Characterization of chitin and chitosan extracted from shrimp shells by two methods

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Carmiña Gartner ◽  
Carlos Alberto Peláez ◽  
Betty Lucy López
Keyword(s):  
Low Cost ◽  
Magic Angle Spinning ◽  
Chemical Extraction ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Shrimp Shells ◽  
Before And After ◽  
Chitin Extraction ◽  
Angle Spinning ◽  
Chitin And Chitosan

AbstractShrimp shells from Penaeus Vannamei species were hydrolyzed for chitin extraction by a chemical and a papain enzymatic method. Composition of shells was analyzed and their microstructure was characterized before and after hydrolysis by microscopy. Chitin fibers arrangement in the tissue was preserved after chemical extraction, but after papain hydrolysis the tissue presented structural disarrangement indicating that papain reacts indistinctly with peptidic and N-acetyl linkages. Although chemical purification is very effective, by-products are not recoverable. Conversely, papain hydrolysis yields partially purified chitosan but permits aminoacids isolation, which is important in food industry. This method has other advantages such as low cost and easy accessibility of papain. Chitin and chitosan were characterized by thermogravimetric analysis, infrared spectrophotometry and capillary electrophoresis. Degree of N-acetylation (DA) was determined by cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS 13CNMR) or potentiometry and crystallinity was measured by X ray diffraction.

MAS NMR investigation of kaolinite-smectite structure using 6Li and 29Si with Mn exchange

Clay Minerals ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 181-186 ◽  
Author(s):  
J. Cuadros ◽  
T. Wing-Dudek
Keyword(s):  
Complex Structure ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Signal Loss ◽  
X Ray Diffraction ◽  
Two Samples ◽  
Before And After ◽  
Angle Spinning ◽  
Mixed Layers

AbstractKaolinite-smectite mixed-layers have been found to have a complex structure with smectite and kaolinite domains within layers. Here we further investigate this structure in samples with 0–80% kaolinite layers, as determined by X-ray diffraction, by means of magic angle spinning nuclear magnetic resonance (MAS NMR) of 29Si and 6Li. The 29Si NMR experiments were carried out on two samples (55 and 80% kaolinite layers), before and after their exchange with Mn2+, a paramagnetic ion that causes NMR signal loss from neighbouring nuclei, in order to investigate the distance between Mn ions and Si atoms in kaolinite sites. The 29Si NMR intensity from such sites (at ~–91 ppm) was reduced upon Mn exchange, indicating that some Mn ions are located near kaolinite Si sites. The position of the 6Li peak changes slightly (–1.3 to –1.8 ppm) but progressively with increasing kaolinite content (0–80% kaolinite layers) of four K-S specimens, suggesting two slightly different chemical environments for interlayer Li, one related to smectite and the other to kaolinite. The two sets of experiments are consistent with a complex structure of kaolinite-smectite, including smectite and kaolinite domains within layers and/or interlayers of varying smectitic and kaolinitic character.

scholarly journals Slag Blended Cement Paste Carbonation under Different CO2 Concentrations: Controls on Mineralogy and Morphology of Products

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3404
Author(s):  
Wei Liu ◽  
Shifa Lin ◽  
Yongqiang Li ◽  
Wujian Long ◽  
Zhijun Dong ◽  
...  
Keyword(s):  
Blended Cement ◽  
Co2 Concentration ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Accelerated Carbonation ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
Co2 Concentrations ◽  
Angle Spinning ◽  
Natural Carbonation

