Dragomir Vassilev | Technical University of Gabrovo (original) (raw)

Papers by Dragomir Vassilev

Sustainable waste management and regulation programs are key to the proper functioning of any cit... more Sustainable waste management and regulation programs are key to the proper functioning of any city. Old disposal methods are not suitable in Europe. This is a problem that will be left for generations to come. Insufficient resources and the constantly growing needs of the population require a balanced approach to solving economical, social and environmental problems. Sustainable development aims to reduce the harmful impact of waste on the environment and the health of the population. Waste management programs achieve this by developing strategies to reduce, recycle and manage waste generation, as well as to operate with the most efficient resources. This study is designed to reflect the current status and plan of waste management activities in the Municipality of Gabrovo, Bulgaria, in accordance with legal requirements, European and national programs, methodological documents.

UNITECH`2023, Nov 2023

The sustainable use of the natural resources and the introduction of the principles of the circul... more The sustainable use of the natural resources and the introduction of the principles of the circular economy are two trends that are particularly relevant in the context of the European efforts for sustainable economic growth. One of the ecologically promising approaches is the municipals's multiannual environmental action programs which sets the framework for future actions in all areas of the environmental protection strategies. The aim of this study was designed to investigate the general nature of environmental protection, waste management, energy use, and conservation practices of the wild nature in Tryavna municipality, Bulgaria. The sustainable development (i.e. environment-development trade-offs), pollution prevention and clean technologies are the key strategy for successful economic development and environmental protection.

One of the country's priority directions in the development and management of the water sector is... more One of the country's priority directions in the development and management of the water sector is related to the construction, reconstruction and modernization of wastewater treatment plants, which are a fundamental element for improving the quality of life in populated areas. In recent years, more than 170 urban waste water treatment plants (WTPs) have been built and are operating in the Republic of Bulgaria. It is known that in the process of wastewater treatment, significant amounts of sewage sludge are released, which make up from 0.5% to 1.5% of the amount of treated water, and in some cases, the percentage can reach up to 10%. Sludge is a big problem, as it accumulates in the area of treatment plants, hinders their functioning and pollutes the natural environment. The present work examines the sludge from the WWTP in the city of Blagoevgrad, by examining the sludge from the WWTP in Blagoevgrad city and Razlog city, evaluating their possibilities to be used in the practice.


Plasticizers are additives that increase the plasticity of polymers by increasing the flexibility... more Plasticizers are additives that increase the plasticity of polymers by increasing the flexibility of macromolecules. The selection of substances with a similar function is carried out in accordance with criteria that include requirements for non-toxicity, good miscibility, low migration ability, low volatility, etc. The plasticizers most used in plastics processing, for example polyvinyl chloride (PVC), are esters of carboxylic acids with linear or branched aliphatic alcohols of moderate chain length. In organic synthesis, research related to the application of ultrasound in the synthesis of esters is promising-the goals set are to reduce reaction time, increase yields, use safe raw materials, and reduce energy consumption. Its influence on the esterification process in the preparation of aliphatic and sucrose esters with short-and medium-chain fatty acids has not been sufficiently studied. The aim of the present study is to apply ultrasound in the esterification of stearic acid with fatty alcohols. The resulting esters are to be used as potential plasticizer additives in plastics, and the possibility of application in polyvinyl chloride has been investigated.

Acta Periodica Technologica, 2004

Copper(II) chloride, in warm ethanolic solution, reacted with 2-amino and 2-methylbenzimidazole d... more Copper(II) chloride, in warm ethanolic solution, reacted with 2-amino and 2-methylbenzimidazole derivatives to give complexes of the formula CuL2Cl2?nH2O, where L=1-benzyl-2-aminobenzimidazole 1-(4-methylbenzyl)-2-aminobenzimidazole, 1-benzyl-2-methylbenzimidazole and 1-(4-methylbenzyl)-2-methylbenzimidazole( n=1 or 2). The complexes were characterized by elemental analysis of the metal, molar conductivity magnetic susceptibility measurements and IR spectra. The molar conductivities of copper(II)complexes in dimethyl formamide (DMF) corresponding to a 1:1 type of electrolyte indicate that in all the complexes one of the coordinated chloride ions has been replaced by DMF molecule. The room temperature effective magnetic moments and IR data of the complexes suggest that all Cu(II) complexes have a tetrahedral configuration, which is realized by participation of the pyridine nitrogen of two organic ligand molecules and two chloride anions. The antimicrobial activity of the ligands and ...

