Sibiescu Doina - Academia.edu (original) (raw)

Papers by Sibiescu Doina

Research paper thumbnail of Benchmarking on Aloe vera Gel Extraction

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

Aloe vera gel is composed of more than 70% saccharide and polysaccharides is the transparent muci... more Aloe vera gel is composed of more than 70% saccharide and polysaccharides is the transparent mucilage contained in the parenchymal cells of the fresh Aloe vera leaf. This study objective was to produce a comparison of a set of extraction methods of Aloe vera in the literature. The methodology used is the synthesis of a set of scientific articles, theses, dissertations dealing with the issue of Aloe vera gel extraction. The databases used are (Science Direct, Google Scholar, and ResearchGate). This work studied 6 types of extractions (traditional extraction, Soxhlet extraction, Organic solvent extraction, Ultrasonic extraction, Supercritical extraction and Microwave). These types of extractions were evaluated on several parameters, namely: extraction principles, solvents, extraction time, yield, liquid ratio, gel efficiency and number of extractions. The analysis shows that the quality and yield of Aloe vera gel depends on the type of extraction it undergoes, organic solvent extraction which are: yield, which is 20.67 per kg, liquid ratio 1:15, number of extraction 2 times. Although other extraction methods have some information like traditional extraction the efficiency of gel is poor, the same Aloe vera can undergo three times traditional

Research paper thumbnail of Preliminary Study on the Interaction of Skin Microbes in the Development of Cosmetic and Textile Products: A Review

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

This work, which aims at realizing a synthesis of the knowledge on cutaneous microbes, shows that... more This work, which aims at realizing a synthesis of the knowledge on cutaneous microbes, shows that the skin is made up of pathogenic microbes and commensal microbes. The resident or commensal microbes are defenders of the skin and are ready to compete for nutrients and available space. Therefore, pathogenic microorganisms will not be able to settle and grow. The textile designer, in his search for an antimicrobial textile, should not be satisfied with the ability to inhibit skin microbes. He should investigate whether his textile promotes the balance of the commensal flora before testing the inhibition of the transient flora. For this reason, it is desirable to know the skin flora before embarking on the implementation of antimicrobial textiles.

Research paper thumbnail of Enhancement of Separation Performances of a New Azoic Derivative from Industrial Water and the Posibility to Recover Its Complex as Nanomaterial

Environmental Engineering and Management Journal, 2010

In order to obtain new complexes of Fe(III) with multiple uses, their characteristics, important ... more In order to obtain new complexes of Fe(III) with multiple uses, their characteristics, important applications and also the obtaining conditions are studied. The obtaining conditions consist in mixing solutions of the same concentrations of ligand 2 amino-6methoxy-benzothiazole sulphonic acid→1-naphtol-4-sulphonic acid with FeCl 3. The solutions are mixed in molar ratios of 1:1, 2:1 and 3:1 (ligand to central metallic atom). For determining the molar ratio ligand:central metallic atom, the methods applied were: pH-metry, conductometry, UV-VIS spectrophotometry. Also, the stability constants for new obtained compounds were determined using Molar Ratio method (J.H.Yoe and A.L.Jones), Continuous Variation method (Job) and Harvay-Manning method. The stability of the new obtained compounds is studied by varying the pH of its solution. The values are K 1 = 2.56•10 6 L/mol for FeL 1 ; K 2 = 19.76•10 13 L/mol for Fe L 2 and K 3 = 30.03•10 32 L/mol for Fe L 3. The higher value for stability is assigned to the compound with molar ratio 3:1 (ligand: metal) in the 1.5÷6.5 pH range. The maxim value for the absorbance was measured at λ max = 601 nm for FeL 1 , λ max = 601 nm for FeL 2 and respective λ max = 600 nm for FeL 3. The studied complexes are very stable in the above-mentioned pH range and could be used for spectrophotometric determination of Fe(III) in visible domain. Another practical importance is represented by wastewater treatments by membranar separation. Thus, the separation process is improved by increasing the volume of these complexes in comparison with both ligand and Fe(III) and further the iron recovery by calcinations was accomplished.

Research paper thumbnail of Coordination compounds with insulating and anticorrosive properties

10th International Symposium on Electrets (ISE 10). Proceedings (Cat. No.99 CH36256)

The present paper is a continuation of our studies regarding the synthesis and the properties of ... more The present paper is a continuation of our studies regarding the synthesis and the properties of some new coordination compounds obtained by the interaction of the “d” block elements acetylacetonates or acetates with diorganophosphinic acids. Its aim is to determine the influence of the metallic cations and of the ligands on the dielectric properties of the obtained coordination polymers. Taking

Research paper thumbnail of STUDY OF A NEW COORDINATION COMPOUNDS BASED ON Cr(III) AND SUCCINIMIDE IN AQUEOUS SOLUTION

In this paper, the study of obtaining new coordination compounds of Cr (III) using as ligand, suc... more In this paper, the study of obtaining new coordination compounds of Cr (III) using as ligand, succinimide and the stability constants, were presented. Conductometric, pH-metric and spectrophotometric studies of Cr(III)-succinimide system were carried out in aqueous medium. The "molar ratio" method was used to study the complex formation in solution and for determine the stability constants was used Harvey-Manning method.From experimental data resulted that the combination ratio of the ligand succinimide with central metallic atoms was: 1:1, 2:1 and respectively 3:1.

