Juan José Santana Rodríguez - Academia.edu (original) (raw)

Papers by Juan José Santana Rodríguez

En este trabajo se presenta un diseño experimental de bajo costo para el aprendizaje de sistemas ... more En este trabajo se presenta un diseño experimental de bajo costo para el aprendizaje de sistemas de control PID. Para el diseño del regulador empleado se ha recurrido a un sistema embebido (Arduino Nano) encargado del control del sistema, y “Processing” un software libre, para el desarrollo de una interfaz que facilite la comunicación con el microcontrolador, así como la recepción y almacenamiento de las variables de proceso. El tratamiento de datos se realiza con Scilab, así como la simulación del lazo de control. Este regulador de bajo costo y “libre” ha sido desarrollado para ayudar a los estudiantes de ingenierías a comprender con mayor profundidad el control PID de procesos químicos. Además, este regulador esta basado en un sistema de software y hardware libre (open-source), siendo ésta su característica más importante, ya que permite a cualquier usuario realizar modificaciones en el diseño, así como sustituir sensores y otros componentes con facilidad. Este método consigue pre...

Ingenieria Quimica, 2006

Se denotan los procesos corrosivos como un grave problema que afecta sobre todo a las centrales q... more Se denotan los procesos corrosivos como un grave problema que afecta sobre todo a las centrales que operan con combustibles fosiles, manifestandose de diversas formas. Se estima que un 14 % del coste del equipamiento en centrales termicas se debe a factores relacionados directamente con la corrosion. En el caso concreto de las Islas Canarias, donde operan 10 centrales termicas, se ha estimado que el coste de la corrosion en el ano 2004 ascendio a unos 21 M_ aproximadamente, tanto en costes directos como indirectos. Todo esto indica que el problema de la corrosion es un problema grave al que hay que prestarle la debida atencion.

Ingenieria Quimica, 2007

Se evaluan las propiedades protectoras frente a la corrosion de varios sistemas de pinturas ecolo... more Se evaluan las propiedades protectoras frente a la corrosion de varios sistemas de pinturas ecologicas sobre distintos sustratos metalicos, utilizando tecnicas clasicas y electroquimicas, encontrando que el sistema mas idoneo de proteccion en los ambientes estudiados es el compuesto por una imprimacion epoxi de dos componentes, curada con poliaminas, y acabado de resina epoxi, tanto para el acero al carbono como para el acero galvanizado. De todos es sabido la importancia que posee el problema de la corrosion, en cualquiera de sus formas. Las perdidas generadas por los procesos corrosivos son considerables [1], y hace que cada ano se gasten cantidades ingentes de dinero en restituir estructuras metalicas y maquinaria que operan al aire libre como consecuencia del deterioro sufrido por el ataque de los agentes corrosivos atmosfericos [2]. Dentro del campo de la corrosion, tan importante como la prevencion y la eleccion adecuada de los materiales a utilizar en un entorno determinado, en funcion de las caracteristicas de su atmosfera, es la de disenar planes de mantenimiento que prevengan y protejan del ataque corrosivo [3]. Dentro de los sistemas de proteccion frente a la corrosion, el mas usado es la proteccion utilizando recubrimientos organicos, tales como las pinturas. Las primeras pinturas que se desarrollaron eran pinturas compuestas por resinas, disolventes organicos y pigmentos anticorrosivos fabricados a partir de compuestos quimicos de metales pesados

Perspectiva De La Investigacion Sobre Materiales En Espana En El Siglo Xxi Vol 2 2006 Isbn 84 8158 323 5 Pags 693 696, 2006

Ingenieria Quimica, 2002

La corrosion atmosferica en el Archipielago Canario se caracteriza por ser muy variada. Asi, tene... more La corrosion atmosferica en el Archipielago Canario se caracteriza por ser muy variada. Asi, tenemos ambientes industriales-marinos y marinos en las zonas costeras, pasando por ambientes urbanos y rurales en zonas de medianias e interior. Debido al fuerte deterioro que sufren los metales en las zonas mas agresivas, se han estudiado distintos tipos de recubrimientos de pinturas con el fin de determinar cual es la que ofrece una mejor proteccion a lo largo del tiempo en metales de gran interes industrial, como son el acero al carbono y el acero galvanizado.

