Maria Harja | "Gheorghe Asachi" Tehnical University of Iasi (original) (raw)

Papers by Maria Harja

International Journal of Energy Research, Sep 11, 2022

Sustainable Energy Technologies and Assessments, Mar 1, 2023

Zenodo (CERN European Organization for Nuclear Research), Jun 30, 2022

Zenodo (CERN European Organization for Nuclear Research), Mar 31, 2023

Journal of Engineering Sciences and Innovation

Magnetochemistry

The effectiveness of a Fe3O4-loaded fly ash composite for the adsorption of Congo red dye was ass... more The effectiveness of a Fe3O4-loaded fly ash composite for the adsorption of Congo red dye was assessed in this work. The structure and properties of the magnetic adsorbent were established by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and dynamic light scattering (DLS). The magnetic results showed a saturation magnetization value of 6.51 emu/g and superparamagnetic behavior. The main parameters that influence the removal of Congo red dye adsorbent such as dose, initial concentration, and contact time were examined. The Freundlich adsorption isotherm and pseudo-second-order kinetic model provided the best fit for the experimental findings. The Congo red dye’s maximum adsorption capacity of 154 mg/g was reported in the concentration range of 10–100 mg/L, using the proposed magnetic adsorbent. The results of the recyclability investigation demonstrated that the circular economy idea is valid...

SGEM International Multidisciplinary Scientific GeoConference� EXPO Proceedings

In this work, a brief assessment of using microalgae (Arthrospira platensis PCC 8005) for lowerin... more In this work, a brief assessment of using microalgae (Arthrospira platensis PCC 8005) for lowering carbon emissions during biotrickling filtration of volatile organic compounds (VOCs) from air is performed. In this regard, the removal efficiency of acetic acid vapors (used as model VOC in this study) and carbon dioxide production from this process are evaluated in the presence of: (1) classical microorganisms (e.g. from compost), (2) mixture of compost microorganisms and microalgae, (3) microalgae. A blank trial (microorganisms-free) was considered as reference. The obtained results indicate the contribution of both microorganism�s type (alone or in mixture) to the VOC removal. Remarkably, their mixture exhibited the lowest carbon emission and thus the highest environmental performance due not only VOC biodegradation, but also simultaneously carbon dioxide uptake by microalgae.

Materials

CeO2/ZnO-based photocatalytic materials were synthesized by the sol-gel method in order to establ... more CeO2/ZnO-based photocatalytic materials were synthesized by the sol-gel method in order to establish heterojunctions that increase the degradation efficiency of some types of antibiotics by preventing the recombination of electron–hole pairs. The synthesized materials were analysed by XRD, SEM, EDAX, FTIR, and UV-Vis. After several tests, the optimal concentration of the catalyst was determined to be 0.05 g‧L−1 and 0.025 g‧L−1 for chlortetracycline and 0.05 g‧L−1 for ceftriaxone. CeO2/ZnO assemblies showed much better degradation efficiency compared to ZnO or CeO2 tested individually. Sample S3 shows good photocatalytic properties for the elimination of ceftriaxone and tetracycline both from single solutions and from the binary solution. This work provides a different perspective to identify other powerful and inexpensive photocatalysts for wastewater treatment.

Oil industry development likes as extraction and as well as production is sometimes accompanied b... more Oil industry development likes as extraction and as well as production is sometimes accompanied by pollution phenomena apparition with prejudices effects on our environment and the peoples health. In oil extraction areas appear soil, ground waters and surface waters pollution phenomena with oil residuum with or without salty water.There are other residual oil products resulted from exploting activities, plus the losses from pipes transporting oil or oil products. This paper is part of a series of papers dedicated to researching environment pollution in oil extraction areas in Bacau district, Romania. The paper present researches concerning ground waters pollution in oil extraction areas in Bacau district on five villages area. The researches made allowed established the device of pollutant migration from soil into ground waters, the identification pollution sources, the establishing pollution causes. Based on the obtained results we have identified necessary measures for reducting o...

