Resultados experimentales de fotogeneración de ROS por perlas alginato-boehmita-riboflavina fosfato

In this work, hybrid composites based on beads of alginate, boehmite and riboflavin-50-phosphate dye (ALG-BRP) were synthesized in order to obtain novel materials capable to generate reactive oxygen species (ROS). The synthesis was performed by adsorbing the dye RP on boehmite (B) and then alginate (ALG) was added forming a homogeneous suspension. This suspension was dripped on a solution of calcium ions resulting in the formation of bead-shaped yellow hydrogels. Beads with different RP content were synthesized. Confocal laser scanning microscope images indicate that the RP is homogeneously distributed in the ALG polymeric matrix. This microscopy, UV–Vis and fluorescence spectroscopies show that dye photophysical properties are not affected. Uptake oxygen experiments show that these beads have the ability to generate ROS, mainly singlet oxygen O2(1Δg). On top of that mentioned above, these materials are economical, environmentally friendly because are synthesized from non-toxic components and their synthesis does not generate waste and only use water as solvent. On the other hand, these beads are easy to handle and their ability to generate ROS making them promising for water remediation.Fil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Resultados experimentales de BAC y PQ adsorbidos en MMT

La mayoría de los estudios sobre surfactantes adsorbidos en arcillas se han centrado en mejorar la reactividad superficial de la arcilla para eliminar contaminantes. Sin embargo, este trabajo de investigación se estudió exhaustivamente cómo la presencia de tensioactivos en medios acuosos puede afectar a la adsorción de otras especies en la superficie de la arcilla. En un estudio anterior se observó que la adsorción de contaminantes catiónicos como el herbicida paraquat (PQ) y el metal pesado cadmio sobre la superficie de la arcilla montmorillonita (MMT) se ve afectada por la presencia del surfactante BAC. En el presente conjunto de datos de investigación se analizó el mecanismo del comportamiento competitivo entre PQ y BAC sobre MMT mediante la combinación de estudios experimentales complementados con un modelo teórico. Este modelo es conocido ya que describió el intercambio de cationes simples (por ejemplo, Na+, K+, Mg2+ y Ca2+) sobre minerales arcillosos. Aunque se aplicó satisfactoriamente para aclarar el intercambio entre los iones mencionados, hasta donde sabemos, este modelo no se ha utilizado para estudiar el intercambio entre cationes orgánicos más grandes como PQ y BAC.Fil: Etcheverry, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Zanini, Graciela Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

A simple cation exchange model to assess the competitive adsorption between the herbicide paraquat and the biocide benzalkonium chloride on montmorillonite

Since adsorption on clay minerals is one of the most popular water-pollutant removal method, it is important to consider the coexistence of several compounds that can affect pollutant retention. In this work, the competitive behaviour between cationic herbicide paraquat (PQ) and a benzalkonium chloride compound (BAC) on montmorillonite (MMT) was performed by adsorption experiments and analysed by a theoretical cation exchange model. Experimental studies included adsorption isotherms, XRD, FTIR and zeta potential (ζ). Binary systems (BAC + PQ) were performed at different initial concentrations ratio BAC/PQ = 0.1; 0.5; 1.0; 2.0 and 3.0. Results showed that at higher BAC initial concentration, the maximum adsorbed PQ amount decreases. X-Ray diffractograms showed that as the BAC/PQ ratio increases, the MMT basal spacing peak shifts to lower angles suggesting that the basal spacing is mainly controlled by the presence of BAC. Besides, the total adsorbed amount (adsorbed PQ plus adsorbed BAC) is closer to clay CEC value (0.91 mEq g−1), at this value ζ ≅ 0 mV suggesting that the adsorption occurs through a cation exchange mechanism. The theoretical model applied was originally developed to describe the exchange of simple cations on clay minerals, however it was effective in predicting the behaviour of larger cations such as PQ and BAC. In this scenario, thermodynamic parameters calculated through the model indicate that cation exchange process is spontaneous towards adsorbed BAC, suggesting that an adsorbed PQ cation is replaced by an equivalent amount of BAC cation (expressed in terms of electrical charge).Fil: Ilari, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Etcheverry, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Zanini, Graciela Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Adsorption of metsulfuron-methyl on soils under no-till system in semiarid Pampean Region, Argentina