Esters are used in the industry. The rapid increase in demand for esters in the food, cosmetics a... more Esters are used in the industry. The rapid increase in demand for esters in the food, cosmetics and pharmaceutical industries makes it mandatory to find alternative ways of synthesis instead of low-yield, expensive, energy-intensive and prolonged reactions. The production process for the synthesis of esters is based on chemical esterification of fatty acids with alcohol in the presence of inorganic catalysts at high temperatures. However, these chemical processes are non-selective and consume a large amount of energy. In this regard, the current situation of environmental degradation requires the development of efficient and environmentally friendly methods in terms of energy consumption and waste reduction. The synthesis of esters by sonication is also an economical and effective method of performing esterification with broad practical application. The article presents a review of research and modern engineering solutions based on "green technologies" for the synthesis of esters. Significant advantages of the method of transesterification of methyl caprate with sucrose, leading to esters with potential biological activity such as antifungal and antimicrobial agents, are highlighted.

The PhD thesis has investigated the application of ultrasonic irradiation in the esterification o... more The PhD thesis has investigated the application of ultrasonic irradiation in the esterification of alcohols - i-propanol, n-, i- and t-butanol with capric, lauric, palmitic, and 10-undecylenic acid. The resulting esters were identified by thin-layer and gas chromatography and characterized by NMR and IR spectroscopy. The applicability of sucroesters as plasticizers in plastics processing were examined by using sucrose plamitate as a plasticizer of polyvinyl chloride (PVC). PVC films with different contents of sucrose palmitate were used and the plasticizing effect was evaluated by determining the glass transition temperature (by differential scanning calorimetry), by the strength characteristics of the PVC film at a tensile load (tensile strength, modulus of elasticity, relative elongation at breaking) and by studying the structure by means of scanning electron microscopy. The intensifying effect of the ultrasonic impact on the esterification process been investigated was proved. As a result the reaction time was reduced, the reaction temperature was lowered, and the composition of the resulting esters was identical to that obtained by the conventional method. Digitally, by using chromatographic and spectral methods, it was established that under the selected conditions of synthesis cleavage of carbon-carbon bonds, isomerization of the cis-isomer of oleic acid and auto-oxidation of the reaction product were not observed. A plasticizing effect of sucrose plamitate was identified for polyvinyl chloride. Consequently, the glass transition temperature, the modulus of elasticity and the stress at break were reduced whereas work to break and the relative elongation at break were increased.

This article gives an example steps about risk assessment of effects of chemicals on the health a... more This article gives an example steps about risk assessment of effects of chemicals on the health and the safety of workers in foundries. The authors prefer and use one of many known risk assessment methods.

Subject of this review are electromagnetic waves generated by currents with low and high frequenc... more Subject of this review are electromagnetic waves generated by currents with low and high frequency. When we talk about the impact of such currents has to be understood not contact their action, and that of the consequences of such an electromagnetic field in space. In this paper the authors suggest an example of the application of the methodology to assess the risk to the health and safety of workers at work with sources of electromagnetic fields. This example can be used by employers to assess the risks in the workplace, as well as from office-Regulations on Safety and Health at Work in the implementation of the regulations.

One of the most reliable and promising methods for the disposal of toxic compounds contained in e... more One of the most reliable and promising methods for the disposal of toxic compounds contained in effluents and gaseous emissions from various chemical industries based on heterogeneous catalytic reactions that can achieve complete oxidation of the substances. The purpose of this study development activity obtained nickel oxide systems for full heterogeneous catalytic oxidation of organic substances. To study the activity of the catalyst systems used are solutions of the phenol and salicylic acid as potential contaminants.

