Investigation of intermolecular interactions using computer simulations

Експериментална мерења и подаци су од суштинског значаја за пружање информација о својствима и понашању смеша. Међутим, компјутерски прорачуни у комбинацији са експерименталним мерењем могу пружити дубљи увид у понашање и интеракције на молекулском нивоу. За течне бинарне смеше нековалентне интеракције су проучаване квантним хемијским прорачунима и молекулско-динамичким симулацијама. Истражен је утицај различитих функционалних група, попут двоструке везе са могућношћу π-π интеракције и -ОН групе са могућношћу водоничне везе. Поред тога, проучавали смо утицај геометрије молекула на својства бинарних смеша.Experimental measurement and data are essential for providing the information of properties and behavior of mixtures. However, the computer calculations combined with experimental measurement can provide a deeper insight of behavior and interactions at the molecular level. For liquid binary mixtures the non-covalent interactions were studied with quantum chemical calculations and molecular dynamic simulations. The influence of different functional groups, like the double bond with possibility for the π-π interactions and the -OH group with possibility for the hydrogen bonding was investigated. In addition, we studied the influence of the geometry of the molecule on the properties of binary mixture

Experimental measurements of thermophysical properties and theoretical quantum chemical calculations of alcohol and hydrocarbon binary systems

Insight in different types of mixtures’ behavior (such as volumetric and transport properties, and related excess properties) has high importance [1]. These properties depend on the intermolecular interactions between molecules in liquid phase. The theoretical aspect can quantitatively and accurately model the non-covalent interactions using the quantum mechanical methods. In theoretical modeling of interaction energies, a benchmark study of quantum mechanical methods is an essential step [2]. So far, we have studied the interactions of double and single bonds and interactions between two double or two single bonds on a model system of 2-butene and n-butane molecules [3]. The results provide the insights of interactions at molecular level, offering an understanding of experimental measured properties of substances and mixtures with double bonds. The aim of this work is to investigate experimental volumetric and transport properties and their deviations from ideal mixtures and use the computational modeling for analyzing the same effects on deviations at molecular level for the mixtures containing alcohols and hydrocarbons. The combination of experimental measurement and computational modeling is the future in predicting chemical processes in systems and mixtures, providing better and more complete information on properties and chemical processes

Energetska valorizacija otpadnih voda iz industrije prerade mleka u Srbiji

Otpadne vode industrije prerade mleka predstavljaju veliko optrećenje po životnu sredinu. U ovom radu istraživan je potecijal za energetsku valorizaciju anaerobnog tretmana otpadnih voda iz indsitrije prerade mleka u Republici Srbiji. Dobijeni rezultati su pokazali da se otpadne vode iz indus-trije prerade mleka mogu uspešno koristiti kao resurs za proizvodnju toplotne i električne energije, kao i u supstituciji prirodnog gasa u Republici Srbiji

Thermodynamic characterization of binary mixtures of poly(propylene glycol) 425 with toluene and o-, m- and p-xylenes

Density ρ viscosity η and refractive index nD have been experimentally measured for four binary mixtures of poly(propylene glycol) of average molecular weight 425 + toluene/o-xylene/m-xylene/p-xylene over the temperature range T = (293.15–333.15) K with temperature step 5 K and at atmospheric pressure. From the experimental data excess molar volumes VE, deviations in refractive index ΔnD, viscosity deviations Δη and excess Gibbs free energy of activation of viscous flow ΔG*E were calculated and fitted with Redlich-Kister polynomial in order to analyze non-ideal behavior of the studied mixtures. From ΔG* values excess entropy ΔS*E and excess enthalpy of activation of viscous flow ΔH*E were also calculated. It was shown that specific weak, but numerous, attractive interactions and entropic effect, due to difference in size of the pure component molecules, are responsible for volumetric and viscosity behaviour of the studied systems. The viscosities of the studied systems were predicted with the UNIFAC-VISCO and ASOG-VISCO models and correlated with the McAllister equation

Molecular Dynamic Simulations in Binary Liquid Mixtures

Experimental data of liquid binary mixtures can provide the thermodynamic and transport properties1 . Molecular dynamics simulations (MD) are preformed on the same mixtures at the same experimental conditions: at different temperatures and different mixture compositions. Molecular dynamics simulations can gain a deeper understanding of the behavior of liquid mixtures at the molecular level. It can be used for analyzing specific properties, such as the radial distribution functions (RDFs), interactions in the mixture, thermodynamic and transport properties, understanding the dynamics of the system. This information can be used to obtain insight into the molecular level, to understand the nature of the interaction and to predict the behavior under specific conditions. The right force field are essential for describing the system and using the density of the simulated systems as a represented data to compare to the experimental data. We performed experimental measurements and molecular dynamics simulations on four systems to study influence of double bonds on the properties of alcohol mixtures. The data of the molecular dynamic simulations are in an agreement with the data from experimental measurement, and at the same time we can observe interactions at the molecular level that indicate different noncovalent interactions of double bonds in comparison with single bonds

Excess molar volumes and viscosity behaviour of binary mixtures of aniline/or N, N-dimethylaniline with imidazolium ionic liquids having triflate or bistriflamide anion

In this study, densities and viscosities of four binary systems {aniline / N, N-dimethylaniline+1-butyl-3-methylimidazolium triflate ([bmim][OTf])} and {aniline/N, N-dimethylaniline + 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][NTf2])} were measured at atmospheric pressure and within the temperature range T = (288.15 to 333.15) K. Excess molar volumes VE, viscosity deviations Δη and excess molar Gibbs energies of activation of viscous flow ∆G∗E were calculated and the results were fitted to a Redlich-Kister polynomial equation. Also, enthalpic and entropic parts of the ∆G∗E function were determined, at the same composition, for three studied systems that exhibit complete miscibility, since {aniline + [bmim][OTf]} is a partially miscible system. Considering the calculated thermodynamic properties, molecular interactions in the investigated binary systems were analysed and are discussed

Influence of functional groups on thermodynamic properties of binary mixtures

The thermodynamic properties of liquid mixtures depend on the geometry, actually on the shape of the molecules and their ability to pack. In addition, the properties also depend on non-covalent interactions like Van der Waals, electrostatic interactions, hydrogen bonding and π-π interactions. Each functional group in a molecule influences the geometry of the molecule and the intermolecular interactions between molecules. In this work, the functional groups of double bond and -OH group has been investigated and their influence on the properties of mixtures. The properties of mixtures (1) nhexane + 1-hexanol and (2) n-hexane + cis-3-hexen-1-ol have been investigated both with experimental measurement and with computation molecular modeling. Experimental measurement considered measurements of density, viscosity, refractive index and speed of sound at a range of temperature from (288.15 to 318.15) K and at complete composition range. Excess molar volume and deviations of viscosity, refractive index and speed of sound has been calculated and Redlich-Kister equation has been used for fitting the data. Considering the molecular modeling, the quantum chemical calculations and molecular dynamic simulations have been performed. Different model systems are used order to investigate the -OH group energy interaction and double bond / single bond intermolecular energy interactions. The molecular dynamic simulations have been performed with the liquid mixtures

Binary Mixtures of Substances with Double and Single Bonds

In this work, we continue the study of the influence of double bonds on properties of mixtures in systems with double and single bonds

Eksperimentalna merenja i teorijske simulacije binarnih sistema alkohola i ugljovodonika