Research paper thumbnail of New Coordination Compounds of Fe(III) with Ligand from N-hydroxysuccinimide, with Applications in Ecologic Leather Tanning Technologies

MARIAN CRUDU1*, DOINA SIBIESCU2, DANA GURAU, RODICA ROXANA CONSTANTINESCU 1, ANA MARIA VASILESCU ... more MARIAN CRUDU1*, DOINA SIBIESCU2, DANA GURAU, RODICA ROXANA CONSTANTINESCU 1, ANA MARIA VASILESCU 1 1National Research and Development Institute for Textiles and Leather, Division: Leather and Footwear Research Institute, 93 Ion Minulescu, 031215, Bucharest, Romania 2 Gheorghe Asachi Technical University, Faculty of Industrial Chemistry and Environmental Protection, 71 A Mangeron Blvd., 700050, Iasi, Romania

Research paper thumbnail of Noi copolimeri de coordinatie hibrizi ai Mn(II)

This paper presents the synthesis and study of some Mn(II) coordination polymers hybrid with the ... more This paper presents the synthesis and study of some Mn(II) coordination polymers hybrid with the following acids as ligands: dibuthilphosphinic, dibuthiltiophosphinic, dibutildithiophosphinic, dioctilphosphinic, dioctiltiophosphinic, dioctilditiophosphinic. The study was performed by means of chemical analysis, gel chromatography, IR spectroscopy, ESR, X-ray diffraction, thermogravimetry. The experimental results were used to propose the structural formulae of these compounds and to calculate the kinetic parameters of the thermal decomposition reactions.

Research paper thumbnail of New Iron (III) Coordination Compounds with Applications in Water Treatment

Environmental Engineering and Management Journal, 2010

Three new iron (III) coordination polymers, namely {Fe[(C 2 H 5)(C 4 H 9)PO 2 ] 3 } n , {Fe[(C 2 ... more Three new iron (III) coordination polymers, namely {Fe[(C 2 H 5)(C 4 H 9)PO 2 ] 3 } n , {Fe[(C 2 H 5)(C 4 H 9)POS] 3 } n , and {Fe[(C 2 H 5)(C 4 H 9)PS 2 ] 3 } n have been synthesised using iron (III) acetylacetonate as iron precursor and a succession of ligands derived from phosphinic acid: ethylbutyl-phosphinic acid, ethylbutylthio-phosphinic acid, and respectively ethylbutyldithiophosphinic acid. Chemical analysis, gel-chromatography, infrared spectroscopy (IR), Mössbauer spectroscopy, X-ray diffraction (XRD) and thermal gravimetric analysis (TGA) have been used as characterization methods. Based on the experimental results and on literature data the structures of the studied compounds were assigned. The organophosphinic acids were also tested as iron chelators for water treatment.

Research paper thumbnail of New complexes of silver (I) with N-hydroxy-succinimide

SPIE Proceedings, 2016

Over the last period of time silver was considerably studied due to its lower resistivity. In the... more Over the last period of time silver was considerably studied due to its lower resistivity. In the field of materials science, silver was used in applications such as: microelectronics components of high – temperature superconductiviting materials, bactericidal coatings and others domains. This study presents the process of obtaining and characterization the new complexes of silver (I) with Nhydroxy- succinimide. In the process of obtaining the new complex compounds in aqous solution, first we have to look at conductometry and UV-Vis absorbtion spectroscopy in order to determine the molar ratio silver : N-hydroxysuccinimide and the stability constants. The obtained solid coordination compounds were characterized by elemental analysis, IR spectroscopy and also was investigated of their thermostability. The X-ray powder diffraction reflects that the complexes compounds of silver (I) with N-hydroxysuccinimide are amorphous. In our further studies we want to determine if the new synthetized compounds will present the same or improuved properties as in the above mentioned silver characteristics.

Research paper thumbnail of Aloe Vera Gel as a Biomordant in the Finishing of Vegetable Textiles: A Review

Zenodo (CERN European Organization for Nuclear Research), Dec 31, 2022

During the dyeing process, the color is maintained over time due to the mordant that creates a st... more During the dyeing process, the color is maintained over time due to the mordant that creates a strong bond between the dye and the fiber. The most common chemical mordants are potassium alum, tartar cream, tin chloride, cupric sulfate, ferrous sulfate and potassium dichromate. The current trend of increasing nature protection requires the use of clean products for the textile finishing sector and the biodegradability of textiles. Aloe vera is known to be a natural mordant. Based on data from the literature, the authors of this paper aimed to identify several behaviors between Aloe Vera gel and textiles. Aloe vera gel macerated on Sida rhombifolia shows (with the residue in the oven) after IR analysis a disappearance of peak 1029 cm-1 which indicated the degree of CO -C bonds of cellulose present in the modification of Sida rhombifolia. The active ingredients of Aloe vera have also been shown to bind to the hydroxyl groups of cotton, which is a crosslinking agent for macromolecules.

