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espanolEn el siguiente trabajo se realiza la impregnacion de diferentes sustratos polimericos con agentes biocidas y con un colorante textil, comunmente empleados en los procesos de acabados textiles. En este estudio se realiza la seleccion del colorante Disperse Red 167 (DR167), mediante la comparacion de solubilidad en CO2 supercritico (scCO2) entre varios colorantes dispersos. Los agentes biocidas seleccionados han sido; esencia de clavo (eugenol) y aceite esencial de oregano. Se ha realizado la impregnacion de diferentes sustratos polimericos; poliester (PES), polipropileno (PP), y algodon (CO), en diferentes condiciones. En total se realizaron impregnaciones utilizando diez concentraciones relativas del DR167. El objetivo principal es determinar las condiciones optimas de procesado para cada sustrato. Para determinar el rendimiento de la tintura en scCO2 se han representado los diagramas cromaticos de las muestras tintadas en diferentes condiciones. Las muestras de PES son las que presentan mayor rendimiento de color, sabiendo que esta es la unica fibra que presenta afinidad con el DR167. Para determinar el efecto de inhibicion de las bacterias se han realizado ensayos de actividad antimicrobiana y actividad fungicida. Puede indicarse que si se observo cierta actividad inhibitoria frente algunos microorganismos, como Staphylococcus aureus, mientras que no se observo una actividad inhibitoria importante frente a otros como Pseudomonas aeruginosa EnglishIn this paper has done an impregnation with biocides agents, and a textile dye, commonly used in textile finishing processes, for different polymeric substrates. In this study has selected the Disperse Red 167 dye (DR167), by comparing solubility in supercritical CO2 (scCO2). Biocide agents have been selected, oil of cloves (eugenol) and essential oil of oregano. Impregnation has been made of different polymeric substrates; polyester (PES), polypropylene (PP), and cotton (CO), under different conditions. Finally impregnations were performed using relative concentrations of DR167. The main objective is to determine an optimum process condition for each substrate. To determine the yield of DR167 are shown scCO2 color diagrams of the samples, dyed under different conditions. PES samples shows the best color results, knowing than this is the only fiber that had affinity for the DR167. To analyze the inhibition bacterial effect, have been done antimicrobial activity test, and fungicidal activity test. It's shows that, if there was some inhibitory activity against some microorganism such as Staphylococcus aureus, while there was no significant inhibitoy activity against Pseudomonas aereuginosa.

Antimony–platinum doped tin dioxide electrodes supported on titanium have been prepared by thermal decomposition. The effect of the progressive replacement of Sb with Ru (x = 0.00; 3.25; 6.50; 13.00 at.%) on their electrochemical response in acid medium has been analysed by cyclic voltammetry. The morphology of the coatings was observed by scanning electron microscopy. Ti/SnO2–Sb–Pt electrodes without Ru presented a cracked-mud structure, typical of oxide electrodes prepared by thermal decomposition. The introduction of Ru in the oxide layer modified the coating morphology. The roughness increased and passed through a maximum with the increase of Ru content. A relation between the surface morphology, the roughness factor, voltammetric charge and the electrochemical activity has been established. The mechanism and electrocatalytic activity towards the oxygen evolution reaction has been studied from Tafel measurements. The progressive introduction of Ru in the electrodes increased their electrocatalytic activity for the oxygen evolution reaction with a change on the mechanism from non-active to active electrodes. The electrocatalytic activity mainly depends on electronic factors. Financial support by the Generalitat Valenciana (RED ARVIV/2007/076) and Ministerio de Ciencia e Innovación-Feder (MAT2007-60621).