Journal of Building Engineering, 2021

Abstract Novel bricks have been produced by firing mixes of water treatment sludge (WTS) and fire... more Abstract Novel bricks have been produced by firing mixes of water treatment sludge (WTS) and fired clay brick waste (BW). The capitalization of sludge in the construction industry is the most economically sound option. In this study, a series of different proportioning ratios of water treatment sludge and fired clay brick waste were studied. The WTS rations were 25, 40, 55, 70, 85, and 100 % of the total weight of the mixture. Each series involved the firing of bricks at 1000 °C for 2 h. The obtained bricks were characterized by bulk density, apparent porosity, water absorption, loss on ignition, compressive strength, thermal conductivity, efflorescence, and freeze thaw, in addition to chemical, mineralogical, and microstructural investigations. From experimental results, it was observed that obtained bricks having over 75, respectively 60% BW, had lower compressive strength compared to bricks obtained only from WTS. The loss of ignition, porosity, and water absorption values slightly decrease, while compressive strength and thermal conductivity values increase, which depends on the amount of WTS waste content. The bricks containing 70 - 85% WTS give better results, while the bricks containing up to 40% WTS waste present a compressive strength that is greater than twice the minimum limit. The efflorescence of all bricks is in the slight level. Tests have shown that bricks with 70 - 85% WTS have proper characteristics and can be effectively used as building materials. The present study demonstrated that by replacing clay (traditional bricks) with proposed wastes, eco-friendly bricks can be obtained that save resources.

Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications, 2020

Marine waters are extreme environment with high ionic intensity conditions, where nanoparticles c... more Marine waters are extreme environment with high ionic intensity conditions, where nanoparticles can transform by adopting strikingly diverse behavior. The nanoparticles may be subject to rapid aggregation, instability as well as sedimentation that exterminate them from water column. Interactions between organic material and metal bearing nanoparticles might adversely change their distribution, physicochemical characteristics, and tenacity in water column. Accurate and sophisticated detection of engineered nanoparticles in marine environments is vital in evaluating the human and environmental threats as well as to create the regulatory standards of engineered nanoparticles discharge. However, understanding the fate of nanoparticles and their behavior in marine environments is still narrow due to limited efficiency of their characterization methods. Electroanalytical approaches (voltammetric, amperometric, chronoamperometric) paired with advanced techniques such as atomic force microscopy have been recognized as suitable choice for analyzing different biogeochemical courses in marine environments, exclusively those associated with sulfur species, organic materials, trace metal cycling, distribution and interaction between colloidal and dissolved phases.

Environmental Engineering and Management Journal, 2009

Geopolymerization is a continuous developing field of research for utilizing solid waste and by-p... more Geopolymerization is a continuous developing field of research for utilizing solid waste and by-products. It provides a solution to many problems where hazardous residue has to be treated and stored under critical environmental conditions. Consumption of fly ash in the manufacture of geopolymer is an important strategy in making materials more environmentally friendly. Fly ash has been chosen as a base material in order to utilize this industrial waste. Previous researches have shown that geopolimerization grade depends on different factors such as: temperature, stirring speed, ratio solid-liquid, the time of contact between phases, etc. This paper reports the results of the study of the influence of temperature and time curing, stirred and ratio s/l on phase composition and microstructure in geopolymer materials prepared using Class F fly ash and sodium hydroxide solutions. Scanning electronic microscopy (SEM) were utilized in this study for characterize the geopolymer formation. The main product of reaction in the geopolymer materials was amorphous alkali aluminosilicate gel. The type of presented material was dependent on the curing history.

Environmental Engineering and Management Journal, 2008

A comprehensive characterization of fly ash from Iasi, Romania has been carried out in order to s... more A comprehensive characterization of fly ash from Iasi, Romania has been carried out in order to set up the utilization potential of fly ash resulting in appreciable amounts from thermal power plants as a waste, which leads to soil and groundwater contamination, as well as atmospheric pollution. This fly ash can be classified on the base chemical and technological properties in F class. Having in mind the assignment of the processing conditions, the fly ash can be used as sorbent for polluting gas (with sulfur dioxide especially), for industrial wastewaters with a high content of Ni, Cu, Cd, Zn, Hg, As, Cr ions, to obtain new building materials, having a reduced specific weight and reduced costs.

tmt.unze.ba

Preventing environmental pollution trough safety measures and intervention in case of technologic... more Preventing environmental pollution trough safety measures and intervention in case of technological process accidents is world wide actuality problem. Ammonia obtained in fertilizer industry, before his use in various technologies, is stocked under pressure in special ammonia tanks, their constructive and operating mode is enough complex to be expose to different types of damages that could produce a major chemical accidents. This paper presents the researches for technology elaboration in obtaining of insulator foam for ammonia tanks in case of their damage and to establish the diffuser type and proper installation for foam dispersion. The use of this protective foam on ammonia tank increase exploitation safety and remove, in case of damage, the losses in human life.