Research paper thumbnail of Cochenille red dye decoloration and chromate reduction simultaneously in acid medium

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IX, 2018

During the last century, the synthetic dyes have taken a pivotal role in many domains. Part of th... more During the last century, the synthetic dyes have taken a pivotal role in many domains. Part of this class is the Cochenille Red dye. It can be used as such for wool, nylon, silk, inks, paper, plastics, wood stains, leather tanning and processing. But still in the above mentioned fields it is used as well or even with much better results as ligand being complexed with different metal cations. This domain has been approached by us in previous studies in various papers. The range of use areas is extended for foods drugs, cosmetics, hematology and histology stains and last but not least, in photography, too. Due to these multiple uses, we have found it useful to study its behavior in an acidic medium in the presence of an oxidizing agent. Chromate [Cr(VI)] and azo dyes like Cochenille Red are common pollutants which may co-exist in some industrial effluents. The degradation kinetics of the oxidation process of Cochenille Red dye using inorganic oxidizing agent (K2CrO4) have been investigated under various experimental conditions: different concentrations of H2SO4 [10-2 -5·10-1 M ] and temperatures [296 and 308 K]. A kinetic model for oxidation of Cochenille Red dye by the combination of chromate was developed based on experimental results. The thermodynamic activation energy was calculated from the rate constants of the oxidation process of the dye, measured at two different temperatures, 296 and 308 K. We concluded that the negative value of entropies of activation indicate that the reaction occurs between ions of similar charge. Based on our experimental and literature data , we conclude that the destruction of azo-chromophore group by the inorganic oxidizing agent (K2CrO4) is explained by the highest oxidation state of this dye.

Research paper thumbnail of COMPOUNDS OF Ti ( IV ) AND Zr ( IV ) IN AQUEOUS SOLUTIONS : SYNTHESIS , STABILITY AND APPLICATION IN CLEANER TECHNOLOGIES OF NATURAL

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: TiOSO4·2H2O and ZrOCl2·8H2O 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...

Research paper thumbnail of Coordination Compound of Fe(III) with N,N'-bis(salicylidene)-methylenediamine

The bis-Schiff base, N,N’-bis(salicylidene)-methylenediamine, (H2L1) known as Salmen, forms toget... more The bis-Schiff base, N,N’-bis(salicylidene)-methylenediamine, (H2L1) known as Salmen, forms together Fe(III) at low acid pH a brown precipitate, which is stable at room temperature. Study of the IR spectroscopy and the chemical analysis has evidenced that the precipitation form is a complex and the combination ratio of M:L is 1:1. The precipitation form will be used as a method for the gravimetric determination of Fe(III) with Salmen. The precipitate was dried at room temperature at constant weight and weighed as C15H12O2N2Fe(OH).2H2O. The analytical application presents an average relative error of + 0.5 %, and interferences with Cu(II), Zn(II), Cr(III), Mn(II), Ni(II), U(VI) and Co(II).

Research paper thumbnail of Synthesis and Study of Some Coordination Polymers of RH(II) with Diphenylphosphinic Acid Derivatives as Ligands

Revue Roumaine De Chimie, 1997

Research paper thumbnail of NEW COMPLEX COMPOUNDS WITH b-AMINOISOBUTYRIC ACID BIDENTATE LIGAND FOR POTENTIAL APPLICATION IN SUSTAINABLE AGRICULTURE

Environmental Engineering and Management Journal, 2018

The synthesis and the study of the complexes obtained in this paper represent the beginning of ou... more The synthesis and the study of the complexes obtained in this paper represent the beginning of our research for applied coordinative compounds of this type in agriculture. The analysis and the study of Mn(II) complexes with DL-β-Aminoisobutyric acid as ligand were accomplished in aqueous and alcoholic solution and also in solid state.The composition ratios and the stability of the synthesised compounds were analysed with specific methods: conductance, pH measurements, spectrophotometry and thermogravimetry. There were obtained two complexes, at the metal:ligand molar ratio 1:1 and 1:2. In order to determine the structures of the new compounds, the following methods were applied: chemical analysis, IR, UV-VIS and XRD spectroscopy. The [MnLCl]2ꞏ2/5H2O and [MnL2]ꞏ1/2H2O presented a triclinic and respectively, monoclinic crystalline structure. From the thermal decomposition data, the kinetic parameters of the studied compounds were calculated observing that both new complex compounds have a higher thermal stability than the ligand. The experimental data confirmed that ligand DL-β-Aminoisobutyric acid presented a bi-dentate behavior towards Mn(II) ions in solution.

