Volume 12, No. 4 (2011)
Articles
IN MEMORIAM: PROFESSOR STELIAN PETRESCU (1951 – 2011)
IOAN MĂMĂLIGĂ
Today, I want to believe in the old saying that the soul, the spirit of the departed lingers on for a while among the living. I like to believe our homage here today will somehow reach Stelian Petrescu, our professor, colleague, mentor and coworker, who put his passion, talent, love and devotion into serving the chemical engineering school in Iaşi. His life and work have been closely related to our Faculty of Chemical Engineering and Environmental Protection. In 1975, he graduated from the Faculty of Industrial Chemistry of the Polytechnic Institute with a degree in the Technology of Inorganic Substances, and in 1980, he went on to teach at the “Gheorghe Asachi” Technical University in Iaşi, where he gradually built an exceptional career. In 1987, he earned a PhD in chemical engineering, and he became a full professor in 1996. A hard worker and brilliant researcher, Professor Petrescu has published over 15 books and textbooks and over 150 valuable scientific articles. He was also the author of over 40 patents, many of which received awards at international invention fairs. An outstanding member of the group of teachers with the Chemical Engineering Department, which he has run and coordinated for a long time, he has contributed to the education of over 30 generations of engineers and the development of a new generation of doctors in chemical engineering. He was beloved and held in high regard both by his students and his colleagues. Professor Petrescu has left this world prematurely, unexpectedly and unjustly. We will all miss him and will surely remember all the wonderful times we spent together. On behalf of his colleagues and students, I would like to extend my deepest condolences to his family. May he rest in peace.
REMOVAL OF AN ACID DYE FROM AQUEOUS SOLUTIONS BY ADSORPTION ON A COMMERCIAL GRANULAR ACTIVATED CARBON: EQUILIBRIUM, KINETIC AND THERMODYNAMIC STUDY
MARIUS SEBASTIAN SECULA(1*), BENOÎT CAGNON(2), IGOR CREŢESCU(1), MARIANA DIACONU(1), STELIAN PETRESCU(1)
The present paper approaches the study of the adsorption of an acid dye on a commercial granular activated carbon (GAC). Batch experiments were conducted to study the equilibrium isotherms and kinetics of Indigo Carmine on GAC. The kinetic data were analyzed using the Lagargren, Ho, Elovich, Weber-Morris and Bangham models in order to establish the most adequate model that describes this process, and to investigate the rate of IC adsorption. Equilibrium data were fitted to Langmuir and Freundlich isotherms. Langmuir isotherm equilibrium model and Ho kinetic model fitted best the experimental data. The effects of temperature (25 – 45 °C), initial concentration of dye (7.5 – 150 mg•L−1), GAC dose (0.02 – 1 g•L-1), particle size (2 – 7 mm in diameter), solution pH (3 – 11) on GAC adsorption capacity were established. The adsorption process is found to be favored by a neutral pH, high values of temperature and small particle sizes. The highest adsorption capacity (133.8 mg•g-1) of the GAC is obtained at 45 °C. The removal efficiency increases with GAC dose at relatively low initial concentrations of dye. Thermodynamic parameters such as standard enthalpy (H), standard entropy (S) and standard free energy (G) were evaluated. The adsorption of Indigo Carmine onto GAC is an endothermic process.
ALTERNATIVE AND COMPLEMENTARY SYNTHETIC APPROACHES TO β CARBOXY-α-METHYLENE-γ-BUTYROLACTONE ETHYL ESTERS<br/> STRATÉGIES DE SYNTHÈSE ALTERNATIVES POUR L'ÉCHAFAUDAGE D'ESTERS ÉTHYLIQUES DE β CARBOXY-α-MÉTHYLÈNE-γ-BUTYROLACTONES
GWENAËLLE LIBERGE(1, 2), STEPHANE LEBRUN(1, 2), AXEL COUTURE(1, 3)ANDPIERRE GRANDCLAUDON(1, 2*)
Alternative synthetic approaches to a variety of β substituted and carboxylated α-methylene-γ-butyrolactones have been developed. In the first approach the mandatory methylene unit was incorporated on precursor compounds at early stage of the synthesis on reliance with Horner-Emmons protocol. In the alternative approach which further tolerates multifarious substituents at γ-position of the lactone template the unsaturated moiety α to the lactone carbonyl group is connected at a later stage through a deprotonation / methoxymethylation / elimination sequence.
CHARACTERIZATION OF RUTIN-CYCLODEXTRIN INCLUSION COMPOUNDS
ANDREIA CORCIOVA(1), DAN CASCAVAL(2*)
The objectives of this study were to examine the potential of beta-cyclodextrin to improve the solubility of rutin and obtain inclusion compounds that were analyzed by different techniques: UV-Vis, IR spectroscopy, thermal analysis. The presence of β-cyclodextrin raises the content of rutin in water. The inclusion compounds were prepared by dry mixing, complexation in semisolid and liquid medium in 1:2 molar ratio rutin - β-cyclodextrin. The UV-Vis and IR analysis demonstrated the obtaining of inclusion compounds and the thermal analysis show that these compounds are more stable than the parent substance.
