Antagonistic Toxic Effects of Surfactants Mixtures to Bacteria Pseudomonas putida and Marine Microalgae Phaeodactylum tricornutum

Surfactants can be found in an ever-widening variety of products and applications, in which the combination of several types of surfactants is used to reinforce their properties, looking for synergistic effects between them. After use, they tend to be discarded into wastewater, ending up in aquatic bodies with concerning harmful and toxic effects. The aim of this study is the toxicological assessment of three anionic surfactants (ether carboxylic derivative, EC) and three amphoteric surfactants (amine-oxide-based, AO), individually and in binary mixtures of them (1:1 w/w), to bacteria Pseudomonas putida and marine microalgae Phaeodactylum tricornutum. Critical Micelle Concentration (CMC) was determined to demonstrate the capacity to reduce surface tension and the toxicity of the surfactants and mixtures. Zeta potential (ζ-potential) and micelle diameter (MD) were also determined to confirm the formation of mixed surfactant micelles. The Model of Toxic Units (MTUs) was used to quantify the interactions of surfactants in binary mixtures and to predict if the concentration addition or response addition principle can be assumed for each mixture. The results showed a higher sensitivity of microalgae P. tricornutum to the surfactants tested and their mixtures than bacteria P. putida. Antagonism toxic effects have been detected in the mixture of EC + AO and in one binary mixture of different AOs; this is to say, the mixtures showed lower toxicity than expected.Ministry of Universities of the Spanish Government within the predoctoral grant FPU (Ayudas para la Formacion de Profesorado Universitario) FPU17/0335

Influence of ozonation processes on the microbial degradation of surfactants

The influence of ozonation of aqueous solutions of non-ionic surfactants was investigated in this study. The research was conducted using solutions of amine oxide based surfactants. These surfactants constitute a particular class of non-ionic surfactants that exhibit cationic behaviour in acid solution, they show good foaming properties and are skin compatible. The ozonation process was carried out at 25ºC in a stirred tank reactor for 30 min, where gaseous ozone was bubbled. The degree of mineralization achieved after the ozonation process was evaluated by measuring the total organic carbon before and after ozonation. The influence of ozonation on biodegradability of the solutions was studied using the biodegradation test by Pseudomonas putida. Biodegradation efficiency of the ozonated amine oxides based surfactants was also evaluated. It was found that the effectiveness of ozonation depended on the chemical structure of surfactant molecule. Ozonation only slightly improved biodegradation of these surfactants

Biodegradación y toxicidad de tensioactivos comerciales

Tesis Univ. Granada. Departamento de Ingeniería Química. Leída el 21 de octubre de 200

Experiencias del uso de plataformas de enseñanza virtual en las enseñanzas técnicas en el curso 2009-2010 en la Universidad de Granada

Resumen tomado de la publicaciónSe plantea la experiencia de varios profesores en el uso de las plataformas de enseñanza virtual, concretamente Moodle, en asignaturas tanto de carácter presencial como de carácter semipresencial dentro de las ramas técnicas de la enseñanza universitaria. Se analizan las ventajas e inconvenientes planteados en su uso, desde el punto de vista de los profesores, durante el curso académico 2009-2010.NavarraUniversidad Pública de Navarra. Biblioteca Universitaria; Campus de Arrosadia; 31006 Pamplona; Tel. +34948169060; Fax +34948169069; [email protected]

Environmental impact assessment of nanofluids containing mixtures of surfactants and silica nanoparticles

Due to widespread use of nanoparticles in surfactant-based formulations, their release into the environment and wastewater is unavoidable and toxic for biota and/or wastewater treatment processes. Because of concerns over the environmental impacts of nanofuids, studies of the fate and environmental impacts, hazards, and toxicities of nanoparticles are beginning. However, interactions between nanoparticles and surfactants and the biodegradability of these mixtures have been little studied until now. In this work, the environmental impacts of nanofuids containing mixtures of surfactants and silica nanoparticles were valuated. The systems studied were hydrophilic silica nanoparticles (sizes 7 and 12 nm), a nonionic surfactant (alkyl polyglucoside), an anionic surfactant (ether carboxylic acid), and mixtures of them. The ultimate aerobic biodegradation and the interfacial and adsorption properties of surfactants, nanoparticles, and mixtures during biodegradation were also evaluated. Ultimate biodegradation was studied below and above the CMCs of the individual surfactants. The interfacial and adsorption properties of surfactant solutions containing nanoparticles were infuenced by the addition of silica particles. It was determined that silica nanoparticles reduced the capability of the nonionic surfactant alkyl polyglucoside to decrease the surface tension. Thus, silica NPs promoted a considerable increase in the surfactant CMC, whereas the efect was opposite in the case of the anionic surfactant ether carboxylic acid. Increasing concentrations of surfactant and nanoparticles in the test medium caused decreases in the maximum levels of mineralization reached for both types of surfactants. The presence of silica nanoparticles in the medium reduced the biodegradability of binary mixtures containing nonionic and anionic surfactants, and this efect was more pronounced for larger nanoparticles. These results could be useful in modelling the behaviour of nanofuids in aquatic environments and in selecting appropriate nanofuids containing nanoparticles and surfactants with low environmental impact

Proyecto de innovación en tutorías para alumnos de ingeniero químico

Resumen tomado de la publicaciónEl proyecto de acción tutorial se ha llevado a cabo en los cinco cursos de la titulación con un doble enfoque. Por una parte se han organizado grupos de tutoría de unos cinco alumnos en los que se han realizado actividades orientadas a mejorar el rendimiento académico, apoyo en la toma de decisiones, mejora del conocimiento que los alumnos tienen sobre la Universidad y los servicios y actividades que pueden realizar. Por otra parte, se han organizado actividades por cursos o varios cursos, para informar sobre temas generales de su interés, facilitar la realización de prácticas y apoyar a los alumnos de último curso en la incorporación al mercado laboral.NavarraUniversidad Pública de Navarra. Biblioteca Universitaria; Campus de Arrosadia; 31006 Pamplona; Tel. +34948169060; Fax +34948169069; [email protected]

Proyecto de innovación en tutorias para alumnos de ingeniería química

El proyecto de acción tutorial se ha llevado a cabo en los cinco cursos de la titulación con un doble enfoque. Por una parte se han organizado grupos de tutoría de unos cinco alumnos en los que se han realizado actividades orientadas a mejorar el rendimiento académico, apoyo en la toma de decisiones, mejora del conocimiento que los alumnos tienen sobre la Universidad y los servicios y actividades que pueden realizar. Por otra parte, se han organizado actividades por cursos o varios cursos, para informar sobre temas generales de su interés, facilitar la realización de prácticas y apoyar a los alumnos de último curso en la incorporación al mercado laboral