Research paper thumbnail of Electrochemical Sensors for Heavy Metal Ions Detection from Aqueous Solutions

Environmental Engineering and Management Journal, 2012

Due to the major negative impact of heavy metal ions toward human health and environment,, even a... more Due to the major negative impact of heavy metal ions toward human health and environment,, even at low concentrations, the development of simple, fast and not expensive detection methods of heavy metals is a major challenge for the scientists. Among the different analytical methods for the analysis of heavy metal ions, the corresponding methods based on electrochemical sensors are discussed in this review, due to their above mentioned advantages. Several types of electrochemical sensors and their analytical applications based on electrochemical methods such as: potentiometry, voltammetry and amperometry, are presented. The electrochemical sensors could revolutionize the field of real-time and on-line environmental analysis, due to their high performances as: low detection limits, a wide linear response range, good stability and reproducibility.

Research paper thumbnail of THE CHARACTERIZATION AND THE SYNTHESIS OF A NEW COORDINATION COMPOUND FOR REMOVAL OF Cr(III) FROM WASTEWATERS

Environmental Engineering and Management Journal, 2010

The Schiff base N,N'-(salicylidene)-methylenediamine, known as Salmen in combination with Cr(III)... more The Schiff base N,N'-(salicylidene)-methylenediamine, known as Salmen in combination with Cr(III) forms at pH = 4.5 a greenish precipitate, which is stable at room temperature but decomposed on heating. The study of the Infrared spectra, Electron Spin Resonance (ESR), X-ray diffraction and thermogravimetry has pointed out that the precipitation form is a complex, while the molar ratio showed that the combination rate of Cr(III): N,N'-bis(salicylidene)-methylenediamine is 1:1. The new complex crystallizes in the triclinic systems. This precipitation reaction can be used as a method for the gravimetric determination of Cr(III) with N,N'-bis(salicylidene)-methylenediamine, known as Salmen The precipitate was dried in vacuum and weighed as C 15 H 13 O 3 N 2 Cr. The overage relative error is ± 0.33%. Salmen can be used in order to precipitate and to recover the chromium from wastewaters consequential to the tanning of natural fells.

Research paper thumbnail of New Complexes Used to Increase the Dying Process Efficiency of the Textile Materials in the Context of Sustainable Development

Environmental Engineering and Management Journal, 2010

This work presentes a study of preparation and stability in aqueous medium of complexes obtained ... more This work presentes a study of preparation and stability in aqueous medium of complexes obtained by the reaction between Fe(III) with 2-amino-6-methoxy-benzothiazol-sodium sulphonate →1 naphtol-4-sodium sulphonate. In this purpose, the investigation methods applied were as follows: pH-metry, conductometry, and the UV-VIS spectrophotometry. The molar combination ratio of ligand to central metallic atom, and the stability constants for new obtained compounds were determined using "molar ratio method" (Yoe and Jones), "Continuous Variation" method (Job) and Harvay-Manning method. Based on the investigations performed, these compounds might be employed for dying white woolen fibers, to obtain colors from blue to violet. The resulted colors after dying are very homogenous and intensive. The exhausted dying bath was about 98% from the complexed compound of Fe(III) with 2-amino-6-methoxybenzothiazol-sodium sulphonate→1 naphtol-4-sodium sulphonate obtaining in acid medium and 30 % from the free dye. Another practical aspect is related to the possibility of iron recovery from the residual processing solution, solving in this way both the environmental problems and technological aspects from the dyeing process in textile industry.

Research paper thumbnail of NEW Ni(II) COORDINATION POLYMERS WITH INSULATING AND ANTICORROSIVE PROPERTIES

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.

Research paper thumbnail of New Coordination Compounds of Fe(III) with Organic Ligands

Revista de Chimie, 2009

In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands deriv... more In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands derived from: 2-(4-chloro-phenylsulfanyl)-1-(2-hydroxy-3,5-diiodo-phenyl)-ethanone (HL1), 1-(3,5-dibromo-2-hydroxy-phenyl)-2-phenylsulfanyl-ethanone(HL2), and 2-(4-chloro-phenylsulfanyl)-1-(3,5-dibromo-2-hydroxy-phenyl)-ethanone (HL3) is presented. The characterization of these complexes is based on method as: the elemental chemical analysis, IR and ESR spectroscopy, M�ssbauer, the thermogravimetric analysis and X-ray diffraction. Study of the IR and chemical analysis has evidenced that the precipitates form are a complexes and the combination ratio of M:L is 1:2. The central atoms of Fe(III) presented paramagnetic properties and a octaedric hybridization. Starting from this precipitation reactions, a method for the gravimetric determination of Fe(III) with this organic ligands has been possible. Based on the experimental data on literature indications, the structural formulae of the complex ...