Journal of Electroanalytical Chemistry, 2014

Localized electrochemical activation of aluminium alloy AA6060 surfaces during immersion in chlor... more Localized electrochemical activation of aluminium alloy AA6060 surfaces during immersion in chloride-containing aqueous solution has been characterised using the scanning vibrating electrode technique (SVET). Ionic current flows in the electrolyte phase adjacent to corroding microcells are imaged in situ, allowing their evolution with time to be monitored with spatial resolution. A heterogeneous response due to the presence of intermetallic inclusions in the material is found on AA6060 surfaces. The highly localized anodic activity was thus detected, which has been interpreted as a result of the galvanic coupling between the matrix and the intermetallic particles. Metallic inclusions behave cathodically whereas the aluminium matrix undergoes metal dissolution due to the activation of anodic sites in the proximity of those inclusions. Hydrolysis of aluminium ions leads to local acidification of the electrolyte adjacent to the anodic sites, and it is accompanied by hydrogen evolution.

European Journal of Science and Theology

This contribution provides a brief review of the applications of the Scanning Electrochemical Mic... more This contribution provides a brief review of the applications of the Scanning Electrochemical Microscope (SECM) and the Scanning Vibrating Electrode Technique (SVET) in measuring, characterising and evaluating surface inhomogeneity and surface chemical activity in the case of heterogeneous materials exposed to aqueous environments. The SECM is a unique microelectrochemical technique that provides in situ topographic and electrochemical reactivity information about the surface evolution at the micrometer scale in aqueous solution, thus becoming a very powerful tool in elucidating the complex processes occurring in the early stages of surface films degradation and metal corrosion. On the other hand, the SVET uses a small vibrating probe allowing measurement of the local potential in solution taking advantage of a synchronous detection with a lock-in amplifier. In this way, ionic current related to degradation reactions on an investigated surface can be monitored in the electrolytic ph...

Electrochimica Acta, 2012

This work contributes to establish the development of an early specific effect of chloride ions i... more This work contributes to establish the development of an early specific effect of chloride ions in defect-free coated metals leading to the heterogeneous swelling at the metal-polymer interface. Frequency-dependent alternating-current scanning electrochemical microscopy (AC-SECM) was successfully applied to visualize spatially-resolved differences in the topography of the coated sample, thus allowing direct evidence of chloride ion permeation through the polymer matrix simultaneous to water uptake to be obtained. The implications of this finding are particularly relevant towards the development of a new mechanistic model for blister initiation in coated metals.

Vector plus: miscelánea …, 2005

International journal of electrochemical science

The behaviour of five different water-based anticorrosive paint systems for the corrosion protect... more The behaviour of five different water-based anticorrosive paint systems for the corrosion protection of carbon steel surfaces was evaluated by electrochemical impedance spectroscopy (EIS). Epoxy-polyamine, epoxy-amine and epoxy-acrylic resins as primer coats, and acrylic-polyurethane and acrylic paints as top coats, were investigated both in single layer and double-layer applications. The best protection was provided by the epoxy-amine resin, whereas acrylic-polyurethane exhibited the poorest characteristics and signs of corrosion could be observed since the initial moments of immersion onwards. The impedance spectra could be satisfactorily fitted by employing an equivalent circuit which corresponds to a porous barrier film.

Electrochimica Acta, 2014

ABSTRACT Passive film breakdown and pit nucleation on 304 and 316 stainless steels in chloride-co... more ABSTRACT Passive film breakdown and pit nucleation on 304 and 316 stainless steels in chloride-containing media were investigated using scanning microelectrochemical microscopy (SECM) and the scanning vibrating electrode technique (SVET). Experiments were performed for the alloys either at their corresponding open circuit potential, or under applied polarization, as to image domains of similar topography but different resistance against breakdown of the passive layers formed on these steels. Identification of the iron released species was accomplished, showing that pitting occurs with the formation of iron (II) species only. Detection of iron (III) species occurred when the steel sample was polarized at high positive overpotentials because it served as the reaction site to oxidize the iron (II) ions released from a propagating pit. The obtained results have revealed some difference of the reactivity of both specimens. Moreover the effect of the galvanic coupling has been investigated.

