scholarly journals OBTAINING AND PHYSICO-CHEMICAL PROPERTIES OF MATERIALS BASED ON EXPANDED VERMICULITES OF VARIOUS COMPOSITIONS

2018 ◽  
Vol 61 (6) ◽  
pp. 76
Author(s):  
Alexander V. Kalashnik ◽  
Sergey G. Ionov
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Properties ◽  
Decomposition Reaction ◽  
Chemical Compositions ◽  
Thermal Treatments ◽  
X Ray ◽  
Expanded Vermiculite ◽  
Physico Chemical ◽  
Developed Surface ◽  
Properties Of Materials

Optimal conditions for chemical and thermal treatments of natural vermiculites from various deposits were determined. The aim of obtaining expanded vermiculites with a minimum bulk density was pursued. Optimum temperature for producing thermal expanded vermiculites was 700 °C. According to scanning electron microscopy chemical expanded vermiculite has more developed surface in comparison with thermal expanded vermiculite. Chemical composition of natural vermiculites of various deposits and expanded vermiculites based on them was defined by X-ray fluorescence. It was shown that the vermiculite of the Tatar deposit contains a large amount of iron distributed over the surface. As a result, the vermiculite from Tatarstan can not be modified by hydrogen peroxide because of the active decomposition reaction of hydrogen peroxide on the surface of vermiculite. It was established that the chemical compositions of natural vermiculites as well as expanded vermiculites based on them do not differ. According to Mössbauer spectroscopy the ratio Fe(II)/Fe(III) in natural vermiculate was 1:4 and in thermal expanded vermiculite was 1:8. It should be noted that chemical expanded vermiculate contains only Fe(III). According to X-ray phase analysis the phase composition of natural vermiculite changes at 350 °C. It was defined that natural vermiculite and thermal expanded vermiculite after adsorption of moisture from the air have the same position of the X-ray maximum. When natural vermiculite was heated two areas of water loss were observed by the thermogravimetric analysis. The anisotropy of tensile strength for samples of the same density taken along and across the rolling axis of vermiculite foil obtained by pressing expanded vermiculite without a binder was described. The thermal conductivity coefficient of vermiculite foil was determined. This makes it possible to use the material as heat shield and fire protector.Forcitation:Kalashnik A.V., Ionov S.G. Obtaining and physico-chemical properties of materials based on expanded vermiculites of various compositions. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 6. P. 76-82

Decomposition of hydrogen peroxide on nickel-silver two-component catalyst

1984 ◽  
Vol 49 (10) ◽  
pp. 2222-2230 ◽  
Author(s):  
Viliam Múčka ◽  
Rostislav Silber
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Properties ◽  
Silver Ions ◽  
Surface Concentration ◽  
Chloride Ions ◽  
Nickel Silver ◽  
Silver Catalysts ◽  
Physico Chemical ◽  
Low Degree ◽  
Defective Crystal

The catalytic and physico-chemical properties of low-temperature nickel-silver catalysts with nickel oxide concentrations up to 43.8% (m/m) are examined via decomposition of hydrogen peroxide in aqueous solution. The mixed catalysts prepared at 250°C are composed of partly decomposed silver carbonate or oxide and nickel carbonate or hydroxide decomposed to a low degree only and exhibiting a very defective crystal structure. The activity of these catalysts is determined by the surface concentration of silver ions, which is affected by the nickel component present. The latter also contributes to the thermal stability of the catalytic centres of the silver component, viz. the Ag+ ions. The concentration of these ions varies with the temperature of the catalyst treatment, the activity varies qualitatively in the same manner, and the system approaches the Ag-NiO composition. The catalytic centres are very susceptible to poisoning by chloride ions. A previous exposition of the catalyst to a gamma dose of 10 kGy from a 60Co source has no measurable effect on the physico-chemical properties of the system.

Physico-Chemical and Morphological Changes of Sayong Kaolinite Clay Treated with Sulphuric Acid for Enzyme Immobilization

2013 ◽  
Vol 832 ◽  
pp. 589-595 ◽  
Author(s):  
N.A. Edama ◽  
A. Sulaiman ◽  
K.H. Ku Hamid ◽  
M.N. Muhd Rodhi ◽  
Mohibah Musa ◽  
...  
Keyword(s):  
Surface Area ◽  
Sulphuric Acid ◽  
Enzyme Immobilization ◽  
Morphological Changes ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
Kaolinite Clay ◽  
X Ray ◽  
Mineral Oxides ◽  
Physico Chemical

