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Physical Chemistry

 

State Behaviour of Aqueous Solutions

Y Doc. Ing. Ivan Cibulka, CSc.

b ivan.cibulka@vscht.cz

e +420220444063, +420220443782

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Accurate measurements of density of and speed of sound in dilute aqueous solutions of organic substances are performed using two experimental setups: automated flow vibrating-tube densimeter constructed in the laboratory (density in the temperature interval 298-573 K and under pressures up to 30 MPa) and the commercial apparatus DSA 5000 (density and speed of sound in the temperature interval 278-343 K under atmospheric pressure). Partial molar volumes and partial molar isentropic compressions at infinite dilution are evaluated from experimental data and analysed from the point of view of structure – property relationships. Group contribution methods for estimation of these two quantities are developed.

 

Laboratory of experimental thermodynamics: Phase and chemical equilibria, and properties of mixtures

Y Doc. Ing. Vladimír Dohnal, CSc.
b dohnalv@vscht.cz

e +420220444297

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The research group is engaged in experimental study of equilibria in multicomponent fluid-phase systems and related thermodynamic and thermophysical properties of dilute aqueous and non-aqueous solutions of organic substances. To this end, we employ a large variety of procedures of experimental thermodynamics including phase equilibria measurements (vapor-liquid, liquid-liquid, solid-liquid), calorimetric measurements (enthalpy of mixing, dissolution, and reaction), volumetric measurements, and measurements of viscosity and optical properties. Currently, we focus mainly on technologically, interesting systems with ionic liquids (IL), and pharmaceutically active ingredients (API), deep eutectic solvents (DES) and dilute aqueous solutions of volatile organic compounds (VOC) environmental and sensoric significance. In the systems mentioned, we study also other specific phenomena as formation of inclusion complexes or micelles or acid-base equilibria. Long-term effort of the group is devoted to experimental method and procedure development. New methods for determination of limiting activity coefficients, selectivity of non-volatile separation agents, mixing enthalpies and solubilities belong to our achievements in this direction.  

 

Laboratory of Membrane Separation Processes

Y Doc. Ing. Karel Friess, Ph.D.
b karel.friess@vscht.cz
e +420220 444 029

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The laboratory is specializes in the study of the transport of gases, vapors and their mixtures through flat polymer membranes. The self-developed permeameters are used to determine the permeability and diffusion coefficients, respectively. The diffusion coefficients of gases and vapors in polymers are evaluated from the (gas or vapor) sorption kinetics. Sorption experiments are performed gravimetrically via Mc Bain spiral balances. These balances are also used to determine the sorption isotherms and the sorption coefficients of gases and vapors in polymers.

 

Computer simulations of complex systems

Y RNDr. Mgr. Jan Heyda, Ph.D.
b Jan.Heyda@vscht.cz
e +420220444257
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In terms of computer simulations, we study the behavior of biomolecules in aqueous solutions, their thermodynamics and kinetics, action of salts and osmolytes. Grounded in the knowledge of molecular interactions we can rationalize the stability of protein native state, determine the solubility, or quantify the electrophoretic mobility. Moreover, for fast qualitative description of polymer and protein thermodynamics, we can determine in silico key parameters, which are further applied in thermodynamic models. Our approach is based on defining system key properties, applying an simulation protocol of optimal sampling efficiency, and finally evaluate the target property via statistical analysis of simulation data.
 

Surface and Interface Phenomena

Y Ing. Štěpán Hovorka, Ph.D.
b hovorkas@vscht.cz
e +420220444163

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The group is focused on a theoretical and experimental study of phase interfaces (vapor-liquid, liquid-liquid and solid-liquid) and colloidal systems. The particular topics are

a) Experimental study of the concentration and temperature dependence of surface and interfacial tension leading to an extension of a database with physical properties (e.g. solutions of organic non-electrolytes in water and aqueous solutions of inorganic salts and denaturants of proteins are the subject of the study)

b) A creation of a correlation equation (based on a theoretical model) that enables a quantitative description of mutual relations among physical properties of mobile phase interfaces (surface and interfacial tension) and a bulk of liquid phase (activity coefficients of components in the solution)

c) Experimental study of wettability of solids by liquids focused on pharmaceutical topics

d) Collaboration with ICPF of the CAS and IMC of the CAS on a project aiming at a resolution of racemic mixtures to particular enantiomers

e) Experimental study of physical properties of polymer membranes immersed in liquid solutions. Permeability and diffusion coefficients (i.e. kinetics of mass transport through the membrane), overall sorption of solution in the membrane and preferential sorption of particular components (phase equilibrium) and swelling of the membrane are measured. This activity is an extension (no duplication) of a research of Laboratory of membrane separation processes of Dr. Friess that is focused on membranes touched by gases and vapors

f) Experimental study of solutions of surfactants

 

Statistical thermodynamics and molecular simulations

Y Prof. RNDr. Jiří Kolafa, CSc.
b Jiri.Kolafa@vscht.cz
e +420220444257

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We investigate systems of many molecules by theoretical as well as pseudoexperimental methods using classical statistical thermodynamics.

While applying theoretical approaches as diagrammatic techniques and integral equations, we make use of modern methods of computer algebra.

The pseudoexperiment includes molecular dynamics and Monte Carlo simulations. We study a broad range of systems, from lattice models (e.g., of ice) to simple molecular system (hard spheres) to atomistic models (water and ice, salts, solutions). We also develop simulation methodology and force fields.

