scholarly journals Retention of Organic Matter Contained in Industrial Phosphoric Acid Solution by Raw Tunisian Clays: Kinetic Equilibrium Study

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Wiem Hamza ◽  
Chaker Chtara ◽  
Mourad Benzina
Keyword(s):  
Phosphoric Acid ◽  
Bentonite Clay ◽  
Phosphoric Acid Solution ◽  
Operating Conditions ◽  
Equilibrium Adsorption ◽  
X Ray Diffraction ◽  
Equilibrium Study ◽  
Freundlich Isotherms ◽  
Different Types ◽  
Kinetic Equilibrium

Purification of industrial phosphoric acid (H3PO4) is considered a major problem and several methods have been evaluated. In this study, two different types of clay, raw bentonite clay (RBC) and raw grey clay (RGC), were used for removal of SOM contained in H3PO4at low pH. The used samples were characterized by X-ray diffraction, chemical analysis, and specific surface area and MET was also realized. The ability of clay samples to remove S.O.M from aqueous solutions of industrial phosphoric acid has been studied at different operating conditions: temperature, agitation speed, contacting time, and so on. The results indicated that adsorption is an exothermic process for lead S.O.M removal. The equilibrium adsorption data were analysed using the Langmuir and Freundlich isotherms. The results showed that the equilibrium adsorption capacities for the two adsorbents followed best the Langmuir model. Thermodynamic parameters showed that the adsorption process was spontaneous and exothermic.

scholarly journals Effect of different types of acid-etching agents and adhesives on enamel discoloration during orthodontic treatment

2021 ◽  
Vol 15 (1) ◽  
pp. 7-10
Author(s):  
Arman Mohmmadi Shayan ◽  
Ahmad Behroozian ◽  
Amirhouman Sadrhaghighi ◽  
Amirmohammad Dolatabadi ◽  
Sevda Hashemzadeh
Keyword(s):  
Phosphoric Acid ◽  
Acid Solution ◽  
Orthodontic Treatment ◽  
Color Change ◽  
Phosphoric Acid Solution ◽  
Acid Etching ◽  
Fluoride Release ◽  
Significant Difference ◽  
Different Types ◽  
The Difference

Background. Acid etching and bonding is a routine process in orthodontic treatment. The present study aimed to evaluate enamel discoloration after using different types of acid etching and adhesive agents. Methods. A total of 105 extracted human premolars were divided into six groups regarding the type of acid etching agent: solution and gel of 37% phosphoric acid, and type of self-cured adhesive agent: Unite (3M, fluoride-free), Resilience (Ortho Technology), and Rely-a-Bond (Reliance, fluoride-releasing adhesive), with each group containing 15 specimens. All the selected teeth were subjected to a staining process, and color parameters were determined using a spectrophotometer. Results. The type of phosphoric acid (solution or gel) had no significant effect on the color change of enamel (P>0.05). Resilience significantly changed the enamel color compared to the Unite and Rely-a-Bond (P<0.001). There was no significant difference in color change between the Unite and Rely-a-Bond adhesives (P=0.67). The difference in color change between all the three time intervals (T0-T1, T1-T2, and T0-T2) was significant (P<0.001). Conclusion. In this study, the type of phosphoric acid (solution or gel) did not result in any significant difference in enamel color. Also, considering the lack of the effect of the orthodontic adhesive type in terms of fluoride release or no fluoride release, it can be concluded that this is most affected by the commercial brand of adhesives.

Study Intercalation and Mechanical Properties of Nanocomposites of HDPE/Organoclay

2012 ◽  
Vol 727-728 ◽  
pp. 1785-1788
Author(s):  
Milena Costa da Silva ◽  
Sara Verusca de Oliveira ◽  
Tomás Jefférson Alves de Mélo ◽  
Edcleide Maria Araújo
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Bentonite Clay ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
New Class ◽  
Different Types ◽  
The Matrix ◽  
Twin Screw ◽  
Xrd Patterns