To investigate the effect of different CO2 concentrations on the carbonation results of slag blended cement pastes, carbonation experiments under natural (0.03% CO2) and accelerated conditions (3, 20, and 100% CO2) were investigated with various microscopic testing methods, including X-ray diffraction (XRD), 29Si magic angle spinning nuclear magnetic resonance (29Si MAS NMR) and scanning electron microscopy (SEM). The XRD results indicated that the major polymorphs of CaCO3 after carbonation were calcite and vaterite. The values of the calcite/(aragonite + vaterite) (c/(a + v)) ratios were almost the same in all carbonation conditions. Additionally, NMR results showed that the decalcification degree of C-S-H gel exposed to 0.03% CO2 was less than that exposed to accelerated carbonation; under accelerated conditions, it increased from 83.1 to 84.2% when the CO2 concentration improved from 3% to 100%. In SEM observations, the microstructures after accelerated carbonation were denser than those under natural carbonation but showed minor differences between different CO2 concentrations. In conclusion, for cement pastes blended with 20% slag, a higher CO2 concentration (above 3%) led to products different from those produced under natural carbonation. A further increase in CO2 concentration showed limited variation in generated carbonation products.

scholarly journals Utilization of Calcium Carbide Residue Using Granulated Blast Furnace Slag

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3511 ◽  
Author(s):  
Joonho Seo ◽  
Solmoi Park ◽  
Hyun No Yoon ◽  
Jeong Gook Jang ◽  
Seon Hyeok Kim ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Calcium Carbide ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Granulated Blast Furnace Slag ◽  
Calcium Carbide Residue ◽  
Angle Spinning ◽  
Furnace Slag

The solidification and stabilization of calcium carbide residue (CCR) using granulated blast furnace slag was investigated in this study. CCR binding in hydrated slag was explored by X-ray diffraction, 29Si and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, and thermodynamic calculations. Mercury intrusion porosimetry and and compressive strength tests assessed the microstructure and mechanical properties of the mixtures of slag and CCR. C-A-S-H gel, ettringite, hemicarbonate, and hydrotalcite were identified as the main phases in the mixture of slag and CCR. The maximum CCR uptake by slag and the highest volume of precipitated solid phases were reached when CCR loading in slag is 7.5% by mass of slag, according to the thermodynamic prediction. This feature is also experimentally observed in the microstructure, which showed an increase in the pore volume at higher CCR loading.

scholarly journals Structure of nanocrystalline calcium silicate hydrates: insights from X-ray diffraction, synchrotron X-ray absorption and nuclear magnetic resonance

2016 ◽  
Vol 49 (3) ◽  
pp. 771-783 ◽  
Author(s):  
Sylvain Grangeon ◽  
Francis Claret ◽  
Cédric Roosz ◽  
Tsutomu Sato ◽  
Stéphane Gaboreau ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Calcium Silicate ◽  
Electron Probe ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcium Silicate Hydrates ◽  
Angle Spinning ◽  
X Ray Absorption

The structure of nanocrystalline calcium silicate hydrates (C–S–H) having Ca/Si ratios ranging between 0.57 ± 0.05 and 1.47 ± 0.04 was studied using an electron probe micro-analyser, powder X-ray diffraction,29Si magic angle spinning NMR, and Fourier-transform infrared and synchrotron X-ray absorption spectroscopies. All samples can be described as nanocrystalline and defective tobermorite. At low Ca/Si ratio, the Si chains are defect free and the SiQ3andQ2environments account, respectively, for up to 40.2 ± 1.5% and 55.6 ± 3.0% of the total Si, with part of theQ3Si being attributable to remnants of the synthesis reactant. As the Ca/Si ratio increases up to 0.87 ± 0.02, the SiQ3environment decreases down to 0 and is preferentially replaced by theQ2environment, which reaches 87.9 ± 2.0%. At higher ratios,Q2decreases down to 32.0 ± 7.6% for Ca/Si = 1.38 ± 0.03 and is replaced by theQ1environment, which peaks at 68.1 ± 3.8%. The combination of X-ray diffraction and NMR allowed capturing the depolymerization of Si chains as well as a two-step variation in the layer-to-layer distance. This latter first increases from ∼11.3 Å (for samples having a Ca/Si ratio <∼0.6) up to 12.25 Å at Ca/Si = 0.87 ± 0.02, probably as a result of a weaker layer-to-layer connectivity, and then decreases down to 11 Å when the Ca/Si ratio reaches 1.38 ± 0.03. The decrease in layer-to-layer distance results from the incorporation of interlayer Ca that may form a Ca(OH)2-like structure, nanocrystalline and intermixed with C–S–H layers, at high Ca/Si ratios.