Research paper thumbnail of Benchmarking on Aloe vera Gel Extraction

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

Aloe vera gel is composed of more than 70% saccharide and polysaccharides is the transparent muci... more Aloe vera gel is composed of more than 70% saccharide and polysaccharides is the transparent mucilage contained in the parenchymal cells of the fresh Aloe vera leaf. This study objective was to produce a comparison of a set of extraction methods of Aloe vera in the literature. The methodology used is the synthesis of a set of scientific articles, theses, dissertations dealing with the issue of Aloe vera gel extraction. The databases used are (Science Direct, Google Scholar, and ResearchGate). This work studied 6 types of extractions (traditional extraction, Soxhlet extraction, Organic solvent extraction, Ultrasonic extraction, Supercritical extraction and Microwave). These types of extractions were evaluated on several parameters, namely: extraction principles, solvents, extraction time, yield, liquid ratio, gel efficiency and number of extractions. The analysis shows that the quality and yield of Aloe vera gel depends on the type of extraction it undergoes, organic solvent extraction which are: yield, which is 20.67 per kg, liquid ratio 1:15, number of extraction 2 times. Although other extraction methods have some information like traditional extraction the efficiency of gel is poor, the same Aloe vera can undergo three times traditional

Research paper thumbnail of Preliminary Study on the Interaction of Skin Microbes in the Development of Cosmetic and Textile Products: A Review

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

This work, which aims at realizing a synthesis of the knowledge on cutaneous microbes, shows that... more This work, which aims at realizing a synthesis of the knowledge on cutaneous microbes, shows that the skin is made up of pathogenic microbes and commensal microbes. The resident or commensal microbes are defenders of the skin and are ready to compete for nutrients and available space. Therefore, pathogenic microorganisms will not be able to settle and grow. The textile designer, in his search for an antimicrobial textile, should not be satisfied with the ability to inhibit skin microbes. He should investigate whether his textile promotes the balance of the commensal flora before testing the inhibition of the transient flora. For this reason, it is desirable to know the skin flora before embarking on the implementation of antimicrobial textiles.

Research paper thumbnail of Enhancement of Separation Performances of a New Azoic Derivative from Industrial Water and the Posibility to Recover Its Complex as Nanomaterial

Environmental Engineering and Management Journal, 2010

In order to obtain new complexes of Fe(III) with multiple uses, their characteristics, important ... more In order to obtain new complexes of Fe(III) with multiple uses, their characteristics, important applications and also the obtaining conditions are studied. The obtaining conditions consist in mixing solutions of the same concentrations of ligand 2 amino-6methoxy-benzothiazole sulphonic acid→1-naphtol-4-sulphonic acid with FeCl 3. The solutions are mixed in molar ratios of 1:1, 2:1 and 3:1 (ligand to central metallic atom). For determining the molar ratio ligand:central metallic atom, the methods applied were: pH-metry, conductometry, UV-VIS spectrophotometry. Also, the stability constants for new obtained compounds were determined using Molar Ratio method (J.H.Yoe and A.L.Jones), Continuous Variation method (Job) and Harvay-Manning method. The stability of the new obtained compounds is studied by varying the pH of its solution. The values are K 1 = 2.56•10 6 L/mol for FeL 1 ; K 2 = 19.76•10 13 L/mol for Fe L 2 and K 3 = 30.03•10 32 L/mol for Fe L 3. The higher value for stability is assigned to the compound with molar ratio 3:1 (ligand: metal) in the 1.5÷6.5 pH range. The maxim value for the absorbance was measured at λ max = 601 nm for FeL 1 , λ max = 601 nm for FeL 2 and respective λ max = 600 nm for FeL 3. The studied complexes are very stable in the above-mentioned pH range and could be used for spectrophotometric determination of Fe(III) in visible domain. Another practical importance is represented by wastewater treatments by membranar separation. Thus, the separation process is improved by increasing the volume of these complexes in comparison with both ligand and Fe(III) and further the iron recovery by calcinations was accomplished.

Research paper thumbnail of Coordination compounds with insulating and anticorrosive properties

10th International Symposium on Electrets (ISE 10). Proceedings (Cat. No.99 CH36256)

The present paper is a continuation of our studies regarding the synthesis and the properties of ... more The present paper is a continuation of our studies regarding the synthesis and the properties of some new coordination compounds obtained by the interaction of the “d” block elements acetylacetonates or acetates with diorganophosphinic acids. Its aim is to determine the influence of the metallic cations and of the ligands on the dielectric properties of the obtained coordination polymers. Taking

Research paper thumbnail of STUDY OF A NEW COORDINATION COMPOUNDS BASED ON Cr(III) AND SUCCINIMIDE IN AQUEOUS SOLUTION

In this paper, the study of obtaining new coordination compounds of Cr (III) using as ligand, suc... more In this paper, the study of obtaining new coordination compounds of Cr (III) using as ligand, succinimide and the stability constants, were presented. Conductometric, pH-metric and spectrophotometric studies of Cr(III)-succinimide system were carried out in aqueous medium. The "molar ratio" method was used to study the complex formation in solution and for determine the stability constants was used Harvey-Manning method.From experimental data resulted that the combination ratio of the ligand succinimide with central metallic atoms was: 1:1, 2:1 and respectively 3:1.