THERMALLY CLEAVABLE HYBRID MATERIALS
CONSTANTIN GAINA, OANA URSACHE, VIORICA GAINA(*)
Thermally cleavable hybrid materials were prepared by the Diels-Alder cycloaddition reaction of poly(vinyl furfural) to N phenylmaleimido-N’-(triethoxysilylpropyl)urea followed by the sol-gel condensation reaction of trietoxysilyl groups with water and acetic acid. Thermal and dynamic mechanical analysis, dielectric and FTIR spectroscopy were used to characterize the structure and properties of the composites. The size of the inorganic silica particles in the hybrid material varied dependent on the silica content. The DSC study of the prepared materials revealed that the cleavage process of the formed cycloadducts takes place at temperatures varying between 143-165°C and is an endothermic process.
NEW MX<sub>2</sub> OXALATO POLYNUCLEAR ADDUCTS (M = Cd, Hg, Zn; X = Cl, Br): SYNTHESIS AND INFRARED STUDY
HAYAT QAMAR-KANE, ALIOUNE FALL, LIBASSE DIOP(*)
Nine mono-, di- and trinuclear MX2 oxalato adducts have been synthesized, their infrared study carried out. The suggested structures are ionic, the oxalate anion behaving as a chelating ligand. Cage structures, when non symmetrical cations are involved,have been suggested.
INDICATORS FOR SUSTAINABILITY IN INDUSTRIAL SYSTEMS. CASE STUDY: PAPER MANUFACTURING
MARIA EMILIANA FORTUNĂ, ISABELA MARIA SIMION, MARIA GAVRILESCU(*)
The paper describes a framework for promoting sustainability by using indicators for sustainable production. The concept of sustainable production is described as it is viewed by various organisms actions involved in the analysis of the sustainable industrial systems. The measure of sustainability is approached considering indicators of sustainable production, addressing both their dimensions and qualitative and quantitative features. The proposed framework refines the sustainability dimension for a case study which envisages sustainability in paper manufacturing. The analysis takes into account the life cycle analysis for the considered process since the environmental impact is seen as an essential sustainability indicator. Paper recycling and reuse is associated environmental and social costs, as a preferred alternative in waste minimization hierarchy in the manufacturing of non-trees eco-friendly paper. Proactive initiatives to improve the environmental performances of production process are considered as powerful tools for improving the paper manufacturing environmental footprint.
THE USE OF FLUORIDE CONTAINING MINERAL WATER IN WORT PRODUCTION
GUNKA YONKOVA, VANJA ZHIVKOVA, ANDRIANA SURLEVA(*)
The present work aims to study the quality of wort produced using fluoride containing mineral water. The results show that the mineral water has a negative impact on the enzymatic destruction of starch, proteins, color intensity and pH of the wort. The changes of pH during mashing process using tap and mineral water was studied. The lower acidity of wort obtained using mineral water didn’t change during the brewing process. The fluoride content of beer is lower than 5 mg.L-1 when wort is produced using mineral and tap water in 1:1 ratio and citric acid for pH correction. At the same time, the final degree of fermentation, α-amine nitrogen content and the intensity of color of produced wort are close to the control sample. The changes in fluoride ion concentration are monitored using ion-selective potentiometry. The fluoride content is decreased from 5.7 to 4.75 mg.L-1, the most intense change is observed during the mashing process.
THE INFLUENCE OF THIAMINE IN THE FERMENTATION OF THE WINE YEASTS
OVIDIU TITA, LETITIA OPREAN, MIHAELA TITA, ENIKO GASPAR, NICOLETA MANDREAN, MARIANA PACALA, ECATERINA LENGYEL(*)
Due to the enzymatic equipment, the yeast cell produces alcoholic fermentation by the meaning of a zimazic complex which catalyzes in different stages the redox processes of the carbohydrates, which are able to ferment, ultimately leading to ethanol. The fermentation rate is an exponential function being influenced by the cells concentration in the development environment and the starter cultures of micro-organisms. Most of the yeast strains do ferment some substrates rich in hexosanes and oligoglucides: sucrose, maltose, raffinose, lactose and celobiose. The biomass quantity may be increased in various ways. An important aspect in the increasing of the multiplication rate of the yeast cells is the determination of the optimum growing conditions. Some kinetic dependencies, mono and multi-factorial, have been observed; they describe the impact of the concentration of the base components in the nutrient environment, temperature, pH, mixing intensity on the multiplication rate of the yeasts.
RHEOLOGY OF CHICKPEA PROTEIN CONCENTRATE DISPERSIONS
AURELIA IONESCU(1), IULIANA APRODU(1*), GABRIELA GURAU(2), IULIANA BANU(1)
Chickpea proteins are used as ingredients in comminuted sausage products and many oriental textured foods. Rheological behaviour of chickpea protein concentrate was studied using a controlled stress rheometer. The protein dispersion prepared with phosphate buffer at pH 7.0 presented non-Newtonian shear thinning behaviour and rheological data well fitted to the Sisko, Carreau and Cross models. The viscoelastic properties of the chickpea protein suspensions were estimated by measuring the storage and loss moduli in oscillatory frequency conditions (0.1-10 Hz) at 20°C. Moreover, thermally induced gelation of the chickpea proteins (16, 24 and 36%) was studied at pH 7.0 and 4.5 in the temperature range 50 to 100oC and salt concentration ranging from 0 to 1 M. Gelling behaviour was quantified by means of dynamic rheological measurements. Gels formation was preceded by the decrease of storage modulus and loss moduli, coupled with the increase of the phase angle (delta). The beginning of thermal gelation was influenced by protein concentration, pH and salt level. In all studied cases, storage modulus increased rapidly in the temperature range 70-90°C. All rheological parameters measured at 90°C were significantly higher at pH 4.5 compared to pH 7.0.