Synthesis, X-ray diffraction and solid-state 31P magic angle spinning NMR study of ?-tricalcium orthophosphate

1996 ◽  
Vol 7 (7) ◽  
pp. 457-463 ◽  
Author(s):  
M. Bohner ◽  
J. LeMa�tre ◽  
A. P. LeGrand ◽  
J.-B. D'Espinose de la Caillerie ◽  
P. Belgrand
Keyword(s):  
Solid State ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Study ◽  
Angle Spinning

Synthesis and characterization of montmorillonite-type phyllosilicates in a fluoride medium

Clay Minerals ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 177-190 ◽  
Author(s):  
M. Reinholdt ◽  
J. Miehé-Brendlé ◽  
L. Delmotte ◽  
R. Le Dred ◽  
M.-H. Tuilier
Keyword(s):  
Atomic Ratio ◽  
Magic Angle Spinning ◽  
Crystallization Time ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Angle Spinning ◽  
Mg Content ◽  
Fluoride Medium

AbstractThe fluorine route is thoroughly investigated for the hydrothermal synthesis of montmorillonite in the Na2O-MgO-Al2O3-SiO2-H2O system. Using the optimal conditions suggested by Reinholdt et al. (2001) for the crystallization of pure montmorillonites with the formula Na2x(Al2(1-x)Mg2x☐)Si4O10(OH)2, several parameters (x, Mg content, duration of crystallization, F/Si atomic ratio, pH, nature of counterbalance cation) are varied independently from their ideal values. The products are analysed by various techniques (X-ray diffraction, thermogravimetric analysis-differential thermal analysis, 29Si, 27Al and 19F magic angle spinning-nuclear magnetic resonance). It appears that a pure montmorillonite can only be obtained within a narrow x range (0.10 ≤ x ≤ 0.20). The presence of F in the starting hydrogel and the crystallization time also have significant effects on the purity of the final products. It is shown that a small amount of fluorine is needed for the crystallization of pure montmorillonite phyllosilicates.

scholarly journals SYSU-6, A New 2-D Aluminophosphate Zeolite Layer Precursor

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2972 ◽  
Author(s):  
Jiang-Zhen Qiu ◽  
Long-Fei Wang ◽  
Jiuxing Jiang
Keyword(s):  
Electron Microscopy ◽  
Single Crystal ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Structure Directing Agent ◽  
X Ray ◽  
Uv Raman ◽  
Angle Spinning ◽  
Inorganic Framework

Two-dimensional aluminophosphate is an important precursor of phosphate-based zeolites; a new Sun Yat-sen University No. 6 (SYSU-6) with |Hada|2[Al2(HPO4)(PO4)2] has been synthesized in the hydrothermal synthesis with organic structure-directing agent (OSDA) of N,N,3,5-tetramethyladamantan-1-amine. In this paper, SYSU-6 is characterized by single-crystal/powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, infrared and UV Raman spectroscopy, solid-state 27Al, 31P and 13C magic angle spinning (MAS) NMR spectra, and elemental analysis. The single-crystal X-ray diffraction structure indicates that SYSU-6 crystallized in the space group P21/n, with a = 8.4119(3), b = 36.9876(12), c = 12.5674(3), α = 90°, β = 108.6770(10)°, γ = 90°, V = 3704.3(2) Å3, Z = 4, R = 5.12%, for 8515 observed data (I > 2σ(I)). The structure has a new 4,12-ring layer framework topology linked by alternating AlO4 and PO4 tetrahedra. The organic molecules reside between the layers and are hydrogen-bonded to the inorganic framework. The new type of layer provides a greater opportunity to construct zeolite with novel topology.

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