Corrosion Science, 2014

The electrochemical behavior of Zr5Ti, Zr25Ti, and Zr45Ti, with and without surface modification ... more The electrochemical behavior of Zr5Ti, Zr25Ti, and Zr45Ti, with and without surface modification were monitored in acidic artificial saliva (pH = 3) containing NaF concentrations 0.2, 0.5, and 1 wt.%, simulating the fluoride concentrations in dental rinses. A passive behaviour for thermally oxidized ZrTi alloys was found using EIS, and XPS data show that the protective oxide film contains both TiO2 and ZrO2, though titanium contents in the outer layer bigger than those in the base alloy result from thermal oxidation. High corrosion resistance to acidic fluoridated environments of ZrTi alloys treated using thermal oxidation in air at 500 ºC.

Journal of Electroanalytical Chemistry, 2014

Corrosion processes occurring on stainless steel 304 surfaces under anodic polarization have been... more Corrosion processes occurring on stainless steel 304 surfaces under anodic polarization have been characterized using scanning electrochemical microscopy (SECM) and the scanning vibrating electrode technique (SVET), complemented with conventional potentiodynamic polarization curves. Stable pit formation has been detected by SVET on the samples as result of surface modification under electrochemical control, which may include the previous electrochemical reduction of passive oxide layer if the media is not aggressive enough to induce pitting at small overpotentials. Additionally, the sample generation-tip collection operation mode of the SECM has enabled the detection of local release of iron (II) ions, as well as their conversion to iron (III), both processes being greatly affected by the potential applied to the substrate.

Int. J. Electrochem …, 2012

... 8. V. Scotto, R. Di Cintio, G. Marcenaro, Corros. Sci., 25 (1985) 185. 9. SC Dexter, DJ Duque... more ... 8. V. Scotto, R. Di Cintio, G. Marcenaro, Corros. Sci., 25 (1985) 185. 9. SC Dexter, DJ Duquette, OW Siebert, HA Videla, Corrosion, 47 (1994) 308. 10. ... Sci., 33 (1992) 295. 23. JEG González, FJH Santana, JC Mirza-Rosca, Corros. Sci., 40 (1998) 2141. 24. ...

Química Nova, 2014

Screening of biomass of a new marine-derived strain of Penicillium roqueforti, as produced by liq... more Screening of biomass of a new marine-derived strain of Penicillium roqueforti, as produced by liquid-state fermentation, led to the identification of several volatile organic compounds active in the fatty acid pathway as well as fragments produced by their catabolism, terpenoids, and metabolites from the shikimic acid pathway. In addition, five non-volatile organic compounds, triolein, ergosterol peroxide, 9(11)-dehydroergosterol peroxide, 4-hydroxybenzaldehyde, and d-mannitol, were isolated and identified by spectroscopy. The results showed that this fungal strain did not produce any mycotoxin in the culture conditions applied, and thus is useful for industrial applications, where high value-added biomolecules are generated.

Annals of Microbiology, 2012

ABSTRACT A new Paecilomyces variotii strain was isolated from the marine habitat. The fungal biom... more ABSTRACT A new Paecilomyces variotii strain was isolated from the marine habitat. The fungal biomass necessary for the chemical study was produced with success, at a laboratory scale. A total of 28 structural groups were identified from volatile compounds that, in the main, are normal lipid compounds involved in the fatty acid pathway, fragments from their catabolism, terpenoids, and a metabolite from the shikimic acid route. In addition, two non-volatile compounds, triolein and ergosterol peroxide, were isolated and identified by spectroscopy. This is the first report to describe these compounds for the species P. variotii, suggesting its potential use as a natural source to produce nutraceuticals and functional foods.

