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1

Study of lignite as the raw material for adsorption of Pb(II) and Cd(II) ions from aqueous solution

Thaçi Bashkim, Gashi Salih, Podvorica Fetah, Sopaj Flamur, Hasani Gentiana, Veseli Albana, Prado-Roller Alexander

Archives of Environmental Protection

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2025

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Vol. 51, no. 3

31--39

EN

The adsorption of two heavy metal ions, lead and cadmium, from an aqueous solution was investigated using Kosovo's lignite as the raw material. The material's properties, including nature, functional groups, surface shape, and charge, were investigated using FTIR, XRD, SEM, and pHPZC techniques. The objective of determining parameters such as initial concentration, pH, contact time, adsorbent dosage, and temperature was to understand how these variables influence adsorption. Under optimal conditions (0.125g/50cm3, 30 mg/dm3, 30 min, 200 rpm, and pH 6), Tthe removal efficiency of Pb(II) was 97.22 %, and 90.04% for Cd(II) under optimal conditions (0.125g/50cm3, 30 mg/dm3, 30 min, 200 rpm, and pH 6). To investigate the achievement of equilibrium between lignite and metal ions, two key isotherm models, Langmuir and Freundlich, were applied. Based on the Langmuir isotherm model, the maximum adsorption capacities for lead and cadmium were 55.55 mg/g and 48.78 mg/g, respectively, at 288 K. The best medium for removing metal ions from lignite (desorption) is was found to be 0.5M HCl. Standard enthalpy change, standard entropy change, and Gibbs free energy indicated that the adsorption of heavy metals with onto lignite is a favorable, exothermic, and spontaneous process and is spontaneous. This investigation study shows that this lignite from Kosovo is highly effective in adsorbing lead and cadmium these two heavy metalsfrom aqueous solutions.

2

Numerical investigation of pre-chamber holes diameter geometry on combustion parameters in a hydrogen-powered Turbulent Jet Ignition engine

Górzyńska Marcelina, Pielecha Ireneusz

Combustion Engines

|

2024

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R. 63, nr 4

126--139

EN

The search for substitutes for conventional fuels leads to the use of non-hydrocarbon fuels or synthetic fuels. One of them is hydrogen. The use of hydrogen in combination with a two-stage charge formation system leads to the combustion of lean (λ > 1) or very lean (λ > 3) charges. The simulation tests carried out were aimed at determining the best configuration of the chamber connecting the pre-chamber with the main combustion chamber. Three variants of the diameter of the holes connecting the chambers were selected (d = 0.5; 1.0 and 1.5 mm) in combination with different fuel doses fed to the pre-chamber. A passive chamber (qo_PC = 0 mg) and an active chamber (qo_PC = 0.4 and 1.2 mg) were used with a constant fuel dose to the main chamber (qo_MC = 6 mg). The research was conducted using AVL Fire 2022.1 software using the moving mesh of the LDV engine. Based on the simulation work, the most favourable conditions for conducting the process were determined, taking into account the thermodynamic effects of the process and acceptable levels of nitrogen oxide concentration. The resulting correlation maps of chamber hole sizes and fuel doses supplied to the pre-chamber can serve as a preliminary basis for selecting control options for hydrogen combustion in the TJI system.

3

Parameters of a cascade two-stage air-to-water heat pump at low ambient temperature

Redko Andriy, Ujma Adam, Pavlovskyi Serhii, Redko Ihor, Gvozdetskii Oleksandr, Chaika Yurii, Borodai Dmytro

Budownictwo o Zoptymalizowanym Potencjale Energetycznym

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2023

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Vol. 12

132-142

EN

The results of the numerical calculation of the thermodynamic parameters of a cascade (two-stage) air-to-water heat pump at low atmospheric air temperatures are presented. A Freon R407c is used in the first circuit and a R152a is used in the second circuit. Calculations are made for ambient temperatures from 7°С to -25°С. The effect of underrecovery temperatures in heat exchange equipment is shown. Cycles with R245fa, R142b, R114, R123, R290, R236fa, R600a refrigerants, a mixture of isobutane and isopentane have been investigated. The effect of the complexity of a two-stage scheme on the efficiency of the cycle has been evaluated. The use of more complex schemes (for example, with liquid injection) does not affect the thermodynamic perfection of the heat pump and may be appropriate only to ensure operational reliability. Reducing the underrecovery temperature to 1K is shown to increase the thermodynamic efficiency of the installation.

