Volume 9, No. 2 (2008)
Articles
THE SOLUBILITY OF CARBON DIOXIDE IN AQUEOUS SOLUTIONS OF N-METHYLDIETHANOLAMINE (MDEA) AND TRIETHYLENE TETRAMINE (TETA). 2. MODELING LA SOLUBILITE DU CO2 DANS DES SOLUTIONS AQUEUSES DE N-METHYLDIETHANOLAMINE (MDEA) ET TRIETHYLENE TETRAMINE (TETA). 2. MODE
JEAN-MARC AMANN, CHAKIB BOUALLOU*
A new solvent based on a blend of N-methyldiethanolamine (MDEA) and Triethylene Tetramine (TETA), an amine very reactive with CO2, was proposed for CO2 post-combustion capture in power plants. The new solubility data generated in our experimental work (Part I) were modelled with the Non Random Two Liquids (NRTL) electrolyte model. The chemical reactions used for the data regression are those relating to the H2O-MDEA-CO2 system and two reactions with TETA: amine dissociation and bicarbamate reversibility to bicarbonate. Objective function is of the Maximum likelihood type. Twenty-two parameters have been regressed on the whole experimental data: pressure, temperature, compositions of the liquid and gas phase (198 experimental points). These parameters are the reaction equilibrium constants of the chemical reactions including TETA, the binary interaction parameters between MDEA and TETA and the electrolytic interaction pair’s parameters relating to the NRTL electrolyte model. The average relative deviation on the pressure was calculated for each solvent. The deviation is acceptable, with a value ranging between 12.8 and 23.2%. For the solvent with the higher ratio between TETA concentration and MDEA concentration, the deviation is higher at 38.2%. The average and high pressures are well represented by the model. The error is more important at low CO2 loadings.
INFLUENCE OF THE CHEMICAL PROPERTIES OF THE GEOLOGICAL FORMATIONS ON THE MIGRATION PARAMETERS OF THE RADIONUCLIDES FROM SALIGNY REPOSITORY
DANIELA DOGARU (1)*, ORTENZIA NICULAE(2), GHEORGHITA JINESCU(3), OCTAVIAN G. DULIU(4)
The radionuclide concentration into the disposal system compartments of Saligny near surface repository is used as safety indicator in order to demonstrate the safety. The disposal system of Saligny near surface repository consists of waste form itself, engineered barriers and natural barriers. The conceptual model of Saligny near surface repository as well as the natural barriers characteristics are described. For the aim of calculation, the disposal system is splitted into eight compartments: waste form, slab foundation, foundation ground, silty loess, clayey loess, red clay, pre-quaternary clay, Barremian limestone. The concentration of the 3H, 60Co, 137Cs, 14C, 90Sr, 99Tc and 129I isotopes in each disposal compartment of Saligny repository is calculated by using AMBER computer code and graphically represented. In order to demonstrate the safety of the disposal system, the calculated values of safety indicators are compared with the regulatory limits for drinking water.
EFFECT OF pH ON THE REMOVAL OF METHYLENE BLUE FROM SYNTHETIC AQUEOUS SOLUTION BY A NATURAL WASTE MATERIAL: ALMOND PEEL EFFET DU pH SUR L’ELIMINATION DU BLEU DE METHYLENE EN SOLUTION AQUEUSE SYNTHETIQUE PAR UN MATERIAU DECHET D’ORIGINE NATURELLE: LA PEAU D
HOUCINE BENAISSA*
In this research, the effect of initial pH of solution on the removal of methylene blue from synthetic aqueous solution by a waste material namely almond peel was studied. The present study reports its sorption potential through kinetics tests and sorption isotherms at 25 °C, in batch conditions. As results obtained here, the initial pH of dye solution has an influence on the kinetics and equilibrium of methylene blue sorption by almond peel. As the initial pH of solution increased, the amount of methylene blue sorbed at equilibrium increased. The optimum initial pH for the removal of dye was about 6. The necessary time to reach equilibrium was initial pH dependent and was in the range of 6 – 8 hours. The results showed that the process followed a pseudo second-order kinetics. Langmuir model gave an acceptable fit to the experimental data over the whole equilibrium dye concentrations range. A high maximum dye sorption capacity was observed by this sorbent material: about 128.53 mg/g at pH0 = 6.