This study analyzed the effects of sulphuric acid (H2SO4) treatment on pysico-chemical properties and morphological changes of clay obtained from Sg. Sayong, Perak. The clay was ground and sieved to <150μm and treated with different concentrations of H2SO4. The treatment was completed by refluxing the clay with different concentration of H2SO4 (1M, 5M and 10M ) at 100 °C for 4 hours and followed by calcination at 500 °C for 1 hour. The physic-chemical properties and morphological changes of the untreated and treated clay were compared using Surface Area Analyser, X-Ray Diffraction (XRD), Field Emission Scanning Electron Micrograph (FESEM), X-Ray Diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR). The results showed that acid treatment of 5M increased the surface area from 25 m2/g to 75 m2/g and the pore volume increased from 0.1518 cc/g to 0.3546 cc/g. The nanopore size of the clay decreased from 24.8 nm to 19.4 nm after treated with acid. This can be explained due to the elimination of the exchangeable cations and generation of microporosity. The results of XRF showed SiO2 increased from 58.34% to 74.52% and Al2O3 reduced from 34.6% to 18.31%. The mineral oxides such as Fe2O3, MgO, CaO, K2O and TiO2 also reduced. This concluded that H2SO4 treatment has led to significant removal of octahedral Al3+, Fe3+ cations and other impurities. In conclusion, this study showed the physico-chemical properties and morphology of Sayong clay were improved once treated with H2SO4 and therefore suggests better supporting material for enzyme immobilization.

Physical Chemistry of the Interface between Attached Micro-Organisms and Their Support

1990 ◽  
Vol 22 (1-2) ◽  
pp. 1-16 ◽  
Author(s):  
P. G. Rouxhet ◽  
N. Mozes
Keyword(s):  
Photoelectron Spectroscopy ◽  
Bacterial Adhesion ◽  
Surface Composition ◽  
Chemical Properties ◽  
Dlvo Theory ◽  
Support Surface ◽  
X Ray ◽  
Polymer Molecules ◽  
Physico Chemical ◽  
Micro Organisms

The thermodynamic approach of adhesion and DLVO theory are complementary to predict initial bacterial adhesion; the interplay between short- and long-range forces, respectively, may be due to surface roughness. Due to the influence of electrical double layer interactions, adhesion can be promoted by treatments leading to modification of the cell or support surface properties. Adhesion is influenced by cell-cell interactions, by the cpresence of polymer molecules on the surface and by the composition of the medium. X-ray photoelectron spectroscopy can be applied to determine the elemental composition of the surface of microorganisms; some information on the chemical functions can also be obtained. The surface composition is related to physico-chemical properties which play a determining role in adhesion and flocculation, in particular the hydrophobicity and the zeta potential.

scholarly journals Effect of TiO2 Addition on Mortars: Characterization and Photoactivity

2019 ◽  
Vol 9 (13) ◽  
pp. 2598 ◽  
Author(s):  
M. J. Hernández-Rodríguez ◽  
R. Santana Rodríguez ◽  
R. Darias ◽  
O. González Díaz ◽  
J. M. Pérez Luzardo ◽  
...  
Keyword(s):  
Mercury Porosimetry ◽  
Setting Time ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Setting Process ◽  
Flow Table ◽  
Negative Effect ◽  
Important Activity

In this study, mortar specimens were prepared with a cement:sand:water ratio of 1:3:0.5, in accordance with standard EN196-1. Portland CEM I 52.5 R grey (G) and white (W) cements were used, together with normalised sand and distilled water. Different amounts of TiO2 photocatalyst were incorporated in the preparation of the mortar samples. The effect of the addition of TiO2 was studied on mechanical properties of the mortar and cement including compressive and flexural strength, consistency (the flow table test), setting time and carbonation. Characterization techniques, including thermogravimetry, mercury porosimetry and X-ray diffraction spectroscopy (XRD), were applied to study the physico-chemical properties of the mortars. It was shown that adding the photocatalyst to the mortar had no negative effect on its properties and could be used to accelerate the setting process. Specimen photoactivity with the incorporated photocatalyst was tested for NOx oxidation in different conditions of humidity (0% RH and 65% RH) and illumination (Vis or Vis/UV), with the results showing an important activity even under Vis radiation.

Effect of Heat Treatment on Phase-Formation Behavior of Agricultural Material

2014 ◽  
Vol 979 ◽  
pp. 323-326
Author(s):  
W. Siriprom ◽  
P. Kuha ◽  
S. Kongsriprapan ◽  
K. Teanchai
Keyword(s):  
Heat Treatment ◽  
Low Cost ◽  
Chemical Properties ◽  
Amorphous Structure ◽  
Raw Material ◽  
Chemical Compositions ◽  
Oxide Compound ◽  
X Ray ◽  
Babylonia Areolata ◽  
Agricultural Material

In present study, the phase transformations upon heat treatment were investigated and assessment the possibilities to produce the raw material in the production of low-cost natural adsorbents which have appropriate physical and mechanical characteristics. The physical-chemical properties of agricultural material were identified by Energy Dispersive X-Ray Fluorescence (EDXRF), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy. The XRD pattern suggest that theBabylonia areolatashells sample have the aragonite phase while the rice husk and the coconut lumber sawdust have amorphous structure. After that, all samples were annealed at different temperatures ranging from 300 to 900°C, another that, all samples have been transform structural in to Oxide compound. Moreover, the chemical compositions were investigated by XRF and FTIR was developed for analysis of functional group and their chemical bonding characteristics.