Adsorption isotherms of metsulfuron-methyl (MM) on thirty soils from the semiarid Pampean Region of Argentina were determined. The effect of total organic carbon (TOC) content on the adsorption was the main focus, but the effects of clay content, specific surface area and pH were also analyzed. pH is a very important factor that affects the adsorption. In fact, this article demonstrates that a good pH control is necessary to investigate the effects of TOC, otherwise results are obscured by changes in pH. Under pH controlled conditions (pH 6.0 ± 0.2), a significant and positive correlation between MM adsorption and TOC was observed for a large range of concentrations (up to 40 mg L- 1). There was no significant correlation between adsorption and inorganic components or specific surface area. The potential mobility of MM in soils was estimated by calculating the groundwater ubiquity score (GUS), using KOC values calculated from adsorption isotherms and appropriate half-times. MM can be ranked as leacher in all the studied soils. The results suggest that MM would be rather mobile and transported by water flows.Fil: Zanini, Graciela Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Maneiro, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Galantini, Juan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Rosell, Ramon Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentin

Novel hybrid materials based on alginate-boehmite-riboflavin for photogeneration of reactive oxygen species in aqueous media: Potential environmental implications

In this work, hybrid composites based on beads of alginate, boehmite and riboflavin-5′-phosphate dye (ALG-B-RP) were synthesized in order to obtain novel materials capable to generate reactive oxygen species (ROS). The synthesis was performed by adsorbing the dye RP on boehmite (B) and then alginate (ALG) was added forming a homogeneous suspension. This suspension was dripped on a solution of calcium ions resulting in the formation of bead-shaped yellow hydrogels. Beads with different RP content were synthesized. Confocal laser scanning microscope images indicate that the RP is homogeneously distributed in the ALG polymeric matrix. This microscopy, UV?Vis and fluorescence spectroscopies show that dye photophysical properties are not affected. Uptake oxygen experiments show that these beads have the ability to generate ROS, mainly singlet oxygen O2(1Δg). On top of that mentioned above, these materials are economical, environmentally friendly because are synthesized from non-toxic components and their synthesis does not generate waste and only use water as solvent. On the other hand, these beads are easy to handle and their ability to generate ROS making them promising for water remediation.Fil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Natera, Jose Eduardo. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Massad, Walter Alfredo. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Zanini, Graciela Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Hybrid mineral@silsesquioxane particles for water remediation: synthesis, characterization and application as adsorbent of As(V) and other water pollutants

Mineral-coated silsesquioxane particles of approximately 600 nm diameter were synthesized from the hydrolytic co-condensation of N-[3-trimethoxysilyl]-propyl]ethylenediamine (DAS) and tetraethyl orthosilicate (TEOS). The hybrid particles involve nanocomposites with a mineral core (montmorillonite—MMT—or goethite—Gt—nanoparticles) and coated with a silsesquioxane shell containing hydroxyl and amine groups. These particles were specially designed (exposing amino groups) to be highly efficient for the removal of As(V) and to enhance the adsorption properties of the minerals employed in this work. They were characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy, zeta potential, dynamic light scattering and thermogravimetric techniques such as dynamic scanning calorimetry and thermogravimetric analysis. The characteristics found in the composite particles compared with pure organosilane DAS/TEOS or with the unmodified minerals proved the effectiveness of the silanization process. As result, hybrid nanocomposite materials were obtained, denoting versatility in their adsorption properties of different types of pollutants. Moreover, all synthesized particles showed a high arsenic retention capacity; experimental results demonstrated that superficial modification of the minerals is the preponderant factor that determines their adsorbent properties, favoring the versatility of these materials making them suitable for the removal of pollutants of diverse charge and nature.Fil: Waiman, Carolina Vanesa. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Dell'Erba, Ignacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Gomez, María Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin

A real time in situ ATR-FTIR spectroscopic study of glyphosate desorption from goethite as induced by phosphate adsorption: Effect of surface coverage

