D. Perju - Academia.edu (original) (raw)
Papers by D. Perju
The most likely process that can lead to the release of radionuclides from radioactive waste repo... more The most likely process that can lead to the release of radionuclides from radioactive waste repository in a geological media is transport by groundwaters. Research in this field has lead to experimental determination of distribution coefficients. Influence of distribution coefficients was studied in detail for uranium and radium adsorbtion on clay. Therefore, with batch tests the influence of sorption and
Chemical and microbiological stability of cosmetic creams is an important parameter for determina... more Chemical and microbiological stability of cosmetic creams is an important parameter for determination of their shelf -life. This stability can be influence by: temperature, homogeneity, amount of emulsifier used, chemical agents, phase inversion and storage conditions.
The most likely process that can lead to the release of radionuclides from radioactive waste repo... more The most likely process that can lead to the release of radionuclides from radioactive waste repository in a geological media is transport by groundwaters. Research in this field has lead to experimental determination of distribution coefficients. Influence of distribution coefficients was studied in detail for uranium and radium adsorbtion on clay. Therefore, with batch tests the influence of sorption and desorption coefficients in rock/groundwater systems of the Ciudanovita site was investigated. Results for corresponding studies with radium and uranium in clay-groundwater system are given which point to the possibility transfering laboratory batch data to field conditions by mathematical model. The present work is based mainly on this research direction: optimization and improvement of the performances obtained from the geo-chemical processes investigation methods in the waste dumps and the surrounding geological structures to isolate them, in order to reduce the negative environ...
This paper describes the geochemical processes regulating the migration of heavy metals and radio... more This paper describes the geochemical processes regulating the migration of heavy metals and radionuclides in uranium mining tailings site Ciudanovita, Caras Severin and to examine the depth-scales of concern resulting from the interaction of different mechanisms. Contaminants of concern for the management of uranium mill tailings include radium 226, uranium 238 and heavy metals (e.g. Ca, Fe, Al, Ni, K, and Na). Residual tailing pyrite oxidation was found to be the critical factor in the transfer of metals and radionuclides to seepage water.
Because the nitrogen dioxide has noxious effects to human health and also to the environment, the... more Because the nitrogen dioxide has noxious effects to human health and also to the environment, the European and the national laws in environmental field impose strict norms to the large polluters. According to these laws, they are obligated to optimize the plants performances in order to reduce the pollution. The case study presented in this paper describes the simulation of the nitrogen dioxide dispersion phenomenon in Timisoara city atmosphere, with the help of analytical-experimental methods. The objective is to establish the influence of micro-plants an also of the two thermal power stations, that make the thermal energy supply of the population, to nitrogen dioxide pollution level, in down town, into a reference point.
The shelf live of soft drink is limited by microbial alteration and chemical reactions. The aim o... more The shelf live of soft drink is limited by microbial alteration and chemical reactions. The aim of this paper is to test the action of commonly used preservatives on the soft drinks quality in different storage conditions. In the mean time, the appropriate concentration of citric acid used for product acidification was established. The samples microbiological analyses together with their physico-chemical parameters allow us to estimate the efficiency of sodium benzoate and potassium sorbate preservatives uses.
This paper deals with a comparative study regarding quality of drinking water from diferent regio... more This paper deals with a comparative study regarding quality of drinking water from diferent regions of Romania. Four types of drinking water were examined in four different regions of the country: West, Centre, North and East. Anions and cations determination was done with high-performance ion chromatography (HPIC). The device used was a Dionex – ICS 3000 type, particularized for anions and cations. The higher concentrations for anions and cations were determinate in the North part of the country.
Environmental technology, 2007
Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: f... more Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: fuels (gasoline or gas oil), fuel oil and lubricants. Pollution by petroleum products is a source of volatile organic compounds in soil. Therefore, laboratory column venting experiments were completed in order to investigate the removal of a pure compound (toluene) and a mixture of two (toluene and n-heptane) and five (toluene, n-heptane, ethylbenzene, m-xylene and p-xylene) compounds. The choice of the compounds, as well as their proportion in the mixture was made on the basis of the real fuel composition. The objective of this study is a comparison between the experimental volatile organic compounds removal results and the predicted values of a simple classical analytical mathematical model that enables the modelling of the venting process. The proposed model for the contaminants transport describes the removal of organic compounds from soil, the contaminants being distributed among fou...
Nitrogen oxides, especially nitrogen dioxide, are pollutant substances that can affect the human ... more Nitrogen oxides, especially nitrogen dioxide, are pollutant substances that can affect the human heal th and the environment. Nitrogen dioxide emissions are important sources in the production of green house effect and photochemical smog. In the current global context when the accent on environmental pollution problems are more and more pressing, the reduction possibilities study of nitrogen dioxide e missions as well as the modelling ways of the pheno menon that accompany the dispersion of this pollutant in its c ycle in nature is current and of a particular impor tance. In this paper the mathematical models that describe the dispersion of nitrogen dioxide emitted from the two thermal powe r stations (Center CET and South CET) of Timisoara city as a function of four meteorological parameters (temperature, humidity, pressure, wind speed) are presented. In order to develop and verify these models, the NO 2 daily average concentrations emitted from the thermal power stations as well a...