One of the most reliable ways to destroy harmful compounds based on their catalytic oxidation inv... more One of the most reliable ways to destroy harmful compounds based on their catalytic oxidation involving catalysts for complete oxidation. Full oxidation of the organic matter is an irreversible process and therefore toxic substances using a suitable catalyst, are converted to innocuous products - CO2, and H2O. This article aims to preparation and characterization of the nickel oxide systems, with application to the purification of fluids (in particular water) by complete catalytic oxidation.

This article presents a method of cold phosphatizing of metals. The authors were developed differ... more This article presents a method of cold phosphatizing of metals. The authors were developed different composition for easier phosphatizing of metals.

Biodiesel is an alternative to conventional diesel fuel, which is produced by a process of transe... more Biodiesel is an alternative to conventional diesel fuel, which is produced by a process of transesterification of vegetable oils derived from oilseed crops (especially rapeseed, soybean, sunflower, palm, etc.). Or used, as well as animal fat, or green algae. Studies on transesterification of waste vegetable oil for biodiesel by ultrasound in Bulgaria in optimizing the process still in its early stages. At various stages of production and processing of waste vegetable oil, products that could be a starting material for the preparation of biodiesel. As waste vegetable oil (sunflower, canola, soybean, etc..) Is a promising feedstock for biodiesel production in the country, inter-est the possibility of obtaining ultrasonic, biodiesel from these products and the influence of the parameters of the transesterification process on the characteristics of resulting fuel.

Pharmacologically interesting sucrose undecylenic acid esters were synthesized by transesterifica... more Pharmacologically interesting sucrose undecylenic acid esters were synthesized by transesterification reaction with methyl ester of 10-undecylenic acid under conventional conditions and ultrasonic irradiation. The effect of catalyst (NaOCH3 and K2CO3), molar ratio of reactant and temperature of esterification on the esters yield was studied. The highest yield was obtained in DMSO with 13 mol % K2CO3 as a catalyst, temperature 45°С for 2 h under 45 kHz ultrasonic frequency. The structure of sucrose esters and the stability of terminal double bond in alkyl chain of undecylenoyl sucrose esters was confirmed by IR-FT and 1H NMR spectra.

Esters are widely used in in-a-kind and are widely used in industry. The rapid increase in demand... more Esters are widely used in in-a-kind and are widely used in industry. The rapid increase in demand for esters in the food industry, cosmetics, pharmaceutical industry makes it imperative to find alternative ways of synthesis instead of reactions that have low yield, expensive, energy-intensive and long lasting. Also, long-chain esters of higher fatty acids are used in industry as biodiesel. The Production process for the synthesis of esters is based on the chemical esterification of fatty acids with an alcohol in the presence of inorganic catalysts at high temperatures. However, these chemical processes are non-selective and consume large amount of energy. In this connection, the current situation of environmental degradation requires the development of efficient and environmentally friendly methods in terms of energy consumption and reduce waste. The synthesis of esters by means of ultrasound is also economical and efficient method for carrying out the esterification with wide pract...

Biointerface Research in Applied Chemistry, 2021

The present study shows the results obtained in the ultrasonic synthesis of sucrose esters with l... more The present study shows the results obtained in the ultrasonic synthesis of sucrose esters with lauric acid, the identification of products, and the study of their possible use as bio-additives with a plasticizing effect in the processing of plastics. Fourier transform infrared spectroscopy (FTIR) and NMR (1H and 13C NMR) were used to identify the synthesized esters. The plasticizing effect of sucrose laurate was assessed by determining the glass transition temperature of thin polyvinyl chloride films by differential scanning calorimetry (DSC). The results show a decrease in the glass transition temperature with an increase in the ester concentration in the polymer, which confirms the plasticizing effect of the obtained esters.

This study aims to demonstrate a simple and rapid “green” method for the ultrasound-assisted synt... more This study aims to demonstrate a simple and rapid “green” method for the ultrasound-assisted synthesis of t-aliphatic esters by reacting t -butanol with saturated (capric, lauric, palmitic) and unsaturated (oleic and undecylenic) acids. The spectral characterization of esters was performed by IR and NMR spectroscopies. The impact of ultrasonic irradiation on the reaction in comparison with the conventional method was analyzed based on the reaction time and the yield of the resulting esters. After spectroscopic studies, the synthesis of the corresponding esters after the ultrasound-assisted irradiation was proven. The yields of the t-butyl fatty acid esters increased between 2 and 10% in comparison with the conventional method for their synthesis. It was also established that the application of ultrasonic irradiation intensifies the esterification process significantly compared to the conventional method. The advantages of the ultrasound-assisted esterification include shortening the...

