Volume 5, No. 1 (2004)
Articles
PROPRIETES PHYSICO-CHIMIQUES DES SOLUTIONS AQUEUSES D’ALCANOLAMINES UTILISEES DANS LE TRAITEMENT DU GAZ
VINEL D.J., BOUALLOU CHAKIB
Dans cet article est proposée une analyse critique des paramètres physico-chimiques utilisés lors de la modélisation et la simulation de colonnes d’absorption et de régénération dans les procédés de traitement de gaz par des solutions aqueuses d’alcanolamines. La realization d’un code de calcul fiable et précis nécessite l’emploi de nombreux paramètres physiques qui permettent de décrire le système. Il est nécessaire de connaître le coefficient de diffusion de chacune des espèces impliquées dans le processus de transfert avec réactions chimiques. Dans les exploitations numériques réalisées dans le cas des systèmes CO2/amines ou CO2/H2S/amines, il faut aussi connaître le coefficient de résistance au transfert côté liquide pour déterminer l’épaisseur du film diffusionnel. La constante de la loi de Henry et le coefficient de résistance au transfert côté gaz sont indispensables pour déterminer la concentration du gaz transféré à l’interface gaz-liquide. De même, la condition limite dans la zone de mélange correspond à l’équilibre chimique des différentes espèces. Il est donc nécessaire de connaître les valeurs des constantes d’équilibres des réactions considérées pour calculer les concentrations des espèces dans la zone de mélange. Enfin, il faut connaître la valeur des vitesses des reactions considérées. La comparaison de ces paramètres aura pour but de s’assurer de leur fiabilité mais également d’homogénéiser l’adjonction de nouveaux paramètres au sein des codes de calcul avec ceux déjà présents. Les valeurs expérimentales ainsi que les corrélations disponibles dans la littérature sont examinées.
MACROCYCLIC DIPHOSPHA-CROWN ETHERS: SYNTHESIS AND ALKALI METAL PICRATE EXTRACTION STUDIES
HANNIOUI A. (1)*, EL MALKI A.(1), RAKIB E. M.(1), KNOUZI N.(2), BERRADA M.(2), EL MALOULI M. B.(3)
A series of cyclic phospha-crown ethers was synthesized through a cyclisation reaction. These compounds were shown to extract alkali metals, ammonium, strontium and calcium ions from the aqueous phase to the organic one. The selectivity in partitioning varied with the relative fit of the ionic radius of the metal ion with the whole size of the macrocycle. For a typical phospa-crown-metal ion combination, the formation of a 1:1 complex was suggested by UV spectroscopy investigation.
ELECTROCHEMICAL REDUCTION OF CF2Br2 ALONE. NUMBER OF ELECTRONS CONSUMED
MEDAGHRI-ALAOUI A.(1)AND(3), CALAS P.(1), CHOUKROUN H.(1), COMMEYRAS A.(1), VERPEAUX J. N.(2), AMATORE C.(2)
Electrochemical reduction of CF2Br2 alone is investigated in DMF. In the absence of an added olefin, the reduction occurs via an overall two-electron ECEC process that proceeds through the intermediary formation of CF2Br.-, CF2Br. and CF2Br- that yields ultimately the carbine: CF2 that reacts with DMF. Also it is possible to determinate the value of the number of electrons consumed directly with the combination of peak current in LSV and limiting current at a rotating disk electrode, we found n = 2, we considered the reduction of CF2Br2 is bielectronic corresponding to the formation of the methide CF2Br-.
SOLVENT EXTRACTION OF COPPER (II) BY SYNERGISTIC MIXTURES OF TRIOCTYLPHOSPHINE OXIDE AND LAURIC ACID
OUKEBDANE K., DIDI MOHAMED-AMINE, AZZOUZ ABDELKRIM(1), VILLEMIN DIDIER(2)*
The liquid-liquid extraction of copper (II) by mixtures containing tri-n-octyl phosphine oxide (TOPO) and lauric acid (LA) was studied. The effects of the concentration of the extracting agent in the organic phase and KCl in the water phase were investigated. The comparison between the results of extraction tests obtained with each separate extracting agent and those obtained with their mixtures, showed a synergistic effect. Yield of 100% in a single stage was attained in the cases of mixture. The ratio TOPO/LA in the complex in cyclohexane solution was determinated as 1: 1. The complex formed in the organic phase may be (CuCl)2 TOPO (LA-H)2. The coordination bonds of the Cu-complex were determined by infrared spectroscopy.
