Calculation of the enthalpy of formation of coal organic matter

The enthalpy of formation for the organic matter of coals in the coal rank series was calculated from the heat of the complete combustion reaction. Three variants were considered in which the experimental heating values Q _i ^daf and the values found from the correlation equation or calculated using the Mendeleev formula were taken as the heat of the complete combustion of coals.     

Composition and properties of coals from the Yurty coal occurrence

Coals from the Yurty coal occurrence were studied. It was found that the samples were brown non-coking coals with low sulfur contents (to 1%) and high yields of volatile substances (V ^daf to 53.4%). The high heat value of coals Q _s ^daf was 20.6–27.7 MJ/kg. The humic acid content varied from 5.45 to 77.62%. The mineral matter mainly consisted of kaolinite, α-quartz, and microcline. The concentration of toxic elements did not reach hazardous values.     

Increased total sulfur content in coal from Donets and other basins

The ash composition is used to assess the conditions of coal-bed formation in the Donets and L’vovsk-Volynsk basins. The experimental data are inconsistent with some aspects of the hypothesis that pyrite and secondary organic sulfur are formed in the coal. The lack of a relationship between the total sulfur content S _t ^d in the coal and the MgO content in its ash does not agree with the notion that sulfates from sea water provide the basis source of nonvegetative sulfur in coal. The actual S _t ^d values do not always correspond to the theory that the source of sulfur depends on the alkalinity of the water and the reducing medium where the deposits accumulate. In the conditions that are most favorable to the formation of coal with high total sulfur content (S _t ^d > 4 wt %) according to the existing hypothesis, the actual value of S _t ^d is no more than 1.5%. The source of pyrite and organic sulfur in coal requires further discussion.     

Metamorphic development, degree of reduction, and other characteristics of Donets Basin coal

Analysis of the elementary composition and parameters V ^daf , y, and Q _s ^daf of coal from more than 100 beds in the Donets Basin indicates that the considerable difference in the properties of coal characterized by reduction (in terms of S _t ^d ) and uniform metamorphic development (according to C ^daf ) is due to variation in the ratio of the number of hydrogen and oxygen atoms (H/O_at) in the molecular component of the coal’s organic mass.     

Coals from the Khingui coal manifestation

The composition and properties of black coals from the Khingui coal manifestation were evaluated. It was found that the test coals are noncaking low-sulfur (Sd to 0.49%) coals with a high yield of volatile substances (V ^daf = 43.52–51.42%). The high heat value of coal is Q _s ^daf = 22.6–32.8 MJ/kg, and the low heat value Q _i ^r on an as received basis is 11.7–20.6 MJ/kg. The humic acid content varies from 5.63 to 44.73%. The results of the analysis of the mineral matter of coal and ecologically harmful elements are given.     

Synthesis and Properties in Solution of Gaussian Homo Asymmetric Polysiloxanes with a Bulky Side Group

Ring opening polymerization (ROP) of 1,3,5-tri-n-hexyl,1,3,5-trimethylcyclotrisiloxane (D ₃ ^Hexa ) and 1,3,5-tri-n-heptyl,1,3,5-trimethylcyclotrisiloxane (D ₃ ^Hepta ) was promoted by acid-treated synthetic silica–alumina to obtain Gaussian homo asymmetric polysiloxanes. M_w was above 70?kg/mol, meaning that homo asymmetric bulky side-group polysiloxane chains with high molecular weight were obtained. The material was treated in an acidic medium to improve the contents of acid sites and successfully tested as an inorganic acidic catalyst for ROP of D ₃ ^Hexa and D ₃ ^Hepta cyclosiloxanes. The samples of poly(methylhexylsiloxane) (PMHS) and poly(methylheptylsiloxane) (PMHepS) obtained were structurally characterized mainly by ²⁹Si NMR. All the experimental values including the refractive index increment (dn/dc), the second virial coefficient (A₂), the square root of the mean square radius of gyration ( $ \langle {{\text{RMS}}_{\text{radius}}}^{ 2} \rangle^{ 1/ 2} $ ), the average molecular weight (M_w), the average molecular numeral (M_n), and the weight polydispersity (M_w/M_n) were obtained using a gel permeation chromatography/light scattering (GPC/LS) coupled system. The A₂ experimental value for the two polymers (between 4 and 6.5?×?10^?4?mol/mL?g²) indicated that toluene was a good solvent. In addition, PMHS and PMHepS $ \langle {{\text{RMS}}_{\text{radius}}}^{ 2} \rangle^{ 1/ 2} $ were greater than 30?nm, indicating that larger chains of high molecular weight were obtained.     

