Authors: Barúa, María Gloria; Escalada, Juan Pablo; Bregliani, Mabel Margarita; Pajares, Adriana Mabel; Criado, Susana Noemi
Publication Date: 2016.
Language: English.
Abstract:
Objectives: Catechins are important components of human diet and have received special attention due to their antioxidant capacity. The purpose of this paper was to study the antioxidant action of (+)-catechin (CTQ) in the presence of vitamin B2 (riboflavin) as light-absorbing agent. Furthermore, two model compounds, catechol (CTC) and resorcinol (RSC), were selected in order to elucidate the reactive target of the CTQ molecule. The influence of pH-medium was investigated. Methods: Stationary photolysis, polarographic detection of dissolved oxygen, reactive oxygen species (ROS)-scavengers, time-resolved near-IR phosphorescence detection, stationary, and time-resolved fluorescence and laser flash photolysis techniques were employed. Results: CTQ interacts with riboflavin under visible-light photoirradiation as well as with different ROS which are generated in this mechanism. Radical-scavenging activity increases with increasing of pH-medium. Discussion: pH-effect of the medium on radical-scavenging activity comes from the increased electron-donating ability of CTQ upon deprotonation. These results are very interesting due to the fact that the pH of the food products displays important variations. The O2(1Δg) -scavenging ability of CTQ, would be equal to the additive contribution of each reactive center, CTC, and RSC, present at the molecule of CTQ. However, CTQ would have a moderate ability to removal of O2(1Δg) -species at pH 7.
Author affiliation: Barúa, María Gloria. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina
Author affiliation: Escalada, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina
Author affiliation: Bregliani, Mabel Margarita. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina
Author affiliation: Pajares, Adriana Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina
Author affiliation: Criado, Susana Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Aparicio, Francisca; Escalada, Juan Pablo; De Geronimo, Eduardo; Aparicio, Virginia Carolina; Gracía Einschlag, Fernando; Magnacca, Giuliana; Carlos, Luciano; Mártire, Daniel
Publication Date: 2019.
Language: English.
Abstract:
The use of iron-based nanomaterials for environmental remediation processes has recently received considerable attention. Here, we employed core-shell magnetite-humic acids nanoparticles as a heterogeneous photosensitizer and iron source in photo-Fenton reaction for the degradation of the psychiatric drug carbamazepine (CBZ). CBZ showed low photodegradation rates in the presence of the magnetic nanoparticles, whereas the addition of hydrogen peroxide at pH = 3 to the system drastically increased the abatement of the contaminant. The measured Fe2+ and Fe3+ profiles point to the generation of Fe3+ at the surface of the nanoparticles, indicating a heterogeneous oxidation of the contaminant mediated by hydroxyl radicals. Products with a higher transformation degree were observed in the photo-Fenton procedure and support the attack of the HO• radical on the CBZ molecule. Promising results encourage the use of the nanoparticles as efficient iron sources with enhanced magnet-sensitive properties, suitable for applications in photo-Fenton treatments for the purification of wastewater.
EEA Balcarce
Author affiliation: Aparicio, Francisca .Universidad Nacional de La Plata. Facultad de Ciencias Exactas, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires; Argentina
Author affiliation: Escalada, Juan Pablo. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.
Author affiliation: De Gerónimo, Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina.
Author affiliation: Aparicio, Virginia Carolina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina.
Author affiliation: García Einschlag, Fernando. Universidad Nacional de La Plata. Facultad de Ciencias Exactas, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires; Argentina
Author affiliation: Magnacca, Giuliana. Università di Torino. Dipartimento di Chimica and NIS Inter-departmental Centre; Italia
Author affiliation: Carlos, Luciano. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; Argentina.
Author affiliation: Mártire, Daniel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires; Argentina.
Repository: INTA Digital (INTA). Instituto Nacional de Tecnología Agropecuaria
Authors: Escalada, Juan Pablo; Arce, Valeria Beatriz; Carlos, Luciano; Porcal, Gabriela Valeria; Biasutti, Maria Alicia; Criado, Susana Noemi; Garcia, Norman Andino; Martire, Daniel Osvaldo
Publication Date: 2014.
Language: English.