The complex problem of small gas flow measuring in chemical industry pilot plants represents a co... more The complex problem of small gas flow measuring in chemical industry pilot plants represents a constant field of research. So, the electrothermal gas micro-flowmeter realized in the Chemical Processes Automation Laboratory of the Industrial Chemistry and Environmental Engineering Faculty of Timisoara, fits the laboratory apparatus requirements. The studied flowmeter can be used with high accuracy as measuring transducer for automatic adjustments of small gas flows. The mathematical correlation of the main constructive and functional parameters of the apparatus allowed obtaining of mathematical models for the assessment of certain predictions of the flowmeter behaviour. The simulation of the static behaviour of the electrothermal gas micro-flowmeter has proven to be a functional simulation and the operation equation can be considered a valid model due to the fact that its manipulation is a real and correct representation of the real system operation.
revistadechimie.ro
The European laws and recently the Romanian ones impose more and more strict norms to the large n... more The European laws and recently the Romanian ones impose more and more strict norms to the large nitrogen dioxide polluters. They are obligated to continuously improve the installations and products so that they limit and reduce the nitrogen dioxide pollution, ...
Environmental Technology, 2007
Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: f... more Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: fuels (gasoline or gas oil), fuel oil and lubricants. Pollution by petroleum products is a source of volatile organic compounds in soil. Therefore, laboratory column venting experiments were completed in order to investigate the removal of a pure compound (toluene) and a mixture of two (toluene and n-heptane) and five (toluene, n-heptane, ethylbenzene, m-xylene and p-xylene) compounds. The choice of the compounds, as well as their proportion in the mixture was made on the basis of the real fuel composition. The objective of this study is a comparison between the experimental volatile organic compounds removal results and the predicted values of a simple classical analytical mathematical model that enables the modelling of the venting process. The proposed model for the contaminants transport describes the removal of organic compounds from soil, the contaminants being distributed among four phases: vapour, nonaqueous liquid phase, aqueous and "solid" phase; local phases equilibrium and ideal behaviour of all four phases were found to be accurate enough to describe the interphase mass transfer. The testing of the mathematical model accuracy has been done by using the following performance criteria: dynamic absolute error, average error, model accuracy and correlation coefficient. The reasonable agreement between the predicted and the experimental results as well as the values of the performance criteria prove that the mathematical model is suitable to describe the removal of volatile organic compounds pollutants by venting in the range of experimental conditions used in the pilot plant.
The most likely process that can lead to the release of radionuclides from radioactive waste repo... more The most likely process that can lead to the release of radionuclides from radioactive waste repository in a geological media is transport by groundwaters. Research in this field has lead to experimental determination of distribution coefficients. Influence of distribution coefficients was studied in detail for uranium and radium adsorbtion on clay. Therefore, with batch tests the influence of sorption and
Chemical and microbiological stability of cosmetic creams is an important parameter for determina... more Chemical and microbiological stability of cosmetic creams is an important parameter for determination of their shelf -life. This stability can be influence by: temperature, homogeneity, amount of emulsifier used, chemical agents, phase inversion and storage conditions.
The most likely process that can lead to the release of radionuclides from radioactive waste repo... more The most likely process that can lead to the release of radionuclides from radioactive waste repository in a geological media is transport by groundwaters. Research in this field has lead to experimental determination of distribution coefficients. Influence of distribution coefficients was studied in detail for uranium and radium adsorbtion on clay. Therefore, with batch tests the influence of sorption and desorption coefficients in rock/groundwater systems of the Ciudanovita site was investigated. Results for corresponding studies with radium and uranium in clay-groundwater system are given which point to the possibility transfering laboratory batch data to field conditions by mathematical model. The present work is based mainly on this research direction: optimization and improvement of the performances obtained from the geo-chemical processes investigation methods in the waste dumps and the surrounding geological structures to isolate them, in order to reduce the negative environ...
This paper describes the geochemical processes regulating the migration of heavy metals and radio... more This paper describes the geochemical processes regulating the migration of heavy metals and radionuclides in uranium mining tailings site Ciudanovita, Caras Severin and to examine the depth-scales of concern resulting from the interaction of different mechanisms. Contaminants of concern for the management of uranium mill tailings include radium 226, uranium 238 and heavy metals (e.g. Ca, Fe, Al, Ni, K, and Na). Residual tailing pyrite oxidation was found to be the critical factor in the transfer of metals and radionuclides to seepage water.
Because the nitrogen dioxide has noxious effects to human health and also to the environment, the... more Because the nitrogen dioxide has noxious effects to human health and also to the environment, the European and the national laws in environmental field impose strict norms to the large polluters. According to these laws, they are obligated to optimize the plants performances in order to reduce the pollution. The case study presented in this paper describes the simulation of the nitrogen dioxide dispersion phenomenon in Timisoara city atmosphere, with the help of analytical-experimental methods. The objective is to establish the influence of micro-plants an also of the two thermal power stations, that make the thermal energy supply of the population, to nitrogen dioxide pollution level, in down town, into a reference point.