MORPHOLOGICAL CHANGES DURING GERMINATION AND GROWTH OF RAPESEED SAMPLES (Brassica napus) EXPOSED TO NON-IONIZING RADIATION
IULIANA MIHAELA LAZĂR(1, 2), DANIELA NICUŢĂ(3), ELENA TROTUŞ(4), IRINA IFRIM(1*)
The UV-A radiation acts on cellular constituents indirectly through oxidative mechanisms involving the radicals’ formation. These species have a relatively short lifespan, but are highly reactive, reacts with most cellular constituents: nucleic acids, proteins, lipids, polysaccharides. The rapeseed samples provided by Agricultural Research Center Secuieni, Neamţ (Romania) were irradiated with a wide band source (UV-B, UV-A, visible) with different non-radiation doses, equivalent to several hours of sun exposure. The exposure to UV radiation determines changes in the metabolism, within the growth and development processes, having positive or negative influences on plant health and vitality. The purpose of this study is to analyze different rapeseed samples in order to identify the differences according to non-radiation effect. Regarding the growth and development of height stems it has been observed that roots length and stem height of rape samples are highest at irradiation time around 280 minutes.
MODELING OF THE THERMO-PHYSICAL PROPERTIES OF GRAPES JUICE III. VISCOSITY AND HEAT CAPACITY
ANDREI I. SIMION(1*), PAULA E. DOBROVICI(2), LĂCRĂMIOARA RUSU(1), LUCIAN GAVRILĂ(1)
When optimizing the process of grapes juice manufacture not just to obtain an excellent quality, but also to develop a data base is essential to know the evolution of physical properties, such as viscosity or heat capacity elevation. These properties are affected by temperature and dry matter content. The aim of this study was to establish a mathematical relation between these variables. In order to assess and select a suitable mathematical model the known data were fitted in different equations. Tests results have shown that at constant dry matter content the temperature and the viscosity are related by an exponential equation while between temperature and heat capacity variation a “heat capacity” model seems to be the most appropriate.
AMINO-2-ETHANE SULFONATO MX<sub>2</sub> (M = Zn, Cd, Hg, X = Cl, Br) ADDUCTS: SYNTHESIS AND INFRARED STUDY
DINORA DE BARROS, LIBASSE DIOP(*)
Eight amino-2-ethane sulfonato MX2 adducts have been synthesized, their infrared study carried out. The structures are discrete, the anion behaving mainly as a chelating ligand and in the dinuclear adducts as a bichelating ligand.
SYNTHESIS OF ALLYL PHENYL ETHER AND CLAISEN REARRANGEMENT
GAGIK TOROSYAN(1*), DEZY HOVHANNISYAN(2)
It has been established the possibility for phenol allylation on natural zeolites and them analogs. Here is demonstrated the synthesis of allyl phenol, which has wide industrial applications. The offered method in comparison with the traditional methods has more advantages – higher selectivity, smaller material and power resources consumption. It has been obtained the mixture of allylating phenols (30%) in general with allyl phenyl ether (1) with 80% yields. At 600 K is obtained allylphenyl ether, at 700 K beginning the formation of allyl phenols, which is the result of direct C-allylation of the aromatic ring. It has been investigated the possibility of Claisen rearrangement in the same conditions. All of that are established by gas-liquid chromatography and liquid chromatography data.
BINDING ISOTHERMS SURFACTANT-PROTEINS<br/> ISOTHERMES DE LIAISON SURFACTANT-PROTEINES
ELENA IRINA MOATER(*), CRISTIANA RADULESCU, IONICA IONITA
The interactions between surfactants and proteins shows some similarities with interactions between surfactants and polymers, but the hydrophobic amphoteric nature of proteins and their secondary and tertiary structure components make them different from conventional polymer systems. Many studies from the past about surfactant - proteins bonding used the dialysis techniques. Other techniques used to determine the binding isotherm, included ultrafiltration, ultracentrifugation, potentiometry, ion-selective electrode method and surface tension. High affinity isotherms which are typical of an anionic surfactant - protein bonding, exhibit an initial increase steep followed by a slow growth region and then a vertical growth above a certain concentration. This isotherm is typical of ionic surfactant to protein binding. Often the high affinity initial bond appears at very low concentrations of surfactant and therefore in some protein-surfactant systems, the exact shape of the isotherm in this region may be missing. The surfactant - protein binding is influenced by a number of variables such as the nature and chain length of surfactant, pH, ionic strength, temperature, nature of this protein and additives.