Nanocomposites are hybrid materials that can be obtained with, three, two or bust one-dimensional in nanoscale found in particles dispersed in the matrix. By presenting a nanometric structure, this new class of materials may have only properties, different from traditional composites and their constituents, which may be established in the synthesis process. The aim of this work is prepare nanocomposites of HDPE/ bentonite clay by melt intercalation technique. Systems were evaluated for the presence of untreated clay and chemically treated (organoclay) with two different types of quaternary ammonium salts, Cetremide and Dodigen. In the preparation of nanocomposites were obtained concentrated using a high speed mixer and then the nominal percentage of clay was dispersed in a twin screw extruder corrotacional. The systems were characterized by X-ray diffraction and mechanical properties. The XRD patterns of nanocomposite of HDPE/organoclay suggest a not intercalated structure. The mechanical properties of nanocomposites presented reducing values in relation to pure polymer.

Instrumental Capabilites in X-Ray Diffraction Analysis: Comparative Techniques

1986 ◽  
Vol 30 ◽  
pp. 407-412 ◽  
Author(s):  
P. J. Kincaid ◽  
R. A. Newman ◽  
T. G. Fawcett
Keyword(s):  
Operating Conditions ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Company ◽  
Different Types ◽  
High Resolution Analysis ◽  
Resolution Analysis ◽  
Typical Day ◽  
Comprehensive Study

The following study is an evaluation of several different types of instrumentation available for use in powder x-ray diffraction work. The particular units used are those at the Dow Chemical Company x-ray diffraction lab. The variety of instrumentation allows analyses from routine phase identification to more specialized work such as low-angle x-ray diffraction of polymers and high-resolution analysis for cell parameter refinements.The purpose of this work is to compare the relative capabilities of these different instruments under typical day-to-day operating conditions. While not a comprehensive study, the conclusions drawn should be applicable to powder x-ray diffraction in general.

In situ x-ray diffraction investigation on early stages of oxidation at 900 °C of γ-TiAl dipped in a phosphoric acid solution

2009 ◽  
Vol 106 (10) ◽  
pp. 103502 ◽  
Author(s):  
S. Y. Brou ◽  
P. O. Renault ◽  
C. Huvier ◽  
J. L. Grosseau-Poussard ◽  
G. Bonnet
Keyword(s):  
Phosphoric Acid ◽  
Acid Solution ◽  
Phosphoric Acid Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Early Stages

scholarly journals Multi-Scale Studies of 3D Printed Mn–Na–W/SiO2 Catalyst for Oxidative Coupling of Methane

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 290
Author(s):  
Tim Karsten ◽  
Vesna Middelkoop ◽  
Dorota Matras ◽  
Antonis Vamvakeros ◽  
Stephen Poulston ◽  
...  
Keyword(s):  
Oxidative Coupling ◽  
Oxidative Coupling Of Methane ◽  
Operating Conditions ◽  
Homogeneous Distribution ◽  
Silica Support ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Multi Scale ◽  
3D Printed

This work presents multi-scale approaches to investigate 3D printed structured Mn–Na–W/SiO2 catalysts used for the oxidative coupling of methane (OCM) reaction. The performance of the 3D printed catalysts has been compared to their conventional analogues, packed beds of pellets and powder. The physicochemical properties of the 3D printed catalysts were investigated using scanning electron microscopy, nitrogen adsorption and X-ray diffraction (XRD). Performance and durability tests of the 3D printed catalysts were conducted in the laboratory and in a miniplant under real reaction conditions. In addition, synchrotron-based X-ray diffraction computed tomography technique (XRD-CT) was employed to obtain cross sectional maps at three different positions selected within the 3D printed catalyst body during the OCM reaction. The maps revealed the evolution of catalyst active phases and silica support on spatial and temporal scales within the interiors of the 3D printed catalyst under operating conditions. These results were accompanied with SEM-EDS analysis that indicated a homogeneous distribution of the active catalyst particles across the silica support.

scholarly journals Synthesis and Characterization of Clay Polymer Nanocomposites of P(4VP-co-AAm) and Their Application for the Removal of Atrazine

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 721 ◽  
Author(s):  
Jorge A. Ramírez-Gómez ◽  
Javier Illescas ◽  
María del Carmen Díaz-Nava ◽  
Claudia Muro-Urista ◽  
Sonia Martínez-Gallegos ◽  
...  
Keyword(s):  
Polymer Nanocomposites ◽  
Nanocomposite Materials ◽  
Synthesis And Characterization ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
Numerous Species ◽  
X Ray ◽  
Different Types ◽  
Synthesized Materials

