Ioan Stefanescu

• Independent Researcher

The article contains examples about hydrogen research and development progress in different countries: Czech Republic, Poland, Romania, Russia and Ukraine. Each chapter describes a specific situation for a country and one of them describes some aspects from Germany for comparison with one of international leaders. The examples described into articl...

We report in this paper the development of Boron-doped Graphene via chemical vapor deposition (CVD) that can serve as an efficient metal-free electrocatalyst for hydrogen evolution reaction (HER) in both alkaline and acidic media. Graphene growth is carried out by the flow of methane and hydrogen gasses, and with a borazine precursor over Ni foil a...

In this work, iodine-doped graphene (I-Gr) was successfully prepared using the electrophilic substitution method and was characterized using micro-Raman spectroscopy, X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. I-Gr was integrated into a cathode electrode, as micr...

Aiming a commercial development of proton exchange membrane fuel cells (PEMFC), a low cost, sustainable and high performance electrocatalyst for oxygen reduction reaction (ORR) with capability to replace/reduce rare metals, are high desirable. In this paper, we present a class of doped graphene, namely iodinated graphene with highly ORR electrochem...

The platinum on charcoal and polytetrafluorethylene (Pt/C/PTFE) is one of the most active and stable catalyst used for tritium removal from nuclear liquid effluents by isotopic exchange between hydrogen and water. This type of catalyst can be used alone or mixed with hydrophilic packing in so-called “mixed catalytic packing”. The mixed catalytic pa...

ICSI Rm. Valcea is the leading research institute involved in the Romanian heavy water detrititiation program. ICSI has built a Tritium Removal Facility which is an experimental pilot plant for deuterium and tritium separation - its main objectives being to demonstrate detritiation technology followed by implementation at the CANDU nuclear power pl...

Water – hydrogen catalytic isotopic exchange is the front-end detritiation technology that is used in the pilot plant at ICSI Rm. Valcea. It is also chosen as the main technology for the Tritium Removal Facility will be built at the Cernavoda NPP, Romania. The performance of the isotopic exchange process is mainly determined by the composition of t...

We prepared iodine-doped graphenes by several techniques (electrophilic substitution and nucleophilic substitution methods) in order to incorporate iodine atoms onto the graphene base materials. The physical characterization of prepared samples was performed by using an array of different techniques, such as scanning electron microscopy (SEM), tran...

The paper presents the variation of tritium activity concentration in the environment of Experimental Pilot Plant for Tritium and Deuterium Separation (PESTD) over 6 years of observations. The tritium level was established in surface water, air, precipitation, home-grown vegetable, meat and milk. The yearly average tritium concentrations in air wer...

On the theoretical predictions, we report the synthesis of iodine intercalated graphene for proton exchange membrane fuel cells (PEMFCs) applications. The structure and morphology of the samples were characterized by X-ray photoelectron spectroscopy (XPS) analysis, specific surface area by BET method, Raman investigations. The presence of elemental...

A study was carried out to determine the accumulation of trace metals in water, sediments, and soil from several locations in the Transylvania region (Romania), using the inductively coupled plasma mass spectrometry (ICP‐MS) technique. A significant number of metals (range of several μg L⁻¹) were identified, the toxic metal concentrations in mostly...

Abstract. Doped graphene-based cathode catalysts are considered as promising competitors for ORR, but their power density has been low compared to Pt-based cathodes, mainly due to poor mass-transport properties. A new electrocatalyst for PEMFCs, an iodine doped grahene was prepared, characterized, and tested and the results are presented in this pa...

Hydrogen in an International Context: Vulnerabilities of Hydrogen Energy in Emerging Markets describes strategies and developments for hydrogen civilization efforts realised by various stakeholders such as authorities, institutes, research, industry, and individuals, in different countries and at different stages of the development cycle. Through t...

Numerical simulations based on ANSYS Fluent software were carried out in order to investigate the effect of the clamping force and MPL addition on the fuel cell performance. The influence of the required gas diffusion layer (GDL) compression, during assembly process, onto fuel cell performance is investigated by considering four cases (0%, 15.7 %,...

High power density along with low gravimetric and volumetric characteristics for Proton Exchange Membrane Fuel Cell stacks are desired in order to be successfully implemented in the stationary applications market. Liquid cooling is currently the most widely used cooling strategy used in PEMFC stacks construction, especially for those who incorporat...

In this paper we report the development of Multi-Walled Carbon Nanotubes (MWCNTs) and graphene via chemical vapor deposition (CVD) for PEM Fuel Cells applications. MWCNTs growth are achieved by the flow of ethylene and hydrogen gasses over iron beased catalytic substrates at different temperatures and gas flow. Graphene growth is carried out by the...

Two components of the PEM fuel cells play a critical role in obtaining a good performance, namely the gas diffusion layer (GDL) and the micro porous layer (MPL). The target of the reported investigation was the influence of the required gas diffusion layer compression, during stack assembly, onto PEM fuel cell performance. For developing a fuel cel...

The feasibility of isotopic and elemental fingerprinting in the classification of wines according to their geographical origin was investigated by applying advanced techniques such as isotope ratio mass spectrometry and inductively coupled plasma mass spectrometry to characterize wines produced in four major vineyards in Romania from both indigenou...

Technological advancement and a growing world economy during the past few decades have led to major improvements in the living conditions of people in the developed world. The need for a sustainable supply of clean energy is one of the main problems facing the world. In this context the hydrogen economy and sustainable energy are becoming of increa...

Structural characterization by Raman spectroscopy and XRD of some carbon molecular sieves is described. These materials, prepared by standard procedure from a native pitcoal, have a turbostratic structure consisting of nanodimensional graphitic platelets, disorderly oriented in a hard amorphous network. In plane dimension of these platelets is obta...

PEM fuel cells have demonstrated their good energy efficiency and high power density per volume, but the high costs due to the noble metal catalysts, electrolyte membranes, and bipolar plates diminish the large scale marketing. Considering the potential of using graphene materials as low cost catalyst for the fuel cell applications, graphene nanoco...

A new and simple synthesis method of Pt nanoparticles supported on graphene materials, as potential candidates for low temperature fuel cell application, has been developed and discussed in detail. Graphene and Pt supported on graphene nano-sheets have been chemically prepared using a soft reduction method via a sequence of preparation steps based...

National Research and Development Institute for Cryogenics and Isotopic Technologies (ICIT) was established in 1970 as a research focused Industrial Pilot Plant. This new Institute was created with the purpose to develop the heavy water production technology. This technology has been successfully transferred to the heavy water production plant in 1...

Taking into consideration their high surface area, high conductivity, unique graphitized basal plane structure and potential low manufacturing cost, graphene nanocomposites such as Pt/graphene nanocomposites have been investigated as catalyst support for PEMFC applications. All materials were synthesized through a simple method of chemical oxidatio...

Tracing pollution sources and transformation of nitrogen compounds in surface- and groundwater is an issue of great significance worldwide due to the increased human activity, translated in high demand of water resources and pollution. In this work, the hydrological basin of an important chemical industrial platform in Romania (Ramnicu Valcea indus...

Proton exchange membrane (PEM) water electrolysis is seen as one of the most efficient and simple way to obtain high purity hydrogen. A major drawback in these systems is the catalysts long term stability in aqueous media. One way to improve that is to use niobium oxides as catalytic support since they have enhanced catalytic stability and high cor...

This paper presents a numerical investigation for a 44 cm² air breathing PEM fuel cell. We analyzed the influence of some operating and design parameters on the cell performance. The numerical solution based on ANSYS Multiphysics software and Fuel Cell Module offered an optimal performance at a cell with the cathode channel dimensions of 1.5 mm x 1...

Methodologies for chemometric classification of five authentic red wine varieties from Murfatlar wine center, Romania, young and aged are reported. The discriminant analysis based on several anthocyanins, organic acids, (13)C/(12)C, (18)O/(16)O and D/H isotopic ratios, (1)H and (13)C NMR fingerprints revealed a very satisfactory categorization of t...

This paper aims to present partial results of a large study regarding the alternative energen solutions (sun, wind, hydrogen) for power supply of passive house placed on Cluj-Napoca, Romania. Five scenarios for different combinations were optimized and analyzed of hybrid energy system. The best energy and environmental performances are achieved by...

The fast renewable energy source penetration is creating often mismatch in grid power demand, and is making the case for new energy storage solutions. Hydrogen-based energy conversion technology is considered the most tenable large and long-term scale alternative, and proton exchange membrane (PEM) water electrolysis is seen as one of the most effi...

Air breathing PEM fuel cells are a promising and a potential power source for portable applications. The challenges that air breathing fuel cells has to overcome in order to be used in portable applications and to be cost competitive are related to the ability to use logistic fuels, to the prevention of cathode contamination with impurities from th...

Based upon the authors’ long experience and upon a literature review, this paper presents an assessment regarding up-to-date R&D activities related to development and application of liquid phase catalytic exchange (LPCE) technology for tritium separation from tritiated water, produced in fission and fusion nuclear reactors. The assessment is focuse...

Energetic securities, low environmental impact, accessibility to energy sources and depletion of fossil fuels have focused the attention on the use of renewable energy sources. The use of renewable energy sources in tandem with fuel cells stack powered with hydrogen is the optimal solution of sustainable energy systems. This paper highlights the r...

Nowadays, carbon dioxide emissions, energy security and decreasing fossil fuel are a top priority in international agenda. Renewable energy sources, available in unlimited quantities, represent a viable alternative in economic terms. Fuel cell and photovoltaic panel (PV) are crucial to meet future energy needs while decarbonization the power sector...

ICSI Rm. Valcea has developed an experimental pilot-scale installation for tritium and deuterium separation. The main objective of this pilot was to demonstrate the water detritiation technology and further to transfer this technology to CANDU nuclear power plant from CNE Cernavoda, in whose development program there is the achieving of a Tritium R...

Cryogenic distillation is the back-end process used in water detritiation technologies with the aim to separate the hydrogen isotopes and concentrate it for further extraction and storage. At ICIT, research towards cryogenic distillation has been approached to develop the technology for heavy water detritiation at CANDU reactors. These results can...

In this study, 44 samples, either pure or combined into binary blends of vegetable oils with different botanical and geographical origin have been analyzed. 1H and 13C NMR analysis was used to determine the saturated fatty acids, oleic acid, linoleic acid, linolenic acid and iodine value. Oil samples were separated according to the botanical origin...

Catalytic tests for carbon dioxide hydrogenation were reported over nickel base catalysts on various supports in this paper. The tests were carried out under atmospheric pressure and for a temperature range between 300 and 550°C. Based on the results of the catalytic activity tests, it was found that from the three investigated catalysts Ni/Al2O3-S...

Despite various technology upgrades to achieve a low cost and reliable proton exchange membrane fuel cell, there is still a pressing need for increasing the catalytic stability and durability. Among others advances, new carbon-based materials are considered to be applied within Membrane – Electrode Assembly. Due to the high surface area, high condu...

A comprehensive multi-physics model has been developed to simulate proton exchange membrane (PEM) fuel cells using commercially available ANSYS MULTIPHYSICS software. The developed model accounts simultaneously for electrochemical kinetics and multi-component species transport. The proposed model is a full cell model, which includes all parts of th...

The objective of this investigation is to study silica doped/sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) composite membranes for operation in hydrogen/oxygen proton-exchange membrane fuel cells from Room Temperature (RT) up to 120 °C. The sulfonated PPO composite membranes were prepared using sol-gel process employing reaction with tetr...

Dezvoltarea pilelor de combustibil si a tehnologiilor aferente acestora reprezintă o prioritate europeană și, în același timp, unul din domeniile în care sunt proiectate investiții semnificative, atât din punct de vedere uman, cât și financiar. Există o largă emulație științifică relativ la dezvoltarea tuturor componentelor lanțului tehnologic al e...

Even if it does not actively participate in the electrochemical reaction, the gas diffusion layer (GDL) plays an important role in the architecture of the PEM fuel cell creating a virtual ideal ohmic contact at the interface with the polymer membrane. GDL properties (porosity, permeability and thickness) are directly influenced by the degree of com...