Spring, 2021

This work focused on the use of cellulose acetate polymer for the preparation of porous asymmetri... more This work focused on the use of cellulose acetate polymer for the preparation of porous asymmetric membranes using a phase inversion process. These membranes were characterised by scanning electron microscopy, a bubble-point method and sorption measurements. The preparation method used induced membrane anisotropy. The capacity of the membranes in the removal of electrolyte (NaCl) from aqueous solution was investigated. A good retention of 58.6% and a high flux rate of 8.9 × 10–4 m/s using NaCl solution of 200 mg/L concentration were obtained by cellulose acetate membranes prepared with water as non-solvent. The results showed that the membrane performance was affected by the membrane structure, which was determined by the conditions of membrane preparation.

Water

TiO2 nanoparticles synthesized by the sol-gel method and doped with Ag were characterized by SEM,... more TiO2 nanoparticles synthesized by the sol-gel method and doped with Ag were characterized by SEM, EDAX, FTIR, BET, XRD and TEM, then tested in the photocatalytic degradation of methylene blue (MB) under UV irradiation. The experimental results indicate that the average size of the raw particles was 10 nm, and their size was increased by calcination. The photocatalytic degradation of MB on nanostructured TiO2-Ag shows a high degradation efficiency upon the addition of a photosensitizer. A parametric study of the process was performed and has revealed the optimal value of the photocatalyst dose (0.3 g L−1) at a MB concentration of 4 ppm. Afterwards, the effect of acetone as a photosensitizer was studied. A MB degradation mechanism was proposed to explain the synergy between the TiO2 and the silver nanoparticles in the degradation performance. Under the optimal experimental conditions, at photosensitizer doses of 0.1 and 0.2%, yields of 92.38% and 97.25% MB degradation were achieved, r...

Polymers

Two types of biosorbents, based on Saccharomyces pastorianus immobilized in calcium alginate, wer... more Two types of biosorbents, based on Saccharomyces pastorianus immobilized in calcium alginate, were studied for the removal of pharmaceuticals from aqueous solutions. Synthetized biocomposite materials were characterized chemically and morphologically, both before and after simulated biosorption. Ethacridine lactate (EL) was chosen as a target molecule. The process performance was interpreted as a function of initial solution pH, biosorbent dose, and initial pharmaceutical concentration. The results exhibited that the removal efficiencies were superior to 90% for both biosorbents, at the initial pH value of 4.0 and biosorbent dose of 2 g/L for all EL initial concentrations tested. Freundlich, Temkin, Hill, Redlich-Peterson, Sips, and Toth isotherms were used to describe the experimental results. The kinetic data were analyzed using kinetic models, such as pseudo-first order, pseudo-second order, Elovich, and Avrami, to determine the kinetic parameters and describe the transport mecha...

Materials

In this study, ethacridine lactate removal from aqueous solution using a biosorbent material base... more In this study, ethacridine lactate removal from aqueous solution using a biosorbent material based on residual microbial biomass and natural polymers in fixed-bed continuous column was investigated. Composite beads of Saccharomyces pastorianus residual biomass and calcium alginate were obtained by immobilization technique. The prepared biosorbent was characterized by Fourier transformed infrared spectroscopy, scanning electron microscopy, and analysis of point of zero charge value. Then, laboratory-scale experiments by fixed-bed column biosorption were conducted in continuous system. To this purpose, the column bed high (5 cm; 7.5 cm), initial pollutant concentration (20 mg/L; 40 mg/L), and solution flow through the column (0.6 mL/min; 1.5 mL/min) were considered the main parameters. Recorded breakthrough curves suggest that lower flow rates, greater bed heights, and a lower concentration of ethacridine lactate led to an increased biosorption of the target compound. The biosorption ...

International Journal of Energy Research, Sep 11, 2022

Sustainable Energy Technologies and Assessments, Mar 1, 2023

Zenodo (CERN European Organization for Nuclear Research), Jun 30, 2022

Zenodo (CERN European Organization for Nuclear Research), Mar 31, 2023

Journal of Engineering Sciences and Innovation

Magnetochemistry

The effectiveness of a Fe3O4-loaded fly ash composite for the adsorption of Congo red dye was ass... more The effectiveness of a Fe3O4-loaded fly ash composite for the adsorption of Congo red dye was assessed in this work. The structure and properties of the magnetic adsorbent were established by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and dynamic light scattering (DLS). The magnetic results showed a saturation magnetization value of 6.51 emu/g and superparamagnetic behavior. The main parameters that influence the removal of Congo red dye adsorbent such as dose, initial concentration, and contact time were examined. The Freundlich adsorption isotherm and pseudo-second-order kinetic model provided the best fit for the experimental findings. The Congo red dye’s maximum adsorption capacity of 154 mg/g was reported in the concentration range of 10–100 mg/L, using the proposed magnetic adsorbent. The results of the recyclability investigation demonstrated that the circular economy idea is valid...

SGEM International Multidisciplinary Scientific GeoConference� EXPO Proceedings

In this work, a brief assessment of using microalgae (Arthrospira platensis PCC 8005) for lowerin... more In this work, a brief assessment of using microalgae (Arthrospira platensis PCC 8005) for lowering carbon emissions during biotrickling filtration of volatile organic compounds (VOCs) from air is performed. In this regard, the removal efficiency of acetic acid vapors (used as model VOC in this study) and carbon dioxide production from this process are evaluated in the presence of: (1) classical microorganisms (e.g. from compost), (2) mixture of compost microorganisms and microalgae, (3) microalgae. A blank trial (microorganisms-free) was considered as reference. The obtained results indicate the contribution of both microorganism�s type (alone or in mixture) to the VOC removal. Remarkably, their mixture exhibited the lowest carbon emission and thus the highest environmental performance due not only VOC biodegradation, but also simultaneously carbon dioxide uptake by microalgae.

Materials

CeO2/ZnO-based photocatalytic materials were synthesized by the sol-gel method in order to establ... more CeO2/ZnO-based photocatalytic materials were synthesized by the sol-gel method in order to establish heterojunctions that increase the degradation efficiency of some types of antibiotics by preventing the recombination of electron–hole pairs. The synthesized materials were analysed by XRD, SEM, EDAX, FTIR, and UV-Vis. After several tests, the optimal concentration of the catalyst was determined to be 0.05 g‧L−1 and 0.025 g‧L−1 for chlortetracycline and 0.05 g‧L−1 for ceftriaxone. CeO2/ZnO assemblies showed much better degradation efficiency compared to ZnO or CeO2 tested individually. Sample S3 shows good photocatalytic properties for the elimination of ceftriaxone and tetracycline both from single solutions and from the binary solution. This work provides a different perspective to identify other powerful and inexpensive photocatalysts for wastewater treatment.

Oil industry development likes as extraction and as well as production is sometimes accompanied b... more Oil industry development likes as extraction and as well as production is sometimes accompanied by pollution phenomena apparition with prejudices effects on our environment and the peoples health. In oil extraction areas appear soil, ground waters and surface waters pollution phenomena with oil residuum with or without salty water.There are other residual oil products resulted from exploting activities, plus the losses from pipes transporting oil or oil products. This paper is part of a series of papers dedicated to researching environment pollution in oil extraction areas in Bacau district, Romania. The paper present researches concerning ground waters pollution in oil extraction areas in Bacau district on five villages area. The researches made allowed established the device of pollutant migration from soil into ground waters, the identification pollution sources, the establishing pollution causes. Based on the obtained results we have identified necessary measures for reducting o...