The shelf live of soft drink is limited by microbial alteration and chemical reactions. The aim o... more The shelf live of soft drink is limited by microbial alteration and chemical reactions. The aim of this paper is to test the action of commonly used preservatives on the soft drinks quality in different storage conditions. In the mean time, the appropriate concentration of citric acid used for product acidification was established. The samples microbiological analyses together with their physico-chemical parameters allow us to estimate the efficiency of sodium benzoate and potassium sorbate preservatives uses.
This paper deals with a comparative study regarding quality of drinking water from diferent regio... more This paper deals with a comparative study regarding quality of drinking water from diferent regions of Romania. Four types of drinking water were examined in four different regions of the country: West, Centre, North and East. Anions and cations determination was done with high-performance ion chromatography (HPIC). The device used was a Dionex – ICS 3000 type, particularized for anions and cations. The higher concentrations for anions and cations were determinate in the North part of the country.
Environmental technology, 2007
Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: f... more Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: fuels (gasoline or gas oil), fuel oil and lubricants. Pollution by petroleum products is a source of volatile organic compounds in soil. Therefore, laboratory column venting experiments were completed in order to investigate the removal of a pure compound (toluene) and a mixture of two (toluene and n-heptane) and five (toluene, n-heptane, ethylbenzene, m-xylene and p-xylene) compounds. The choice of the compounds, as well as their proportion in the mixture was made on the basis of the real fuel composition. The objective of this study is a comparison between the experimental volatile organic compounds removal results and the predicted values of a simple classical analytical mathematical model that enables the modelling of the venting process. The proposed model for the contaminants transport describes the removal of organic compounds from soil, the contaminants being distributed among fou...
Nitrogen oxides, especially nitrogen dioxide, are pollutant substances that can affect the human ... more Nitrogen oxides, especially nitrogen dioxide, are pollutant substances that can affect the human heal th and the environment. Nitrogen dioxide emissions are important sources in the production of green house effect and photochemical smog. In the current global context when the accent on environmental pollution problems are more and more pressing, the reduction possibilities study of nitrogen dioxide e missions as well as the modelling ways of the pheno menon that accompany the dispersion of this pollutant in its c ycle in nature is current and of a particular impor tance. In this paper the mathematical models that describe the dispersion of nitrogen dioxide emitted from the two thermal powe r stations (Center CET and South CET) of Timisoara city as a function of four meteorological parameters (temperature, humidity, pressure, wind speed) are presented. In order to develop and verify these models, the NO 2 daily average concentrations emitted from the thermal power stations as well a...
The complex problem of small gas flow measuring in chemical industry pilot plants represents a co... more The complex problem of small gas flow measuring in chemical industry pilot plants represents a constant field of research. So, the electrothermal gas micro-flowmeter realized in the Chemical Processes Automation Laboratory of the Industrial Chemistry and Environmental Engineering Faculty of Timisoara, fits the laboratory apparatus requirements. The studied flowmeter can be used with high accuracy as measuring transducer for automatic adjustments of small gas flows. The mathematical correlation of the main constructive and functional parameters of the apparatus allowed obtaining of mathematical models for the assessment of certain predictions of the flowmeter behaviour. The simulation of the static behaviour of the electrothermal gas micro-flowmeter has proven to be a functional simulation and the operation equation can be considered a valid model due to the fact that its manipulation is a real and correct representation of the real system operation.
revistadechimie.ro
The European laws and recently the Romanian ones impose more and more strict norms to the large n... more The European laws and recently the Romanian ones impose more and more strict norms to the large nitrogen dioxide polluters. They are obligated to continuously improve the installations and products so that they limit and reduce the nitrogen dioxide pollution, ...
Environmental Technology, 2007
Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: f... more Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: fuels (gasoline or gas oil), fuel oil and lubricants. Pollution by petroleum products is a source of volatile organic compounds in soil. Therefore, laboratory column venting experiments were completed in order to investigate the removal of a pure compound (toluene) and a mixture of two (toluene and n-heptane) and five (toluene, n-heptane, ethylbenzene, m-xylene and p-xylene) compounds. The choice of the compounds, as well as their proportion in the mixture was made on the basis of the real fuel composition. The objective of this study is a comparison between the experimental volatile organic compounds removal results and the predicted values of a simple classical analytical mathematical model that enables the modelling of the venting process. The proposed model for the contaminants transport describes the removal of organic compounds from soil, the contaminants being distributed among four phases: vapour, nonaqueous liquid phase, aqueous and "solid" phase; local phases equilibrium and ideal behaviour of all four phases were found to be accurate enough to describe the interphase mass transfer. The testing of the mathematical model accuracy has been done by using the following performance criteria: dynamic absolute error, average error, model accuracy and correlation coefficient. The reasonable agreement between the predicted and the experimental results as well as the values of the performance criteria prove that the mathematical model is suitable to describe the removal of volatile organic compounds pollutants by venting in the range of experimental conditions used in the pilot plant.