Study on Isothermal Formation Dynamics of Calcium Barium Sulphoaluminate Mineral

The formation dynamics of calcium barium sulphoaluminate mineral with the composition of 2.75CaO·1.25BaO·3Al₂O₃·SO₃ (C_2.75B_1.25A₃ $\overline{\text{S}}$ S ¯ ) was studied. The results suggest that, under the preparative conditions, the formation of C_2.75B_1.25A₃ $\overline{\text{S}}$ S ¯ mineral is controlled by a diffusion mechanism from 1,100 to 1,380 °C; and, the formation dynamics fits nicely with D ₄ = 1 ? 2α/3 ? (1 ? α)^2/3 = Kt. From 1,100 to 1,300 °C, the apparent activation energy is 227.45 kJ mol^?1. From 1,300 to 1,380 °C, the apparent activation energy decreases to 175.94 kJ mol^?1, making the formation of C_2.75B_1.25A₃ $\overline{\text{S}}$ S ¯ mineral faster and easier.     

Trace element compositions of coal,shale, and petroleum from various sedimentary basins

The concentrations of trace elements in caustobioliths from particular deposits in various coal, shale, and oil-and-gas bearing basins with different ages of bearing deposits and geostructural types are considered. The degrees of trace element concentration by the caustobioliths and their mineral matter were calculated with reference to Clarke numbers in clay rocks. Typomorphic trace elements were separated, and trace elements were classified by concentration factors in caustobioliths from deposits in platform and geosynclinal basins. Considerable differences in the characters of concentration of typomorphic elements in these caustobioliths were revealed.     

Towards an Understanding of the Reaction Pathways in Propane Ammoxidation Based on the Distribution of Elements at the Active Centers of the M1 Phase of the MoV(Nb,Ta)TeO System

The M1 phase of the MoV(Nb,Ta)TeO system is one of the most effective catalysts for the ammoxidation and selective oxidation of propane to acrylonitrile (AN) and acrylic acid, respectively. The active centers of the M1 phase reside on the ab planes of this crystalline material (i.e., the (001) lattice face). Early on we proposed that the thus located active centers contain all key catalytic elements strategically placed for the conversion of propane to AN. These seven element comprising active centers contain: five metal oxide octahedra (2 V _0.32 ⁵⁺ /Mo _0.68 ⁶⁺ , 1 V _0.62 ⁴⁺ /Mo _0.38 ⁶⁺ , 2Mo _0.5 ⁶⁺ /Mo _0.5 ⁵⁺ ) and two Te⁴⁺??oxygen sites. In this contribution we analyze the various compositional probabilities of the seven element active centers and their additional eight element surroundings and conclude that there are 32 possible compositional arrangements of this 15 element assembly. From the diverse structural arrangements, diverse catalytic properties can be assigned to the individual sites, leading to diverse propane reaction pathways. We conclude that there are 22% AN forming, 22% propylene, 10% waste and 46% inert sites. After normalization these sites are deemed to lead to the following product yields: 41% AN, 41% propylene and 18% waste. The highest experimentally attained AN yield from propane is 42%, employing M1 phase only, which coincides with the predicted value of a concerted mechanism. Higher AN yields are, however, anticipated, up to a lofty upper limit of 82%, by allowing also for a consecutive mechanism (C₃° ?? C ₃ ⁼ ??AN). This possibility can be rationalized on the basis of the existence of vicinal C₃° ?? C ₃ ⁼ /C ₃ ⁼ ??AN sites whose presence is plentiful on the catalytically important ab planes of M1. The placement and efficiency of these sites is, however, not perfect; therefore the upper AN yield limit is not realized in practice. Our analysis of the elemental distribution at the active centers and their immediate surroundings provides us with new insights into the relationship between structure and catalytic reaction mechanisms of the M1 phase and might serve as a guide towards a redesign of the M1 composition, so as to attain higher AN yields from propane. It provides a challenging task for the synthetic chemist.     