PILLARED CLAYS AS ADSORBENTS FOR SOME ACID DYES
INGRID BUCIŞCANU(1)*, STELIAN S. MAIER(1), VIORICA DESELNICU(2)
This paper is dealing with the obtaining of some pillared smectites (SmP) and with the assessment of their adsorptive affinity for several azoic acid dyes, used for leather and fur dyeing. Three SmPs were obtained by the reaction between a native Na-smectite (Sm) and partially hydrolyzed solutions of: AlCl3 (PAC), FeCl3 (PFC) and Fe2(SO4)3 (PFS). The adsorption capacity of three acid dyes – Acid yellow 166, Acid Red 337 and the Acid Green 73 1:2 Cr-complex, was determined at pH = 5.5, over a 25 ÷ 300 mg/L dye concentration range and adsorbent dosage of 2 g/L. The minimal metal/Sm ratios required for a permanent pillaring effect are: 3 mmol Al/g Sm and 4 mmol Fe/g Sm, respectively. The adsorbents efficiency decreases in the order: Sm-PAC > Sm-PFC > Sm-PFS, while the dyes adsorption capacity decreases as follows: Yellow > Green > Red. The maximum uptake was of 232 mg Yellow dye/g Sm-PAC and the minimal uptake was of 28.35 mg Red dye/g Sm-PFS. The S-shaped experimental adsorption isotherms confirm the SmPs mesoporous solids behaviour.
NOVEL FERRIC SULFATE – BASED COAGULANTS
INGRID BUCIŞCANU*, MELINDA PRUNEANU, VASILICA MAIER
This paper is dealing with the obtaining of some coagulants from the polyferric sulfate (PFS) and Fe-based metal-polysilicate (PFSiS) classes and the preliminary assessment of the products performances. A series of partially hydrolyzed ferric solutions were obtained starting from copperas (FeSO4•7H2O), using exclusively hydrogen peroxide (H2O2) as oxidation – basification agent, in a molar ratio FeSO4/ H2O2 = 1:1 and FeSO4/H2SO4 molar ratios, from 20:1 to 2:1. The basification degree and stability of the basic Fe(III) salt solutions are mainly controlled by the FeSO4/H2SO4 ratio; FeSO4/H2SO4 ratios between 2.03:1 and 5:1 result in extremely stable solutions. The PFSiS coagulants were obtained through a modified copolymerization technique, involving the in situ generation of silicic acid (SA) at a Si/Fe molar ratio of 1:10, followed by oxidation-basification. Stable solutions were obtained over a narrow FeSO4/H2SO4 range, located around 2.5:1. All the solutions were characterized in terms of Fe(III) and residual Fe(II) concentration, free acidity, density, stability and time evolution of basicity. The coagulation tests indicate improved coagulation ability of the prehydrolized coagulants over the ferrous salt.
HEAVY METALS ANALYSIS IN SOME MOLLUSKS SHELLS FROM BLACK SEA
MAGDALENA MITITELU(1)*, ELENA DOGARU(1), TEODOR O. NICOLESCU(2), LUCIAN HÎNCU(3), ANA BĂNCESCU(4), CORINA IONIŢĂ(1)
This work presents aspects regarding some heavy metals (Cd, Pb, Cu and Zn) concentration in shells of different mollusks (Mytilus galloprovincialis, Rapana thomasiana, Mya arenaria, Scapharca) collected from the Romanian Black Sea Coast (Mamaia zone), in August 2007. The heavy metals were analyzed using atomic absorption spectrometry. We used atomic absorption spectrometry to establish the concentration of heavy metals: Cd (? = 228.8 nm), Cu (? = 324.7 nm), Zn (? = 213.9 nm) and Pb (? = 217 nm). We observed a high concentration of Zn in the Mytilus [22.99 ?g•g-1] and Rapana [16.82 ?g•g-1] samples comparing to the other samples. In the Rapana samples we have detected the lower concentration in Cu [5.88 ?g•g-1]. In the shells samples of Rapana we have detected the highest concentration in Cd [0.94 ?g•g-1]. The shells of Scapharca have presented the lower concentration in Pb [3.11 ?g•g-1]. In Mya arenaria samples it has been detected the highest concentration in Pb [9.93 ?g•g-1].
CORRECTION OF THE ENZYMATIC DEFICIT OF WHEAT FLOURS
IULIANA BANU(1)*, VIOLETA IONESCU(2), GEORGETA STOENESCU(2)
In the last years’ crop, the flour obtained in the Romanian wheat grinding showed an enzymatic deficit. The purpose of this paper was to correct the rheological indices of the wheat flour using an ameliorator based on enzymes, soybean flour and emulgator. The rheological determinations were made using the following equipment: the Alveograph NG Chopin, the Rheofermentometer F3 Chopin and the Mixolab Chopin. The results show that a significant improvement of the rheological parameters occurs for the doses of 0.6 – 0.1% enzymatic ameliorator. The slope ß which indicates the gelatinization rate significantly decreases from 0.568 Nm/min to –0.014 Nm/min, for the witness sample, and the couple C5 that characterizes the starch retrogradation during the cooling stage also shows smaller values. These results obtained for the additivated samples help in obtaining bakery products with high volume and porosity.