HYDROGELS A BASE DE CARBOXYMETHYLCELLULOSE DESTINES A L’INCLUSION DES MEDICAMENTS
BAJAN N. (1), POPA MARIA (1), POPA MARCEL (2)
RÉSUME: Le travail présente quelques résultats concernant la reticulation de la carboxyméthyl cellulose (sel de sodium) à l’épichlorhydrine, dans un milieu fort basique. On étudie l’influence de certains paramètres de la réaction (température, durée, rapport polymère/agent de réticulation) sur le degré de réticulation, apprécié d’une manière indirecte par le degré de gonflement dans l’eau. Les produits de réticulation présentent un caractère d’hydrogel superabsorbant, le degré de gonflement à l’équilibre prenant des valeurs qui varient entre 200-800 %, en fonction de la valeur des parameters de réticulation. Le degré de gonflement varie en fonction de l’agent de gonflement utilisé: l’augmentation du taux d’alcool dans un mélange eau/alcool diminue par l’augmentation du ce dernier.
TECHNOLOGIE DE FABRICATION DES COMPRIMÉES D’ACIDE ASCORBIQUE. INFLUENCE DES MATERIAUX PRIMES
MATEESCU MONICA*(1), TRANDAFIR ION(1), PETRESCU MANUELA(2)
We studied two different formulas for the tablets, with the addition substance (PVP) for the A formula in the solid state, and for the second formula, B in an aqueous solution. These both formulas were granulated and tableted in order to obtain the ascorbic acid tablets. These tablets were used for the study of the dissolving process of the active principle, and the influence of the PVP on the rate of this process.
EVOLUTION DES BIFIDOBACTERIES DANS LES CULTURES MIXTES AVEC STREPTOCOCCUS THERMOPHILUS ET LACTOBACILLUS HELVETICUS
BARASCU E.
In this study was monitored growth of bifidobacteria in single or mixed cultures with Streptococcus thermophilus and Lactobacillus helveticus with the purpose of fructification the results in the technology of probiotic dairy products. The cultures used in this experiment were inoculated in different proportion in the base medium (milk reconstituted with 12.4% nonfat dry matter) and for diversification the studied variants and the cultivation conditions was used both simultaneous inoculation of the cultures and inoculation with Streptococcus thermophilus and Lactobacillus helveticus after 4 hours from inoculation of bifidobacteria. Concerning the growth of bifidobacteria in mixed cultures with Streptococcus thermophilus and Lactobacillus helveticus was acceptable only in variants with simultaneous inoculation, when the number of cells was greater than the variant with single culture. In consequence, the association of cultures in report of 4:1:1 (bifidobacteria: Streptococcus thermophilus: Lactocillus helveticus) results in obtaining a considerable number of the bifidobacteria(1.13x109 cfu/cm3) after only 6 hours of optimal incubation for this bacteria.
DETERMINATION OF STARCH SUPPLEMENT IN MEAT PRODUCTS (SALAMI)
MIRON DORU NECULAI, DAVIDESCU ALINA, ARTENIE NICOLETA, DRON PAUL IONUŢ
The goal of the present work was to determine the starch supplement in salami type meat products. A percent higher than 0.5% starch in these products shows a supplement with a fraud intention. The analyzed samples were bought from the free market and the experimental protocols that were applied are known from the specialized literature.
OBTAINING WINE COOLER PRODUCTS
DABIJA ADRIANA, SION IULIANA
“Wine coolers” – drinks that can be easily prepared in short time and effortless, accessible and easily distributed, bought everywhere. This study is about the wine cooler obtainment on laboratory scale with red wine and orange juice. The achieved products have sensorial and physic-chemical properties that are specifically related, with two components of blend
THE INFLUENCE OF THE DEBURBAGE AND THE ROLE OF FAT SUBSTANCES IN WHITE WINE MAKING
TITA OVIDIU
The deburbage operation has an important role concerning the alcoholic fermentation of the grapes juices, influencing positively the sensorial quality of the wines and their physical-chemical composition. Through the metabolism of the sweet substances in the process of the alcoholic fermentation, the efficiency regarding the ethyl alcohol is higher in case of the deburbaged juices or with a high content of fat substances which is possible in case the juice is maintained for a long period in contact with the sediment [9 - 11]. After the deburbage, the obtained wines have a relatively low content of fatty volatile acids and a lower content of unwanted smelling substances.
ASPECTS CONCERNING THE BIOCHEMICAL MODIFICATIONS DURING MUSCEL CREAM CHEESE MATURATION
TITA MIHAELA
The scaled cheese has a very important and old tradition in Romania. It is prepared after a special technology, and then follows maturation in certain conditions assuring its specific sensorial characteristics. In this study a series of analysis were made on the fresh product and during the maturation, watching the modifications that took place.