Interaction Between Cationic and Anionic Surfactants: Detergency and Foaming Properties of Mixed Systems

The micellar and interfacial behavior of mixtures of the anionic surfactant (alcohol ether sulfate, AES) with quaternary ammonium type cationic surfactants dodecyltrimethyl ammonium chloride (DTAC), dodecyl-(2-hydroxyethyl)-dimethyl ammonium chloride (DHDAC), dodecyl-di(2-hydroxyethyl)-methyl ammonium chloride (DHHAC) were investigated by means of surface tension measurements. Various physicochemical properties such as surface activity parameters (CMC, γ _CMC, Г _max, A _min), the micellar and interfacial compositions (x ₁ ^m , x ₁ ^σ ), interaction parameters (β ^m , β ^σ ), and activity coefficients ( \(f_{1}^{m}\) , \(f_{2}^{m}\) , \(f_{1}^{\sigma }\) , \(f_{2}^{\sigma }\) ) were evaluated. The influence of the hydroxyethyl groups of cationic surfactant component on the physicochemical properties of mixed systems has been analyzed. It is observed that the CMC values of the three mixed systems decrease with increases in the number of hydroxyethyl groups of the cationic surfactant component. From the results of β ^σ and β ^m values, the interactions between molecules for the three surfactant mixtures at the air/liquid interface increase in the following order DHHAC/AES < DHDAC/AES < DTAC/AES, but it is the opposite for the interactions in mixed micelles. The detergency and foaming properties of mixed systems were also studied. As expected, complex surfactant systems exhibit good detergency and foaming properties.     

Synthesis and single-crystal structure of lead oxide nanoclusters in zeolite Y, |Pb 15.5 2+ (Pb4O4(Pb 16/19 2+ Pb 3/19 4+ )4)4.75|[Si117Al75O384]-FAU

A single crystal of excessively Pb²⁺-exchanged zeolite Y (|Pb _15.5 ²⁺ (Pb₄O₄(Pb _16/19 ²⁺ Pb _3/19 ⁴⁺ )₄)_4.75|[Si₁₁₇Al₇₅O₃₈₄]-FAU) was prepared by exchange of Na–Y (|Na₇₅|[Si₁₁₇Al₇₅O₃₈₄]-FAU, Si/Al = 1.56) with an aqueous stream 0.05 M Pb(C₂H₃O₂)₂ at 294 K, followed by vacuum dehydration at 1 × 10^?6 Torr and 693 K. Its structure was determined at 100 K, by X-ray diffraction techniques in the cubic space group Fd $ \overline{3} $ 3 ¯ m and was refined to the final error indices R ₁/wR ₂ = 0.0639/0.1323. About 53.5 Pbⁿ⁺ ions per unit cell occupy three different equipoints; 26 are at site I′, 19 are at site II, and the remaining 8.5 are at another site II. Three Pb⁴⁺ ions at some of the positions must have higher oxidation states due to elevated dehydration temperature; Pb(IIa) is supposed to coexist with Pb²⁺ and Pb⁴⁺ ions assuming the charge balance of the zeolite framework. A distorted Pb₄O₄ cube, alternating Pb²⁺ at Pb(I′) and O^2? at O(5), coordinates with four Pb²⁺ and/or Pb⁴⁺ ions through its oxygen atoms to give a [Pb ₄ ²⁺ O ₄ ^2? (Pb _16/19 ²⁺ Pb _3/19 ⁴⁺ )₄]^176/19+ cluster in 4.75 of eight sodalite cavities per unit cell in zeolite Y.     

Anodization of molybdenum. I. Galvanostatic anodization

Molybdenum was anodized at different current densities (10^?4–10^?2 A cm^?2) in various aqueous solutions. Potential-time curves obtained in strong acid solutions are similar to those usually reported for the valve metals, and the anodization kinetics were found to obey the familiar exponential law $$i = A \exp BH$$ and also to obey the empirical relation, $$(dE/dt)_i = a(i)^b $$ Using both polarization and capacitance measurements, it was found that the field strength,H, the electrolytic parametersA andB and the constantsa andb are comparable with those previously reported for many valve metals. Except in strong acid solutions,E-time curves showed an induction period before oxide formation. The duration time of the induction period,t _i, was found to increase with decrease of solution acidity and current density and with increase of temperature. Although chloride ion may act as a depolarizer,t _i was found to decrease with increase of chloride ion concentration, probably by increasing the anodization field strength.     