The paper features an analysis of the Romania's potential in the context of hydrogen economy. A relatively recent concern in Europe is the use of hydrogen in energy storage. The transition to a renewable energy based power generation system will introduce a new challenge: Management of fluctuating renewable sources to provide constant power supply....

The Nuclear Power Plant Cernavoda is equipped with a CANDU reactor and is one of the most powerful tritium sources from Europe. The reactor is moderated and cooled with heavy water that is continuous enriched with tritium. The presence of the tritium decreases the capacity of the heavy water to moderate the nuclear reactions. For this reason, I.C.I...

Energia ocupă un loc vital în lumea modernă. Cum energia bazată pe combustibili fosili nu mai poate fi considerată o opţiune găsirea unei tehnologii alternative de producere şi stocare a energiei este necesară. Ca urmare, un nou concept privind o tehnologie alternativă de stocare şi generare a energiei sub formă de metan regenerabil s-a investigat...

Originating from Cindrel Mountains (Southern Carpathians, Romania), the Cibin River, one of the Olt River tributaries, with a total length of 82 km, is formed at the junction of two headwaters Raul Mare and Raul Mic. In the area of headwaters Raul Mare and Raul Mic and dam - accumulation lake Gura Raului, the Cibin River waters fall in class I of q...

Nafion/oxide composite membranes were produced by pulsed laser ablation method using UV laser pulses generated by a COMPEXPro 205 KrF∗ excimer laser source. TiO2 material was uniformly distributed over the surface of Nafion 112 membrane using 100, 250 and 500 laser pulses and an incident laser fluence set at 5 J cm-2 were applied to improve the wat...

The aim of this paper is the parametric investigation of methane steam reforming to synthesis gas in a membrane reactor. Steam methane reforming in a membrane reactor is investigated in this paper using ANSYS Fluent software. The influence of some parameters on mass and heat transfer is analyzed. Thus, the influence of pressure, inlet temperature f...

În ultimii ani, au fost instalate un număr mare de centrale electrice bazate pe energia provenită din surse regenerabile (solare, fotovoltaice, eoliene, geotermale, etc), însă problema intermitenţelor şi a variaţiilor locale şi temporale ce caracterizează aceste surse reprezintă un dezavantaj major al acestora. Hidrogenul pare să rezolve această p...

The paper deals with an electrical power management solution for combining renewable energy sources (RES) with hydrogen technologies in order to overcome the problems generated by the natural fluctuations and intermittencies that characterize RES. A "Hydrogen-based Peak Power Management Unit" has been designed and built to allow the use of solar an...

The paper deals with a 5 kW Proton Exchange Membrane Fuel Cells Stack Combined Heat and Power prototype system for a residential application, designed to study the mass and energy flows for the optimal strategy to operate it in order to provide efficient, clean, on-site electricity and heat to residential users. Preliminary testing of the system wa...

The National Research and Development Institute for Cryogenics and Isotopic Technologies (ICIT Rm. Valcea) was established in 1970 as a research focused Industrial Pilot Plant with the main goal of developing a heavy water production technology. Within ICIT there is an experimental pilot plant for tritium and deuterium separation, which has as main...

Solar energy can provide a clean, reliable, renewable source of electric power. However, the present increasing cost of silicon requires that we find a more efficient means of utilising available silicon resources

Sunlight that is incident on the front surface of a luminescent solar concentrator (LSC) is absorbed and subsequently re-emitted by luminescent materials. The resulting luminescence is transported to the edge of the LSC sheet and concentrated onto photovoltaic devices. This paper outlines the loss mechanisms that limit conversion efficiency of the...

A comprehensive multi-physics model has been developed to simulate proton exchange membrane fuel cells using commercially available COMSOL MULTIPHYSICS software. The developed model accounts simultaneously for electrochemical kinetics and multi-component species transport. The proposed model is a full cell model, which includes all the parts of the...

Technological advancement and a growing world economy during the past few decades have led to major improvements in the living conditions of people in the developed world. The need for a sustainable supply of clean energy is one of the main problems facing the world. In this context the hydrogen economy and sustainable energy are becoming of increa...

