional Evolution ◽  
X Ray Scattering ◽  
Ray Scattering

scholarly journals Alteration of nanocrystalline calcium silicate hydrate (C-S-H) at pH 9.2 and room temperature: a combined mineralogical and chemical study

2015 ◽  
Vol 79 (2) ◽  
pp. 437-458 ◽  
Author(s):  
Nicolas C. M. Marty ◽  
Sylvain Grangeon ◽  
Fabienne Warmont ◽  
Catherine Lerouge
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Early Stage ◽  
Structural Similarity ◽  
Integrated Approach ◽  
Chemical Study ◽  
Chemical Compositions ◽  
Experimental Conditions ◽  
X Ray ◽  
Flow Through

AbstractCalcium silicate hydrate (C-S-H) alteration was studied with flow-through experiments at 25°C and pH 9.2. Three materials with apparent Ca/Si ratios (C/S ratios) of 1.47, 1.38 and 0.86 were investigated. Physical (thermogravimetric analyses/differential thermal analysis), mineralogical (X-ray diffraction) and chemical (electron probe microanalysis, transmission electron microscopy/energy dispersive X-ray spectrometry) analyses were performed to characterize the reacting minerals. Initial stoichiometric C/S ratios were 1.22, 1.22 and 0.85, respectively. The excess of Ca is attributed mainly to the presence of calcium hydroxide intimately mixed in with C-S-H particles.The C-S-H chemical compositions were monitored during flow-through experiments in order to determine the mineral stoichiometry needed for reaction kinetics. Under our experimental conditions the stoichiometric C/S ratios decreased continuously with time. A close to stoichiometric dissolution was observed after 2 days of experiments. Using an integrated approach, the kinetics was found to be a function of the C/S.A decrease in layer-to-layer distance in the early stage of the alteration process is interpreted as interlayer Ca/Na exchange (Na being part of the pH buffering solution). A second dissolution step, marked by a close to stoichiometric release of Ca and Si, undoubtedly results from layer dissolution. The structural similarity of C-S-H and tobermorite was confirmed.

Sorption Mechanisms of Zinc to Calcium Silicate Hydrate:  X-ray Absorption Fine Structure (XAFS) Investigation

2001 ◽  
Vol 35 (7) ◽  
pp. 1550-1555 ◽  
Author(s):  
Felix Ziegler ◽  
André M. Scheidegger ◽  
C. Annette Johnson ◽  
Rainer Dähn ◽  
Erich Wieland
Keyword(s):  
Fine Structure ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
X Ray ◽  
Absorption Fine ◽  
Sorption Mechanisms ◽  
X Ray Absorption

Synthesis of Calcium Silicate Hydrate Compounds From Wet Flue Gas Desulfurization (FGD) Waste

2020 ◽  
Vol 1 (2) ◽  
pp. 88-95
Author(s):  
Denise Alves Fungaro ◽  
Lucas Caetano Grosche ◽  
Juliana de Carvalho Izidoro
Keyword(s):  
Adsorption Capacity ◽  
Flue Gas ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Flue Gas Desulfurization ◽  
Maximum Adsorption Capacity ◽  
Fusion Temperature ◽  
Hydrothermal Temperature ◽  
X Ray ◽  
Wide Range

In this study Calcium silicate hydrate based products (CSHP) were synthesized from wet flue gas desulfurization waste (FGD) by alkali fusion followed by hydrothermal treatment. The effect of various factors on the formation of products, such as mineralizing agent, fusion temperature and time, crystallization time and addition of Ca and Si were studied as well as the conditions optimized. The FGD and synthesized materials were characterized by using X-Ray (XRD), Scanning Electron Microscope (SEM), X-ray fluorescence (XFR), among other methods. A fusion temperature of 600 °C with NaOH, fusion duration of 1 h, and a subsequent hydrothermal temperature of 100 °C for a reaction of 24 h were found to be the optimal conditions. In these synthesis conditions, CSHP containing tobermorite and Al-tobermorite was the major phases. The synthesized CSHP revealed high selective uptake for Cs+ in water. The maximum adsorption capacity of Cs+ onto the synthesized material, as calculated from the Langmuir model, was 1949 µmol g-1. The performance on the Cs+ removal in the presence of high Na+ contents was also evaluated. The adsorbent material showed a high Cs+ adsorption capacity in deionized water and a decrease of 56% and 62% in saturated media with the Na+ ions and seawater, respectively. Therefore, CSHP as a higher value-added product can be obtained from a by-product of a coal-fired power plant, which has wide range applications, including for Cs+ removal from wastewater.

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