En este trabajo se presenta un diseño experimental de bajo costo para el aprendizaje de sistemas ... more En este trabajo se presenta un diseño experimental de bajo costo para el aprendizaje de sistemas de control PID. Para el diseño del regulador empleado se ha recurrido a un sistema embebido (Arduino Nano) encargado del control del sistema, y “Processing” un software libre, para el desarrollo de una interfaz que facilite la comunicación con el microcontrolador, así como la recepción y almacenamiento de las variables de proceso. El tratamiento de datos se realiza con Scilab, así como la simulación del lazo de control. Este regulador de bajo costo y “libre” ha sido desarrollado para ayudar a los estudiantes de ingenierías a comprender con mayor profundidad el control PID de procesos químicos. Además, este regulador esta basado en un sistema de software y hardware libre (open-source), siendo ésta su característica más importante, ya que permite a cualquier usuario realizar modificaciones en el diseño, así como sustituir sensores y otros componentes con facilidad. Este método consigue pre...

Ingenieria Quimica, 2006

Se denotan los procesos corrosivos como un grave problema que afecta sobre todo a las centrales q... more Se denotan los procesos corrosivos como un grave problema que afecta sobre todo a las centrales que operan con combustibles fosiles, manifestandose de diversas formas. Se estima que un 14 % del coste del equipamiento en centrales termicas se debe a factores relacionados directamente con la corrosion. En el caso concreto de las Islas Canarias, donde operan 10 centrales termicas, se ha estimado que el coste de la corrosion en el ano 2004 ascendio a unos 21 M_ aproximadamente, tanto en costes directos como indirectos. Todo esto indica que el problema de la corrosion es un problema grave al que hay que prestarle la debida atencion.

Ingenieria Quimica, 2007

Se evaluan las propiedades protectoras frente a la corrosion de varios sistemas de pinturas ecolo... more Se evaluan las propiedades protectoras frente a la corrosion de varios sistemas de pinturas ecologicas sobre distintos sustratos metalicos, utilizando tecnicas clasicas y electroquimicas, encontrando que el sistema mas idoneo de proteccion en los ambientes estudiados es el compuesto por una imprimacion epoxi de dos componentes, curada con poliaminas, y acabado de resina epoxi, tanto para el acero al carbono como para el acero galvanizado. De todos es sabido la importancia que posee el problema de la corrosion, en cualquiera de sus formas. Las perdidas generadas por los procesos corrosivos son considerables [1], y hace que cada ano se gasten cantidades ingentes de dinero en restituir estructuras metalicas y maquinaria que operan al aire libre como consecuencia del deterioro sufrido por el ataque de los agentes corrosivos atmosfericos [2]. Dentro del campo de la corrosion, tan importante como la prevencion y la eleccion adecuada de los materiales a utilizar en un entorno determinado, en funcion de las caracteristicas de su atmosfera, es la de disenar planes de mantenimiento que prevengan y protejan del ataque corrosivo [3]. Dentro de los sistemas de proteccion frente a la corrosion, el mas usado es la proteccion utilizando recubrimientos organicos, tales como las pinturas. Las primeras pinturas que se desarrollaron eran pinturas compuestas por resinas, disolventes organicos y pigmentos anticorrosivos fabricados a partir de compuestos quimicos de metales pesados

Perspectiva De La Investigacion Sobre Materiales En Espana En El Siglo Xxi Vol 2 2006 Isbn 84 8158 323 5 Pags 693 696, 2006

Ingenieria Quimica, 2002

La corrosion atmosferica en el Archipielago Canario se caracteriza por ser muy variada. Asi, tene... more La corrosion atmosferica en el Archipielago Canario se caracteriza por ser muy variada. Asi, tenemos ambientes industriales-marinos y marinos en las zonas costeras, pasando por ambientes urbanos y rurales en zonas de medianias e interior. Debido al fuerte deterioro que sufren los metales en las zonas mas agresivas, se han estudiado distintos tipos de recubrimientos de pinturas con el fin de determinar cual es la que ofrece una mejor proteccion a lo largo del tiempo en metales de gran interes industrial, como son el acero al carbono y el acero galvanizado.