The performance of a fuel cell is determined by several parameters, which describe the fundamental, electrochemical and physical properties of the fuel cell layers, operational conditions, geometry/structure of the flow field. One of these parameters is the permeability of the porous layers.The paper presents results obtained for different cases in...

Icons and paintings have an historic and personal significance, so that their preservation and restauration is an important part of keeping our cultural heritage. In our country the paintings have been rarely studied through modern chemical techniques and therefore very few information is available on the material used by the painter and restaurato...

The Cryogenic Pilot is an experimental project in the national nuclear energy research program, which has the aim of developing technologies for tritium and deuterium separation by cryogenic distillation. The process used in this install ation is based on a combined method for Liquid-Phase Catalytic Exchange (LPCE) and cryogenic distillation. There...

The Cernavoda Nuclear Power Plant is the biggest operational source of tritium, in Europe and one of the most important in the world. The recovery of tritium from the moderator of operating Candu reactors and from the reactors to operate, represents a good opportunity for Romania to be involved in international collaboration programs in the field o...

In the experiments performed in mouse (Mus musculus) the radioprotective effect of Deuterium Depleted Water (DDW, with 30 ppm deuterium) and a 0.01% total extract of polyphenols (from Aralia mandshurica cortex)), applied individually or together was tested, towards a sublethal dose of X-rays (5.28 Gy). The animals were intraperitoneal injected (fiv...

Environmentally harmless energy sources, like hydrogen, will become important in a future sustainable system based on renewable energy. Hydrogen is an important, though little studied, trace component of the atmosphere. It is present at the mixing ratio of about 510 ppb. Hydrogen is therefore an indirect greenhouse gas with a global warming potenti...

Hydrogen has the potential to be a sustainable alternative to the fossil fuels currently used in the transportation sector. The aim of our study is to appoint that producing hydrogen from biomass can be considered a green technology. There are three options for producing hydrogen from biomass. Our efforts must be focused on maximizing the reforming...

A new method was proposed for the preconcentration of copper ions using a column packed with SBA-15 mesoporous silica functionalized with N-Propylsalicylaldimine. The effects of various parameters such as pH, flow rate of sample, elution conditions, sample volume and enrichment factor, and the influence of some matrix elements have been studied. Th...

Administration of DDW (deuterium depleted water) represents a proper method to reduce deuterium in biological systems. In present study experiments were performed in order to observe the deuterium's concentration decrease in laboratory animals' bodies using DDW as depleting agent, the main ingredient for the commercial product QLARIVIA™ 2. Deuteriu...

Large amounts of tritium can be stored, in a safely manner, as metal tritides. An experimental model of a tritium storage bed with integrated system for in situ tritium inventory accountancy was designed and manufactured at ICIT Rm. Valcea. The calibration curve and the detection limit for this experimental model of tritium storage bed were determi...

During the water detritiation process most of the tritium inventory is transferred from water into the gaseous phase. Tritium is further enriched and finally extracted and safely stored. The control of tritium inventory is an important issue from several points of view, viz., (i) tritium is an expensive material, (ii) safeguard-tritium is considere...

Deuterium content of living animals body can be increased, with dramatical effect over the health state, through bioaccumulation process by continuously adding of heavy water in their nourishment. On the other hand, deuterium depletion has been mentioned in literature as a health stimulator and a new possible anticancer tool. In this context, the p...

In this paper we present the results obtained from the study of Ni‐Ti alloy obtained by arc melting method. To define the alloy’s shape, this is constrained under deformation and then heat treated. The heat treatment is performed at temperatures ranging between 325–525 °C. Shape memory bands were obtained from these ingots, with a band—thickness of...

In this paper, we investigate a procedure for radiocarbon determination in forest soil and slurry from lake sediments. The total carbon in these samples can be both inorganic and organic. Inorganic carbon can be analyzed in a straightforward manner using the direct absorption method by sample acidification and CO2 capture. For organic carbon, we in...