4

A model of the steam compression process in a piston reactor

Joachimiak Damian, Borowczyk Tomasz, Joachimiak Magda

Archives of Thermodynamics

|

2023

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Vol. 44, no. 4

261--284

EN

The paper discusses the possible determination of steam parameters in a new type of piston machine for steam compression to generate supercritical water parameters. It presents a calculation model that allows one to simulate the process of steam compression in a cylinder with volume regulated by the piston position. In each calculation step, the steam parameters were determined on the basis of fast adiabatic changes which were corrected by the effect of leakage and heat transfer occurrence. The seal of the reactor was assumed to be a compression ring. Depending on the pressure drop on the seal, subcritical and supercritical flow was taken into account. The leak was corrected by the coefficient of flow contraction. Heat transfer was determined by equations for the Nusselt number for water and steam from the homogenous area. The programmed model allows one to simulate changes in the thermodynamic parameters of steam during the process of steam compression with any calculation step. The results presented in this paper show that the application of one compression ring allows us to obtain supercritical steam parameters. Various degrees of sealing leak tightness and their impact on the changeability of steam parameters were analyzed. Heat transfer was shown to have an impact not only on changes in steam temperature, but also on pressure. This paper analyzes the impact of the temperature of the walls of the compression chamber on the value and direction of heat transfer.

5

Adsorption of CO2 by surface modified coal-based activated carbons: kinetic and thermodynamic analysis

Xinzhe Liu, Mingyang Zhang, Juan Chen, Zhengyu Hu, Shuaifei Xian, Mingxuan Tang, Chenchen Zhang

Polish Journal of Chemical Technology

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2022

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Vol. 24, nr 3

19--28

EN

The effects of different surface modifiers on the CO2 adsorption capacity of coal-based activated carbons were studied, and the diffusion behavior, adsorption kinetics and thermodynamic parameters of CO2 in activated car-bons were analyzed. The results show that compared with ethylene glycol, 1,2-propylenediamine and zinc chloride, potassium hydroxide and sodium hydroxide can greatly improve CO2 adsorption capacity. The adsorption rate is faster, and the adsorption capacity is larger, with the maximum CO2 adsorption capacity being 33.54 mL/g. Fick’s law can well describe the diffusion behavior of CO2 in activated carbon. The addition of a surface modifier can increase the diffusion coefficient. The diffusion of CO2 in activated carbon falls into the category of crystal diffusion. The adsorption kinetics of CO2 before and after surface modification follow the Bangham equation. During the adsorption process, δ H < 0, δ G < 0, δ S < 0. Surface modification can reduce adsorption heat and promote adsorption, and the adsorption process is dominated by physisorption.

6

The elimination of lead(II) ions in a solution by bio-adsorption: Kinetics, equilibrium, and thermodynamics

Tejada-Tovar Candelaria, Bonilla-Mancilla Humberto, Ortega-Toro Rodrigo, Villabona-Ortíz Ángel, Díaz-Illanes Manuel

