HIDROFORMILACION DEL OCTENO POR CATALISIS EN FASE ACUOSA SOPORTADA. CINETICA, PARAMETROS DE INGENIERIA Y PROPIEDADES FISICO-QUIMICAS DEL SISTEMA

Los procesos catalíticos se utilizan ampliamente en las industrias química y biotecnológica, especialmente, en la petroquímica, química fina y farmacéutica. En Cuba, con una industria química modesta, los procesos catalíticos desempeñan un papel importante en la mayoría de sus producciones, específicamente en la industria del petróleo y la química de base. La catálisis está igualmente presente en el control de las emanaciones, en las producciones biotecnológicas y farmacéuticas y en la industria alimentaria. El 80 % de los productos químicos pasan, al menos, por una etapa catalítica durante su síntesis. Los procesos catalíticos son cada vez más importantes en la química ambiental y en la producción de alimentos, donde tanto la catálisis convencional como la enzimática representan un papel protagónico. Lo anterior evidencia que los avances de la ciencia y la tecnología han puesto en manos de la sociedad contemporánea miles de productos obtenidos por vía catalítica, que van desde derivados del petróleo hasta los más disímiles principios activos farmacéuticos. Los volúmenes de producción y la complejidad de algunos de estos productos imponen nuevos retos en la búsqueda de procedimientos más económicos desde el punto de vista energético y más seguros para la protecci ón del hombre y el medio ambiente

Chemistry course for radiochemistry engineers on the platform Moodle: a support to self-education for undergraduate students

The education challenges at present times include the incorporation of information and communication technologies (ICT) in the learning-teaching process. In Higher Education the agreement between the volume of information to be processed by the student, the available student’s time and the assimilation of the courses contents is very important. The new study plans in Cuban Universities include the reduction of the number of face to face hours and the increase of the available time for the student’s independent study. Then, it is necessary to develop abilities that upgrade learning capacity during a lifetime through the self-education. The first version of a course on chemistry for radiochemistry students using the platform Moodle and Open Educational Resources (OER) as a support to the undergraduate course is presented. The detailed topic plan of the course of chemistry for radiochemists, which was distributed week by week, and different activities combining communication, interactive and collaborative modules were implemented on the platform Moodle. The whole system was tested during the first semester of the 2010-2011 academic year. The course evaluation results were carried out through a survey among the students and discussion forums. The results showed a good acceptance by the students, a better efficiency in the teaching-learning process given by better planning of the individual study, a better preparation to perform the laboratory practices, the new possibilities of communication between students and teachers, the access to OER and greater self-conscious of the students on their own process of learning

Dynamical Modelling and Simulation of Waste water Filtration Process by Submerged Membrane Bioreactors

A mathematical model was developed for the filtration process and the influence of aeration on Submerged Membrane Bioreactors. The dynamics of sludge attachment to and detachment from the membrane, in relation to the filtration and a strong intermittent aeration, were included in the model. The influence on the membrane fouling of intermittent aeration injected on the membrane surface, and its synchronization with intermittent filtration, were studied numerically and experimentally. For the evaluation of filtration cake development, the assumption of the presence of two cake layers (one dynamic and the other stable) was considered. The model development and simulation focused on the description of existing relationships among important system variables like mixed liquor suspended solids concentration, aeration, temperature of the sludge suspension, transmembrane pressure, and the fouling increase during the filtration process. The model obtained offers the possibility of improving the design configuration and operation strategies of Submerged Membrane Bioreactors in wastewater treatment, and it allows the of aeration-filtration cycles to be optimized

Flow Induced by Dual-Turbine of Different Diameters in a Gas-Liquid Agitation System: the Agitation and Turbulence Indices

Flow induced by a dual turbine stirred tank was characterized measuring local velocities with a LDV and drawing the main velocity fields and the maps of turbulence intensities. The hydrodynamic regime studied in all the experiments was the so-called merging flow regime. Two impeller configurations were studied. In the first one, two disk style turbine of the same dimensions (configuration A) were used, while in the second one, the dimensions of the upper turbine were 20 % proportionally smaller than those of the lower turbine (configuration B). The agitation and turbulence indices were used to evaluate, as a first order approximation, the power consumption distribution between convective and turbulent flows. The comparison of the two-phase agitation systems studied showed that configuration B seems to be more efficient than configuration A, since both induce a similar global convective flow, but the first one assures a significant reduction of power consumption. The distribution of power consumption between convective and turbulent flows was evaluated using the agitation index and a new global parameter: turbulence ind

Modelling of submerged membrane bioreactor: Conceptual study about link between activated slugde biokinetics, aeration and fouling process

A mathematical model was developed to simulate filtration process and aeration influence on Submerged Membrane Bioreactor (SMBR) in aerobic conditions. The biological kinetics and the dynamic effect of the sludge attachment and detachment from the membrane, in relation to the filtration and a strong intermittent aeration, were included in the model. The model was established considering soluble microbial products (SMP) formation-degradation. The fouling components responsible of pore clogging, sludge cake growth, and temporal sludge film coverage were considered during calculation of the total membrane fouling resistance. The influence of SMP, trans-membrane pressure, and mixed liquor suspended solids on specific filtration resistance of the sludge cake was also included. With this model, the membrane fouling under different SMBR operational conditions can be simulated. The influence of a larger number of very important process variables on fouling development can be well quantified. The model was developed for evaluating the influence on fouling control of an intermittent aeration of bubbles synchronized or not with the filtration cycles, taking into account the effects of shear intensity on sludge cake removal