Journal of Electroanalytical Chemistry, 2014

Localized electrochemical activation of aluminium alloy AA6060 surfaces during immersion in chlor... more Localized electrochemical activation of aluminium alloy AA6060 surfaces during immersion in chloride-containing aqueous solution has been characterised using the scanning vibrating electrode technique (SVET). Ionic current flows in the electrolyte phase adjacent to corroding microcells are imaged in situ, allowing their evolution with time to be monitored with spatial resolution. A heterogeneous response due to the presence of intermetallic inclusions in the material is found on AA6060 surfaces. The highly localized anodic activity was thus detected, which has been interpreted as a result of the galvanic coupling between the matrix and the intermetallic particles. Metallic inclusions behave cathodically whereas the aluminium matrix undergoes metal dissolution due to the activation of anodic sites in the proximity of those inclusions. Hydrolysis of aluminium ions leads to local acidification of the electrolyte adjacent to the anodic sites, and it is accompanied by hydrogen evolution.

European Journal of Science and Theology

This contribution provides a brief review of the applications of the Scanning Electrochemical Mic... more This contribution provides a brief review of the applications of the Scanning Electrochemical Microscope (SECM) and the Scanning Vibrating Electrode Technique (SVET) in measuring, characterising and evaluating surface inhomogeneity and surface chemical activity in the case of heterogeneous materials exposed to aqueous environments. The SECM is a unique microelectrochemical technique that provides in situ topographic and electrochemical reactivity information about the surface evolution at the micrometer scale in aqueous solution, thus becoming a very powerful tool in elucidating the complex processes occurring in the early stages of surface films degradation and metal corrosion. On the other hand, the SVET uses a small vibrating probe allowing measurement of the local potential in solution taking advantage of a synchronous detection with a lock-in amplifier. In this way, ionic current related to degradation reactions on an investigated surface can be monitored in the electrolytic ph...

Electrochimica Acta, 2012

This work contributes to establish the development of an early specific effect of chloride ions i... more This work contributes to establish the development of an early specific effect of chloride ions in defect-free coated metals leading to the heterogeneous swelling at the metal-polymer interface. Frequency-dependent alternating-current scanning electrochemical microscopy (AC-SECM) was successfully applied to visualize spatially-resolved differences in the topography of the coated sample, thus allowing direct evidence of chloride ion permeation through the polymer matrix simultaneous to water uptake to be obtained. The implications of this finding are particularly relevant towards the development of a new mechanistic model for blister initiation in coated metals.

Vector plus: miscelánea …, 2005

International journal of electrochemical science

The behaviour of five different water-based anticorrosive paint systems for the corrosion protect... more The behaviour of five different water-based anticorrosive paint systems for the corrosion protection of carbon steel surfaces was evaluated by electrochemical impedance spectroscopy (EIS). Epoxy-polyamine, epoxy-amine and epoxy-acrylic resins as primer coats, and acrylic-polyurethane and acrylic paints as top coats, were investigated both in single layer and double-layer applications. The best protection was provided by the epoxy-amine resin, whereas acrylic-polyurethane exhibited the poorest characteristics and signs of corrosion could be observed since the initial moments of immersion onwards. The impedance spectra could be satisfactorily fitted by employing an equivalent circuit which corresponds to a porous barrier film.

Electrochimica Acta, 2014

ABSTRACT Passive film breakdown and pit nucleation on 304 and 316 stainless steels in chloride-co... more ABSTRACT Passive film breakdown and pit nucleation on 304 and 316 stainless steels in chloride-containing media were investigated using scanning microelectrochemical microscopy (SECM) and the scanning vibrating electrode technique (SVET). Experiments were performed for the alloys either at their corresponding open circuit potential, or under applied polarization, as to image domains of similar topography but different resistance against breakdown of the passive layers formed on these steels. Identification of the iron released species was accomplished, showing that pitting occurs with the formation of iron (II) species only. Detection of iron (III) species occurred when the steel sample was polarized at high positive overpotentials because it served as the reaction site to oxidize the iron (II) ions released from a propagating pit. The obtained results have revealed some difference of the reactivity of both specimens. Moreover the effect of the galvanic coupling has been investigated.

