Abstract: This study aims to provide a new thermodynamic method for determining the value of Drago's four interaction parameters, namely Ea, Eb, Ca, and Cb (kcal1/2 mol-1/2). The method is based on the following fundamental novelties:

The values of the parameters Ea, Eb, Ca, and Cb are simultaneously determined for seven amphoteric substances. Thus, there are a total of 28 values to be determined, with each set consisting of seven substances. For the seven selected amphoteric substances, there are seven equations of the type:

V∂2h / n = (Ea Eb + Ca Cb)

Next, all possible 2-to-2 combinations of these seven substances are generated. For each 2-to-2 combination, one of the two is selected as a solute (2) and the other as a solvent (1), or vice versa. By measuring the mixing energy, ΔEmix (2.1), of these combinations, the 21 measurements available to extract the energy, ΔEint, of chemical bonds, according to the enclosed Buchmann paper:

ΔEmix (2.1) = (Ea1 Eb2 + Ca1 Cb2) + (Ea2 Eb1 + Ca2 Cb1)

Next, the seven equalities of the type V∂2h / nj = (Eaj Ebj + Caj Cbj) (kJ / mol) with j = 1,7 are put together with 21 equalities of the type ΔEint = (Eaj Ebj+1 + Caj Cbj+1) + (Eaj+1 Ebj + Caj+1 Cbj). This will generate a system comprising 28 equations for 28 unknown parameters. The resolution of this system will afford the 28 sought values of Drago’s four parameters Ea, Eb, Ca, Cb for the seven selected substances.

Keywords: Mixing energy, chemical interaction energy, Hansen's solubility parameters, Drago's interaction parameters, orthogonal matrix of experiments.

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Ionic Liquids as Efficient Extractants for Quercetin from Red Onion (Allium cepa L.) - Pages 21-38

Urszula Domańska, Anna Wiśniewska, Zbigniew Dąbrowski and Mikołaj Więckowski

DOI: https://doi.org/10.6000/1929-5030.2018.07.04

Published: 06 November 2018

Abstract: The solubility of Quercetin in alcohols, esters and in 1-ethyl-3-methylimidazolium trifluoroacetate, [EMIM][TFA] ionic liquid (IL) using the dynamic method was measured at constant pH in a range of temperature 233-373 K and compare to the literature data. The experimental solubility data have been correlated by means of commonly known G^E models,UNIQUAC and NRTL with the assumption that the systems studied here present simple eutectic behaviour. The basic thermal properties of Quercetin, i.e., fusion temperature and the enthalpy of fusion have been measured with differential scanning microcalorimetry technique (DSC).The application of alcohols, esters and ionic liquids (ILs) as alternatives to conventional organic solvents in the liquid-liquid extraction of Quercetin from different medicinal plants, flowers and frozen red onion (Allium cepa L.) was investigated. The parameters affecting the extraction yield using ILs such as chemical structures of the IL cation and anion, the phase volume ratio of extracting solvent, time of extraction and the Quercetin form of sample and concentration were evaluated. Specific Quercetin composition was performed through HPLC measurements. Using the most effective ILs in extraction, the 14.3±0.1g∙kg^-1 and 5.9±0.1 g∙kg^-1of Quercetin from frozen pure red onion was obtained with N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate, [N_2,2,1,2OCH3][BF₄] and 1-ethyl-3-methylimidazolium trifluoroacetate, [EMIM][TFA], respectively.

Keywords: Quercetin, Ionic liquids, Solubility, Extraction from red onion, Hydrogen bonding interaction.

Abstract: The influence of low-frequency sonolysis on the kinetics of liquid-phase bimolecular liquid-phase reactions was studied by mathematical modeling with due regard for the association of starting reagents into dimers and trimers. With increasing frequency and amplitude of low-frequency sonic waves (up to some critical value), we observed the disappearance of trimers and concomitant cessation of the reaction. This observation offers an additional tool for controlling reaction rate by the external action of low-frequency vibrations.

Keywords: Chemical reaction, Kinetics, Liquid medium, Reagent association, Low-frequency action.

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Mathematical Models of Water and Solute Transport in Soil - Pages 98-104

A. Erfani Agah, P. Meire and E. De Deckere

DOI: https://doi.org/10.6000/1929-5030.2017.06.03.2

Published: 01 November 2017

Abstract: Improved understanding of water flow and solute transport through the unsaturated zone is important for the sustainable management of soils. As soils are complex and heterogeneous systems, quantification of the transport processes is difficult. More knowledge on the relationship between solute transport process, soil structure, hydrologic initial and boundary conditions, and observation scale is needed here.Modeling unsaturated flow and transport with mathematical or numerical methods is an important tool for predicting the infiltration and redistribution of soil water and the transport of solutes in the unsaturated zone. Flow and transport models are commonly used to support the decision making process in agricultural management, environmental impact assessment, toxic waste control, remediation design, and subsurface cleanup monitoring.The movement of contaminants through porou media describs by the combination of advection, diffusion-dispersion and chemical retardation.The most common model that describes solute transport by convection and dispersion is the convection-dispersion equation (CDE).This equation describes the change in concentration at any point along the flow path as a function of time. This paper is mainly dedicated to a discussion of basic processes for modelling of water flow and contaminant transport in saturated and unsaturated soils. After a brief description of the classical approach for simulating water flow and solute transport in porous media, issues related to water and solute trasport equation in soil.

Keyword: Soil water flow and solute transfer, Breakthrough curves (BTCs), Pore water velocity, Dispersivity.