Name: Dr. Epaminondas C. Voutsas, Assistant Professor
Tel:  +30 210  772 39 71
Address: Heroon Polytechniou 9, 157 80 Zographou, Athens, GREECE

Diploma, Chemical Engineering, Aristotle University of Thessaloniki, Greece, 1991.

Ph.D., Chemical Engineering, National Technical University of Athens, Greece, 1997.

  Assistant Professor, National Technical University of Athens, 2009-today.

Full CV

Recent Research Activities
Phase equilibrium measurements and modelling of ionic liquid solutions

Ionic liquids (ILs) steadily gain wide recognition as environmentally benign alternatives of volatile organic solvents in a variety of physical and chemical processes. Ionic liquids are molten salts or molten oxides with melting points below 100oC. Moreover, they are often in the liquid state at ambient or even lower temperatures, referred to as Room-Temperature ILs (RTILs). The increasing attention paid for ILs from both the industrial and the academic community stems from their unique properties such as negligible vapor pressures, non-flammability, high thermal stability, high electrical conductivity, large electrochemical window, wide liquid range, good solvating properties for diverse kinds of materials. On top of that, ILs are characterized as designer solvents since it is possible to finely tune their intrinsic thermophysical properties by simply changing the cation and/or the anion, making them appropriate for a specific application.

On the other hand, cinnamic acid derivatives like ferulic acid, p-coumaric acid etc. are natural hydrophilic antioxidants, which occur ubiquitously in fruits, vegetables, spices, and aromatic herbs. They are of particular interest because of their potential biological properties, such as antioxidant, chelating, free radical scavenging, anti-inflammatory, antiallergic, antimicrobial, antiviral, anticarcinogenic, and UV filter properties. Also cinnamic acid esters (CAEs) like methyl ferulate, methyl p-coumarate, and methyl sinapate, can be used in used in oil-based processes, which are often encountered in industrial applications because of their lipophilic character. Moreover, CAEs have been utilized in the production of phenolic acid sugar esters,6 which have antitumoric activity as well as the potential to be used in the formulation of antimicrobial, antiviral, and anti-inflammatory agents.

A systematic research in the field of ionic liquids has taken place only the last few years, where ionic liquids are examined more and more instead of the conventional organic solvents not only in chemical reactions but also in separation methods.

With a view of a better understanding of the usage of ionic liquids for chemical reactions or separation processes, the knowledge of thermodynamic properties and, especially, phase equilibrium data is needed. Such data in the case of mixtures containing antioxidants are almost inexistent.

This project involves:
(a) a systematic experimental study of the solubilities of cinnamic acid derivatives and CAEs in ionic liquids or mixtures of ionic liquids with classical organic solvents
(b) modelling of the solid-liquid equilibrium using both conventional and advanced thermodynamic tools.

More information and detailed results can be found in:

- E.K. Panteli, E.K. Voutsas, "Solubilities of Cinnamic Acid Esters in Ionic Liquids", J. Chem. Eng. Data, 54/3 (2009) 812.
- E. Alevizou, G. Pappa, E. Voutsas, "Prediction of phase equilibrium in mixtures containing ionic liquids using UNIFAC", Fluid Phase Equil., 284/2 (2009) 99.
- E. Panteli, P. Saratsioti, H. Stamatis, E. Voutsas, "Solubilities of Cinnamic Acid Esters in Organic Solvents", J. Chem. Eng. Data, 55 (2010) 745.
- E. Panteli, E. Voutsas, "Solubilities of Cinnamic Acid Esters in Binary Mixtures of Ionic Liquids and Organic Solvents", Fluid Phase Equilib. 295 (2010) 201.

Phase equilibrium of natural gas mixtures (The project is financially supported by STATOIL, Norway)

The knowledge of the hydrocarbon dew point is of great importance for the oil & gas industry as it is one of the gas quality specifications used for ensuring safe transport of natural gas. Avoiding hydrocarbon condensation is crucial as the presence of liquids in the pipelines increases the pressure drop and introduces operational problems resulting from the two phase flow in pipelines designed for single phase transportation. Thus, accurate prediction of hydrocarbon dew point temperatures and pressures are of great importance to obtain a safe and effective utilization of the natural gas pipelines.

Cubic equations of state (EoS), such as the Peng-Robinson (PR) and Soave-Redlich-Kwong, coupled with the classical van der Waals mixing rules, are routinely used by the oil and gas industry for the design of recovery and processing operations of natural gases.

Previous studies have pointed out that currently all thermodynamic models have difficulty in representing correctly the whole phase envelope with both the cricondentherm and the cricondenbar.

In the framework of this project the performance of the UMR-PRU model that has been developed in our laboratory is tested in the prediction of experimental dew point data of synthetic and real natural gases.