Journal of Water and Land Development

|

2022

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no. 53

118--127

EN

In the present study, the removal capacity of Pb(II) ions was investigated using the biomass of dried cattle manure in an aqueous solution. The biomaterials were characterized using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) techniques. The results reveal that the adsorption mechanism may be associated with the interaction between Pb(II) ions and functional groups through aggregation, coordination, ion exchange, microprecipitation, oxidation, and hydrophobicity. The bio-adsorption of the metal was analysed in discontinuous tests; the effect of temperature, pH, agitation, and adsorbent dose was evaluated. The maximum adsorption capacity was determined at pH 7.5, 18°C and 200 rpm. The bio-adsorption of Pb(II) was best fitted to the pseudo-second order model. The experimental data of the isotherm were adjusted to the models of Langmuir, Freundlich and Dubinin-Radushkevich; while Langmuir’s model related better to the experimental data forming a single layer at saturation. The rate of adsorption was rapid, reaching equilibrium after 25 min and removal of 96.8%. Thermodynamic parameters determined that the process was viable, spontaneous, and exothermic. The present study contributes mainly to demonstrating that a biomaterial prepared from bovine manure is a promising adsorbent for heavy metals such as Pb(II). It also reduces the environmental impact of this waste through the generation of greenhouse gases in countries that maintain intensive livestock. Another important aspect is the reduction of the micro- and macronutrients accumulation in soil and contamination of surface waters and aquifers by runoff and seepage during rainy periods.

7

Wyniki prób zastosowania materiałów wybuchowych emulsyjnych Hydromite 100 i Emulexu 100 AL w KGHM Polska Miedź S.A. Oddział Zakłady Górnicze „Rudna”

Maranda Andrzej, Gołąbek Barbara, Suszka Jacek, Pawłowicz Jerzy

Przegląd Górniczy

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2020

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T. 76, nr 8

39--44

PL

Materiały wybuchowe emulsyjne (MWE) są jednym z dominujących środków strzałowych stosowanych w kopalniach rud miedzi. W pracy przedstawiono parametry termodynamiczne i detonacyjne dwóch MWE oraz podano parametry techniczne urządzenia mieszalniczo-załadowczego UGPL-1 stosowanego podczas eksperymentów do ich produkcji i załadunku do otworu strzałowego. Opisano technologię formowania materiałów wybuchowych i wyniki prób kopalnianych.

EN

Emulsion explosives are one of the dominant blasting agents used in copper ore mines. The paper presents thermodynamic and detonation parameters of two emulsion explosives and technical parameters of the UGPL-1 mixing and loading device used during experiments for their production and loading into the blast hole. The technology of preparation explosives and the results of mine tests are described.

8

Study of thermal degradation behavior and kinetics of ABS/PC blend

Bano Saira, Ramzan Naveed, Iqbal Tanveer, Mahmood Hamayoun, Saeed Farhan

Polish Journal of Chemical Technology

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2020

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Vol. 22, nr 3

64--69

EN

This work investigated kinetics and thermal degradation of acrylonitrile butadiene styrene and polycarbonate (ABS/PC) blend using thermogravimetric analysis in the range of 25 to 520°C. For thermal degradation of blend, activation energy (Ea) and pre-exponential factor (A) were calculated under various heating rates as 5, 10, 15 and 20°C/min using iso-conversional model-free methods (Kissinger, Flynn-Wall- Ozawa and Friedman). Mass loss of the blend as a function of temperature was plotted as thermogravimetric curve (TG) while derivative values of mass loss were drawn as derivative thermogravimetric (DTG) curve. Using Kissinger method, Ea was 51.4 kJ/mol, while values calculated from FWO and Friedman method were 86–161 and 30–251 kJ/mol respectively. Results showed increasing trend of Ea with higher conversion values indicating different degradation mechanisms at the initial and final stages of the experiment. Thermodynamic parameters such as enthalpy change (ΔH), Gibbs free energy (ΔG) and entropy change (ΔS) were also calculated.