Experimental and theoretical methods were used to study two mixtures, 1-hexanol with n-hexane and cis-3-hexen-1-ol with n-hexane. The experimental technics were used to determine excess molar volume and viscosity deviations in the temperature range from 288.15K to 318.15K. The data of excess molar volume indicate similar behavior of the two alcohols, 1-hexanol and cis-3-hexen-1-ol in mixtures with n-hexane. The experimental data are in accordance with molecular dynamics simulation of these mixtures, showing similar number of hydrogen bonds in the two mixtures. The experimental data of viscosity deviations show difference of the two mixtures, where the deviation is significantly larger for cis-3-hexen-1-ol and n-hexane mixture, indicating stronger interactions within cis-3-hexen-1-ol and n-hexane binary mixture. These experimental data are in accordance with quantum chemical calculations on interactions energies. Namely, calculated interaction energies show that interaction between single and double bonds are stronger, than interactions between two single bonds.Eksperimentalne i teorijske metode korišćene su za proučavanje dve smeše, 1-heksanola sa n-heksanom i cis-3-heksen-1-ola sa n-heksanom. Eksperimentalne tehnike su korišćene za određivanje dopunskih zapremina i promene viskoznosti za temperaturni opseg od 288.15K do 318.15K. Podaci o dopunskoj molarnoj zapremini ukazuje na slično ponašanje dva alkohola, 1-heksanola i cis-3-heksen-1-ola u smešama sa n-heksanom. Eksperimentalni podaci su u skladu sa simulacijom molekularne dinamike ovih smeša, pokazujući sličan broj vodoničnih veza u dve smeše. Eksperimentalni podaci o promeni viskoznosti pokazuju značajnu razliku između dve smeše, odstupanje je značajno veće za smešu cis-3-heksen-1-ol i n-heksan, što ukazuje na jaču interakciju u binarnoj smeši cis-3-heksen-1-ola i nheksana. Ovi eksperimentalni podaci su u skladu sa kvantno-hemijskim proračunima energija interakcija na molekulskom nivou. Naime, izračunate energije interakcije pokazuju da je interakcija između jednostrukih i dvostrukih veza jača, nego interakcija između dve jednostruke veze.Related to: [http://cer.ihtm.bg.ac.rs/handle/123456789/3291

Eksperimentalna merenja i teorijske simulacije binarnih sistema alkohola i ugljovodonika

Experimental and theoretical methods were used to study two mixtures, 1-hexanol with n-hexane and cis-3-hexen-1-ol with n-hexane. The experimental technics were used to determine excess molar volume and viscosity deviations in the temperature range from 288.15K to 318.15K. The data of excess molar volume indicate similar behavior of the two alcohols, 1-hexanol and cis-3-hexen-1-ol in mixtures with n-hexane. The experimental data are in accordance with molecular dynamics simulation of these mixtures, showing similar number of hydrogen bonds in the two mixtures. The experimental data of viscosity deviations show difference of the two mixtures, where the deviation is significantly larger for cis-3-hexen-1-ol and n-hexane mixture, indicating stronger interactions within cis-3-hexen-1-ol and n-hexane binary mixture. These experimental data are in accordance with quantum chemical calculations on interactions energies. Namely, calculated interaction energies show that interaction between single and double bonds are stronger, than interactions between two single bonds.Eksperimentalne i teorijske metode korišćene su za proučavanje dve smeše, 1-heksanola sa n-heksanom i cis-3-heksen-1-ola sa n-heksanom. Eksperimentalne tehnike su korišćene za određivanje dopunskih zapremina i promene viskoznosti za temperaturni opseg od 288.15K do 318.15K. Podaci o dopunskoj molarnoj zapremini ukazuje na slično ponašanje dva alkohola, 1-heksanola i cis-3-heksen-1-ola u smešama sa n-heksanom. Eksperimentalni podaci su u skladu sa simulacijom molekularne dinamike ovih smeša, pokazujući sličan broj vodoničnih veza u dve smeše. Eksperimentalni podaci o promeni viskoznosti pokazuju značajnu razliku između dve smeše, odstupanje je značajno veće za smešu cis-3-heksen-1-ol i n-heksan, što ukazuje na jaču interakciju u binarnoj smeši cis-3-heksen-1-ola i nheksana. Ovi eksperimentalni podaci su u skladu sa kvantno-hemijskim proračunima energija interakcija na molekulskom nivou. Naime, izračunate energije interakcije pokazuju da je interakcija između jednostrukih i dvostrukih veza jača, nego interakcija između dve jednostruke veze.Related to: [http://cer.ihtm.bg.ac.rs/handle/123456789/3291