The effect of the electrochemical treatment (galvanostatic electrolysis in a filter-press electrochemical cell) on the surface chemistry and porous structure of a granular activated carbon (GAC) has been analyzed by means of temperature-programmed desorption and N2 (at 77 K) and CO2 (at 273 K) adsorption isotherms. The anodic and cathodic treatments, the applied current (between 0.2 and 2.0 A) and the type of electrolyte (NaOH, H2SO4 and NaCl)have been studied as electrochemical variables. Both anodic and cathodic treatments lead to an increase in the surface oxygen groups. A suitable choice of the electrochemical variables allows a selective modification of the amount and the nature of the surface oxygen groups of the GAC. In general, the electrochemical treatment does not modify significantly the textural properties of the GAC. However, an increase in the porosity of the activated carbon occurs during the cathodic treatment in oxygen-saturated solutions. This result is interpreted as a consequence of carbon gasification driven by reaction with peroxide species generated by electroreduction of oxygen. The anodic treatment in NaCl produces oxidation degrees comparable to those achieved by classical chemical oxidations. Ministerio de Ciencia e Innovación-FEDER (MAT2007-60621 and CTQ2006-08958) and Generalitat Valenciana (Ayudas REVIV, ARVIV/2007/076).

This communication deals with the vibrational behaviour of cyanide adlayers formed on Pt(111) and Pt(100) surfaces in the electrochemical environment. In situ FTIR spectroscopy can be employed to follow the potential dependence of the C–N stretching frequency in acidic electrolytes with quite a low uncertainty. Owing to the stability of the cyanide adlayer in alkaline solutions, experiments performed in NaOH medium are usually perturbed by the significant overlapping of the reference and the sample FTIR spectra. Deconvolution of the spectra was carried out assuming a Lorentz oscillator. The procedure allowed to confirm that two potential regions with different band centre frequency tuning coexist for Pt(111)–CN in perchloric acid medium. Conversely, in the alkaline electrolyte a single tuning rate for the band position was found for both surfaces studied. The lack of reorientation of the C–N molecular axis together with the occurrence of a certain screening effect of negatively charged hydroxyl anions on the electric field at the interface could be at the origin of the different behaviour displayed in both electrolytic media. Ministerio de Ciencia y Tecnología (MAT2004-1479); Generalitat Valenciana (GRUPOS04/75 y GV5/136) Programa Juan de la Cierva.

Modified electrodes with poly(2,2’-dithiodianiline),PDTDA, were prepared from the corresponding monomer by cyclic voltammetry between 0.0 V and 1.5-1.6 V on gold or stainless steel respectively. The potentiodynamic method proved to bring about good quality and adherent thin films. The wide potential window shown by this modified electrode allowed attempting the insertion of copper in the polymeric matrix using several strategies. The response of this modified electrode copper was checked in the presence of γ-aminobutyric acid (GABA). Copper loaded on PDTDA/Au electrodes showed the highest sensitivity along with a stable and reproducible response for the detection of GABA. The surface morphology and composition analysis by SEM and XPS shows that copper is deposited in the polymeric matrix as uniformly scattered microparticles. The surface of these particles is mainly composed of Cu(I) species. Financial support of projects 3020033 and 1020520 from FONDECYT (Chile) and project MAT2004-01479 from Ministerio de Educación y Ciencia (Spain).

The electrochemical reactivity of dissolved SO2 on glassy carbon (GC) electrodes was studied in sulfuric and perchloric acid solutions. The surface changes accompanying voltammetric scans were analysed with the aid of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The influence of the GC pretreatment (polished versus electrochemically activated) on the oxidation of SO2 was examined. It was found that GC samples electrochemically treated so to develop a reduced graphite oxide film on the surface were more active for SO2 oxidation. The reduction of SO2 was observed to take place at potentials below 0.0V to yield soluble sulfide species. This species was reoxidized on positive scans to form a sulfur deposit, consisting of an underlying layer of chemisorbed sulfur (161.9–162.3 eV)and an on-top layer of bulk elemental sulfur with S8-like structure (163.6–163.8 eV). Surface sulfur did not impart electrocatalytic activity for the oxidation of SO2. Spanish Ministerio de Ciencia y Tecnología (Projects MAT2001-1007 and MAT2004-01479)

