The effect of origin and physico-chemical properties on the kinetics of reduction of mixed NiO-Fe2O3 oxides with hydrogen

1986 ◽  
Vol 51 (10) ◽  
pp. 2098-2108 ◽  
Author(s):  
Milan Pospíšil ◽  
Jan Topinka
Keyword(s):  
Mixed Oxides ◽  
Mutual Influence ◽  
Spinel Phase ◽  
Chemical Properties ◽  
Inhibitory Effect ◽  
Chemical Parameters ◽  
Physico Chemical ◽  
Preliminary Annealing ◽  
Kinetics Of ◽  
Kinetics Of Reduction

We investigated the effect of origin and some physico-chemical parameters on the kinetics of reduction with hydrogen of two series of mixed NiO-Fe2O3 oxides differing by their composition, the character of their precursors (mixed crystalline nitrates and coprecipitated hydroxides) and their decomposition temperature.This effect manifested itself by different magnitudes of specific surfaces of the mixed oxides and coherent regions of present phases as well as by different oxidizing abilities of the surface and differences in morphology and phase composition of corresponding samples in both series investigated. Nonlinear or nonmonotonous composition dependences of physico-chemical parameters investigated point to a mutual influence of individual components, which is also a function of the system origin and which modifies its reactivity during its reduction with hydrogen. The kinetics of the reduction was studied thermogravimetrically at 320-410 °C. The reduction of oxides of the hydroxide origin is catalytically accelerated by primarily reduced nickel, whereas in corresponding samples of the nitrate series, the total NiO is bound to the spinel phase and the reduction is delayed. Experimental IR spectra, the effect of preliminary annealing and DTA of the mixed oxides point to an inhibitory effect of water, which is constitutionally bound in trace admixtures of the goethite phase, on the kinetics of reduction of samples in the hydroxide series.

PHYSICO-CHEMICAL PROPERTIES OF A NEW CLAY-BASED SORBENT

2019 ◽  
Vol 9 (1) ◽  
pp. 52-56
Author(s):  
Sergey V. STEPANOV ◽  
Olga N. PANFILOVA ◽  
Kristina K. ADDUGAFFAROVA
Keyword(s):  
Ion Exchange ◽  
Chemical Properties ◽  
Thermal Method ◽  
Chemical Parameters ◽  
Aluminum Oxides ◽  
Ir Spectrometry ◽  
Physico Chemical ◽  
Preliminary Preparation ◽  
Physical And Chemical ◽  
Finished Sample

The main physical and chemical parameters of a new sorbent developed on the basis of the minerals of the Samara region: clays, peat and dolomite are considered. The particle size of the clay after grinding at the stage of preliminary preparation was less than 1 nm, which relates them to highly dispersed materials. A chemical analysis of the composition of the components showed a high content of silicon and aluminum oxides, which possess ion exchange properties, and also made it possible to assign clays to montmorillonite rocks. The modification of the sorbent was carried out by thermal method. The density of the finished sample was 1.8 g / cm3. The method of scanning electron microscopy showed that the structure of the finished sample belongs to spongy bodies. The method of IR spectrometry confirmed the presence of functional groups in the crystal lattice of the sorbent, which cause not only the physical, but also the ion exchange and chemical nature of sorption.

scholarly journals Physico-chemical Parameters of Honey From Melipona mondury Smith, 1863 (Hymenoptera: Apidae: Meliponini)

2018 ◽  
Vol 10 (7) ◽  
pp. 196 ◽  
Author(s):  
Rogério Marcos de Oliveira Alves ◽  
Jacqueline Lemos Viana ◽  
Henrique de Abreu Cerqueira Sousa ◽  
Ana Maria Waldschmidt
Keyword(s):  
Electrical Conductivity ◽  
Water Activity ◽  
Reducing Sugars ◽  
Chemical Properties ◽  
Northeastern Brazil ◽  
Chemical Parameters ◽  
Technical Regulation ◽  
Mean Values ◽  
Physico Chemical

The physico-chemical properties of honey produced by the stingless bee Melipona mondury from Atlantic Forest in the state of Bahia, northeastern Brazil were evaluated. The evaluated characteristics included: water content, electrical conductivity, pH, acidity, water activity, ashes, diastase, hydroxymethylfurfural (HMF), reducing sugars and saccharose values. The honey samples showed mean values of 29.18% for moisture; 391.5 μS for electrical conductivity; pH of 4.06; 34.3 meq kg-1 for acidity; 0.73 for water activity; 0.18% for ashes; 4.05 (Goethe unit) for diastase; 1.60% for HMF; 65.42% for reducing sugars; and 2.14% of saccharose. Only the diastase activity was above the limits accepted by the Technical Regulation for Identity and Quality of Honey (Brazilian Ministry of Agriculture and Supplies). Most parameters are according to those reported in honeys from other species of stingless bees in Brazil.

Influence of the physico-chemical properties of CeO2–ZrO2 mixed oxides on the catalytic oxidation of NO to NO2

2010 ◽  
Vol 256 (24) ◽  
pp. 7706-7712 ◽  
Author(s):  
Idriss Atribak ◽  
Noelia Guillén-Hurtado ◽  
Agustín Bueno-López ◽  
Avelina García-García
Keyword(s):  
Catalytic Oxidation ◽  
Mixed Oxides ◽  
Chemical Properties ◽  
Physico Chemical ◽  
Oxidation Of No

scholarly journals The Influence of the Preparation Method on the Physico-Chemical Properties and Catalytic Activities of Ce-Modified LDH Structures Used as Catalysts in Condensation Reactions

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6191
Author(s):  
Alexandra-Elisabeta Stamate ◽  
Rodica Zăvoianu ◽  
Octavian Dumitru Pavel ◽  
Ruxandra Birjega ◽  
Andreea Matei ◽  
...  
Keyword(s):  
Preparation Method ◽  
Mixed Oxides ◽  
Condensation Reaction ◽  
Chemical Properties ◽  
Precipitation Method ◽  
Synthesis Methods ◽  
Molar Ratios ◽  
Base Catalysts ◽  
Physico Chemical ◽  
Co Precipitation

Mechanical activation and mechanochemical reactions are the subjects of mechanochemistry, a special branch of chemistry studied intensively since the 19th century. Herein, we comparably describe two synthesis methods used to obtain the following layered double hydroxide doped with cerium, Mg3Al0.75Ce0.25(OH)8(CO3)0.5·2H2O: the mechanochemical route and the co-precipitation method, respectively. The influence of the preparation method on the physico-chemical properties as determined by multiple techniques such as XRD, SEM, EDS, XPS, DRIFT, RAMAN, DR-UV-VIS, basicity, acidity, real/bulk densities, and BET measurements was also analyzed. The obtained samples, abbreviated HTCe-PP (prepared by co-precipitation) and HTCe-MC (prepared by mechanochemical method), and their corresponding mixed oxides, Ce-PP (resulting from HTCe-PP) and Ce-MC (resulting from HTCe-MC), were used as base catalysts in the self-condensation reaction of cyclohexanone and two Claisen–Schmidt condensations, which involve the reaction between an aromatic aldehyde and a ketone, at different molar ratios to synthesize compounds with significant biologic activity from the flavonoid family, namely chalcone (1,3-diphenyl-2-propen-1-one) and flavone (2-phenyl-4H-1benzoxiran-4-one). The mechanochemical route was shown to have indisputable advantages over the co-precipitation method for both the catalytic activity of the solids and the costs.

scholarly journals Physico-chemical properties of water of Ramshagar dighi, the largest man made historical reservoir in northern Bangladesh

2018 ◽  
Vol 23 ◽  
pp. 29-37
Author(s):  
Ashaduzzaman ◽  
MJ Hossain ◽  
S Akther
Keyword(s):  
Carbon Dioxide ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Air Temperature ◽  
Water Depth ◽  
Chemical Properties ◽  
Current Status ◽  
Chemical Parameters ◽  
Monthly Average ◽  
Physico Chemical

Ramshagar dighi is a larger historical man made reservoir (Dighi, Bengali meaning) situated at Tajpur village in Dinajpur, Bangladesh. This study was aimed to estimate current status of physico-chemical variables of water of Ramshagar dighi at Dinajpur District, Bangladesh. Monthly average changes in physico-chemical parameters such as water temperature, total dissolved oxygen, air temperature, humidity, rainfall, water depth and pH of water were analyzed for the period of 11 months from May 2011 to March 2012. The average air temperature (°C) at the study area of Ramshagar dighi at Dinajpur District was determined as 24.97 ± 4.92. Our present study showed that physico-chemical properties of water in Ramshagar dighi were monthly average of water temperature (°C) as 24.68 ± 4.77, air temperature (°C) 24.97 ± 4.92, humidity as 82.075 ± 4.14, rainfall as 1534.5 mm, water depth as 9.10 m ± 1.286, pH as7.67± 0.48 and carbon dioxide as 0.85 ± 0.92 as well as dissolved oxygen as 4.65 ± 0.62 respectively during the period of May 2011 to March 2012. Therefore, present study was conducted to assess physico-chemical properties of water of Ramshagar dighi, Dinajpur, Bangladesh.J. bio-sci. 23: 29-37, 2015