Corrosion Science, 2014

The electrochemical behavior of Zr5Ti, Zr25Ti, and Zr45Ti, with and without surface modification ... more The electrochemical behavior of Zr5Ti, Zr25Ti, and Zr45Ti, with and without surface modification were monitored in acidic artificial saliva (pH = 3) containing NaF concentrations 0.2, 0.5, and 1 wt.%, simulating the fluoride concentrations in dental rinses. A passive behaviour for thermally oxidized ZrTi alloys was found using EIS, and XPS data show that the protective oxide film contains both TiO2 and ZrO2, though titanium contents in the outer layer bigger than those in the base alloy result from thermal oxidation. High corrosion resistance to acidic fluoridated environments of ZrTi alloys treated using thermal oxidation in air at 500 ºC.

Journal of Electroanalytical Chemistry, 2014

Corrosion processes occurring on stainless steel 304 surfaces under anodic polarization have been... more Corrosion processes occurring on stainless steel 304 surfaces under anodic polarization have been characterized using scanning electrochemical microscopy (SECM) and the scanning vibrating electrode technique (SVET), complemented with conventional potentiodynamic polarization curves. Stable pit formation has been detected by SVET on the samples as result of surface modification under electrochemical control, which may include the previous electrochemical reduction of passive oxide layer if the media is not aggressive enough to induce pitting at small overpotentials. Additionally, the sample generation-tip collection operation mode of the SECM has enabled the detection of local release of iron (II) ions, as well as their conversion to iron (III), both processes being greatly affected by the potential applied to the substrate.

Int. J. Electrochem …, 2012

... 8. V. Scotto, R. Di Cintio, G. Marcenaro, Corros. Sci., 25 (1985) 185. 9. SC Dexter, DJ Duque... more ... 8. V. Scotto, R. Di Cintio, G. Marcenaro, Corros. Sci., 25 (1985) 185. 9. SC Dexter, DJ Duquette, OW Siebert, HA Videla, Corrosion, 47 (1994) 308. 10. ... Sci., 33 (1992) 295. 23. JEG González, FJH Santana, JC Mirza-Rosca, Corros. Sci., 40 (1998) 2141. 24. ...

Química Nova, 2014

Screening of biomass of a new marine-derived strain of Penicillium roqueforti, as produced by liq... more Screening of biomass of a new marine-derived strain of Penicillium roqueforti, as produced by liquid-state fermentation, led to the identification of several volatile organic compounds active in the fatty acid pathway as well as fragments produced by their catabolism, terpenoids, and metabolites from the shikimic acid pathway. In addition, five non-volatile organic compounds, triolein, ergosterol peroxide, 9(11)-dehydroergosterol peroxide, 4-hydroxybenzaldehyde, and d-mannitol, were isolated and identified by spectroscopy. The results showed that this fungal strain did not produce any mycotoxin in the culture conditions applied, and thus is useful for industrial applications, where high value-added biomolecules are generated.

Annals of Microbiology, 2012

ABSTRACT A new Paecilomyces variotii strain was isolated from the marine habitat. The fungal biom... more ABSTRACT A new Paecilomyces variotii strain was isolated from the marine habitat. The fungal biomass necessary for the chemical study was produced with success, at a laboratory scale. A total of 28 structural groups were identified from volatile compounds that, in the main, are normal lipid compounds involved in the fatty acid pathway, fragments from their catabolism, terpenoids, and a metabolite from the shikimic acid route. In addition, two non-volatile compounds, triolein and ergosterol peroxide, were isolated and identified by spectroscopy. This is the first report to describe these compounds for the species P. variotii, suggesting its potential use as a natural source to produce nutraceuticals and functional foods.