The electrocatalytic behaviour of poly(aniline-co-4adpa), Pan-4adpa, films against some redox couples and ascorbic acid was tested in aqueous buffering solutions of pH = 5. The film catalysed the redox process of all the couples investigated although it has been observed that positively charged species such as dopamine/dopaminequinone display more irreversible voltammetric behaviour than negative (ferro/ferricyanide) or neutral (hydroquinone/quinone) ones. The voltammetric results point that the catalytic sites of the Pan-4adpa are probably located at the surface of the film. The oxidation peak of ascorbic acid on Pan-4adpa films is shifted 170mV to more cathodic potentials with respect to the Pt with no generation of adsorbed residues. Ministerio de Ciencia y Tecnlogía (MAT2001-1007)(REN2001-2304-C02-02/TECNO)

The electrochemical oxidation of aniline and p-aminodiphenylamine (ADPA) was carried out in a phosphate buffer solution at pH 5. Cyclic voltammetry and ‘‘in situ’’ FTIR spectroscopy were combined to study the redox behavior of the oxidation products. When ADPA is oxidized in the presence of aniline, two redox processes are observed. One of these redox processes is related to a soluble species, while the other pertains to a species attached to the electrode surface. Only those films synthesized from ADPA oxidation in the presence of aniline are electroactive in this buffered medium. No evidence pointing to the occurrence of autocatalytic polymerization exists under the experimental conditions employed. Ministerio de Ciencia y Tecnología (MAT2001-1007)(REN2001-2304-C02-02/TECNO); Generalitat Valenciana (GV01-313).

Carbon monoxide has been adsorbed at controlled potential on a Pt(111) electrode, which was pre-covered with cyanide up to saturation. From the results obtained, it has been deduced that CO occupies platinum sites between CN molecules with no distortion of the pre-adsorbed cyanide layer. The anodic stripping of CO does not induce modifications of the CN adlayer either. These observations allow the estimation of θCO rather accurately by means of the coulometric method. Keywords: Cyclic voltammetry, Adsorption, Cyanide, Carbon monoxide, Pt(111) electrode

Se presenta una revisión de los principales conceptos y definiciones sobre nanopigmentos, además de algunos acercamientos interesantes mediante técnicas espectrofotométricas para la determinación de las características estructurales de los agregados moleculares de colorante formados sobre partículas de arcilla. Ministerio de Ciencia e Innovación del Gobierno de España (ayuda DPI2008-06455-C02-02).

Póster presentado en el IX Congreso Nacional del Color, Alicante, 29-30 junio, 1-2 julio 2010. Este trabajo presenta un resumen de prospectiva sobre la idoneidad y viabilidad técnica de incorporar y sintetizar nanopigmentos para realizar tintura de fibras sintéticas y fibras naturales en CO2 supercrítico (scCO2) con el objeto de plantear futuras líneas de investigación que posibiliten el empleo de esta técnica a nivel industrial. Una de las principales limitaciones de esta técnica de tintura es la naturaleza de los colorantes solubles en scCO2, cuya estructura debe ser apolar. Para ampliar la selección de colorantes solubles en este estudio se plantea la síntesis de nanopigmentos, derivados del intercambio iónico entre nanoarcillas y colorantes orgánicos. Si el conjunto resultara soluble en scCO2 se pretende abrir con ello una nueva línea de investigación en tintura supercrítica cuyo objetivo final es reducir sus limitaciones y potenciar sus ventajas. Por otro lado existe la posibilidad de sintetizar estos nanocompuestos en medio supercrítico con el consecuente ahorro en agua, y la posibilidad de recuperar los excedentes y subproductos del proceso de síntesis. Además en esta línea de investigación queda abierta la posibilidad de funcionalizar los nanopigmentos sintetizados en función de su campo de aplicación. Ministerio de Ciencia e Innovación (proyecto “Aplicación de la tecnología de fluidos supercríticos en la impregnación de sustratos poliméricos” ref.: CIT-20000-2009-2).

Nanostructured cobalt oxide (Co3O4) electrodes were prepared by two different methods. The first one involved the synthesis of Co3O4 nanoparticles through a nanocasting route using commercial silica gel as a sacrificial template, and in the second one, the Co3O4 electrodes were prepared by thermal decomposition. The electrodes were characterized by different techniques, such as scanning electron microscopy, energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. EDX, XRD, and XPS show a characteristic spinel-type structure and a similar chemical composition for the two nanostructured cobalt oxides. However, the surface morphology is different. The electrochemical oxidation of cyanide and phenol in alkaline medium were used as test reactions. The electrocatalytic activity of the nanocrystalline Co3O4 electrodes for cyanide and phenol oxidation turned out to be highly dependent on the electrode preparation method. Financial support by the Generalitat Valenciana grant no. GV05/136, no. GV06/106, and no. RED ARVIV/2007/076) and Ministerio de Educación y Ciencia (MAT2007-60621 and MAT2005-00262) projects.

The electrochemical oxidation of the aniline dimers 2-aminodiphenylamine (2-adpa) and 4-aminodiphenylamine (4-adpa) has been performed in strongly acidic medium on platinum, graphite, and indium tin oxide electrodes. The resulting films have been characterized by a number of electrochemical, microscopic, and spectroscopic techniques in order to gain some insight on their respective chemical structures. Both poly(2-adpa) and poly(4-adpa) are electroactive species which differ significantly one from another. It was found that aged poly(4-adpa)displayed electrochemical, morphologic and spectroscopic characteristics similar to those shown by polyaniline. On the contrary, poly(2-adpa) is really a mixture of three oligomerization products. The two main oligomers contain both open-ring and cycled phenazine centers, although their chemical structures seem to differ in the cap-end of the chain growth. The third oligomer is a minor product which seems a highly symmetric macrocycle involving several 2-adpa molecules. This work has been cofinanced by the European Commission (ERDF funds) and the Spanish Ministerio de Educación y Cultura (MAT2004-01479). University of Alicante assisted in meeting the publication costs of this article.

The electrochemical oxidation of 2-aminodiphenylamine (2ADPA) was performed by cyclic scanning of the potential in aqueous HCl solutions. A mixture of oligomeric compounds, named poly(2ADPA), was deposited on the surface of the electrode. The chemical structures present in poly(2ADPA) containing phenazine units and open-ring units were assigned by 1H NMR spectroscopy. CV results revealed that the redox transformation of poly(2ADPA) from the fully reduced to the fully oxidized state occurs under a single voltammetric peak. The SEM images obtained for the polymer deposited on platinum substrates showed a “fallen leaves” morphology. In situ FTIR spectroscopy experiments carried out during the reversible oxidation of the polymer revealed that the conversion of aromatic rings (1500 cm−1) into quinoid structures (1524–1590 cm−1) is of major significance. Besides, the transformation of secondary aromatic amines (1301 cm−1) into fully oxidized imines and polaronic structures (1470, 1389, 1330 and 1250 cm−1) has been observed. Ministerio de Ciencia y Tecnlogía (MAT2004-1479); Comisión Europea (Fondos ERDF).

Hybrid material polypyrrole/PW12O-340 was electrosynthesised on carbon steel electrodes in acetonitrile medium. Passivation pretreatment of carbon steel in acetonitrile/perchlorate medium was used to avoid electrodissolution of electrode during the polymerisation. These hybrid coatings were evaluated against corrosion in chloride-containing 0.05 M NaOH and solutions obtained by filtering Portland cement slurries. Cyclic voltammetry, polarisation resistance(Rp), and Fe2+ concentrations measurements showed that the obtained coatings provide good protection against corrosion in chloride-containing media. Ministerio de Ciencia y Tecnología (MAT2001-1007) (REN 2001-2304-C02-02/TECNO)