9

Temperature influence on the electrode process in the presence of 6-thioguanine and surfactants

Nosal-Wiercińska Agnieszka, Kaliszczak Waldemar, Martyna Marlena, Szabelska Anna, Gołębiowska Beata, Wiśniewska Małgorzata

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 6

14--21

EN

The measurements concerning the process of the electroreduction of Bi(III) ions in the presence of 6–thioguanine (6TG) and Triton X-100 as well as Tween 80 in the 2 mol·dm-3 chlorates(VII) demonstrate a dependence of the process rate on temperature. The applied electrochemical techniques (DC polarography, cyclic and SWV voltammetry) allowed to determine the kinetic and thermodynamic parameters as well as their correlation with changes in kinetics of the electrode process. The catalytic activity of 6TG was confirmed by the decrease of overall enthalpies of activation. Different values of ∆𝐻# and ∆𝑆° for Bi(III) electroreduction in the presence of 6–thioguanine as well as Triton X-100 and Tween 80 suggest changes in kinetics of the electrode process towards inhibition.

10

Thermal Degradation Behaviour and Kinetics of aged TNT-based Melt Cast Composition B

Singh Arjun, Sharma Tirupati Chander, Singh Vasundhara, Mukherjee Niladri

Central European Journal of Energetic Materials

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2019

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Vol. 16, no. 3

360--379

EN

In the present paper, three kinds of aged and freshly prepared 2,4,6-trinitrotoluene (TNT) based Composition B stockpiled, for a period of 20 and 32 years, were investigated for the effect of natural ageing on their thermal degradation behaviour and kinetic parameters. The properties investigated indicated that there was no significant change in the thermal stability of the samples aged under natural environmental conditions. The kinetic parameters were studied by means of the Kissinger method using the peak temperature at maximum reaction rate from DSC data, and the isoconversional Kissinger-Akahira-Sunnose (KAS) and ASTM E689 methods from TGA data. The apparent activation energies calculated by the Kissinger method were 173.8 kJ·mol–1 for fresh, 170.4 kJ·mol–1 for 20 y old and 187.1 kJ·mol–1 for 32 y old Composition B, respectively. The values calculated by the KAS method were found to be in the range 77.2-235.8 kJ·mol–1 for fresh Composition B, 75.7-224.0 kJ·mol–1 for 20 y old and 70.4-196.0 kJ·mol–1 for 30 y old Composition B, respectively. The activation energies obtained from the KAS methods are in good agreement and consistent with the isoconversional ASTM E689 kinetic method. The thermodynamic parameters, such the Gibbs free energy of activation (ΔG#), activation enthalpy (ΔH#) and activation entropy (ΔS#) for the formation of activated complexes were also studied and are discussed.

11

Peculiarities of convective flows formation in the solar photosphere

Stodilka Myroslaw I., Baran Oleksandra A.

Zeszyty Naukowe. Telekomunikacja i Elektronika / Uniwersytet Technologiczno-Przyrodniczy w Bydgoszczy

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2018

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nr 21

61--68

EN

We studied the development of convective flows in the solar photosphere on the basis of semi-empirical models of granulation constructed from observable profiles in the neutral iron line λ ≈ 639,3 nm (taken on VTT with high spatial resolution) by solving the inverse radiative transfer problem. We analysed the temporal changes in the reproduced variations of kinematic and thermodynamic parameters of the solar convection at different heights of the photosphere (h = 0–550 km). Peculiarities of the formation of convective flows (ascending and descending ones) associated with differences in vertical velocities, temperature and pressure variations were established.

PL

Zbadano rozwój potoków konwekcyjnych w fotosferze słonecznej na podstawie półempirycznych modeli granulacji, zbudowanych z obserwowalnych profili neutralnej linii żelaza λ ≈ 639,3 nm (wykonanych na VTT o wysokiej rozdzielczości przestrzennej), rozwiązując problem odwrotnego transferu promieniowania. Analizowano zmiany czasowe odtwarzanych wariacji parametrów kinematycznych i termodynamicznych konwekcji słonecznej na różnych wysokościach fotosfery słonecznej (h = 0–550 km). Wyznaczono osobliwości tworzenia potoków konwekcyjnych (rosnących i malejących), związane z różnicami prędkości pionowych, wariacjami temperatury i ciśnienia.