The Universal Mixing Rule (UMR) is a mixing rule for cubic equations of state (CEoS) applicable to all type of system asymmetries. For the cohesion parameter of the CEoS the mixing rule involves the Staverman-Guggenheim part of the combinatorial term and the residual term of the original UNIFAC Gibbs free energy expression. For the co-volume parameter of the CEoS the quadratic concentration dependent mixing rule is used with the combining rule for the cross parameter. The UMR is applied to the Peng-Robinson equation of state leading to what is referred to as the UMR-PRU model. Very satisfactory results are obtained using the existing interaction parameters of the Original UNIFAC model for fluid phase equilibrium predictions at low and high pressures for a wide range of system asymmetries including mixtures containing polymers.

More information and detailed results can be found in:

- E. Voutsas, K. Magoulas and D. Tassios, Ind. Eng. Chem. Res., (2004), 43, 6238-6246.
- E. Voutsas, V. Louli, C. Boukouvalas, K. Magoulas and D. Tassios, Fluid Phase Equil., (2006), 241, 216-228.
- V. Louli, C. Boukouvalas, E. Voutsas, K. Magoulas and D. Tassios, Fluid Phase Equil., (2007), 261, 351-358.

Phase equilibrium in associating mixtures: The Cubic-plus-Association (CPA) EoS

An equation of state (EoS) suitable for describing associating fluids has been developed. The equation combines the simplicity of a cubic equation of state (Soave-Redlich-Kwong or Peng-Robinson), which is used for the physical part and the theoretical background of the perturbation theory employed for the chemical (or association) part. The resulting EoS (Cubic Plus Association, CPA). Excellent description are obtained of both vapor pressures and saturated liquid volumes of pure associating compounds such as alcohols, phenols, glycols, acids and water.

CPA has been also successfully applied to the correlation and prediction of phase equilibria (vapour-liquid, liquid-liquid, vapor-liquid-liquid) in a variety of systems where association is present as described in several publications.

More information and detailed results can be found in:

- Kontogeorgis, G.M., Voutsas, E.C., Yakoumis, I. and Tassios, D.P., "An Equation of State for Associating Fluids" Ind. Eng. Chem. Res., 35 (1996) 4310-4318.
- Yakoumis, I.V., Kontogeorgis, G.M., Voutsas E.C., Tassios, D.P., "Vapor-Liquid Equilibria for Alcohol/Hydrocarbon Mixtures Using the CPA Equation of State" Fluid Phase Equil., 130 (1997) 31.
- Voutsas, E.C., Kontogeorgis, G.M, Yakoumis I.V., Tassios, D.P., "Correlation of Liquid-Liquid Equilibria for Alcohol/Hydrocarbon Mixtures Using the CPA Equation of State" Fluid Phase Equil., 132 (1997) 61.
- Yakoumis, I.V., Kontogeorgis, G.M., Voutsas, E.C., Hendriks, E.M., Tassios, D.P., "Prediction of Phase Equilibria in Binary Aqueous Systems Containing Alkanes, Cycloalkanes and Alkenes with the CPA EoS" Ind. Eng. Chem. Res., 37 (1998) 4175.
- Voutsas, E.C., Yakoumis I.V., Tassios, D.P., "Prediction of Phase Equilibria in Water/Alcohol/Alkane Systems" Fluid Phase Equil., 158(1) (1999) 151.
- E.C. Voutsas, G.C. Boulougouris, I.G. Economou and D.P. Tassios "Water/ hydrocarbon Phase Equilibria Using the Thermodynamic Perturbation Theory" Ind. Eng. Chem. Res., 39 (2000) 797.
- Ch. Perakis, E. Voutsas, K. Magoulas, D. Tassios, "Thermodynamic Modeling of the Vapor-Liquid-Equilibrium of the Water/Ethanol/CO2 System", Fluid Phase Equil., 243 (2006) 142.
- Ch. Perakis, E. Voutsas, K. Magoulas, D. Tassios, "Thermodynamic Modeling of the Water + Acetic Acid + CO2 System: The Importance of the Number of Association Sites of Water and of the Nonassociation Contribution for the CPA and SAFT-Type Models", Ind. Eng. Chem. Res., 46/3 (2007) 932.
- E. Voutsas, Ch. Perakis, G. Pappa, D. Tassios, "An Evaluation of the Performance of the Cubic-Plus-Association Equation of State in Mixtures of non-Polar, Polar and Associating Compounds: Towards a Single Model for non-Polymeric Systems", Fluid Phase Equil., 261/1-2 (2007) 343.
- G. Pappa, C. Perakis, I. Tsimpanogiannis, E. Voutsas, "Thermodynamic Modeling of the vapor–liquid equilibrium of the CO2/H2O mixture" Fluid Phase Equil., 284/1 (2009) 56. 

Experimental measurements and modelling in acid gas-alkanolamine-water solutions

The most mature acid gas (CO2, H2S) capture processes rely on the use of amine solvents to wash acid gases out of a gas mixture, such as flue gas.  The accurate design of acid gas treatment processes requires the knowledge of vapor-liquid equilibrium (VLE) of aqueous alkanolamine solutions containing acid gas.