The electrochemical homo-polymerization of o-, m- and p-aminobenzoic acids has been performed on Pt electrodes in perchloric acid aqueous medium by cyclic scanning of the potential. Different limit potentials were employed to obtain thin polymeric films. When the switching potential was extended beyond the respective monomer oxidation peak, a rather degraded material was obtained. In situ FTIR spectroscopy has been used to characterize the redox response of films synthesized at the lower potential limits. Characteristic absorption features related with benzenoid and quinoid rings and different types of C–N bonds suggest the presence of redox processes similar to those undergone by the parent compound polyaniline. In addition, the existence of a chemical interaction between –COOH and –NH– groups in the reduced state of the three homopolymers studied can be suggested. Carbon dioxide has been detected at potentials higher than 1.0 V (RHE) irrespective of the polymeric material, thus indicating its degradation. Ministerio de Ciencia y Tecnología (MAT2001-1007) (MAT2004-01479); Generalitat Valenciana (Grupos04/75)

The electrochemical oxidation of p-aminodiphenylamine (4ADPA) in the presence of aniline in phosphate medium of pH ranging from 1 to 10.5 has been investigated. Mixtures of both monomers can be co-polymerized to produce electroactive poly aniline-co-4ADPA (Pan-4adpa) films if the pH of the medium is kept, approximately, within 3 and 9 and the upper potential limit is lower than the oxidation potential of aniline. Pan-4adpa growth rates are pH dependent and are also affected by the amount of polymeric material deposited on the electrode surface. It has been suggested the existence of a certain inhibition effect of both H+ and OH− on the polymerization reaction. Contrary to what is observed for those films synthesized at pH 5 and 7, the growth of Pan-4adpa at pH 8 seems to be an autocatalytic process until the inhibition of the polymerization reaction takes place. Ministerio de Ciencia y Tecnología MAT2001-1007, MAT2004-01479 y REN2001-2304-C02-02/TECNO

The adsorption and reactivity of citrate anions, cyanide anions, and the Au(I) and Au(III) cyanocomplexes (KAu(CN)2 and KAu(CN)4, respectively) on gold polycrystalline electrodes have been investigated by means of cyclic voltammetry and in situ FTIR spectroscopy in pH 7 sodium citrate medium. It was found that citrate anion adsorbs reversibly through the carboxylate groups from 0.4 V (RHE) on bare gold surfaces. However, the onset of this adsorption process is shifted by 600 mV in the positive direction when adsorbed cyanide species are present at the electrode surface. The Au(I) cyanocomplex produces a film on the gold electrode that inhibits the oxidation of both citrate anions and the gold surface. The reduction of the Au(III) cyanocomplex gives rise to the formation of the Au(I) cyanocomplex at potentials less negative than those required for gold deposition. Upon reduction, both cyanocomplexes release adsorbed cyanide on the gold electrode, which can be subsequently oxidized to cyanate at higher potentials. Generalitat Valenciana (GV01-313); Ministerio de Ciencia y Tecnología (MAT2001-1007).

Cyclic voltammetry has been employed to investigate the behaviour of carbon steel and stainless steel electrodes in solutions obtained by filtering of calcium aluminate cement and portland cement slurries. Electro-polymerized phenol coating on steel electrodes has also been studied in carbonate medium. The phenol electro-polymerization occurs on a passivated surface and leads to adherent and stable polymeric film exhibiting a partial protection against corrosion. The Fourier transform infrared–attenuated total reflection spectroscopy shows that this film maintains the aromatic character and contains ether-linked rings. Dirección General de Enseñanza Superior e Investigación Científica (PB97-0130); Generalitat Valenciana (GV-1159/93) AE97-2).

In the present paper, the corrosion levels of reinforcing steels embedded in Calcium Aluminate Cement (CAC) mortars have been studied. Experiments were designed to investigate the influence of the following factors in steel corrosion: cover thickness, type of steel (carbon steel (CS) and stainless steel (SS)), temperature at mixing and curing, influence of chloride concentration, nitrite ion as corrosion inhibitor and carbonation of mortar. The reinforcing steel bars do not become more corroded because of the carbonation of the CAC mortar cover; in some cases, this carbonation seems to have an inhibitor effect in the steel corrosion. The higher the process of carbonation in CAC, the higher the intensity of the X-ray reflections of Friedel's salt and the smaller the values of corrosion rates. Generalitat Valenciana (GV-1159/93); Ministerio de Educación y Ciencia (PV-97-130).

