Papers by Daniel M Sutiman
DOAJ (DOAJ: Directory of Open Access Journals), Jun 1, 2007
DergiPark (Istanbul University), Oct 1, 2017
In the present work, a green emitting composite with attractive photoluminescent properties was o... more In the present work, a green emitting composite with attractive photoluminescent properties was obtained through the embedding of the Tb 3+ complex with N-hydroxyphthalimide in a poly-(N-vinyl-pyrrolidone) matrix, which was further processed in thin or thick films. First, several complexes of Gd 3+ , Tb 3+ , and Y 3+ with N-hydroxyphthalimide with the general formula [M(NHF) 3 (DMF) 2 ] were prepared at a 1:3 metal/ligand ratio. The Tb 3+ complex presents specific emission peaks, with the most intense peak located at 543 nm, thus being selected for incorporation in the poly(N-vinyl-pyrrolidone) matrix. The prepared complexes and composites were investigated through elemental analysis, thermal analysis, FT-IR, P-XRD, and SEM. The photoluminescent properties were studied in detail. Remarkably, through the embedding in the poly(vinyl-pyrrolidone) matrix, the photoluminescent properties of the Tb 3+ complex are notably enhanced compared to the free complex.
Journal of Alloys and Compounds, Aug 1, 1998
During the heating up to 5008C of a Cu-Zn-Al based Shape Memory Alloy, a marked texturing effect,... more During the heating up to 5008C of a Cu-Zn-Al based Shape Memory Alloy, a marked texturing effect, caused by the preferred formation of the a-phase has been revealed by means of X-ray diffraction and DTA. Kinetic analyses were also performed.
Korean Journal of Chemical Engineering, May 15, 2015
Pollution with cadmium ions has serious negative consequences on human health and environment. Ad... more Pollution with cadmium ions has serious negative consequences on human health and environment. Adsorption of low-cost materials represents a viable option for the removal of cadmium ions from aqueous media. In this study are comparatively discussed the adsorption behaviour of cadmium(II) on two low-cost materials, one of biologic nature (marine algae) and other of inorganic nature (ash), after their treatment with alkaline solution. The influence of contact time and initial cadmium ions concentration was studied in batch system, for each type of adsorbent. In optimum experimental conditions (solution pH of 5.0; adsorbent dose of 8 g L −1) and an initial cadmium concentration of 360 mg L −1 , the obtained uptake capacities reach to 34.15 mg g −1 for the modified algae and to 43.12 mg g −1 for the modified ash, respectively. The uptake data were analyzed using two isotherm models (Langmuir and Freundlich) and the models' parameters were evaluated. The results indicate that t heLangmuir model provides the best correlation of experimental data for both adsorbents, and the maximum adsorption capacities were 41.8 mg g −1 for modified algae and 48.0 mg g −1 for modified ash, respectively. The kinetics of the cadmium uptake was modelled using the pseudofirst order, pseudo-second order and intra-particle diffusion model equations. It was shown that the pseudo-second order kinetic equation could best describe the adsorption kinetics of cadmium ions, whatever the nature of adsorbent.
In this study patina was formed on bronze substrate by electrochemical technique. The linear pola... more In this study patina was formed on bronze substrate by electrochemical technique. The linear polarization curves and electrochemical impedance spectroscopy (EIS) have been employed to study the corrosion performance of the patined bronze sample in simulated acid rain at the beginning of long-term immersion; with the increase of immersion time. However, the corrosion resistance of the patined bronze sample was deteriorating after 1 day of immersion. Moreover, the large areas of the patining have fallen off the substrate after 30 days of immersion.
Environmental Engineering and Management Journal, 2012
CoCrMo alloy used currently as metallic biomaterial was investigated in view of dental applicatio... more CoCrMo alloy used currently as metallic biomaterial was investigated in view of dental applications using electrochemical methods. The prevalence of dental corrosion in human mouth has increased in the few decades as a result of an increasing consumption of commercial fruit juices. Two electrochemical techniques were used: cyclic potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in non-pasteurized and pasteurized apple juice at 25 o C. The electrochemical corrosion properties of CoCrMo alloy was measured in terms of zero current potential (ZCP) and corrosion current density (i corr). EIS technique was applied to study the nature of the passive film formed on CoCrMo sample at various time immersed in nonpasteurized and pasteurized apple juice: 1 minute, 1 hour and 3 hours. From EIS data, an equivalent circuit (EC) with on time constant was modelled.