Biointerface Research in Applied Chemistry, 2021

An environmentally friendly and sustainable ultrasound-assisted esterification of long-chained in... more An environmentally friendly and sustainable ultrasound-assisted esterification of long-chained inulin and sucrose with monounsaturated 10-undecylenic acid was performed. The obtained esters were characterized by thin-layer chromatography (TLC), Fourier transforms infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) spectroscopy. The spectral analyses demonstrated the successful incorporation of the hydrophobic 10-undecylenoyl residue in the water-soluble carbohydrate backbone. Additionally, the antimicrobial potential of 10-undecylenic esters of inulin and sucrose were tested against nine microorganisms (Gram-positive and Gram-negative bacteria, yeasts, and fungi). Both esters inulin 10-undecylenate and sucrose 10-undecylenate (1 mg/ml) inhibited Bacillus subtilis ATCC 6633, Listeria monocytogenes ATCC 8632, Staphylococus aureus 745, Escherichia coli 3398, yeast Candida albicans 8673, and fungi Penicillium sp. Only inulin 10-undecylenate demonstrated antimicrobial acti...

Sustainable waste management and regulation programs are key to the proper functioning of any cit... more Sustainable waste management and regulation programs are key to the proper functioning of any city. Old disposal methods are not suitable in Europe. This is a problem that will be left for generations to come. Insufficient resources and the constantly growing needs of the population require a balanced approach to solving economical, social and environmental problems. Sustainable development aims to reduce the harmful impact of waste on the environment and the health of the population. Waste management programs achieve this by developing strategies to reduce, recycle and manage waste generation, as well as to operate with the most efficient resources. This study is designed to reflect the current status and plan of waste management activities in the Municipality of Gabrovo, Bulgaria, in accordance with legal requirements, European and national programs, methodological documents.

UNITECH`2023, Nov 2023

The sustainable use of the natural resources and the introduction of the principles of the circul... more The sustainable use of the natural resources and the introduction of the principles of the circular economy are two trends that are particularly relevant in the context of the European efforts for sustainable economic growth. One of the ecologically promising approaches is the municipals's multiannual environmental action programs which sets the framework for future actions in all areas of the environmental protection strategies. The aim of this study was designed to investigate the general nature of environmental protection, waste management, energy use, and conservation practices of the wild nature in Tryavna municipality, Bulgaria. The sustainable development (i.e. environment-development trade-offs), pollution prevention and clean technologies are the key strategy for successful economic development and environmental protection.

One of the country's priority directions in the development and management of the water sector is... more One of the country's priority directions in the development and management of the water sector is related to the construction, reconstruction and modernization of wastewater treatment plants, which are a fundamental element for improving the quality of life in populated areas. In recent years, more than 170 urban waste water treatment plants (WTPs) have been built and are operating in the Republic of Bulgaria. It is known that in the process of wastewater treatment, significant amounts of sewage sludge are released, which make up from 0.5% to 1.5% of the amount of treated water, and in some cases, the percentage can reach up to 10%. Sludge is a big problem, as it accumulates in the area of treatment plants, hinders their functioning and pollutes the natural environment. The present work examines the sludge from the WWTP in the city of Blagoevgrad, by examining the sludge from the WWTP in Blagoevgrad city and Razlog city, evaluating their possibilities to be used in the practice.


Plasticizers are additives that increase the plasticity of polymers by increasing the flexibility... more Plasticizers are additives that increase the plasticity of polymers by increasing the flexibility of macromolecules. The selection of substances with a similar function is carried out in accordance with criteria that include requirements for non-toxicity, good miscibility, low migration ability, low volatility, etc. The plasticizers most used in plastics processing, for example polyvinyl chloride (PVC), are esters of carboxylic acids with linear or branched aliphatic alcohols of moderate chain length. In organic synthesis, research related to the application of ultrasound in the synthesis of esters is promising-the goals set are to reduce reaction time, increase yields, use safe raw materials, and reduce energy consumption. Its influence on the esterification process in the preparation of aliphatic and sucrose esters with short-and medium-chain fatty acids has not been sufficiently studied. The aim of the present study is to apply ultrasound in the esterification of stearic acid with fatty alcohols. The resulting esters are to be used as potential plasticizer additives in plastics, and the possibility of application in polyvinyl chloride has been investigated.