The electrochemical oxidation of aniline at low concentration was carried out in phosphate buffer solutions of pH 5. Both electrochemical and spectroscopic results indicate that during the initial stages of aniline oxidation, a dimerisation process takes place. The dimer has been identified as p-aminodiphenylamine (ADPA). No evidence supporting the formation of other dimerisation products, such as benzidine or hydrazobenzene has been found. The hydrolysis of ADPA seems to be a very slow process at pH 5 and, consequently, the formation of hydroquinone/p-benzoquinone has not been observed. ADPA is poorly soluble in aqueous medium and a part of these species precipitates on the electrode surface when formed. This precipitated dimer could act as an active centre for the further growth of the polymeric chains. Ministerio de Educación y Cultura (PB97-0130)

Voltammetry and FTIR–ATR techniques have been employed to investigate polyphenol films formed on platinum surfaces by electrochemical oxidation of phenol. The media used in the electropolymerization were aqueous carbonate solutions, with and without Na2S. The polymeric films created are not permeable to ferrocyanide and ferricyanide species and present low water mobility. The presence of sulfide in the electropolymerization solution enhances these characteristics. The amount of sulfur detected by an energy dispersive X-ray detector (EDX) in the polymeric films created in the presence and in the absence of sulfide in the solution is very similar. Thus, the sulfur present in the polymer created in solutions with a sulfide concentration up to 10−3 M is not representative. A strong stretching vibration band at 900–1150 cm−1 is obtained in the IR spectrum that can be associated to the ether linkages of the phenolic rings (=C-O-C=). Generalitat Valenciana (GV-1159:93)(AE97-2); Fundación Cultural CAM.

University of Alicante assisted in meeting the publication costs of this article. The redox process undergone by the electrochemically synthesized poly(2,2-dithiodianiline), poly(DTDA), has been examined in acetonitrile-water mixtures by electrochemical and spectroscopic techniques. The spectroscopic properties of this material are equivalent to those exhibited by the chemically synthesized one. The polymeric structure displays a ladder structure, with S-S bonds serving as interconnections between two adjacent polyaniline chains. The kinetic reversibility of the RS–SR 2RS− reaction is very poor for the DTDA monomer species, and this irreversibility is retained in the polymeric material. According to the results presented, the hypothesis that poly(DTDA) could display a high energy density due to the simultaneity of the leucoemeraldine emeraldine and dithiolate disulfide electrochemical transformations does not seem justified. Ministerio de Ciencia y Tecnología (MAT2004-1479); Generalitat Valenciana (GV06-106).

The electrochemical oxidation of SO2 on polycrystalline gold electrodes has been studied by means of cyclic voltammetry and in situ vibrational techniques. On bare gold electrodes, SO2 is irreversibly oxidised on forward scans at ~0.6 V/RHE, featuring a diffusion-limited peak. Oxidation is inhibited by the formation of chemisorbed oxygen. A SO2 anodic current rise occurs on the reverse scan in parallel with the reduction of the metal oxide layers. As shown by FT-IR, oxidation proceeds to yield a mixture of soluble S(VI) species as stable reaction products. From vibrational spectra and results from the irreversible adsorption method, it follows that no strongly adsorbed S–O-like residues are present onto the gold surface in the region 0.3–0.5 V/RHE. On sulphur-modified electrodes improved electrocatalysis is manifested by the shift of the diffusion-limited peak to lower potentials. The best performance is observed at a sulphur coverage of 0.5. At higher coverage, sulphur adlayers impart lower catalytic efficiency and eventually show strong poisoning properties. This behaviour is exhibited by sulphur adlayers generated either in situ by SO2 reduction or ex situ by sulphide adsorption/oxidation in acidic or alkaline media. Ministerio de Educación y Cultura, Programa F.P.I. y proyecto PB97-0130; Instituto de Cultura J. Gil Albert.