Research paper thumbnail of New Coordination Compounds of Fe(III) with Ligand from N-hydroxysuccinimide, with Applications in Ecologic Leather Tanning Technologies

MARIAN CRUDU1*, DOINA SIBIESCU2, DANA GURAU, RODICA ROXANA CONSTANTINESCU 1, ANA MARIA VASILESCU ... more MARIAN CRUDU1*, DOINA SIBIESCU2, DANA GURAU, RODICA ROXANA CONSTANTINESCU 1, ANA MARIA VASILESCU 1 1National Research and Development Institute for Textiles and Leather, Division: Leather and Footwear Research Institute, 93 Ion Minulescu, 031215, Bucharest, Romania 2 Gheorghe Asachi Technical University, Faculty of Industrial Chemistry and Environmental Protection, 71 A Mangeron Blvd., 700050, Iasi, Romania

Research paper thumbnail of Noi copolimeri de coordinatie hibrizi ai Mn(II)

This paper presents the synthesis and study of some Mn(II) coordination polymers hybrid with the ... more This paper presents the synthesis and study of some Mn(II) coordination polymers hybrid with the following acids as ligands: dibuthilphosphinic, dibuthiltiophosphinic, dibutildithiophosphinic, dioctilphosphinic, dioctiltiophosphinic, dioctilditiophosphinic. The study was performed by means of chemical analysis, gel chromatography, IR spectroscopy, ESR, X-ray diffraction, thermogravimetry. The experimental results were used to propose the structural formulae of these compounds and to calculate the kinetic parameters of the thermal decomposition reactions.

Research paper thumbnail of New Iron (III) Coordination Compounds with Applications in Water Treatment

Environmental Engineering and Management Journal, 2010

Three new iron (III) coordination polymers, namely {Fe[(C 2 H 5)(C 4 H 9)PO 2 ] 3 } n , {Fe[(C 2 ... more Three new iron (III) coordination polymers, namely {Fe[(C 2 H 5)(C 4 H 9)PO 2 ] 3 } n , {Fe[(C 2 H 5)(C 4 H 9)POS] 3 } n , and {Fe[(C 2 H 5)(C 4 H 9)PS 2 ] 3 } n have been synthesised using iron (III) acetylacetonate as iron precursor and a succession of ligands derived from phosphinic acid: ethylbutyl-phosphinic acid, ethylbutylthio-phosphinic acid, and respectively ethylbutyldithiophosphinic acid. Chemical analysis, gel-chromatography, infrared spectroscopy (IR), Mössbauer spectroscopy, X-ray diffraction (XRD) and thermal gravimetric analysis (TGA) have been used as characterization methods. Based on the experimental results and on literature data the structures of the studied compounds were assigned. The organophosphinic acids were also tested as iron chelators for water treatment.

Research paper thumbnail of New complexes of silver (I) with N-hydroxy-succinimide

SPIE Proceedings, 2016

Over the last period of time silver was considerably studied due to its lower resistivity. In the... more Over the last period of time silver was considerably studied due to its lower resistivity. In the field of materials science, silver was used in applications such as: microelectronics components of high – temperature superconductiviting materials, bactericidal coatings and others domains. This study presents the process of obtaining and characterization the new complexes of silver (I) with Nhydroxy- succinimide. In the process of obtaining the new complex compounds in aqous solution, first we have to look at conductometry and UV-Vis absorbtion spectroscopy in order to determine the molar ratio silver : N-hydroxysuccinimide and the stability constants. The obtained solid coordination compounds were characterized by elemental analysis, IR spectroscopy and also was investigated of their thermostability. The X-ray powder diffraction reflects that the complexes compounds of silver (I) with N-hydroxysuccinimide are amorphous. In our further studies we want to determine if the new synthetized compounds will present the same or improuved properties as in the above mentioned silver characteristics.

Research paper thumbnail of Aloe Vera Gel as a Biomordant in the Finishing of Vegetable Textiles: A Review

Zenodo (CERN European Organization for Nuclear Research), Dec 31, 2022

During the dyeing process, the color is maintained over time due to the mordant that creates a st... more During the dyeing process, the color is maintained over time due to the mordant that creates a strong bond between the dye and the fiber. The most common chemical mordants are potassium alum, tartar cream, tin chloride, cupric sulfate, ferrous sulfate and potassium dichromate. The current trend of increasing nature protection requires the use of clean products for the textile finishing sector and the biodegradability of textiles. Aloe vera is known to be a natural mordant. Based on data from the literature, the authors of this paper aimed to identify several behaviors between Aloe Vera gel and textiles. Aloe vera gel macerated on Sida rhombifolia shows (with the residue in the oven) after IR analysis a disappearance of peak 1029 cm-1 which indicated the degree of CO -C bonds of cellulose present in the modification of Sida rhombifolia. The active ingredients of Aloe vera have also been shown to bind to the hydroxyl groups of cotton, which is a crosslinking agent for macromolecules.