Atrazine (ATZ) is an herbicide which is applied to the soil, and its mechanism of action involves the inhibition of photosynthesis. One of its main functions is to control the appearance of weeds in crops, primarily in corn, sorghum, sugar cane, and wheat; however, it is very toxic for numerous species, including humans. Therefore, this work deals with the adsorption of ATZ from aqueous solutions using nanocomposite materials, synthesized with two different types of organo-modified clays. Those were obtained by the free radical polymerization of 4-vinylpyridine (4VP) and acrylamide (AAm) in different stoichiometric ratios, using tetrabutylphosphonium persulfate (TBPPS) as a radical initiator and N,N′-methylenebisacrylamide (BIS) as cross-linking agent. The structural, morphological, and textural characteristics of clays, copolymers, and nanocomposites were determined through different analytical and instrumental techniques, i.e., X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Adsorption kinetics experiments of ATZ were determined with the modified and synthesized materials, and the effect of the ratio between 4VP and AAm moieties on the removal capacities of the obtained nanocomposites was evaluated. Finally, from these sets of experiments, it was demonstrated that the synthesized nanocomposites with higher molar fractions of 4VP obtained the highest removal percentages of ATZ.

scholarly journals Microwave-Assisted Fabrication of Mesoporous Silica-Calcium Phosphate Composites for Dental Application

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 53
Author(s):  
Adrian Szewczyk ◽  
Adrianna Skwira ◽  
Marta Ginter ◽  
Donata Tajer ◽  
Magdalena Prokopowicz
Keyword(s):  
Calcium Phosphate ◽  
Mesoporous Silica ◽  
Octacalcium Phosphate ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Coating Solution ◽  
X Ray ◽  
Microwave Assisted ◽  
Calcium Orthophosphates ◽  
Different Types

Herein, the microwave-assisted wet precipitation method was used to obtain materials consisting of mesoporous silica (SBA-15) and calcium orthophosphates (CaP). Composites were prepared through immersion of mesoporous silica in different calcification coating solutions and then exposed to microwave radiation. The composites were characterized in terms of molecular structure, crystallinity, morphology, chemical composition, and mineralization potential by Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX). The application of microwave irradiation resulted in the formation of different types of calcium orthophosphates such as calcium deficient hydroxyapatite (CDHA), octacalcium phosphate (OCP), and amorphous calcium phosphate (ACP) on the SBA-15 surface, depending on the type of coating solution. The composites for which the progressive formation of hydroxyapatite during incubation in simulated body fluid was observed were further used in the production of final pharmaceutical forms: membranes, granules, and pellets. All of the obtained pharmaceutical forms preserved mineralization properties.

Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash

1987 ◽  
Vol 113 ◽  
Author(s):  
Scott Schlorholtz ◽  
Ken Bergeson ◽  
Turgut Demirel
Keyword(s):  
Fly Ash ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Physical And Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
High Calcium ◽  
Physical And Chemical ◽  
And Chemical Properties

ABSTRACTThe physical and chemical properties of fly ash produced at Ottumwa Generating Station have been monitored since April, 1985. The fly ash is produced from burning a low sulfur, sub-bituminous coal obtained from the Powder River Basin near Gillette, Wyoming. One-hundred and sixty samples of fly ash were obtained during the two year period. All of the samples were subjected to physical testing as specified by ASTM C 311. About one-hundred of the samples were also subjected to a series of tests designed to monitor the self-cementing properties of the fly ash. Many of the fly ash samples were subjected to x-ray diffraction and fluorescence analysis to define the mineralogical and chemical composition of the bulk fly ash as a function of sampling date. Hydration products in selected hardened fly ash pastes, were studied by x-ray diffraction and scanning electron microscopy. The studies indicated that power plant operating conditions influenced the compressive strength of the fly ash paste specimens. Mineralogical and morphological studies of the fly ash pastes indicated that stratlingite formation occurred in the highstrength specimens, while ettringite was the major hydration product evident in the low-strength specimens.

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