The desorption of glyphosate from goethite as induced by the adsorption of phosphate was investigated by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy in combination with adsorption isotherms. Desorption of glyphosate was very low in the absence of phosphate. Addition of phosphate promoted glyphosate desorption. At low initial surface coverages, added phosphate adsorbed on free surface sites, mainly, displacing a small amount of glyphosate. At high initial surface coverages, on the contrary, phosphate adsorption resulted in a significant glyphosate desorption. In the latter conditions, the ratio desorbed glyphosate to adsorbed phosphate was 0.60. The desorption process can be explained by assuming that phosphate adsorbs first forming a monodentate mononuclear complex, which rapidly evolves into a bidentate binuclear complex that displaces glyphosate.Fil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Avena, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Regazzoni, Alberto Ernesto. Comision Nacional de Energia Atomica. Centro Atomico Bariloche; Argentina. Universidad Nacional de San Martin. Instituto Sabato; ArgentinaFil: Zanini, Graciela Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentin

Effect of humic acid on the adsorption/desorption behavior of glyphosate on goethite: Isotherms and kinetics

The effects of humic acid (HA) on the adsorption/desorption of glyphosate (Gly) on goethite were investigated under pseudo equilibrium conditions by adsorption isotherms and under kinetic conditions by ATR-FTIR spectroscopy. Isotherms reveal that the attachment of Gly is almost completely inhibited by HA molecules. The opposite effect is not observed: HA adsorption is not affected by the presence of Gly. ATR-FTIR allowed the simultaneous detection of adsorbed HA and Gly during kinetic runs, revealing that HA at the surface decreases markedly the adsorption rate of Gly likely as a result of a decreased availability of sites for Gly adsorption and because of electrostatic repulsion. In addition, HA in solution increases the desorption rate of Gly. The rate law for Gly desorption could be determined giving important insights on the desorption mechanism. The herbicide is desorbed by two parallel processes: i) a direct detachment from the surface, which is first order in adsorbed Gly; and ii) a ligand exchange with HA molecules, which is first order in adsorbed Gly and first order in dissolved HA. Rate constants for both processes were quantified, leading to half-lives of 3.7 h for the first process, and 1.4 h for the second process in a 400 mg L-1 HA solution. These data are important for modeling the dynamics of glyphosate in environmentally relevant systems, such as soils and surface waters.Fil: Arroyave Rodriguez, Jeison Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Zanini, Graciela Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Avena, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Interacción del Metsulfuron-materia orgánica en suelos con siembra directa

La intensificación agrícola en nuestro país está asociada a un uso creciente de agroquímicos (fertilizantes, herbicidas, insecticidas, etc.) en los sistemas productivos. Cuando ellos exceden los límites críticos para su uso y la capacidad del ambiente para neutralizarlos, constituyen una fuente de contaminación para los sistemas adyacentes.Fil: Zanini, Graciela Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Maneiro, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Zabala, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Brigante, Marcelo. Universidad Nacional del Sur. Departamento de Química; ArgentinaFil: Galantini, Juan. Universidad Nacional del Sur. Departamento de Química; ArgentinaFil: Rosell, Ramon Antonio. Universidad Nacional del Sur. Departamento de Química; Argentin

Photophysical Behavior of Modified Xanthenic Dyes Embedded into Silsesquioxane Hybrid Films: Application in Photooxidation of organic molecules

Polymeric materials based on a bridged silsesquioxane with pendant dodecyl chains were synthesized and modified with different xanthenic dyes with the aim of developing a material with potential application in photooxidation of organic compounds. The employed dyes constitute a family of novel xanthenic chromophores with outstanding properties as singlet oxygen photosensitizers. The hybrid matrix was chosen for its enhanced properties such as flexibility and chemical resistance. The employed dyes were easily incorporated into the hybrid polymer obtaining homogeneous, transparent, and low-refractive-index materials. The polymeric films were characterized using UV-Vis absorption, fluorescence, and laser flash photolysis techniques. The ability of these materials to produce singlet oxygen was tested following the photooxidation of 9,10-dimethylanthracene which is a well-known chemical trap for singlet oxygen. High photooxidation efficiencies were observed for these materials, which present the advantage of being easily removed/collected from the solution where photooxidation takes place. While photobleaching of the incorporated dyes is commonly observed in the solution, it takes place very slowly when dyes are embedded in the hybrid matrix. These properties bode well for the potential use of these materials in novel wastewater purification strategies.Fil: Waiman, Carolina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Palacios, Rodrigo Emiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Montejano, Hernan Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Chesta, Carlos Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, María Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin