Chavdar Petrov Chilev

University of Chemical Technology and Metallurgy | UCTM · Department of Chemical Engineering

This study aimed to investigate the biological activity of aqueous mixtures of two essential oils. The mixtures were prepared by mixing certain amounts of lavender and clove oils with distilled water at room temperature. In the case of lavender oil, a relatively clear saturated aqueous phase was obtained after mixing with an excess of the essential...

A mathematical model for modeling solid-liquid extraction from plants was developed. Two extraction systems, System I Nicotiana tabacum L.-water and System II Geranium sanguineum L.-water, were investigated. The effect of agitation rate on the mode of the extraction process was studied, as the limit values in the case of internal diffusion for Syst...

A new procedure for quantitative characterization of different types of solid materials is proposed. The technique is based on the Scanning Electron Microscopy (SEM) analysis results of porous materials and their processing by the software ImageJ. Several types of porous adsorbents AX21, AC35, GAC250, ACENO and IRH3 activated carbons were investiga...

We describe a model and calculation technique that supports the design of reactive distillation columns using ChemCAD simulation software. The approach is illustrated for the production of ethyl acetate because it is inevitably needed as an active solvent used in a wide range of applications across many industries. Ethyl acetate is normally produce...

A comprehensive systematic study on the mechanism of solid-liquid extraction of valuable components from plant materials was conducted. Experimental series of extraction of flavonoids from red geranium roots - Geranium Sanguineum L. (extractant 70% C2H5OH), and of tobacco concrete from tobacco leaves - Nicotiana tabacum L. (extractant H2O), were do...

The present paper reviews the different types of adsorbents that could be used for CO2 capture from flue gases. They include carbon-based adsorbents, zeolites, molecular sieves, metal-organic frameworks, hydrotalcite-like compounds and advanced adsorbents. Their possibilities are described and confronted. In particular, it has been demonstrated tha...

A brief review of the different methods of hydrogen storage process for application in automobile manufacturing was presented and discussed. The hydrogen storage by adsorption on super activated carbon AX21 at various thermodynamic conditions was investigated. In order to describe the reality of the system, we planned a brief review, a discussion a...

Experimental kinetics has been obtained by extraction from leaves of Nicotiana tabacum L. at periodical conditions in a stirred vessel. The influence of the liquid-solid ratio and the kind of the solvent have been determined. A four parameters model for calculating the values of Deffhas been found using non-linear regression of the experimental res...

The current work is concerned with obtaining a new empirical model for the time-variable effective diffusion coefficient (Deff) by extraction from plant materials. It has been applied for describing a solid liquid extraction from Cotinus coggygria and compared with experimentally obtained extraction kinetics. The experiments have been performed by...

This work presents an ChemCAD 6.0 Simulation study for biodiesel production. The simulation illustrates the production of biofuel from pure vegetable oil with an alkaline catalyst. The main areas are transesterification, methanol separation, water washing, FAME purification, catalyst neutralization and glycerol purification. The equipment used incl...

Different models have been used to correlate single component adsorption data and to predict multi-component equilibrium. Some of them consider an ideal behavior of the system, without taking into account the possible sources of non-ideal behavior, like the adsorbate–adsorbate interactions in the adsorbed phase, the heterogeneity of the adsorbent s...

Using a scanning electronic microscope have been investigated three types of adsorbents Zeolite 13X, activated carbon AC35, IRH3 and clays. The structure of the samples in the form of powder, granules, and compact formations of cylinders or tablets are observed. The materials have been tested before and after the adsorption process at high pressure...

The adsorption data of the pure gases methane, ethylene and hydrogen on two types of zeolites and two types of activated carbon materials were measured using a volumetric method at 293 K and at pressure up to 26.8 MPa. Four different approaches were tested for description of the experimental equilibrium data. Based on the experimental data obtained...

The possibility of application of new materials for storage of hydrogen in automotive industry is examined Materials are active carbon AC35 in whose structure, particles from various metals: Ni, Ni + La and Ni + MM are implanted. The last mentioned material called “mixed metal MM” contains approximately 51% La, 33% Ce, 12% Nd, 4% Pr. The study of t...

A mathematical model with four parameters describing the adsorption equilibrium of supercritical gases on microporous adsorbents in a wide range of pressures is studied. Numerical experiments related to determining the model parameters by nonlinear regression process of experimental data are carried out. From a physical point of view for a particul...

The kinetics of the extraction of useful components from vegetable raw materials has been studied experimentally. The experiments have been carried out with the system Cotinus coggygria - ethanol Kinetic curves for the extracted valuable components (total polyphenols and flavonoids) have been obtained at certain technological parameters. The experi...

Experimentally the kinetics of the extraction of useful components for the system Cichorium intybus -70% ethyl alcohol has been studied. The experiments have been carried out at periodical conditions in a stirring vessel. Kinetic curves for the extracted valuable components (total phenols, flavonoids, rutin and tannins) for certain technological pa...

Scientific work published in Food Science, Engineering and Technologies.

Experimental kinetics was obtained by extraction from plants. The experiments were carried out with the solid-liquid system Tribulus terrestris – ethanol in a periodical stirred vessel. The impact of the temperature, liquid – solid ratio and ethanol content in the extraction solvent on the furostanal saponins’ rate of extraction is investigated. Th...

Scientific work published in Food Science, Engineering and Technologies.

In this article, we present a new approach to describe adsorption equilibrium of pure gases in a wide range of pressure. This approach is based on a simple statistical mechanics treatment combining the potential theory and lattice fluid models. The obtained equation for the calculation of the excess adsorption can predict the curve progression of i...

A new approach for a description of the adsorption equilibrium gas-solid was developed. This method combines the quantum-mechanical treatment of the classical theory of Polanyi and the conception of the lattice gas. This leads to a three parameters equation describing the adsorption equilibrium. A thermodynamical treatment of the temperature depend...

The topic of this work is to compare several experimental methods such as volumetric and volumetric-gravimetric methods for measuring the equilibrium states of pure gases being adsorbed on the surface of solid materials. The investigation of different type methods and their advantages end disadvantages are discussed. The installations used for meas...