STUDY ON THE CROSSLINK-INDUCED RADICAL INTERCOUPLING BETWEEN ATELOCOLLAGEN AND IN SITU-GENERATED (CO)POLYMERS
STELIAN S. MAIER*, VASILICA MAIER, MELINDA PRUNEANU
The paper presents a study on the obtaining of collagen-based interpenetrated and intercoupled networks, involving short chains of (co-)polymers as linking bridges, in order to generate loose hydrogels with a definite rheological personality, enabling convenient handling for cell culture techniques. The steps involved are: (i) obtaining tactoidal atelocollagen entities, by transglutaminase assisted cross-linking, (ii) atelocollagen conjugation with glycidil methacrylate (GMA), in order to attach ethylenically unsaturated functions and (iii) involving these functions in radical (co-)polymerization with GMA or other biotolerable monomers. The (co-)polymerization process is induced at low temperature (below 6 °C), using a ternary initiator mixture including H2O2, ascorbic acid (AA) and uric acid (UA). The optimal composition of the mixture, which assure a minimal gelation time (640 min) and a maximal hydrogel consistency (0.61 Pa•s), comprises 0.67 H2O2, 0.22 AA, 0.11 UA expressed as mass fractions.
ON ENCAPSULATING AND DELIVERY OF POLYPHENOLS IN SUPERPARAMAGNETIC POLYMER NANOSPHERES
VASILE BADESCU(1)*, LAURA E. UDREA(1), OVIDIU ROTARIU(1), RODICA BADESCU(2), GABRIELA APREOTESEI(2)
In this work we report on an encapsulating and delivery study of a red grape skins antioxidant extract (polyphenols) in a superparamagnetic composite matrix. The encapsulating matrixes used were sodium alginate base aqueous ferrofluid, obtained by an in situ precipitation of magnetite, and chitosan in acetic acid. Red grape skins lyophilized extracts were encapsulated with two different systems: calcium alginate and calcium alginate–chitosan. FT-IR spectra were useful to confirm the interaction of the two polysaccharides. DLS measurements allowed determining the average size and size distribution of the polymeric nanoparticles encapsulating polyphenols. Transmission electron microscopy (TEM) of nanoparticles allowed studying their morphology and polydispersity. Release of the antioxidants in water was measured to analyze the diffusion and kinetic behavior of the system. Different matrix destabilizing agents (HCl 0.1 N, NaOH 0.1 N and sodium citrate 1 and 10% w/v as a calcium chelator at ambient temperature, and distilled water at 50 and 100 °C) were tested. Sodium citrate was found to be the most effective agent to disintegrate the beads. Superparamagnetic polymer nanoparticles encapsulating polyphenols opens up avenues for targeted therapy of some human diseases that are in part a result of free radical damage.
INORGANIC-ORGANIC HYBRIDS FOR ADVANCED COMPOSITES OBTAINING
ANDREI A. SARBU(1)*, ANITA-LAURA C. RADU(1), LUMINITA A. MARA(2), VICTOR V. FRUTH(3), GHEORGHE G. NECHIFORI(4), STEFANIA S. MOTOC(5), STEFAN-OVIDIU O. DIMA(1), MARIANA M. BEDA(1)
Hybrid inorganic-organic nanocomposites were synthesized in order to subsequently generate silicon nitride by carbothermal nitridation. We intended to obtain in this manner an extraordinary ceramic material, with important characteristics: thermal resistance over 1400 °C, small dilation modulus and reduced friction coefficient. The radical polymerization of acrylonitrile took place in nanoporous silica, by the initiation with azoizobutirodinitrile (AIBN). It was intended to enhance the homogeneity between constitutive parts by a larger period of imbibition of the silica with the monomer, through a better absorption capacity of the silica for the monomer and by the application of ultrasonication technique. In the work different silica samples were used, in different polymerization conditions, by varying the monomer imbibition period and the ultrasonication time. The nanoporous silica and the obtained nanocomposites were analyzed by various methods: BET, DTA, DSC, TEM, SEM, FTIR and XRD. The following conclusions were drawn: ultrasonication is a better way to homogenize the constitutive parts of the hybrid materials; the structural homogeneity of nanocomposites is influenced by the purity of samples; a great importance has also the nature of the mineral acid used for the acid attack of the serpentinite.
THE ENERGY EFFICIENCY OF DIFFERENT PHOTOELECTRODES IN A PHOTOELECTROCHEMICAL CELL (PECC)
ALEXANDRU I. ENESCA*, ANCA DUTA
Hydrogen production via water photolysis represents a topic very much addressed to considering the output – the cleanest fuel – and the problems to be solved, mainly the conversion efficiency. The latest is strongly linked with the photoanod material properties and represents an advanced application of thin films of wide band gap semiconductors. The paper presents a study concerning the energy efficiency of different photoelectrodes used hydrogen production in a photoelectrochemicall cell (PECC). The morphological, electrical and optoelectrical analysis were done considering the influence of bulk and surface composition on the photoelectrolysis process. The contribution of the crystalline structure, morphology and dopants is discussed in terms of optical efficiency for films obtained using an up-scalable technique: spray pyrolysis deposition. The influence of the deposition parameters is also considered correlated with the optimized values.
COMPACT CONDENSED SYSTEMS THIAZOLO – PYRIDINE WITH BIOLOGICAL ACTIVITY REVIEW SYSTÈMES COMPACTS CONDENSÉES THIAZOLE – PYRIDINIQUES AVEC ACTIVITÉ BIOLOGIQUE MISE AU POINT
CRISTIANA RADULESCU*, IONICA IONITA, ELENA IRINA MOATER, CLAUDIA STIHI
In this article are studied some thiazolo-pyridine systems, witch are obtained very easy, but witch present a great stability and a special biologic activity. In medical research the new classes of thiazolo-pyridines and thiazolo-pyridazines are known. These compounds are studied as medicaments with anti-inflammatory and analgesic action. Also, the thiazolo-pyridine products are demonstrated the special antihelminthic properties. In this paper are presented the most recent studies concerning the synthesis, characterization and evaluation of biological and therapeutically activities of the new thiazolo-pyridine systems. The originality of this study consists in the association of more active biological fragments in a single molecule: pyridinic ring or pyridine derivatives, thiazolic ring and other amino-thiazolic, thiadiazolic, and thiazinic, triazinic rings. The chemical structures of these new heterocyclic systems, obtained by chemical syntheses, will be purified by TLC and HPLC methods and characterized by spectroscopic analyses: MS, FTIR, UV-VIS, and RMN. Also, will be concerned the influence of substitutes grafted on aromatic and hetero-aromatic rings for antimicrobial activity.
DEVELOPMENT OF NEW ACCESS ROADS TO THE IMIDAZO[1,2-b]PYRIDAZINS DI- AND TRISUBSTITUTED DEVELOPPEMENT DE NOUVELLES VOIES D’ACCES AUX IMIDAZO[1,2-b]PYRIDAZINES DI- ET TRISUBSTITUEES
AHMED EL AKKAOUI(1 2), JAMAL KOUBACHI(1 2), SABINE BERTEINA-RABOIN(1)*, ABDERRAHIM MOUADDIB(2), GÉRALD GUILLAUMET(1)
In this paper we propose a new efficient and fast strategy for the synthesis of di- and tri-substituted derivates of imidazo[1,2 b]pyridazines via palladium-catalyzed couplings of Sonogashira, Heck and Stille type on the 6 chloro 3 iodo imidazo[1,2 b]pyridazines.
FRESH DAIRY, APPETIZER TYPE: SENSORIAL AND RHEOLOGICAL ASPECTS
ELISABETA BOTEZ, LILIANA GÎTIN, DOINA–GEORGETA ANDRONOIU*, GABRIEL-DĂNUŢ MOCANU
Cheese is the most complex and dynamic food product. By mixing fresh cheese with flavors or salt and other spices it could be obtained fresh dairy appetizer type. Supplements used for the study were: dill, bunch onion, red pepper thinly minced (supplements were included in the coagulum). Fresh cow cheese was analyzed by physical-chemical, rheological and sensorial point of view. The rheological analysis of the appetizer type cheese that was produced aimed at establishing the variation of the dynamic viscosity depending on the share rate, as well as the variation of the share stress depending on the share rate. The variation of these parameters determined the rheological behavior of the appetizer type cheese. During the sensorial analysis of the fresh cow cheese and supplements were taken into consideration the following characteristics: taste, odor, color, consistency and appearance.