Mass spectrometry study of glasses based on sulfur, phosphorus, and arsenic

The mass spectrometry study of chalcogenide glasses in the P-S binary system and P-As-S ternary system is used to demonstrate that the composition of the gas phase in binary samples is characterized by the conventional spectra of ions, such as PS ₂ ⁺ , P₂S ₇ ⁺ , P₂S ₇ ⁺ and P₄S ₁₀ ⁺ . The introduction of As to the binary glass systems first demonstrated the presence of ions AsPS⁺, AsPS ₄ ⁺ , AS_{2 5} ⁺ and As₂PS₅ ⁺ in the gas phase of the ternary chalcogenide system, which correspond to the ternary compositions AsPS₄ and As₂P₂S₇ in the solid phase.     

Moisture-holding capacity of coals

As a result of a comprehensive study of 63 samples of coal concentrates (from Ukraine, Russia and countries outside the former Soviet Union), it was established that the prediction of the moisture-holding capacity of coals can be appropriately performed according to their values of W ^a, R ₀, O _d ^daf , and O _s ^daf . It was found that the oxidation of coal increased its moisture-holding capacity; however, in this case, the absolute change in this parameter was smaller than the error of its determination (0.5%). Therefore, upon the oxidation of almost 30% of the organic matter of coal, the moisture-holding capacity increased by only 0.4%. There is a close correlation between the maximum moisture capacity of coals and the water pore volume, and this correlation was described by a linear equation in the studies.     

Composition, structure, and properties of Donetsk Basin and United States coal of the same metamorphic stage

The composition, structure, and properties of Donetsk Basin and United States coal of the same metamorphic stage are compared. The samples represent coal from the whole metamorphic series, with vitrinite reflection coefficient R _o = 0.7?C1.8%. Separate regression equations for Donetsk Basin and United States coal describe the relation between the composition (C ^daf , H ^daf , O ^daf ), structural characteristics (C_ar, f _a, ??, and B) calculated from the elementary composition, the technological properties (V ^daf , y, Q _s ^daf ), and the vitrinite reflection coefficient. Significant differences are found in these properties for Donetsk Basin and United States coal of the same metamorphic stage. These differences are mainly due to the different degrees of reduction of the coal. With a vitrinite reflection coefficient up to 1%, the degree of reduction is greater for United States coal than for Donetsk Basin coal. With greater metamorphic development (R _o ?? 1.0%), Donetsk Basin coal is characterized by even lower degrees of reduction.     

Ion exchange and charge transport properties of polymeric tris(4-vinyl-4′-methyl-2,2′-bipyridine) ruthenium(II) films

Multiply charged electroactive anions [IrCl ₆ ^2? , Fe(CN) ₆ ^3? , and W(CN) ₈ ^4? ] are electrostatically incorporated in polymeric films of tris(4-vinyl-4′-methyl-2,2′-bipyridine) ruthenium(II) [poly-Ru(vbpy) ₃ ²⁺ ] from aqueous trifluoroacetate solution. Values of apparent diffusion coefficients (D _ct) and heterogenous electron transfer rates (k _et) are measured for these anions as a function of their relative concentration (Γ _M/Γ _Ru) in the film.D _ct andk _et decrease systematically asΓ _M/Γ _Ru increases in a manner that is independent of charge and chemical identity of the ion. This result suggests that a nonchemical process, presumably electrostatic cross-linking, limits diffusional motion and is responsible for the decrease inD _ct andk _et with increasing anion content. Protonated polyvinyl-pyridine films exhibit similar ranges and variations inD _ct andk _et, which suggest similar structures and mechanisms of charge transport for these films and poly-Ru(vbpy) ₃ ²⁺ .     