Journal of Building Engineering, 2021

Abstract Novel bricks have been produced by firing mixes of water treatment sludge (WTS) and fire... more Abstract Novel bricks have been produced by firing mixes of water treatment sludge (WTS) and fired clay brick waste (BW). The capitalization of sludge in the construction industry is the most economically sound option. In this study, a series of different proportioning ratios of water treatment sludge and fired clay brick waste were studied. The WTS rations were 25, 40, 55, 70, 85, and 100 % of the total weight of the mixture. Each series involved the firing of bricks at 1000 °C for 2 h. The obtained bricks were characterized by bulk density, apparent porosity, water absorption, loss on ignition, compressive strength, thermal conductivity, efflorescence, and freeze thaw, in addition to chemical, mineralogical, and microstructural investigations. From experimental results, it was observed that obtained bricks having over 75, respectively 60% BW, had lower compressive strength compared to bricks obtained only from WTS. The loss of ignition, porosity, and water absorption values slightly decrease, while compressive strength and thermal conductivity values increase, which depends on the amount of WTS waste content. The bricks containing 70 - 85% WTS give better results, while the bricks containing up to 40% WTS waste present a compressive strength that is greater than twice the minimum limit. The efflorescence of all bricks is in the slight level. Tests have shown that bricks with 70 - 85% WTS have proper characteristics and can be effectively used as building materials. The present study demonstrated that by replacing clay (traditional bricks) with proposed wastes, eco-friendly bricks can be obtained that save resources.

Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications, 2020

Marine waters are extreme environment with high ionic intensity conditions, where nanoparticles c... more Marine waters are extreme environment with high ionic intensity conditions, where nanoparticles can transform by adopting strikingly diverse behavior. The nanoparticles may be subject to rapid aggregation, instability as well as sedimentation that exterminate them from water column. Interactions between organic material and metal bearing nanoparticles might adversely change their distribution, physicochemical characteristics, and tenacity in water column. Accurate and sophisticated detection of engineered nanoparticles in marine environments is vital in evaluating the human and environmental threats as well as to create the regulatory standards of engineered nanoparticles discharge. However, understanding the fate of nanoparticles and their behavior in marine environments is still narrow due to limited efficiency of their characterization methods. Electroanalytical approaches (voltammetric, amperometric, chronoamperometric) paired with advanced techniques such as atomic force microscopy have been recognized as suitable choice for analyzing different biogeochemical courses in marine environments, exclusively those associated with sulfur species, organic materials, trace metal cycling, distribution and interaction between colloidal and dissolved phases.

Environmental Engineering and Management Journal, 2009

Geopolymerization is a continuous developing field of research for utilizing solid waste and by-p... more Geopolymerization is a continuous developing field of research for utilizing solid waste and by-products. It provides a solution to many problems where hazardous residue has to be treated and stored under critical environmental conditions. Consumption of fly ash in the manufacture of geopolymer is an important strategy in making materials more environmentally friendly. Fly ash has been chosen as a base material in order to utilize this industrial waste. Previous researches have shown that geopolimerization grade depends on different factors such as: temperature, stirring speed, ratio solid-liquid, the time of contact between phases, etc. This paper reports the results of the study of the influence of temperature and time curing, stirred and ratio s/l on phase composition and microstructure in geopolymer materials prepared using Class F fly ash and sodium hydroxide solutions. Scanning electronic microscopy (SEM) were utilized in this study for characterize the geopolymer formation. The main product of reaction in the geopolymer materials was amorphous alkali aluminosilicate gel. The type of presented material was dependent on the curing history.

Environmental Engineering and Management Journal, 2008

A comprehensive characterization of fly ash from Iasi, Romania has been carried out in order to s... more A comprehensive characterization of fly ash from Iasi, Romania has been carried out in order to set up the utilization potential of fly ash resulting in appreciable amounts from thermal power plants as a waste, which leads to soil and groundwater contamination, as well as atmospheric pollution. This fly ash can be classified on the base chemical and technological properties in F class. Having in mind the assignment of the processing conditions, the fly ash can be used as sorbent for polluting gas (with sulfur dioxide especially), for industrial wastewaters with a high content of Ni, Cu, Cd, Zn, Hg, As, Cr ions, to obtain new building materials, having a reduced specific weight and reduced costs.

tmt.unze.ba

Preventing environmental pollution trough safety measures and intervention in case of technologic... more Preventing environmental pollution trough safety measures and intervention in case of technological process accidents is world wide actuality problem. Ammonia obtained in fertilizer industry, before his use in various technologies, is stocked under pressure in special ammonia tanks, their constructive and operating mode is enough complex to be expose to different types of damages that could produce a major chemical accidents. This paper presents the researches for technology elaboration in obtaining of insulator foam for ammonia tanks in case of their damage and to establish the diffuser type and proper installation for foam dispersion. The use of this protective foam on ammonia tank increase exploitation safety and remove, in case of damage, the losses in human life.

