Identification and quantification of the interaction mechanisms between the cationic surfactant HDTMA-Br and montmorillonite

Using a montmorillonite and the cationic surfactant hexadecyltrimethylammonium bromide (HDTMABr), a series of organoclays were synthesized with progressively increasing surfactant loads of between 0.2 and 4.0 times the cation exchange capacity of the starting clay. Different experimental techniques were used (thermal techniques, XPS, zeta potential) for characterizing the solids. The results obtained allowed to distinguish between the fraction of surfactant adsorbed by strong interactions and the fraction adsorbed by weak interactions. Adsorption isotherms of each of these processes were constructed, and were then adjusted using the Langmuir and Dubinin-Radusquevich adsorption models. Three types of interaction between the surfactant and the clay were identified and described, qualitatively and quantitatively. Two of these interactions, strong and weak, involve the hexadecyltrimethylammonium cation (HDTMA+). The third is a weak interaction involving the ion pair HDTMA+Br-.Fil: Naranjo, Pablo Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigación Para la Industria Química (i); ArgentinaFil: Sham, Edgardo Ling. Universidad Nacional de Salta. Facultad de Ingenieria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigación para la Industria Química (i); ArgentinaFil: Rodriguez Castellón, Enrique. Universidad de Malaga; EspañaFil: Torres Sanchez, Rosa Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro Tecnológico de Recursos Minerales y Cerámica (i); ArgentinaFil: Farfan Torres, Elsa Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigación Para la Industria Química (i); Argentina. Universidad Nacional de Salta. Facultad de Ciencias Exactas; Argentin

Valorización conjunta de glicerol y furfural asistida por catalizadores ácidos para la obtención de bioaditivos

En la última década, los combustibles renovables han cobrado gran interés en las investigaciones en el campo de la energía, así como la producción de moléculas plataforma derivadas de desechos de biomasa en busca de soluciones sustentables a la crisis energética

Valorización conjunta de glicerol y furfural asistida por catalizadores ácidos para la obtención de bioaditivos

En la última década, los combustibles renovables han cobrado gran interés en las investigaciones en el campo de la energía, así como la producción de moléculas plataforma derivadas de desechos de biomasa en busca de soluciones sustentables a la crisis energética. En este contexto, se propone la valoración del exceso de glicerol en la producción de biodiesel a través de la reacción catalítica de acetalización con furfural compuesto carbonílico que proviene de biomasa lignocelulósica para la obtención de dioxolanos. Estos productos tienen aplicación como bio-aditivos de naftas y biodiesel.Centro de Investigación y Desarrollo en Ciencias Aplicada

Comparative study of surface chemical composition and oxide layer modification upon oxygen plasma cleaning and piranha etching on a novel low elastic modulus Ti25Nb21Hf alloy

Metals are widely employed for many biological artificial replacements, and it is known that the quality and the physical/chemical properties of the surface are crucial for the success of the implant. Therefore, control over surface implant materials and their elastic moduli may be crucial to avoid undesired effects. In this study, surface modification upon cleaning and activation of a low elastic modulus Ti alloy (Ti25Hf21Nb) was investigated. Two different methods, oxygen plasma (OP) cleaning and piranha (PI) solution, were studied and compared. Both surface treatments were effective for organic contaminant removal and to increase the Ti-oxide layer thickness rather than other metal-oxides present at the surface, which is beneficial for biocompatibility of the material. Furthermore, both techniques drastically increased hydrophilicity and introduced oxidation and hydroxylation (OH)-functional groups at the surface that may be beneficial for further chemical modifications. However, these treatments did not alter the surface roughness and bulk material properties. The surfaces were fully characterized in terms of surface roughness, wettability, oxide layer composition, and hydroxyl surface density through analytical techniques (interferometry, X-ray photoelectron spectroscopy (XPS), contact angle, and zinc complexation). These findings provide essential information when planning surface modifications for cleanliness, oxide layer thickness, and surface hydroxyl density, as control over these factors is essential for many applications, especially in biomaterials.Peer Reviewe