Research paper thumbnail of Cochenille red dye decoloration and chromate reduction simultaneously in acid medium

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IX, 2018

During the last century, the synthetic dyes have taken a pivotal role in many domains. Part of th... more During the last century, the synthetic dyes have taken a pivotal role in many domains. Part of this class is the Cochenille Red dye. It can be used as such for wool, nylon, silk, inks, paper, plastics, wood stains, leather tanning and processing. But still in the above mentioned fields it is used as well or even with much better results as ligand being complexed with different metal cations. This domain has been approached by us in previous studies in various papers. The range of use areas is extended for foods drugs, cosmetics, hematology and histology stains and last but not least, in photography, too. Due to these multiple uses, we have found it useful to study its behavior in an acidic medium in the presence of an oxidizing agent. Chromate [Cr(VI)] and azo dyes like Cochenille Red are common pollutants which may co-exist in some industrial effluents. The degradation kinetics of the oxidation process of Cochenille Red dye using inorganic oxidizing agent (K2CrO4) have been investigated under various experimental conditions: different concentrations of H2SO4 [10-2 -5·10-1 M ] and temperatures [296 and 308 K]. A kinetic model for oxidation of Cochenille Red dye by the combination of chromate was developed based on experimental results. The thermodynamic activation energy was calculated from the rate constants of the oxidation process of the dye, measured at two different temperatures, 296 and 308 K. We concluded that the negative value of entropies of activation indicate that the reaction occurs between ions of similar charge. Based on our experimental and literature data , we conclude that the destruction of azo-chromophore group by the inorganic oxidizing agent (K2CrO4) is explained by the highest oxidation state of this dye.

Research paper thumbnail of COMPOUNDS OF Ti ( IV ) AND Zr ( IV ) IN AQUEOUS SOLUTIONS : SYNTHESIS , STABILITY AND APPLICATION IN CLEANER TECHNOLOGIES OF NATURAL

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: TiOSO4·2H2O and ZrOCl2·8H2O 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...

Research paper thumbnail of Coordination Compound of Fe(III) with N,N'-bis(salicylidene)-methylenediamine

The bis-Schiff base, N,N’-bis(salicylidene)-methylenediamine, (H2L1) known as Salmen, forms toget... more The bis-Schiff base, N,N’-bis(salicylidene)-methylenediamine, (H2L1) known as Salmen, forms together Fe(III) at low acid pH a brown precipitate, which is stable at room temperature. Study of the IR spectroscopy and the chemical analysis has evidenced that the precipitation form is a complex and the combination ratio of M:L is 1:1. The precipitation form will be used as a method for the gravimetric determination of Fe(III) with Salmen. The precipitate was dried at room temperature at constant weight and weighed as C15H12O2N2Fe(OH).2H2O. The analytical application presents an average relative error of + 0.5 %, and interferences with Cu(II), Zn(II), Cr(III), Mn(II), Ni(II), U(VI) and Co(II).

Research paper thumbnail of Synthesis and Study of Some Coordination Polymers of RH(II) with Diphenylphosphinic Acid Derivatives as Ligands

Revue Roumaine De Chimie, 1997

Research paper thumbnail of NEW COMPLEX COMPOUNDS WITH b-AMINOISOBUTYRIC ACID BIDENTATE LIGAND FOR POTENTIAL APPLICATION IN SUSTAINABLE AGRICULTURE

Environmental Engineering and Management Journal, 2018

The synthesis and the study of the complexes obtained in this paper represent the beginning of ou... more The synthesis and the study of the complexes obtained in this paper represent the beginning of our research for applied coordinative compounds of this type in agriculture. The analysis and the study of Mn(II) complexes with DL-β-Aminoisobutyric acid as ligand were accomplished in aqueous and alcoholic solution and also in solid state.The composition ratios and the stability of the synthesised compounds were analysed with specific methods: conductance, pH measurements, spectrophotometry and thermogravimetry. There were obtained two complexes, at the metal:ligand molar ratio 1:1 and 1:2. In order to determine the structures of the new compounds, the following methods were applied: chemical analysis, IR, UV-VIS and XRD spectroscopy. The [MnLCl]2ꞏ2/5H2O and [MnL2]ꞏ1/2H2O presented a triclinic and respectively, monoclinic crystalline structure. From the thermal decomposition data, the kinetic parameters of the studied compounds were calculated observing that both new complex compounds have a higher thermal stability than the ligand. The experimental data confirmed that ligand DL-β-Aminoisobutyric acid presented a bi-dentate behavior towards Mn(II) ions in solution.