scholarly journals Estimation of The Physico-Chemical Parameters in Marine Environment (Yumurtalik Bight- Iskenderun Bay)

2016 ◽  
Vol 4 (2) ◽  
pp. 97
Author(s):  
Gökhan Tamer Kayaalp ◽  
Oya Işık ◽  
Benin Toklu Alıçlı
Keyword(s):  
Light Intensity ◽  
Analysis Of Variance ◽  
Chemical Properties ◽  
Effect Of Temperature ◽  
Chemical Parameters ◽  
Marine Life ◽  
Multiple Comparison Test ◽  
Physico Chemical ◽  
Iskenderun Bay ◽  
Dissolved O2

The study was carried out to estimate the temperature, light intensity, salinity, Dissolved O2 (DO), pH values and the biotic parameter chlorophyll- a in the water column related with the depth. Because, the physico-chemical parameters affect greatly both primary and secondary producers in marine life. For this purpose the physico-chemical properties were determined day and night for 40 meter depth during the eight days. The means were compared by using the analysis of variance method and Duncan’s Multiple Comparison Test. Also physico-chemical parameters were estimated by using the analysis of regression and correlation. The effect of temperature and salinity were found significant according to the result of the analysis of variance during the day. Also the similar results were found for the night. While the effect of the depth on the chloropyll-a a was significant in the night, the effect of the depth on the DO was not significant in the day and night. The correlations among the depth and the parameters were defined. It was found the negative correlation between the depth and the temperature and light intensity. Determination coefficient of the model for salinity was also found different for day time. The correlation values among the depth and the temperature, salinity and pH were found different for the night.

scholarly journals Development of mango flavored Soy Dahi

2013 ◽  
Vol 42 (1) ◽  
pp. 44-48 ◽  
Author(s):  
TA Rakhi ◽  
MN Islam ◽  
SAM Hoque ◽  
MM Rahman
Keyword(s):  
Low Cost ◽  
Chemical Properties ◽  
Cow Milk ◽  
High Price ◽  
Soy Milk ◽  
Chemical Parameters ◽  
Physico Chemical ◽  
Mango Juice ◽  
Beany Flavour ◽  
Physical And Chemical

The experiment was aimed to prepare mango flavored soy milk based dahi (whole cow milk : soy milk=1:1). To remove the beany flavour of soybean as well as to add the mango flavour, mango juice were added at the rate of 0, 5, 10 and 15%. Data on physical and chemical parameters were recorded and analyzed. It was observed that smell and taste, body and consistency, color and appearance as well as total score were significantly increased (p<0.01) when 5% mango juice added to soy milk based dahi. These properties could further be increased significantly (p<0.01) by increasing the level up to 10% but increasing the level of mango juice up to 15% were significantly decreased (p<0.01) the physical properties. After chemical analysis, a significant increasing (p<0.05) in acidity, total solids and carbohydrate content but a significantly decresing (p<0.05) in fat and ash content of dahi were observed due to the addition of mango juice. Compilation of physico-chemical properties it was observed that addition of 10% mango juice prepared a high quality low cost mango flavored soy milk based dahi. Considering the shortage along with high price of milk we could transfer the techniques to the manufacturer to produce and market the mango flavored soy milk based dahi. DOI: http://dx.doi.org/10.3329/bjas.v42i1.15779 Bang. J. Anim. Sci. 2013. 42 (1): 44-48

scholarly journals Synthesis and investigation of the physico-chemical properties of catalysts based on mixed oxides CexZr1−xO2

2015 ◽  
Vol 8 (2) ◽  
pp. 222-227 ◽  
Author(s):  
S. Nousir ◽  
R. Maache ◽  
S. Azalim ◽  
M. Agnaou ◽  
R. Brahmi ◽  
...  
Keyword(s):  
Mixed Oxides ◽  
Chemical Properties ◽  
Physico Chemical
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