12

Odwrócona chromatografia gazowa i jej zastosowanie do charakteryzowania surowców do farb i lakierów

Kamińska-Bach G., Langer E.

Farby i Lakiery

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2018

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nr 5

11--18

PL

Chromatografia gazowa (GC) stanowi cenną metodę analityczną do badania lotnych związków organicznych. W przeciwieństwie do tej metody, odwrócona chromatografia gazowa (IGC), umożliwia badanie właściwości fizykochemicznych organicznych jak i nieorganicznych substancji nielotnych, takich jak polimery, pigmenty, wypełniacze, kataliza-tory, adsorbenty. W artykule scharakteryzowano odwróconą chromatografię gazową, omó-wiono zasadę pomiaru, podstawowe oznaczane wielkości termodynamiczne i przykłady za-stosować w przemyśle farb i lakierów.

EN

Gas chromatography (GC) is a valuable analytic method for evaluating volatile organic compounds. Inverse gas chromatography (IGC), on the other hand, is a method used in evaluating the physical and chemical properties of organic and inorganic non-volatile com-pounds such as polymers, pigments, fillers, catalysts or active solids. In this paper inverse gas chromatography was characterized reverse gas chromatography, the principle of measurement, basic thermodynamic parameters as well as examples of using IGC in the paint and varnish industry were discussed.

13

Functional dependencies of thermodynamic and thermokinetic parameters of refrigerants used in mine air refrigerators. Part 2 – Rrefrigerant R404A

Nowak B., Życzkowski P., Łuczak R.

Archives of Mining Sciences

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2018

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Vol. 63, no. 1

27--41

EN

This paper deals with thermodynamic and thermokinetic properties of R404A refrigerant, which is one of the more commonly used in mine air compression refrigerators. Knowledge of these parameters is essential to analyze performance of such refrigeration equipment, to design it, or to estimate efficiency of air refrigerators using various refrigerants. These properties can be defined using 27 simple computational formulas, contained in 4 tables (Tables 2, 6, 10 and 12). The relationships determining thermodynamic and thermokinetic parameters of R404A occur in saturated liquid region, dry saturated vapor region, superheated vapor region and supercooled liquid region. The developed relationships were subjected to statistical verification. For this purpose, correlation coefficients, coefficients of determination, as well as absolute and relative deviations were determined by comparing results of the calculations with the corresponding results obtained by REFPROP 7 (Lemmon et al., 2002). Results of verification are contained in Tables 14 and 15.

PL

Artykuł dotyczy właściwości termodynamicznych i termokinetycznych czynnika chłodniczego R404A, który jest jednym z częściej stosowanych w górniczych sprężarkowych chłodziarkach. Znajomość tych parametrów jest wymagana do analizy pracy takich chłodziarek, do ich projektowania, czy też do oceny efektywności pracy chłodziarek wykorzystujących różne czynniki chłodnicze. Wymienione właściwości określić można korzystając z utworzonych 27 prostych formuł obliczeniowych. Podano je w 4 tabelach (tabela 2, 6, 10 i 12). Przedstawione zależności określające parametry termodynamiczne i termokinetyczne czynnika chłodniczego R404A obowiązują w stanie cieczy nasyconej, w stanie pary nasyconej suchej, w stanie pary przegrzanej oraz w stanie cieczy przechłodzonej. Opracowane zależności poddano weryfikacji statystycznej. W tym celu, porównując wyniki obliczeń z odpowiednimi wynikami uzyskanymi programem REFPROP 7 (Lemmon i inni, 2002) określono współczynniki korelacji, determinacji oraz odchyłki bezwzględne i względne. Rezultaty weryfikacji zamieszczono w tabelach 14 i 15.

14

Wpływ dodatków odpadowych tworzyw sztucznych na parametry energetyczne materiałów wybuchowych typu ANFO

Biegańska J., Barański K.