Acta Periodica Technologica, 2004

Copper(II) chloride, in warm ethanolic solution, reacted with 2-amino and 2-methylbenzimidazole d... more Copper(II) chloride, in warm ethanolic solution, reacted with 2-amino and 2-methylbenzimidazole derivatives to give complexes of the formula CuL2Cl2?nH2O, where L=1-benzyl-2-aminobenzimidazole 1-(4-methylbenzyl)-2-aminobenzimidazole, 1-benzyl-2-methylbenzimidazole and 1-(4-methylbenzyl)-2-methylbenzimidazole( n=1 or 2). The complexes were characterized by elemental analysis of the metal, molar conductivity magnetic susceptibility measurements and IR spectra. The molar conductivities of copper(II)complexes in dimethyl formamide (DMF) corresponding to a 1:1 type of electrolyte indicate that in all the complexes one of the coordinated chloride ions has been replaced by DMF molecule. The room temperature effective magnetic moments and IR data of the complexes suggest that all Cu(II) complexes have a tetrahedral configuration, which is realized by participation of the pyridine nitrogen of two organic ligand molecules and two chloride anions. The antimicrobial activity of the ligands and ...

Esters are used in the industry. The rapid increase in demand for esters in the food, cosmetics a... more Esters are used in the industry. The rapid increase in demand for esters in the food, cosmetics and pharmaceutical industries makes it mandatory to find alternative ways of synthesis instead of low-yield, expensive, energy-intensive and prolonged reactions. The production process for the synthesis of esters is based on chemical esterification of fatty acids with alcohol in the presence of inorganic catalysts at high temperatures. However, these chemical processes are non-selective and consume a large amount of energy. In this regard, the current situation of environmental degradation requires the development of efficient and environmentally friendly methods in terms of energy consumption and waste reduction. The synthesis of esters by sonication is also an economical and effective method of performing esterification with broad practical application. The article presents a review of research and modern engineering solutions based on "green technologies" for the synthesis of esters. Significant advantages of the method of transesterification of methyl caprate with sucrose, leading to esters with potential biological activity such as antifungal and antimicrobial agents, are highlighted.

The PhD thesis has investigated the application of ultrasonic irradiation in the esterification o... more The PhD thesis has investigated the application of ultrasonic irradiation in the esterification of alcohols - i-propanol, n-, i- and t-butanol with capric, lauric, palmitic, and 10-undecylenic acid. The resulting esters were identified by thin-layer and gas chromatography and characterized by NMR and IR spectroscopy. The applicability of sucroesters as plasticizers in plastics processing were examined by using sucrose plamitate as a plasticizer of polyvinyl chloride (PVC). PVC films with different contents of sucrose palmitate were used and the plasticizing effect was evaluated by determining the glass transition temperature (by differential scanning calorimetry), by the strength characteristics of the PVC film at a tensile load (tensile strength, modulus of elasticity, relative elongation at breaking) and by studying the structure by means of scanning electron microscopy. The intensifying effect of the ultrasonic impact on the esterification process been investigated was proved. As a result the reaction time was reduced, the reaction temperature was lowered, and the composition of the resulting esters was identical to that obtained by the conventional method. Digitally, by using chromatographic and spectral methods, it was established that under the selected conditions of synthesis cleavage of carbon-carbon bonds, isomerization of the cis-isomer of oleic acid and auto-oxidation of the reaction product were not observed. A plasticizing effect of sucrose plamitate was identified for polyvinyl chloride. Consequently, the glass transition temperature, the modulus of elasticity and the stress at break were reduced whereas work to break and the relative elongation at break were increased.

This article gives an example steps about risk assessment of effects of chemicals on the health a... more This article gives an example steps about risk assessment of effects of chemicals on the health and the safety of workers in foundries. The authors prefer and use one of many known risk assessment methods.

