Ángeles Cancela

Mass transfer and influence of physical properties of solutions in a bubble column

The absorption of CO2 by aqueous solutions of sucrose and surfactants was studied in a bubble column under batch conditions. The volumetric mass transfer coefficients, kLa, were determined for each of the solutions and of the gas rate flow, and the experimental values were correlated with the superficial gas velocity and the physical properties of the liquid phase. The proposed equation reproduces the experimental kLa with an error of less than 10%.

Aplicación de Nuevas Tecnologías en la Docencia Universitaria

Resumen Se presenta una aplicacion de las llamadas pildoras del conocimiento en el marco de las nuevas tecnologias en la docencia universitaria, desarrolladas en la Universidad de Vigo, Espana. Se analiza el concepto de pildora del conocimiento y se presenta una sobre el tema de equilibrio quimico de interes en Ingenieria Quimica y estudios afines. Las pildoras creadas tienen igual formato, y se basan en la definicion de Polimedia, tecnica muy valorada en desarrollos de nuevas tecnologias para la ensenanza ya que permite que el ponente interactue con la presentacion. El objetivo ultimo de las pildoras y en particular de la discutida en este trabajo es mejorar el proceso de aprendizaje del alumno y facilitar la integracion de las materias, todo esto en el marco del Espacio Europeo de Educacion Superior. Se analiza finalmente la cantidad de accesos de dichas pildoras en el tiempo y se concluye sobre las ventajas de su uso como tecnologia docente de apoyo a la ensenanza-aprendizaje. Palabras Clave: docencia universitaria, objeto de aprendizaje, pildora de conocimiento, ingenieria.

Experience of cooperative learning in engineering

The objective of this work is to share the authors’ experience towards a different mode of teaching/learning method. Cooperative learning (Jigsaw) was employed on the University of Vigos fourth-year engineering students. The results of the experience show that cooperative learning is quite a viable alternative to the classical way of lecturing at the university when the number of students is not too high. The authors’ observation indicates that students did not show a lot of interest towards the new learning style but their resistance changed once they began the activity. The Jigsaw method has proved to be a useful tool for improving the learning process so that students have the opportunity to participate actively in the learning activities.

Harvesting green algae from eutrophic reservoir by electroflocculation and post-use for biodiesel production

Each year there are more frequent blooms of green algae and cyanobacteria, representing a serious environmental problem of eutrophication. Electroflocculation (EF) was studied to harvest the algae which are present in reservoirs, as well as different factors which may influence on the effectiveness of the process: the voltage applied to the culture medium, run times, electrodes separation and natural sedimentation. Finally, the viability of its use to obtain biodiesel was studied by direct transesterification. The EF process carried out at 10V for 1min, with an electrode separation of 5.5cm and a height of 4cm in culture vessel, obtained a recovery efficiency greater than 95%, and octadecenoic and palmitic acids were obtained as the fatty acid methyl esters (FAMEs). EF is an effective method to harvest green algae during the blooms, obtaining the greatest amount of biomass for subsequent use as a source of biodiesel.

Rheological Behavior of Powdered Baby Foods

The rheological properties of four types of powdered baby foods have been investigated. Density and apparent viscosity have been measured at different temperatures. The values of the both properties decrease with the temperature. The experimental data belonging to apparent viscosity are represented by a power law. The relationship between the power law parameters and temperature has been analyzed.

La Gestión de Calidad ante la Actual Dimensión Universitaria en España

Resumen Se describen y analizan las principales iniciativas para la garantia y mejora de la calidad que involucran a las universidades espanolas, impulsadas fundamentalmente por el denominado Espacio Europeo de Educacion Superior. A partir de un breve recorrido historico del termino “calidad”, se establece el importante cambio, que aunque de forma lenta, ha ido penetrando en las Universidades Espanolas, hasta alcanzar la dimension actual. La calidad de las universidades ha dejado el segundo plano que ocupaba, para convertirse en el verdadero eje sobre el que gira toda su actividad socio-educativa. Se ofrece una vision general, de las acciones institucionales y estrategicas que en terminos de calidad estan asumiendo las universidades espanolas, discutiendo los principales retos que todavia quedan por conseguir. Palabras clave: calidad, garantia de calidad, certificacion de calidad, planes de estudios, indicadores . The Qualit Management before the Current University Dimension in Spain

Use of learning miniprojects in a chemistry laboratory for engineering

The aim of this paper is to describe the design of chemical engineering laboratory sessions in order to focus them on the learning company approach. This is an activity carried out in the classroom similar to the activities that exist in real companies. This could lead classroom practice to a more cooperative learning and a different style of experimentation. The stated goal is to make a design that seeks to motivate students in a cooperative manner to perform their experiments self-directed and self-organised. The teaching organisation and development of participatory action research are described.

Bioenergy Use from Pavlova lutheri Microalgae

A competitive price of biofuels is necessary for large-scale development. To reduce the overall costs of biofuels production from microalgae, a total use of feedstock was pursued in this research. Besides, the optimization of the different stages involved in biodiesel synthesis process was carried out. The use of algal waste, residue after biodiesel production, as raw material for pellets manufacturing, was analysed. In addition, other techniques as microwave irradiation or ultrasound were used to extract the algal oil and subsequently characterize the oil by gas chromatography. The highest yield of oil extracted (24.77%) was obtained when a microwave irradiation took place previously to ultrasound-assisted extraction. However, less than half of oil was extracted by ultrasound (11.74%). The results showed that high biodiesel conversions, about 50–67%, were achieved by direct transesterification. In addition, pellets from waste biomass could be used as fuel in biomass boilers. Therefore, an integral use of the microalgal raw material was accomplished. No residues were generated and two valuable biofuels were obtained: biodiesel and pellets.Graphical abstract

Pellets valorization of waste biomass harvested by coagulation of freshwater algae

There is a comparison of different coagulants: calcium chloride (20, 60, 120 and 180 mg/L); sodium alginate (10 and 20 mg/L) and tannins of Eucalyptus globulus bark (10 and 20 mg/L) in order to make the most of each method. The results show that 20 mg/L of tannin achieved a recovery efficiency of 95.35±1.16, sodium alginate 90.49±0.53 and 84.04±2.29 for calcium chloride. Taking into account the economic side of the coagulants, obtaining tannins is a profitable process. Bark is waste biomass obtained in the forestry process; therefore it does not involve extra costs. Finally, the feasibility of making pellets from harvested algae was studied, and the results suggest that waste biomass pellets may be used as fuel in boilers in a mixture <54% with other waste sources as Eucalyptus g. branches.

Lipids extraction from microalgae for biodiesel production

Microalgae are being used as an alternative raw material for biodiesel production. This purpose involves the microalgae cultivation, biomass harvesting, lipids extraction and transesterification. In this work, different methods for lipids extraction from Chlorella Vulgaris are evaluated. The different extractions were carried out using Soxhlet method or ultrasound irradiation. In both cases, different solvents were used. Among the analyzed methods, the methanol extraction assisted by ultrasound resulted in the highest extraction of Chlorella Vulgaris oil.