1-Hexene Double Bond Isomerization Reaction Over SO 4 = Promoted NiO, Al2O3 and ZrO2 Acid Catalysts

Sulfated mixed oxides, SO ₄ ⁼ /Ni–Al–O and SO ₄ ⁼ /Zr–Al–O were evaluated for double bond isomerization (DBI) of 1-hexene using helium and hydrogen as carrier gases. The increase of temperature from 100 to 200 °C seems to favor the deprotonation pathway and contribute to increase the 1-hexene conversion for both catalysts and without regard of the carrier gas. The results indicate that temperature it is the main factor that contributes to improve both conversion and selectivity towards (cis + trans)-2-hexene, while the reductive atmosphere beneficiate only the SO ₄ ⁼ /Ni–Al–O catalyst performance, as hydrogen prevents this catalyst from a fast deactivation.     

Mixed Micellar Properties and Related Interaction Parameters of Butanediyl-1,4-bis(dodecyl dimethyl ammonium bromide) Gemini Surfactant with Nonionic Amphiphiles

Mixed micellization of cationic gemini surfactant butanediyl-1,4-bis(dimethyldodecylammonium bromide) with nonionic surfactants (sorbitan esters, alcohols and phenol ethoxylates) and triblock copolymers has been studied tensiometrically. Various physicochemical parameters of the studied systems including ideal CMC values, experimental and ideal micellar compositions, interaction parameters, activity coefficients of the components, etc. have been evaluated by considering theoretical models of Clint, Rubingh, Rosen and Maeda. The experimental critical micelle concentration (CMC) values of the mixed micelles were lower than the CMC values of the individual components and showed a negative deviation from ideal CMC (CMC*) values. The analysis reveals that the mole fractions of gemini are lower compared to the nonionic surfactants/triblock polymers and the values of ΔG _m ^° , ΔG _ad ^° , G _min and ΔG _ex ^m show that the spontaneity of the studied mixed micelles relatively decreases as the content of the gemini in the bulk phase increases.     

Chitosan effects on glass matrices evaluated by biomaterial. MAS-NMR and biological investigations

Bioactive glass 46S6 and biodegradable therapeutic polymer (Chitosan: CH) have been elaborated to form 46S6-CH composite by freeze-drying process. The kinetics of chemical reactivity and bioactivity at the surface were investigated by using physicochemical techniques, particularly solid-state MAS-NMR. Immortalized cell line used to construct multicellular spheroids was employed as three-dimensional (3D) cell cultures for in vitro studies. Obtained results showed a novel structure of the composite; the chemical treatment (ultrasound, magnetic stirring, freeze drying process and lyophilization) led the bioactive glass particles to be loaded in the chitosan-based materials. ²⁹Si and ³¹P MAS-NMR results showed the emergence of two new species, Q _Si ³ (OH) and Q _Si ⁴ , which are characteristic of the vitreous network dissolution in simulated body fluid (SBF). MAS-NMR also confirmed the formation of amorphous calcium phosphate (ACP) at the surface of the initial 46S6-CH. Three-dimensional (3D) cell cultures highlighted the effect of chitosan, where the cell viability reached up to 78% in 46S6-CH composite and up to 67% in 46S6. The association of (CH) and bioactive glass (BG) matrix promotes a highly significant bioactivity, demonstrating surface bone formation and satisfactory behavior in biological environment.     

Excess molar enthalpies of ternary and constituent binary systems {1,2-dichloropropane+2-propanol+2-butanol} at T=298.15 K

Ternary excess molar enthalpies at T=298.15 K and P=101.3 kPa for the system of {1,2-dichloropropane+2-propanol+2-butanol} and their constituent binary systems {1,2-DCP+2-propanol}, {1,2-DCP+2-butanol}, and {2-propanol+2-butanol} have been measured over the whole composition range using an isothermal micro-calorimeter with flow-mixing cell. All of the binary and ternary systems, including three pseudobinary systems, show endothermic behavior except for the binary mixture {2-propanol+2-butanol}, which shows small exothermicity. The Redlich-Kister equation was used to correlate the binary H _{m, ij} ^E data, and the Morris equation to correlate the ternary H _{m, 123} ^E data. Comparisons between the Morris and Radojkovi equations for the prediction of H _m,123 ^E have been also made. The experimental results have been qualitatively discussed in terms of self-association, isomeric effect and chain length among molecules.