Spring, 2021

This work focused on the use of cellulose acetate polymer for the preparation of porous asymmetri... more This work focused on the use of cellulose acetate polymer for the preparation of porous asymmetric membranes using a phase inversion process. These membranes were characterised by scanning electron microscopy, a bubble-point method and sorption measurements. The preparation method used induced membrane anisotropy. The capacity of the membranes in the removal of electrolyte (NaCl) from aqueous solution was investigated. A good retention of 58.6% and a high flux rate of 8.9 × 10–4 m/s using NaCl solution of 200 mg/L concentration were obtained by cellulose acetate membranes prepared with water as non-solvent. The results showed that the membrane performance was affected by the membrane structure, which was determined by the conditions of membrane preparation.

Water

TiO2 nanoparticles synthesized by the sol-gel method and doped with Ag were characterized by SEM,... more TiO2 nanoparticles synthesized by the sol-gel method and doped with Ag were characterized by SEM, EDAX, FTIR, BET, XRD and TEM, then tested in the photocatalytic degradation of methylene blue (MB) under UV irradiation. The experimental results indicate that the average size of the raw particles was 10 nm, and their size was increased by calcination. The photocatalytic degradation of MB on nanostructured TiO2-Ag shows a high degradation efficiency upon the addition of a photosensitizer. A parametric study of the process was performed and has revealed the optimal value of the photocatalyst dose (0.3 g L−1) at a MB concentration of 4 ppm. Afterwards, the effect of acetone as a photosensitizer was studied. A MB degradation mechanism was proposed to explain the synergy between the TiO2 and the silver nanoparticles in the degradation performance. Under the optimal experimental conditions, at photosensitizer doses of 0.1 and 0.2%, yields of 92.38% and 97.25% MB degradation were achieved, r...

Polymers

Two types of biosorbents, based on Saccharomyces pastorianus immobilized in calcium alginate, wer... more Two types of biosorbents, based on Saccharomyces pastorianus immobilized in calcium alginate, were studied for the removal of pharmaceuticals from aqueous solutions. Synthetized biocomposite materials were characterized chemically and morphologically, both before and after simulated biosorption. Ethacridine lactate (EL) was chosen as a target molecule. The process performance was interpreted as a function of initial solution pH, biosorbent dose, and initial pharmaceutical concentration. The results exhibited that the removal efficiencies were superior to 90% for both biosorbents, at the initial pH value of 4.0 and biosorbent dose of 2 g/L for all EL initial concentrations tested. Freundlich, Temkin, Hill, Redlich-Peterson, Sips, and Toth isotherms were used to describe the experimental results. The kinetic data were analyzed using kinetic models, such as pseudo-first order, pseudo-second order, Elovich, and Avrami, to determine the kinetic parameters and describe the transport mecha...

Materials

In this study, ethacridine lactate removal from aqueous solution using a biosorbent material base... more In this study, ethacridine lactate removal from aqueous solution using a biosorbent material based on residual microbial biomass and natural polymers in fixed-bed continuous column was investigated. Composite beads of Saccharomyces pastorianus residual biomass and calcium alginate were obtained by immobilization technique. The prepared biosorbent was characterized by Fourier transformed infrared spectroscopy, scanning electron microscopy, and analysis of point of zero charge value. Then, laboratory-scale experiments by fixed-bed column biosorption were conducted in continuous system. To this purpose, the column bed high (5 cm; 7.5 cm), initial pollutant concentration (20 mg/L; 40 mg/L), and solution flow through the column (0.6 mL/min; 1.5 mL/min) were considered the main parameters. Recorded breakthrough curves suggest that lower flow rates, greater bed heights, and a lower concentration of ethacridine lactate led to an increased biosorption of the target compound. The biosorption ...