Chemical Compositions and Physico-chemical Properties of Three Varieties Essential oils of Cymbopogon giganteus Growing to the Spontaneous State in Benin

2013 ◽  
Vol 29 (1) ◽  
pp. 59-67 ◽  
Author(s):  
J.P. Noudogbessi ◽  
G.A. Alitonou ◽  
T. Djenontin ◽  
G. Figueredo ◽  
G. Figueredo ◽  
...  
Keyword(s):  
Essential Oils ◽  
Chemical Properties ◽  
Chemical Compositions ◽  
Physico Chemical

The Electrochemical Synthesis of Neutral Zinc(II) Complexes of Schiff Base Ligands: The Crystal Structure of Bis[N-(4-methylphenyl)salicylaldiminato]zinc(II)

1988 ◽  
Vol 43 (5) ◽  
pp. 611-615 ◽  
Author(s):  
T. Sogo ◽  
J. Romero ◽  
A. Sousa ◽  
A. de Blas ◽  
M. L. Durán ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Schiff Base ◽  
Schiff Bases ◽  
Electrochemical Synthesis ◽  
Chemical Properties ◽  
Zinc Atom ◽  
Schiff Base Ligands ◽  
Space Group ◽  
X Ray ◽  
Physico Chemical

Abstract The electrochemical synthesis and physico-chemical properties of neutral zinc(II) complexes of bidentate Schiff bases derived from salicylaldehydes are presented together with the X-ray structure of bis[N-(4-methylphenyl)salicylaldiminato]zinc(II). The crystal is monoclinic, a = 21.877(3), b = 8.801(2), c = 12.027(5) Å, β = 96.55(3)°, space group C2/c. The complex is a monomer, and the zinc atom is tetrahedrally coordinated.

The Distortion of Metals by Cold Working

1937 ◽  
Vol 137 (1) ◽  
pp. 311-332
Author(s):  
H. A. Wainwright
Keyword(s):  
Cold Working ◽  
Cold Work ◽  
Chemical Properties ◽  
Polycrystalline Metal ◽  
Flow Lines ◽  
X Ray ◽  
Polycrystalline Aggregates ◽  
The Subject ◽  
Properties Of Materials ◽  
And Chemical Properties

The paper deals with current conceptions of cold working and its varied effects on the metal undergoing deformation. The mechanism and behaviour of single metal crystals and polycrystalline aggregates, whilst undergoing cold working deformation, are outlined. Two aspects are treated, namely, block slip and “twinning”. The X-ray examination of a polycrystalline metal under deforming stresses is mentioned, together with the formation of flow lines, better known as Lüder's lines. The effect of cold work on the mechanical, physical, electrical, and chemical properties of materials is then considered in some detail, together with the practical aspects of the changes wrought. The paper concludes with a brief summary of the subject, and the more important theories are reviewed in order to see how far they explain all the phenomena observed.

scholarly journals ONE-POT-TWO-STEP SYNTHESIS OF BIOLUBRICANT BASE STOCK FROM RUBBER SEED OIL

2020 ◽  
Vol 45 (5) ◽  
Author(s):  
G.O . Madojemu ◽  
E.A. Elimian ◽  
M.C. Ejimadu ◽  
C.O. Okieimen ◽  
F.E. Okieimen
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Response Surface ◽  
Seed Oil ◽  
Chemical Properties ◽  
Base Stock ◽  
One Pot ◽  
Rubber Seed Oil ◽  
Rubber Seed ◽  
Physico Chemical

Biolubricant base stock was synthesized in this work from rubber seed oil in a one-pot-two-step process of epoxidation and hydroxylation. Rubber seed oil was extracted using a Soxhlet apparatus. The in situ epoxidation of the rubber seed oil with peracid (hydrogen peroxide and acetic acid) was analysed and optimized considering three process variables with their range of values given as temperature of 35-50 , time of 60-180 mins and mole ratio of hydrogen peroxide to acetic acid of 1:0.25-1:1 by applying the central composite design of response surface methodology. The ring opening reaction (hydroxylation) of the epoxide to polyhydroxylated oil (lubricant basestock) with ethanol was carried out using the optimum conditions obtained from the epoxidation process. The rubber seed oil, epoxide and lubricant basestock were characterized in terms of physico-chemical properties using standard methods and in terms of functional groups using Fourier Transform Infrared (FTIR) spectroscopy. Maximum epoxide content of 4.85% and maximum conversion of 71% of rubber seed oil to epoxide was achieved at a temperature of 50􀀀 , reaction time of 180 mins and 1: 0.39 mol/mol of hydrogen peroxide to acetic acid. The predicted values of the epoxidation process reasonably agreed with the experimental ones and model R-squared value of about 95% showed that response surface method can reasonably predict the epoxidation process using a quadratic polynomial model. There was 75% conversion of the epoxide to polyhydroxylated oil (biolubricant basestock), which represents a very high yield. The formation of epoxides and polyhydroxylated oil lead to modification (improvement) in the properties of rubber seed oil as confirmed by the physico-chemical properties and FTIR spectra analysis of the oil, epoxide and lubricant basestock. The study showed that chemical derivatives of rubber seed oils are an attractive, renewable, and ecofriendly alternative to mineral oils for lubricant formulations.

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