Materiały Wysokoenergetyczne

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2017

|

T. 9

145--158

PL

W artykule przeprowadzono symulację wpływu dodatków wybranych odpadowych tworzyw sztucznych na właściwości strzałowe materiałów wybuchowych typu ANFO (saletrol, ang. Ammonium Nitrate-Fuel Oil) za pomocą programu do obliczeń termodynamicznych ZMWCyw. Zaproponowano modyfikację składu chemicznego saletrolu poprzez zastępowanie jego składników wybranymi odpadowymi tworzywami sztucznymi w różnych proporcjach. Przedstawiono wyniki obliczeń parametrów termodynamicznych zmodyfikowanych w ten sposób ANFO. Określono efektywność energetyczną nowo powstałych mieszanek w celu wyboru optymalnego składu nowo powstałego materiału wybuchowego.

EN

In this article, the influence of additives of selected waste plastics on ANFO (Ammonium Nitrate Fuel Oil) type explosives was investigated using the thermodynamic calculation program ZMWCyw. It was proposed to modify the chemical composition of ANFO by replacing its components with selected plastic waste in varying proportions. Results of calculations of the thermodynamic parameters modified in this way are presented. The energy efficiency of the newly formed blends was determined to select the optimum composition of the newly created explosive.

15

Mechanism and kinetics oxidation of inconel 617 and 625 alloys

Staszewska K., Scendo M.

Technical Issues

|

2016

|

nr 1

82--89

EN

The mechanism and kinetics of oxidation of Inconel 617 and 625 alloys in air atmosphere were investigated. Materials were examined by the thermogravimetric method. The X-ray diffraction spectrometer (XRD) was used to observation change in chemical composition the oxide scales of Inconel alloys specimens. Oxidation kinetics was determined from weight-change measurements. The surface and microstructure of the sample were observed in an optical microscope (OM) and a scanning electron microscope (SEM). The results showed that the oxide scales of the alloys were compact and continuous. The layer were contained as the outer of Cr2O3, and the internal of NiCr2O4 spinel, NiO and other oxides. Oxides’ scales with good adherence were formed on the surface of alloys. The kinetics and thermodynamic parameters of oxides formation were calculated and discussed for both alloys.

16

Wodorek magnezu : nowy sensybilizator emulsyjnych materiałów wybuchowych

Maranda A., Sitkiewicz-Wołodko R., Bajdor K., Florczak K.

Przemysł Chemiczny

|

2016

|

T. 95, nr 12

2444--2447

PL

Dokonano przeglądu danych literaturowych dotyczących materiałów wybuchowych emulsyjnych uczulanych wodorkiem magnezu. Wyeksponowano wyższe parametry detonacyjne i większą odporność na desensybilizującą falę uderzeniową tych materiałów w porównaniu z materiałami wybuchowymi emulsyjnymi uczulanymi innymi substancjami. Przedstawiono interpretację fizykochemiczną danych doświadczalnych.

EN

A review, with 29 refs., of the glass microspheres, NaNO₂ and MgH₂-sensitized emulsion explosives. A special attention was given to the pressure changes and shock wave energy curves.

17

Parametry termodynamiczne i mechanizm degradacji redukcyjnej polihalogenowanych związków organicznych istotnych dla środowiska

Romańczyk P. P., Kurek S. S.

Przemysł Chemiczny

|

2016

|

T. 95, nr 10

2099--2103

PL

Badanie mechanizmu i kinetyki dehalogenacji redukcyjnej oraz reakcji następujących po przeniesieniu elektronu, w tym wyznaczanie standardowych potencjałów redukcji, jest niezwykle ważne do określenia termodynamicznych parametrów przebiegu tych procesów w praktyce, w warunkach naturalnej degradacji anaerobowej polihalogenowanych trwałych zanieczyszczeń środowiska. Podano wyniki badań polihalogenowanych związków aromatycznych i alifatycznych, ważnych z punktu widzenia ochrony środowiska. Wykazano, że dopiero połączenie metod elektrochemicznych z obliczeniami kwantowo-chemicznymi umożliwia wyjaśnienie mechanizmu i określenie termodynamicznych parametrów tych procesów, przede wszystkim potencjału redukcyjnego procesu dehalogenacji zgodnego z przewidywanym mechanizmem.