Electrochimica Acta, Sep 1, 2017
The potential biomedical application of three new quaternary Zr alloys, namely Zr6Ti15Nb4Al, Zr32... more The potential biomedical application of three new quaternary Zr alloys, namely Zr6Ti15Nb4Al, Zr32Ti15Nb4Al, and Zr49Ti15Nb4Al, was evaluated in vitro using electrochemical methods complemented with surface analysis of corrosion resistance. Cyclic potentiodynamic polarization (CCP) and electrochemical impedance spectroscopy (EIS) tests were performed in Ringer's solution at 37 ºC. The electrochemical behavior of the ZrTiNbAl quaternary alloys was consistent with the formation of passivating oxide films on the surfaces of these materials. Localized breakdown of the oxide layer occurred on Zr6Ti15Nb4Al and Zr32Ti15Nb4Al alloys subjected to positive anodic polarization, a feature confirmed by scanning electron microscopy (SEM) on retrieved samples. The Zr49Ti15Nb4Al alloy, which had the highest titanium (49 wt.%) content, exhibited a larger passive range in the polarization curve and was immune to localized corrosion breakdown in a simulated physiological solution for the range of polarizations that can occur in the human body.
International Journal of Electrochemical Science
Scanning electrochemical microscopy (SECM) was employed for in situ characterization of surface c... more Scanning electrochemical microscopy (SECM) was employed for in situ characterization of surface chemical activity of various Ti-Mo and Ti-Ta alloys for biomedical application. In this work the local differences in surface reactivity for different Ti-Mo and Ti-Ta alloys were analyzed when they were polarized in 0.1 M NaCl solution and in Ringer's physiological solution using SECM, and results compared to those for the unbiased samples. The analysis of the shape of the approach curves obtained for the Ti-Mo and Ti-Ta alloys shows a different behaviour to be distinguished depending on the nature of the alloying element. There are also differences among the various Ti-Ta alloys tested, that cause changes in the shape of the approach curves with the value of the polarization applied to the substrate, defining a transition potential between-0.30 and-0.40 V vs. Ag/AgCl/KCl(3M) for most of the systems under study. Furthermore, from the line scans and array scans, a change in reactivity of the surface has been observed corresponding to the activation of the localized sites which occurs selectively with the applied potential. SECM is shown to be a powerful technique for the investigation of the surface characteristics of biomaterials in simulated physiological environments.
TURKISH JOURNAL OF CHEMISTRY
In the present work, a green emitting composite with attractive photoluminescent properties was o... more In the present work, a green emitting composite with attractive photoluminescent properties was obtained through the embedding of the Tb 3+ complex with N-hydroxyphthalimide in a poly-(N-vinyl-pyrrolidone) matrix, which was further processed in thin or thick films. First, several complexes of Gd 3+ , Tb 3+ , and Y 3+ with N-hydroxyphthalimide with the general formula [M(NHF) 3 (DMF) 2 ] were prepared at a 1:3 metal/ligand ratio. The Tb 3+ complex presents specific emission peaks, with the most intense peak located at 543 nm, thus being selected for incorporation in the poly(N-vinyl-pyrrolidone) matrix. The prepared complexes and composites were investigated through elemental analysis, thermal analysis, FT-IR, P-XRD, and SEM. The photoluminescent properties were studied in detail. Remarkably, through the embedding in the poly(vinyl-pyrrolidone) matrix, the photoluminescent properties of the Tb 3+ complex are notably enhanced compared to the free complex.
Metalurgia International [ISSN 1582-2214], v. 14 (12), p. 41-50, 2009
AgroLife Scientific Journal, 2012
Ash from thermal power plant was used as raw material for new adsorbents synthesis using alkaline... more Ash from thermal power plant was used as raw material for new adsorbents synthesis using alkaline attack and ultrasonic methods. In detail, it was mixed with 5M NaOH solution and treated at different contact time. The ash and the adsorbents were characterized by electron microscopy/energy dispersive spectroscopy (SEM/EDS), and Fourier Transform Infrared Spectroscopy (FT-IR). The new materials based on ash were applied as water sorbent to remove copper ions. The determination of copper ions was performed by atomic absorption. The results showed that these types of new adsorbents have a good capacity to remove copper ions from aqueous solution. For all synthesized adsorbents the predominant mechanism can be described by pseudo-second order kinetics. The alkaline attack method seems to be the most effective compared with the ultrasonic method and could present application potential for the copper removal.
Environmental Engineering and Management Journal, 2021
The industry generates large quantities of waste, which must be capitalized and transformed in co... more The industry generates large quantities of waste, which must be capitalized and transformed in compounds with high added value. The objective of the present study is to obtain white waterborne paint using calcium carbonate as filler, a waste results from Romanian plant fertilizer manufacturing. The paints are used for protection of surfaces, with the focus on durability. Natural or synthetic calcium carbonate can be successful used as filler in paints, they have an alkaline pH-value and low oil absorption, very important technological properties. The calcium carbonate can significantly improve paint properties as sheen, opacity, viscosity, density and wear resistance. This study is focused on the possibility to replace commercial filler with calcium carbonate waste and establishes the optimal content for obtaining waterborne paints with imposed properties. For obtaining white paint, the resin was mixed with 5-30 g precipitated calcium carbonate /300 mL resin. The properties of paints obtained were determined and comparison with witness. Experimental data demonstrated that precipitated calcium carbonate (PCC) with particle diameters over 0.5 µm influenced negative opacity properties. For improved this property grinding for obtaining particles smaller than 0.5 µm is necessary. Using calcium carbonate waste, experimentally were obtained for waterborne paint properties close properties with witness. The PCC content can be increased to 30 g/300 mL resin, without affecting the paint properties, less the viscosity which is 14% above the required value.
Environmental Engineering and Management Journal, 2009
The aim of this study is to investigate the electrochemical behavior of a three casting non-preci... more The aim of this study is to investigate the electrochemical behavior of a three casting non-precious dental alloys: Vera PDI (Co-Cr based), Heraenium (Ni-Cr based) and NPG+2 (Cu-Al based) three test solutions: artificial saliva (AFNOR, pH = 8), acidified saliva (pH = 2.5) and fluoridated acidified saliva (1000 ppm F-, pH = 2.5). Open circuit potential (E OC) measurement; potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) are the electrochemical procedures selected for this work. Our results have shown that Vera PDI and Heraenium dental alloys have a good corrosion resistance in artificial saliva, but in acidified saliva the corrosion currents increase. Corrosion currents are also higher in fluoridated acidified saliva as expected because the presence of fluoride ions. The NPG+2 casting alloy present a low corrosion resistance in artificial saliva and a very low corrosion resistance in acidified and fluoridated acidified saliva. The EIS results show that all three dental alloys exhibit passivity at open circuit potential in artificial saliva. For NPG+2 alloy in acidified saliva and fluoridated acidified saliva, the protectiveness of oxide film was no more present. The corrosion resistance of the three non-precious alloys are in the following order: Vera PDI > Heraenium > NPG+2.
Environmental Engineering and Management Journal, 2008
The behaviour of three types of steel, with a variable carbon concentration (from 0.20 to 0.40 %)... more The behaviour of three types of steel, with a variable carbon concentration (from 0.20 to 0.40 %) is studied in medium of ethylene glycol-10 % methanol-5 % succinic or adipic acid with water concentration varying between 1 % to 5 %. IR spectroscopy, Xray diffraction and chemical analysis were the methods used for corrosion compounds analysis. The weight losses were measured; also the polarization curves were plotted and the corrosion parameters were established. Based on the obtained results, a corrosion mechanism was assigned for each type of steel.
Environmental Engineering and Management Journal, 2007
A series of new Ni(II) poly-phosphinates have been synthesised using Ni(II) acetylacetonate as ni... more A series of new Ni(II) poly-phosphinates have been synthesised using Ni(II) acetylacetonate as nickel precursor and a succession of ligands derived from phosphinic acid: ethyl-butyl-phosphinic acid, ethyl-butyl-thio-phosphinic acid, and respectively ethylbutyl-di-thio-phosphinic acid. Chemical analysis gel-chromatography, infrared spectroscopy (IR), spin electronic resonance (RES), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), electrical resistance measurements at different temperatures, dielectric loss and electrical discharges have been used as characterization methods. Based on the experimental results and on literature data the structures of the studied compounds are predicted. All the investigated samples revealed good insular properties having the electrical resistance around 10-15 Ω•cm-1. Also, they presented anticorrosive protecting properties resisting to caloric effects in a normal atmosphere pending temperatures of 300 ºC.
Environmental Engineering and Management Journal, 2005
Two different methods of preparation (solid state exchange and aqueous exchange) with two differe... more Two different methods of preparation (solid state exchange and aqueous exchange) with two different iron precursors (ferrous chloride, respectively ferric oxalate) have been used to introduce iron species in the zeolite ZSM-5. A special attention was devoted to the aqueous exchange method. The catalysts thus prepared were tested for direct N 2 O decomposition. The results of catalytic tests show that the Fe-ZSM-5 catalyst prepared by aqueous exchange in ferric oxalate solutions is much more active than the one prepared by solid state exchange.