PRODUCTION D’ACIDE LACTIQUE SUR JUS DE DATTE EN CULTURE PURE ET MIXTE PAR LACTOBACILLUS CASEI ET LACTOCOCCUS LACTIS
NANCIB NABIL*, NANCIB AICHA*, BOUDRANT JOSEPH**
Lactic acid is considered as a very important chemical compound with significant applications in pharmaceuticals, cosmetics and especially in the food industry. New applications, such as degradable plastics made from poly(lactic) acid, have the potential to greatly expand the market for lactic acid, if more economical processes could be developed. Industrial processes for the production of lactic acid typically use sucrose from cane and beet sugar, whey containing lactose and maltose and dextrose from hydrolysed starch. Algeria produces more than 400 different varieties of dates with an annual production of over 300.000 tons. However, about 20 % of the production is lost due to over-ripening and improper handling, processing, and marketing. Dates contain large amounts of reducing sugars, especially glucose, fructose and sucrose at levels of (73 – 83 %) (dry basis). The date also contains protein, lipid, fibre, mineral elements and some vitamins. Thus making date extracts quite suitable as feedstock for fermentation. Complex mixed cultures have also been used in several fermentation processes, e.g. the production of ethanol, aspartic, and succinic acid from glucose and lactic acid from starch. Mixed cultures have not been used yet on an industrial scale, because it is difficult to establish optimum culture conditions for both strains for parameters such as nutrient supply, temperature, oxygen demand, pH, etc. Only a few reports concern the production of lactic acid from starch, non-fat dry milk, and whey permeate by mixed cultures in batch fermentation. Lactic acid production from date juice extract by mixed culture of Lactobacillus casei and Lactococcus lactis cells has not been investigated. In this study, date juice was used as substrate for production of lactic acid by single and mixed culture system containing Lactobacillus casei and Lactocccus lactis. One important parameter in sustaining an economically viable production of lactic acid is the interaction between feedstock and microorganism. The bacteria must be able to convert all the available carbohydrates to lactic acid. All experiments were performed as batch. Lactobacillus casei and Lactococcus lactis were incubated at their optimum temperatures of 30 and 38°C, respectively. A temperature of 30°C was used for co-cultivation. In batch culture, the results have shown that the highest concentration of residual date sugar extract was obtained in fermentation with L. lactis while the lowest concentration was found in fermentation with mixed cultures of L. casei and L. lactis. This coincides with lactic acid production. The highest concentration of lactic acid (60 g/l) was obtained in the mixed culture system while in single culture fermentations of Lactobacillus casei or Lactococcus lactis, the maximum concentration of lactic acid was 53 and 46 g/l, respectively. Our results showed an important aspect of lactic acid production from date juice by single and mixed cultures of Lactobacillus casei and Lactococcus lactis. The mixed culture system gave better results than single cultures regarding lactic acid concentration, and sugar utilization. The date juice extract was an attractive medium for the production of lactic acid by single and mixed culture.
INVESTIGATIONS REGARDING THE USE OF SOY FLOUR AND ZARA IN THE BAKERY PRODUCTS
GROSU LUMINIŢA*, LEONTE MIHAI**, PĂDURARU LĂCRĂMIOARA*
This paper evidences the positive influence of the addition of zara, a by product of dairy industry, in order to obtain dough with soy flour. A 34 – 40 % zara addition in the liquid used for the preparation of dough serves as nourishing compound, improves the dough quality and contributes to the decrease of water consumption in dough preparation.
CONTRIBUTIONS REGARDING THE USE OF WHEAT CHAFF AND WHEY IN THE BAKERY PRODUCTS INDUSTRY
GROSU LUMINIŢA*, LEONTE MIHAI**, CIOBANU DOMNICA*, PĂDURARU LĂCRĂMIOARA*
The research program done to obtain bakery products with wealthy fibres content was achieved through the use of wheat chaff, secondary product of wheat flour technology. It was used the whey, secondary product of milk industrialization, for bettering of technological parameters.
CONTRIBUTIONS REGARDING THE USE OF BARLEY FLOUR AND ZARA IN THE BAKERY PRODUCTS INDUSTRY
PĂDURARU LĂCRĂMIOARA*, CIOBANU DOMNICA*, LEONTE MIHAI**, GROSU LUMINIŢA*
The results of research program praised the conditions used to obtain dough through the capitalization of cereals resources with poor gluten content (barley flour) and zara, secondary product resulted from technological process of milk industrialization. Barley flour adding of 6 – 9 % and 40 % zara can be considered sufficient quantities for our goal: dietetic bakery products with reduced gluten content and increased proteins content because of zara adding.
POSSIBILITIES OF EMISSIONS REDUCTION IN NITROGEN-BASED FERTILIZER PLANTS
GAVRILĂ LUCIAN(1), GAVRILĂ DANIELA(2), SIMION ANDREI(1), GRANERO RODRÍGUES ALBERTO JAVIER(3)
The paper compares from the standpoint of harmful emissions typical nitrogen-based fertilizer plants producing ammonia and urea with hypothetical plants using the best available technologies. The critical emission points are established and analyzed. Several possible actions to be taken in order to minimize the emissions are presented.