Enseignement de la chimie pour ingénieurs : premier cours de l’INSTEC sur plateforme MOODLE

Les développements scientifique et technique imposent de nouveaux challenges à l’éducation, tels que l’utilisation des Technologies de l’Information et des Communications. A l’INSTEC de La Havane (Cuba), le plan D d’enseignement a commencé dans les spécialités de Radiochimie et Génie Nucléaire, la chimie générale étant une des matières du cursus. Dans ce travail, il est présenté la première version d’un cours sur la plateforme MOODLE comme support au cours de chimie pour Ingénieurs. Le plan d’activités et d’évaluations du cours par semaine a été défini, de même que le plan thématique, les normes de sécurité pour le travail dans le laboratoire de chimie et son évaluation en ligne, le manuel des travaux pratiques de laboratoire et le texte digitalisé des conférences et séminaires. Un espace de communication professeurs-élèves à travers un forum a été ouvert. Le système a été testé pendant un semestre. Les résultats de l’application du système ont été évalués

Adsorption of levodopa from aqueous solution on granular activated carbon

Granular activated carbon filtration has been successfully used in wastewater and drinking water treatment plants, for removal of different pollutants and it is the most efficient conventional treatment method for the purification of water contaminated by other pollutants like pesticides. Levodopa is a drug used to treat Parkinson disease, a progressive condition in which the part of the brain responsible for controlling movement stops functioning properly. In the present study, is reported, for the first time, the adsorption of levodopa from water solution onto activated carbon. The activated carbon was characterized using the low temperature nitrogen adsorption. The equilibrium isotherms at 25 oC were determined. Five models (Langmuir, Jovanovic, Freundlich, Jovanovic-Freundlich and Radke-Prausnitz) were evaluated to fit the experimental data. The characteristic parameters for each isotherm were calculated and the selection of the most adequate model was performed using the Fisher’s test. From the obtained experimental results, the adsorption process can be well described with Jovanovic-Freundlich model (q=369,21 mg/g, a=0,0042 and =0,52) with an average standard error of estimation of 3,62 %

Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons

The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties

Sonolysis of levodopa and paracetamol in aqueous solutions.

Pharmaceutical products are often present in wastewater treatment effluents, rivers, lakes and, more rarely, in groundwater. The advanced oxidation methods, like ultrasound, find a promising future in the area of wastewater treatment. The aim of this paper is to evaluate the influence of several parameters of the ultrasound process on the degradation of paracetamol, a widely used non-steroidal anti-inflammatory recalcitrant drug found in water and levodopa, the most frequently prescribed drug for the treatment of Parkinson disease. Experiments were carried out at 574, 860 and 1134 kHz of ultrasonic frequency with horn-type sonicator and actual power values of 9, 17, 22 and 32 W at 20 °C. Initial concentrations of 25, 50, 100 and 150 mg L−1 of both products were used. Treatment efficiency was assessed following changes in pharmaceuticals concentration and chemical oxygen demand. The sonochemical degradation of both products follows a pseudo-first-order reaction kinetics. Complete removal of pharmaceuticals was achieved in some cases but some dissolved organic carbon remains in solution showing that long lived intermediates were recalcitrant to ultrasound irradiation. Pollutants conversion and COD removal were found to decrease with increasing the initial solute concentration and decreasing power. The best results were obtained with 574 kHz frequency. Investigations using 1-butanol as radical scavenger and H2O2 as promoter revealed that pollutants degradation proceeds principally through radical reactions, although some differences were observed between both molecules. Addition of H2O2 had a positive effect on degradation rate, but the optimum concentration of hydrogen peroxide depends on the pollutant

Comparative adsorption of levodopa from aqueous solution on different activated carbons

Adsorption on activated carbon has been successfully used in wastewater and drinking water treatment plants for the removal of various pollutants. Among them, pharmaceutical compounds have become a growing issue. The present study has focused on levodopa molecule, which is one of the drugs used to treat symptoms of Parkinson's disease. The adsorption of levodopa onto three activated carbons from different source materials is reported for the first time and analyzed according to both textural and surface chemical properties of the carbons.The activated carbons are characterized using low temperature nitrogen adsorption, thermogravimetry analysis and Boehm titration. The equilibrium isotherms are measured at 25 °C and five models (Langmuir, Jovanovic, Freundlich, Redlich–Peterson and Khan) are evaluated to fit the experimental data. The characteristic parameters of each isotherm model are optimized and the selection of the most adequate one is performed using statistical regression criteria. For two of the studied carbons the adsorption process can be well described by Freundlich model with an average relative error of 5%, while for the last carbon only three-parameter models gives good fitting