Research paper thumbnail of Electrochemical Sensors for Heavy Metal Ions Detection from Aqueous Solutions

Environmental Engineering and Management Journal, 2012

Due to the major negative impact of heavy metal ions toward human health and environment,, even a... more Due to the major negative impact of heavy metal ions toward human health and environment,, even at low concentrations, the development of simple, fast and not expensive detection methods of heavy metals is a major challenge for the scientists. Among the different analytical methods for the analysis of heavy metal ions, the corresponding methods based on electrochemical sensors are discussed in this review, due to their above mentioned advantages. Several types of electrochemical sensors and their analytical applications based on electrochemical methods such as: potentiometry, voltammetry and amperometry, are presented. The electrochemical sensors could revolutionize the field of real-time and on-line environmental analysis, due to their high performances as: low detection limits, a wide linear response range, good stability and reproducibility.

Research paper thumbnail of THE CHARACTERIZATION AND THE SYNTHESIS OF A NEW COORDINATION COMPOUND FOR REMOVAL OF Cr(III) FROM WASTEWATERS

Environmental Engineering and Management Journal, 2010

The Schiff base N,N'-(salicylidene)-methylenediamine, known as Salmen in combination with Cr(III)... more The Schiff base N,N'-(salicylidene)-methylenediamine, known as Salmen in combination with Cr(III) forms at pH = 4.5 a greenish precipitate, which is stable at room temperature but decomposed on heating. The study of the Infrared spectra, Electron Spin Resonance (ESR), X-ray diffraction and thermogravimetry has pointed out that the precipitation form is a complex, while the molar ratio showed that the combination rate of Cr(III): N,N'-bis(salicylidene)-methylenediamine is 1:1. The new complex crystallizes in the triclinic systems. This precipitation reaction can be used as a method for the gravimetric determination of Cr(III) with N,N'-bis(salicylidene)-methylenediamine, known as Salmen The precipitate was dried in vacuum and weighed as C 15 H 13 O 3 N 2 Cr. The overage relative error is ± 0.33%. Salmen can be used in order to precipitate and to recover the chromium from wastewaters consequential to the tanning of natural fells.

Research paper thumbnail of New Complexes Used to Increase the Dying Process Efficiency of the Textile Materials in the Context of Sustainable Development

Environmental Engineering and Management Journal, 2010

This work presentes a study of preparation and stability in aqueous medium of complexes obtained ... more This work presentes a study of preparation and stability in aqueous medium of complexes obtained by the reaction between Fe(III) with 2-amino-6-methoxy-benzothiazol-sodium sulphonate →1 naphtol-4-sodium sulphonate. In this purpose, the investigation methods applied were as follows: pH-metry, conductometry, and the UV-VIS spectrophotometry. The molar combination ratio of ligand to central metallic atom, and the stability constants for new obtained compounds were determined using "molar ratio method" (Yoe and Jones), "Continuous Variation" method (Job) and Harvay-Manning method. Based on the investigations performed, these compounds might be employed for dying white woolen fibers, to obtain colors from blue to violet. The resulted colors after dying are very homogenous and intensive. The exhausted dying bath was about 98% from the complexed compound of Fe(III) with 2-amino-6-methoxybenzothiazol-sodium sulphonate→1 naphtol-4-sodium sulphonate obtaining in acid medium and 30 % from the free dye. Another practical aspect is related to the possibility of iron recovery from the residual processing solution, solving in this way both the environmental problems and technological aspects from the dyeing process in textile industry.

Research paper thumbnail of NEW Ni(II) COORDINATION POLYMERS WITH INSULATING AND ANTICORROSIVE PROPERTIES

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.

Research paper thumbnail of New Coordination Compounds of Fe(III) with Organic Ligands

Revista de Chimie, 2009

In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands deriv... more In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands derived from: 2-(4-chloro-phenylsulfanyl)-1-(2-hydroxy-3,5-diiodo-phenyl)-ethanone (HL1), 1-(3,5-dibromo-2-hydroxy-phenyl)-2-phenylsulfanyl-ethanone(HL2), and 2-(4-chloro-phenylsulfanyl)-1-(3,5-dibromo-2-hydroxy-phenyl)-ethanone (HL3) is presented. The characterization of these complexes is based on method as: the elemental chemical analysis, IR and ESR spectroscopy, M�ssbauer, the thermogravimetric analysis and X-ray diffraction. Study of the IR and chemical analysis has evidenced that the precipitates form are a complexes and the combination ratio of M:L is 1:2. The central atoms of Fe(III) presented paramagnetic properties and a octaedric hybridization. Starting from this precipitation reactions, a method for the gravimetric determination of Fe(III) with this organic ligands has been possible. Based on the experimental data on literature indications, the structural formulae of the complex ...