 

Statistical theory of inhomogeneous fluids

Y Mgr. Alexandr Malijevský, Ph.D.
b Alexandr.Malijevsky@vscht.cz
e +420220444093

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We study structure and phase behaviour of fluids that are in contact with confining (solid) walls using methods of statistical mechanics. It is well know that in the case of a planar wall, the wall-gas interface can exhibit wetting transition at a particular subcritical temperature. Our primary concern is to investigate the role of a wall geometry in adsorption behaviour of generic fluid models and to predict possible novel surface phase transitions induced by the wall geometry. In particular, we wish to determine their order and, in the case of continuous transitions, to evaluate the pertinent critical exponents. These studies can also be extended for dynamical processes of non-equilibrium systems.

 

Laboratory of Enhanced Spectroscopies and Near-Field Microscopy

Y Prof. Dr. RNDr. Pavel Matějka
b Pavel.Matejka@vscht.cz
e +420220443687

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The research of the laboratory if focused on plasmonic nanomaterials and their use in the field of plasmonic-enhanced optical spectroscopies and near-field microscopy. We are interested in new preparation methods of metallic (Au, Ag and Cu) nanostructured systems applying different approaches (from classical chemical reduction, over electrochemical metal coating, vacuum sputtering, to “green” synthesis using natural products). We develop methodologies of surface-enhanced and tip-enhanced vibrational spectroscopic techniques (SEVS, TERS, SNIM) for characterization of nanostructured surfaces, studies of physico-chemical processes in single molecular layer on plasmonic antennas, e.g. in the presence of radiation (surface photocatalytic reactions). We study assembled systems in micron and sub-micron scale starting from model monolayers of small organic molecules, over biologically important compounds to real samples – tissues, extracts of natural materials. We use advanced instrumental equipment which allows us to combine optical spectroscopies with microscopic techniques from optical microscopy to nanoscopic techniques (AFM, STM etc.).

 

Laboratory of phase equilibria. Measurement and prediction of solubilities

Y Doc. Ing. Karel Řehák, CSc.
b karel.rehak@vscht.cz
e +420220 444 039

The group focus on experimental determination of solubilities of solids, liquids and gases and on computational treatment of data that involves correlations and prediction of solubilities by means of equations of state and other thermodynamic models. The laboratory is equipped with experimental apparatuses (usually of own design) for measurement of phase equilibria and analytical instruments (GC, UV-Vis spectrophotometer, KF-coulometer, vibration tube density meter). An apparatus for determination of vapour–liquid equilibrium (at low pressures), an apparatus for measurement of gas solubilities (0.1–5 MPa) and various experimental devices for determination of liquid–liquid and solid–liquid equilibria are operated in the laboratory.

Correlations and predictions of solubilities are based on utilization of models for the excess Gibbs energy (Wilson equation, NRTL, UNIQUAC, UNIFAC, NRTL-SAC) and equations of state of the PC-SAFT type. Computational treatments of data are usually done by self-made programs.
 

Applied Thermodynamics

Y Doc. Ing. Květoslav Růžička, CSc.
Y Doc. Ing. Michal Fulem, Ph.D.
b ruzickak@vscht.cz, fulemm@vscht.cz
e +420220 444 116

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Description of the vapor-liquid and vapor-solid equilibria for i) high-boiling substances classified as potential contaminants; ii) organometallic compounds used as MOVPE precursors; iii) biogenic compounds (terpenes, fragrances, H-bonding compounds, infochemicals). This includes a) experimental determination of vapor pressure in low-pressure region (below 1 kPa); b) calorimetric determination of heat capacities and enthalpies of phase transitions for solids and moderately volatile liquids (temperature range from 2 K to 600 K); c) state of the art ab-initio calculations of ideal gas thermodynamic properties; d) simultaneous correlation (SimCor) of vapor pressures and thermal derived quantities, which allows evaluation of vapor pressure (and vaporization/sublimation enthalpies) in the region of extremely low vapor pressures, where direct determination is not feasible.
Sublimation enthalpies obtained by SimCor are used as a benchmark for development of ab initio methodologies leading to reliable  lattice energies and prediction of sublimation equilibria.
Calorimetry is used also for studying novel inorganic materials used for fabrication of semiconductors; polyaromatic hydrocarbons and bitumens; compounds of pharmaceutical interest.

 

Theoretical Photodynamics Research Group

Y Prof. RNDr. Petr Slavíček, Ph.D.
b petr.slavicek@vscht.cz
e +420220444064

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Laboratory of Theoretical Photodynamics aims at modeling interactions between photons and molecules. Due to advancement of laser technologies, light can be these days controlled in time, energy, or position with unprecedented precision. Our goal is to understand how we can control the molecules via the light. In our work we investigate a wide range of topics, e.g., biomolecular photostability, atmospheric photodynamical processes following the excitation of the molecules, interaction of molecules with high energy radation or photoionization and charge-transfer reactions. At the same time, we aim to model molecules beyond the gas phase, investigating finite molecular aggregates or molecules in the condensed phase. Part of our work is also necessarily devoted to the development of new and more efficient techniques of molecular simulations. We develop new methods for simulating electronic spectra, new quantum chemical approaches or novel approaches for modeling solvent.

Updated: 5.1.2016 12:22, Author: fchi

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