This project involves:
(a) Experimental VLE measurements of aqueous solutions containing N-methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP)
(b) Thermodynamic modelling of acid gas-alkanolamine-water systems. To this purpose, a thermodynamic framework for representing chemical and vapor-liquid equilibria in acid gas-alkanolamine-water systems has been developed, where the vapor-liquid equilibrium is calculated through a new EoS/GE model called the electrolyte-LCVM model.

More information and detailed results can be found in:

- Vrachnos, E. Voutsas, K. Magoulas, A. Lygeros, "Thermodynamics of Acid Gas-MDEA-Water Systems" Ind. Eng. Chem. Res., 43 (2004) 2798.
- E. Voutsas, A. Vrachnos, K. Magoulas, "Measurement and Thermodynamic Modeling of the Phase Equilibrium of Aqueous N-Methyldiethanolamine Solutions" Fluid Phase Equil., 224 (2004) 191.
- A. Vrachnos, G. Kontogeorgis, E. Voutsas, "Thermodynamic Modeling of Acidic Gas Solubility in Aqueous Solutions of MEA, MDEA and MEA-MDEA Blends" Ind. Eng. Chem. Res., 45 (2006) 5148.
- G. Pappa, Ch. Anastasi, E. Voutsas, "Measurement and Thermodynamic Modeling of the Phase Equilibrium of Aqueous 2-amino-2-methyl-1-propanol Solutions", Fluid Phase Equil., 243 (2006) 193.

Energy and Exergy Analysis of Waste-to-Energy Processes

The application of various technologies that convert Municipal Solid Waste (MSW) to energy and other by-products for beneficial reuse has become an issue at the forefront of integrated solid waste management.

Plasma arc gasification offers a solution that could effectively and safely dispose municipal as well as hazardous and toxic wastes that are generated by the residential, commercial, and industrial sectors.

This study focuses on the thermodynamic analysis of plasma gasification technology, which includes prediction of the produced synthesis gas, energy and exergy calculations. To that purpose, an equilibrium plasma gasification model, called GasifEq, has been developed. The GasifEq model has the capability of energy and exergy calculations that are required for the optimization of such the gasification process. This is demonstrated by the presentation of the effect of the most important process parameters on the energetic performance of the process.

More information and detailed results can be found in:

- A. Mountouris, E. Voutsas, D. Tassios "Solid Waste Plasma Gasification: Equilibrium Model Development and Exergy Analysis", Energy Conversion & Management, 47 (2006) 1723.
- A. Mountouris, E. Voutsas, D. Tassios, "Plasma Gasification of Sewage Sludge: Process Development and Energy Optimization", Energy Conversion & Management, 49/8 (2008) 2264.

Dr. E. Voutsas is a member of the Waste-to-Energy Research and Technology Council-Greece (see in

Applications in supercritical fluids

Supercritical extraction: Recovery of high value added components from natural products

The objective of this project is the recovery of high valued components from natural products using supercritical CO2. In the framework of this project the effect of various process parameters (pressure, temperature, solvent flow rate and particle size) in the recovery of oil from parsley and dittany have been examined:

More information and detailed results can be found in:

- V. Louli, G. Folas, E. Voutsas, K. Magoulas, ''Extraction of Parsley Seed Oil by Supercritical CO2'', J. Supercritical Fluids, 30 (2004) 163.
- C. Perakis, V. Louli, E. Voutsas, K. Magoulas, ''Supercritical CO2 extraction of dittany oil: Experiments and modelling'', J. Supercritical Fluids, 55 (2010) 573.

Melting Point Depression of organic compounds with Supercritical CO2

(In collaboration with Dr. Ralf Dohrn, Bayer Technology Services GmbH, Thermophysical Properties, Leverkusen, Germany)

The melting point of solid substances can be depressed considerably by using supercritical fluids. This characteristic property can be used in processes for fine  particles  generation such as: the  Particle  from  Gas  Saturated  Solutions (PGSS),  the  Gas  Antisolvent  Solutions (GAS)  and  the  Rapid  Expansion  of  Supercritical  Solutions (RESS). For  the design and optimization of these processes the  knowledge  of  the  solid – liquid – gas (SLG)  equilibrium  of  the  systems involved  is  of  great  importance.

More information and detailed results can be found in:

- E. Bertakis, I. Lemonis, S. Katsoufis, E. Voutsas, R. Dohrn, K. Magoulas, D. Tassios, "Measurement and Thermodynamic Modeling of Solid-Liquid-Gas Equilibrium of Some organic Compounds in the Presence of CO2", J. Supercritical Fluids, 41/2 (2007) 238.
- R. Dohrn, E. Bertakis, O. Behrend, E. Voutsas, D. Tassios, "Melting Point Depression by Using  Supercritical CO2 for a Novel Melt Dispersion Micronization Process", J. of Molecular Liquids, 131-132 (2007) 53.