Subject of this review are electromagnetic waves generated by currents with low and high frequenc... more Subject of this review are electromagnetic waves generated by currents with low and high frequency. When we talk about the impact of such currents has to be understood not contact their action, and that of the consequences of such an electromagnetic field in space. In this paper the authors suggest an example of the application of the methodology to assess the risk to the health and safety of workers at work with sources of electromagnetic fields. This example can be used by employers to assess the risks in the workplace, as well as from office-Regulations on Safety and Health at Work in the implementation of the regulations.

One of the most reliable and promising methods for the disposal of toxic compounds contained in e... more One of the most reliable and promising methods for the disposal of toxic compounds contained in effluents and gaseous emissions from various chemical industries based on heterogeneous catalytic reactions that can achieve complete oxidation of the substances. The purpose of this study development activity obtained nickel oxide systems for full heterogeneous catalytic oxidation of organic substances. To study the activity of the catalyst systems used are solutions of the phenol and salicylic acid as potential contaminants.

One of the most reliable ways to destroy harmful compounds based on their catalytic oxidation inv... more One of the most reliable ways to destroy harmful compounds based on their catalytic oxidation involving catalysts for complete oxidation. Full oxidation of the organic matter is an irreversible process and therefore toxic substances using a suitable catalyst, are converted to innocuous products - CO2, and H2O. This article aims to preparation and characterization of the nickel oxide systems, with application to the purification of fluids (in particular water) by complete catalytic oxidation.

This article presents a method of cold phosphatizing of metals. The authors were developed differ... more This article presents a method of cold phosphatizing of metals. The authors were developed different composition for easier phosphatizing of metals.

Biodiesel is an alternative to conventional diesel fuel, which is produced by a process of transe... more Biodiesel is an alternative to conventional diesel fuel, which is produced by a process of transesterification of vegetable oils derived from oilseed crops (especially rapeseed, soybean, sunflower, palm, etc.). Or used, as well as animal fat, or green algae. Studies on transesterification of waste vegetable oil for biodiesel by ultrasound in Bulgaria in optimizing the process still in its early stages. At various stages of production and processing of waste vegetable oil, products that could be a starting material for the preparation of biodiesel. As waste vegetable oil (sunflower, canola, soybean, etc..) Is a promising feedstock for biodiesel production in the country, inter-est the possibility of obtaining ultrasonic, biodiesel from these products and the influence of the parameters of the transesterification process on the characteristics of resulting fuel.

Pharmacologically interesting sucrose undecylenic acid esters were synthesized by transesterifica... more Pharmacologically interesting sucrose undecylenic acid esters were synthesized by transesterification reaction with methyl ester of 10-undecylenic acid under conventional conditions and ultrasonic irradiation. The effect of catalyst (NaOCH3 and K2CO3), molar ratio of reactant and temperature of esterification on the esters yield was studied. The highest yield was obtained in DMSO with 13 mol % K2CO3 as a catalyst, temperature 45°С for 2 h under 45 kHz ultrasonic frequency. The structure of sucrose esters and the stability of terminal double bond in alkyl chain of undecylenoyl sucrose esters was confirmed by IR-FT and 1H NMR spectra.

Esters are widely used in in-a-kind and are widely used in industry. The rapid increase in demand... more Esters are widely used in in-a-kind and are widely used in industry. The rapid increase in demand for esters in the food industry, cosmetics, pharmaceutical industry makes it imperative to find alternative ways of synthesis instead of reactions that have low yield, expensive, energy-intensive and long lasting. Also, long-chain esters of higher fatty acids are used in industry as biodiesel. The Production process for the synthesis of esters is based on the chemical esterification of fatty acids with an alcohol in the presence of inorganic catalysts at high temperatures. However, these chemical processes are non-selective and consume large amount of energy. In this connection, the current situation of environmental degradation requires the development of efficient and environmentally friendly methods in terms of energy consumption and reduce waste. The synthesis of esters by means of ultrasound is also economical and efficient method for carrying out the esterification with wide pract...