Revista de Chimie, 2008
The electrochemical behavior of a three Ag-Pd alloys used in dental prosthetics construction for ... more The electrochemical behavior of a three Ag-Pd alloys used in dental prosthetics construction for crowns and bridges was studied in artificial saliva using the polarization curves and electrochemical impedance spectroscopy (EIS). The corrosion resistance was evaluated by means of the corrosion currents value and by coulometric analysis. The open circuit potential of Ag-Pd are attributed to dealloying followed by surface enrichment with Ag and the possible formation of an insoluble AgCl surface film on the respective alloy surfaces. Our results have shown that these alloys have a somewhat good corrosion resistance in artificial saliva. When increasing the content of Cu, corrosion resistance decreases. The passivation of all samples occurred spontaneously at the open circuit potential. The electrochemical properties of the spontaneously passivated electrodes at the open circuit potential were studied by EIS. The polarization resistance (Rp) and the electrode capacitance (Cdl) were dete...
Revista de Chimie, 2008
The corrosion behaviour of nickel-based alloys (Heraenium, Verabond and V alloy) in simulated sal... more The corrosion behaviour of nickel-based alloys (Heraenium, Verabond and V alloy) in simulated saliva was studied by gravimetric, pH-metric and conductometric methods, as well as by potentiodynamic polarization and by electrochemical impedance spectroscopy (EIS). The main parameters of the corrosion process were established. Additionally, the results obtained with SEM and AAS analyses were reported. All alloys pass directly into a stable passive region, without exhibiting the usual active-passive transition. The EIS results show that a Ni-based alloy exhibits passivity at open circuit potential. The proposed equivalent circuit contains two R-CPE elements in parallel. The physical meaning given to the circuit is the association of the film/electrolyte interface with the passive film itself. The corrosion resistance of the studied non-precious alloys is in the following order: Heraenium alloy ] V alloy ] Verabond alloy.
Environmental Engineering and Management Journal, 2008
In this paper, the study of synthesis and stability in aqueous solutions of new coordination comp... more In this paper, the study of synthesis and stability in aqueous solutions of new coordination compounds of Ti(IV) and Zr(IV) with ligand N-hydroxy-succinimide is presented. The salts: TiOSO 4 •2H 2 O and ZrOCl 2 •8H 2 O used for obtaining the studied coordination complexes, can derive from recycling metallic residues resulted in mechanical technologies applied for titanium and zirconium in S.C. ZIROM S.A. Giurgiu. The new complexes were synthesized in aqueous solutions and stability were study using specific methods for coordination compounds: UV-VIS spectroscopy, conductance and pH-metric measurements. The molar ratios between central atom and ligand and also the partial and total equilibrium constants have been determined, applying the specific methods for study in aqueous solutions. From experimental data resulted that in aqueous medium, two complex compounds are obtained for each central atom Ti(IV) and Zr(IV). The metallic ion is bonded with one and respectively two ligands derived from N-hydroxy-succinimide. The obtained compounds are: [dihydroxo-N-succinimide, diaqua Ti(IV)] sulfate; [dihydroxo-diN -succinimide Ti(IV)]; [dihydroxo-N-succinimide, diaqua Zr(IV)] chloride and [dihydroxo-di-Nsuccinimide Zr(IV)]. In strong acidic or alkaline media, the complex compounds are instable. The optimal stability of the studied compounds is between the values of pH: 1÷5.5; these are identical with the acidity of the tanning bathes for natural leathers. This fact is favorable for the use of these compounds as a desirable alternative in ecological tanning processes. The importance of this paper consists in studying and obtaining of new soluble and stable in aqueous solution products that can be used in ecological tanning technologies for natural leather as a replacement for the toxic chrome compounds. In adding, a way of using the residues of titanium and zirconium derived from mechanical industrial processes of these metals is also of economical importance. From these residues, sulfates, chlorides or complex compounds can be obtained determining the necessary quantities of these metals for our country.
Environmental Engineering and Management Journal, 2010
The influence of potential on electrochemical behaviour of Ti6Al4Zr alloy under simulated physiol... more The influence of potential on electrochemical behaviour of Ti6Al4Zr alloy under simulated physiological condition was investigated by electrochemical impedance spectroscopy (EIS). The experimental results were compared with those obtained for titanium Ti6Al4V alloy. All measurements were obtained in aerated artificial saliva at 25 o C and at different potentials 0 mV (SCE), 500 mV (SCE) and 1000 mV (SCE). Equivalent circuits (EC) were used to modeling EIS data, in order to characterize samples surface and better understanding the effect of zirconium addition on the titanium alloy. The Ti6Al4Zr alloy appears to posses' superior corrosion resistance than the Ti6Al4V alloy in artificial saliva.
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Papers by Daniel M Sutiman