The Lower Danube Basin covers the Romanian-Bulgarian sub-basin downstream from Cazane Gorge and the sub-basins of the Siret and Prut rivers. To extensively survey the Romanian nuclear power plant impact on the Danube water, tritium and radiocarbon baseline values are required. Therefore, the reported study tried to establish these values based on a...

A high temperature thermostat TS-3000K has been designed for investigation of structure and dynamics in condensed matter by scattering neutron methods. It allowed measurements of large targets at temperatures up to 2500K. The thermostat TS-3000K is operating at the DIN-2PI spectrometer installed on the channel two of the IBR-2 reactor. The thermos...

Asian J Chem, 2010, 22(6): 4275-4280. ISSN: 0970-7077

To build a detritiation facility for heavy water that has been used as moderator and cooling agent in the CANDU reactor from Cernavoda, Romania is necessary to have in place a storage vessel to deposit the hydrogen isotopes, especially tritium. In preparation for the design of the storage vessel, sponge titanium and hydrogen gas were used during ex...

In this paper, the analysis of heavy metals from Olt river around Ramnicu Valcea chemical platform and from Jiu river around Craiova chemical platform during three months before and after industrial zone are presented.

Export Date: 20 February 2014, Source: Scopus, Language of Original Document: English, Correspondence Address: Diana, V.; University Politehnica of BucharestRomania; email: vranceanudiana@gmail.com, Chemicals/CAS: chitosan, 9012-76-4; hyaluronic acid, 31799-91-4, 9004-61-9, 9067-32-7, References: Frey, N.A., Peng, S., Cheng, K., Sun, S., Magnetic n...

In this experiment it was analyzed the effect of some biologically active substances extracted from the cortex of the Aralia mandshurica plants (Chisinau population) on laboratory mice (Mus muscullus), compared with a stress factor (X- ray radiation). The dilutions were made in distilled water and in deuterium depleted water. The combined administr...

In this paper, we investigate a procedure for radiocarbon determination in forest soil and slurry from lake sediments. The total carbon in these samples can be both inorganic and organic. Inorganic carbon can be analyzed in a straightforward manner using the direct absorption method by sample acidification and CO 2 capture. For organic carbon, we i...

The Lower Danube Basin covers the Romanian-Bulgarian sub-basin downstream from Cazane Gorge and the sub-basins of the Siret and Prut rivers. To extensively survey the Romanian nuclear power plant impact on the Danube water, tritium and radiocarbon baseline values are required. Therefore, the reported study tried to establish these values based on a...

Danube-Black Sea Channel is situated in the south east part of Romania. It takes its waters from Danube upstream of Cernavoda town, and flows into the Black Sea at Agigea. The main uses of the channel are numerous, but it can be mentioned navigation and nuclear power generation - Cernavoda Nuclear Power Plant. Maximum weigh carrying of the canal is...

The process for hydrogen isotopes separation is important for nuclear technology. Thus, the preoccupation is to find more efficient catalysts with a long operating time. The paper presents comparative studies between the physical and structural properties of hydrophobic catalysts. For the study of the isotope exchange water-hydrogen there were prep...

Different types of procedures could be applied to measure environmental tritium level, but usually all are based on measuring tritium concentration in extracted samples water by liquid scintillation counting techniques. There are two standard methods published for tritium measurement in aqueous samples. The recommended tritium activities for tritiu...

A three-dimensional computational fluid dynamics model of a PEM fuel cell with serpentine flow field channels that encounter co-flow and counter-flow configuration is presented in this paper. We consider that the PEM fuel cell performance is significantly influenced by the flow direction of fuel and oxidant. Starting from this point, the CFD model,...

An adequate gas and water flow management is a key issue to reach and maintain a higher output power for a PEM fuel cell stack. One of the main aspects which could limit the performance of a PEM fuel cell stack is the weak capability for a non-uniform water distribution management within the fuel cell. The produced water could become a handicap to...

This paper presents recent results concerning a new preparation method and characteristics of the hydrophobic catalysts used in hydrogen isotopes separation. The objectives of the paper are: (1) to assess the current status and find a new procedure for the preparation of a new improved hydrophobic catalyst; (2) to improve the characteristics and pe...