Cobalt and KNO3 supported on alumina catalysts for diesel soot combustion

The catalytic combustion of diesel soot was studied in the presence of fresh and aged catalysts: Co/Al2O3, KNO3/Al2O3 and Co/KNO3/Al2O3. The catalysts were prepared by impregnation using nitrate solutions. The catalysts were characterized by X-ray diffraction, thermal programmed reduction, vibrational spectroscopy and X-ray photoelectron spectroscopy. Fresh and aged catalysts present high activity in presence of O2 and O2/NO. The values of the combustion temperature decrease more than 200 °C with respect to that observed in the process without catalysis. The activity is associated with the presence of KNO3 and the role of this salt can be attributed to the contribution of NO3−/NO2− redox cycle.Fil: Grzona, Claudia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Lick, Ileana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Rodriguez Castellón, Enrique. Universidad de Málaga; EspañaFil: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ponzi, Esther Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentin

Study on the use of 3-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane to surface biochemical modification of a novel low elastic modulus Ti-Nb-Hf alloy

A biocompatible new titanium alloy Ti-16Hf-25Nb with low elastic modulus (45 GPa) and the use of short bioadhesive peptides derived from the extracellular matrix have been studied. In terms of cell adhesion, a comparative study with mixtures of short peptides as RGD (Arg-Gly-Asp)/PHSRN (Pro-His-Ser-Arg-Asn) and RGD (Arg-Gly-Asp)/FHRRIKA (Phe-His-Arg-Arg-Ile-Lys-Ala) have been carried out with rat mesenchymal cells. The effect of these mixtures of short peptides have already been studied but there are no comparative studies between them. Despite the wide variety of silane precursors available for surface modification in pure titanium, the majority of studies have used aminosilanes, in particular 3-minopropyltriethoxysilane (APTES). Nevertheless, the 3-chloropropyltriethoxysilane (CPTES) is, recently, proposed by other authors. Unlike APTES, CPTES does not require an activation step and offers the potential to directly bind the nucleophilic groups present on the biomolecule (e.g., amines or thiols). Since the chemical surface composition of this new alloy could be different to that pure titanium, both organosilanes have been compared and characterized by means of a complete surface characterization using contact angle goniometry and X-ray photoelectron spectroscopy. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B:495-502, 2015.Peer ReviewedPostprint (author's final draft

Study on the use of 3-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane to surface biochemical modification of a novel low elastic modulus Ti-Nb-Hf alloy

A biocompatible new titanium alloy Ti-16Hf-25Nb with low elastic modulus (45 GPa) and the use of short bioadhesive peptides derived from the extracellular matrix have been studied. In terms of cell adhesion, a comparative study with mixtures of short peptides as RGD (Arg-Gly-Asp)/PHSRN (Pro-His-Ser-Arg-Asn) and RGD (Arg-Gly-Asp)/FHRRIKA (Phe-His-Arg-Arg-Ile-Lys-Ala) have been carried out with rat mesenchymal cells. The effect of these mixtures of short peptides have already been studied but there are no comparative studies between them. Despite the wide variety of silane precursors available for surface modification in pure titanium, the majority of studies have used aminosilanes, in particular 3-minopropyltriethoxysilane (APTES). Nevertheless, the 3-chloropropyltriethoxysilane (CPTES) is, recently, proposed by other authors. Unlike APTES, CPTES does not require an activation step and offers the potential to directly bind the nucleophilic groups present on the biomolecule (e.g., amines or thiols). Since the chemical surface composition of this new alloy could be different to that pure titanium, both organosilanes have been compared and characterized by means of a complete surface characterization using contact angle goniometry and X-ray photoelectron spectroscopy. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B:495-502, 2015.Peer Reviewe

Efecto promotor del agregado de rodio a catalizadores de Co/ZnAl₂O₄ para la combustión catalítica de hidrocarburos

Una serie de catalizadores de cobalto soportados sobre aluminato de zinc (Cox-ZnAl) modificados con Rh, fue preparada, caracterizada mediante diversas técnicas (BET, XRD, TPR, DRS, FTIR y XPS) y aplicados en las reacciones de oxidación catalítica de propano y naftaleno.Centro de Investigación y Desarrollo en Ciencias Aplicada