Biointerface Research in Applied Chemistry, 2021

The present study shows the results obtained in the ultrasonic synthesis of sucrose esters with l... more The present study shows the results obtained in the ultrasonic synthesis of sucrose esters with lauric acid, the identification of products, and the study of their possible use as bio-additives with a plasticizing effect in the processing of plastics. Fourier transform infrared spectroscopy (FTIR) and NMR (1H and 13C NMR) were used to identify the synthesized esters. The plasticizing effect of sucrose laurate was assessed by determining the glass transition temperature of thin polyvinyl chloride films by differential scanning calorimetry (DSC). The results show a decrease in the glass transition temperature with an increase in the ester concentration in the polymer, which confirms the plasticizing effect of the obtained esters.

This study aims to demonstrate a simple and rapid “green” method for the ultrasound-assisted synt... more This study aims to demonstrate a simple and rapid “green” method for the ultrasound-assisted synthesis of t-aliphatic esters by reacting t -butanol with saturated (capric, lauric, palmitic) and unsaturated (oleic and undecylenic) acids. The spectral characterization of esters was performed by IR and NMR spectroscopies. The impact of ultrasonic irradiation on the reaction in comparison with the conventional method was analyzed based on the reaction time and the yield of the resulting esters. After spectroscopic studies, the synthesis of the corresponding esters after the ultrasound-assisted irradiation was proven. The yields of the t-butyl fatty acid esters increased between 2 and 10% in comparison with the conventional method for their synthesis. It was also established that the application of ultrasonic irradiation intensifies the esterification process significantly compared to the conventional method. The advantages of the ultrasound-assisted esterification include shortening the...

Biointerface Research in Applied Chemistry, 2021

An environmentally friendly and sustainable ultrasound-assisted esterification of long-chained in... more An environmentally friendly and sustainable ultrasound-assisted esterification of long-chained inulin and sucrose with monounsaturated 10-undecylenic acid was performed. The obtained esters were characterized by thin-layer chromatography (TLC), Fourier transforms infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) spectroscopy. The spectral analyses demonstrated the successful incorporation of the hydrophobic 10-undecylenoyl residue in the water-soluble carbohydrate backbone. Additionally, the antimicrobial potential of 10-undecylenic esters of inulin and sucrose were tested against nine microorganisms (Gram-positive and Gram-negative bacteria, yeasts, and fungi). Both esters inulin 10-undecylenate and sucrose 10-undecylenate (1 mg/ml) inhibited Bacillus subtilis ATCC 6633, Listeria monocytogenes ATCC 8632, Staphylococus aureus 745, Escherichia coli 3398, yeast Candida albicans 8673, and fungi Penicillium sp. Only inulin 10-undecylenate demonstrated antimicrobial acti...

The PhD thesis has investigated the application of ultrasonic irradiation in the esterification o... more The PhD thesis has investigated the application of ultrasonic irradiation in the esterification of alcohols - i-propanol, n-, i- and t-butanol with capric, lauric, palmitic, and 10-undecylenic acid. The resulting esters were identified by thin-layer and gas chromatography and characterized by NMR and IR spectroscopy. The applicability of sucroesters as plasticizers in plastics processing were examined by using sucrose plamitate as a plasticizer of polyvinyl chloride (PVC). PVC films with different contents of sucrose palmitate were used and the plasticizing effect was evaluated by determining the glass transition temperature (by differential scanning calorimetry), by the strength characteristics of the PVC film at a tensile load (tensile strength, modulus of elasticity, relative elongation at breaking) and by studying the structure by means of scanning electron microscopy.
The intensifying effect of the ultrasonic impact on the esterification process been investigated was proved. As a result the reaction time was reduced, the reaction temperature was lowered, and the composition of the resulting esters was identical to that obtained by the conventional method.
Digitally, by using chromatographic and spectral methods, it was established that under the selected conditions of synthesis cleavage of carbon-carbon bonds, isomerization of the cis-isomer of oleic acid and auto-oxidation of the reaction product were not observed.
A plasticizing effect of sucrose plamitate was identified for polyvinyl chloride. Consequently, the glass transition temperature, the modulus of elasticity and the stress at break were reduced whereas work to break and the relative elongation at break were increased.