EN

A summary of authors’ research on polyhalogenated aromatic and aliphatic compounds, leading to a conclusion that only a combination of experimental and quantumchemical studies allows elucidation of the reaction mechanism and the determination of redox potentials of dehalogenation processes.

18

Characteristics of natural and synthetic molecular sieves and study of their interactions with fragrance compounds

Kasperkowiak M., Strzemiecka B., Voelkel A.

Physicochemical Problems of Mineral Processing

|

2016

|

Vol. 52, iss. 2

789--802

EN

Structural, physicochemical and adsorption properties of two natural and one synthetic molecular sieves were investigated by various techniques: X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, low-temperature nitrogen adsorption and inverse gas chromatography. The influence of these properties on the ability to adsorb two model fragrances: p-cymene and menthol was studied. The free enthalpy, entropy and Gibbs free energy of adsorption of fragrance molecules on the surface of zeolite and zeolite-like materials were estimated by using inverse gas chromatography. Also, the influence of temperature on the stability of solid-fragrance compound systems as well as the release of the adsorbed fragrance compounds was studied. The obtained results exhibit that both porosity and chemical composition of molecular sieves influence the size and strength of adsorption of fragrance compounds. The study indicated different release characteristics for p-cymene and menthol.

19

Thermo-acoustical study of biologically active 1,1’-bis(3-methyl-4-carboxyethylphenoxy) cyclohexane at four different temperatures

Dhaduk B. B., Parsania P. H.

International Letters of Chemistry, Physics and Astronomy

|

2015

|

Vol. 47

1--14

EN

Density (ρ), viscosity (η), ultrasonic speed (U), and thermo-acoustical parameters such as specific acoustical impedance (Z), adiabatic compressibility (κa), internal pressure (π), free volume (Vf), inter molecular free path length (Lf), Van der Waals constant (b), viscous relaxation time (τ), classical absorption coefficient (α/f2)cl, Rao’s molar sound function (Rm), solvation number (Sn), Gibbs free energy of activation (ΔG*), enthalpy of activation (ΔH*) and entropy of activation (ΔS*) of biologically active 1,1’-bis(3-methyl-4-carboxyethylphenoxy)cyclohexane (BMCPC) in 1,4-dioxane (DO), ethyl acetate (EA), tetrahydrofuran (THF) have been studied at four different temperatures: 298, 303, 308 and 313 K to understand the molecular interactions in the solutions. A good to excellent correlation between a given parameter and concentration is observed at all temperatures and solvent systems studied. Linear increase or decrease [except (α/f2)cl ] of acoustical parameters with concentration and temperature indicated the existence of strong molecular interactions. ΔG* decreased linearly with increasing concentration and temperature in DO and EA systems and increased with temperature in THF system. ΔH* and ΔS* are found practically concentration independent in case of DO and EA system but both are found concentration dependent in THF system.

20

Chalcones: A Solubility study at different temperatures

Bhalu A. A., Bhesaniya K. D., Vekariya N. J., Baluja S. H.

International Letters of Chemistry, Physics and Astronomy

|

2014

|

Vol. 12

7--19

EN

Some new chalcones are synthesized by the condensation of aryl ketones with aromatic aldehydes and solubility of these synthesized chalcones is determined in chloroform and dichloromethane at temperatures ranging between 293.15 K and 313.15 K by gravimetric method. The experimental data was correlated well with modified Apelblat equation. Further, from the experimental solubility data, some thermodynamic parameters such as dissolution enthalpy, Gibb’s energy and entropy etc. were evaluated using van’t Hoff equation. The positive Gibb’s energy and negative entropy suggests spontaneous dissolution and more ordered structure in solution.