Abstract:
Some organic contaminants dissolved in natural waters tend to adsorb on suspended particles and sediments. In order to mimic the photodegradation routes in natural waters of bromoxynil (BXN) adsorbed on silica, we here prepare and characterize silica nanoparticles modified with BXN (NP-BXN). We measure the direct photolysis quantum yield of aqueous BXN at 307 nm (0.064 ± 0.001) and detect the formation of bromide ions as a reaction product. Under similar conditions the photolysis quantum yield of BXN bonded to NP-BXN is much lower (0.0021 ± 0.0004) and does not lead to formation of bromide ions. The rate constant of the reaction of NP-BXN with the excited triplet states of riboflavin, a molecule employed as a proxy of chromophore dissolved organic matter (DOM) was measured in laser flash-photolysis experiments. The rate constants for the overall (kt) and chemical interaction (kr) of singlet oxygen with NP-BXN were also measured. Kinetic computer simulations show that the relevance of the direct and indirect (through reactions with reactive species generated in photoinduced processes) photodegradation routes of BXN is very much affected by sorption on silica. Immobilization of the herbicide on the particles, on one hand, affects the photolysis mechanism and lowers its photolysis quantum yield. On the other hand, the results obtained in aqueous suspensions indicate that immobilization also lowers the rate of collisional encounter, which affects the quenching rate constants of excited triplet states and singlet oxygen with the herbicide.
Author affiliation: Escalada, Juan Pablo. Universidad Nacional de la Patagonia Austral; Argentina
Author affiliation: Arce, Valeria Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Author affiliation: Carlos, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Author affiliation: Porcal, Gabriela Valeria. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Biasutti, Maria Alicia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Criado, Susana Noemi. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Garcia, Norman Andino. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Martire, Daniel Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Escalada, Juan Pablo; Arce, Valeria Beatriz; Porcal, Gabriela Valeria; Biasutti, Maria Alicia; Criado, Susana Noemi; Garcia, Norman Andino; Martire, Daniel Osvaldo
Publication Date: 2014.
Language: English.
Abstract:
The production of dichlorophen (2,2′-methylenebis(4-chlorophenol), DCP) and its use as an anthelmintic and in pesticide products result in its direct release to the environment. To the purpose of modelling the possible photodegradation routes of DCP sorbed on sediments or suspended particles, the synthesis and characterization of silica nanoparticles modified with DCP (NP–DCP) is reported. The reactivity of NP–DCP with the excited states of riboflavin, a sensitizer usually present in natural waters, and with singlet oxygen were investigated. Comparison of the kinetic results obtained here to those previously reported for irradiated aqueous solutions of DCP allowed the discussion of the effect of adsorption of the pesticide on its photodegradation. We show with the aid of computer simulations that in natural waters the relevance of the different photodegradation routes dichlorophen is very much affected by attachment to sediments.
Author affiliation: Escalada, Juan Pablo. Universidad Nacional de la Patagonia Austral; Argentina
Author affiliation: Arce, Valeria Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Author affiliation: Porcal, Gabriela Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Biasutti, Maria Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Criado, Susana Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Garcia, Norman Andino. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Martire, Daniel Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Morales, María Gisela; Pajares, Adriana Mabel; Natera, Jose Eduardo; Escalada, Juan Pablo; Massad, Walter Alfredo; Garcia, Norman Andino
Publication Date: 2017.
Language: English.
Abstract:
The visible-light-promoted photodegradation of two carcinogenic primary azo-dye metabolites (BZ-C), represented by the colourless water-contaminants Benzidine (BZ) and o-Tolidine (OT), was studied in water-methanol solution. It was done in the presence of air and the natural pigment riboflavin (Rf) as a photosensitizer. These conditions reasonably mimic a natural environment scenery. Both BZ-C interact with the reactive oxygen species (ROS) singlet molecular oxygen (O2(1Δg)), superoxide radical anion (O2[rad]–), hydrogen peroxide (H2O2) and hydroxyl radical (OH[rad]), all photogenerated in situ through energy-transfer and electron-transfer processes. The interaction of BZ-C with O2(1Δg) is essentially physical in nature and occurs with a relatively high rate constant value. The effective BZ-C degradation is mainly driven by the remaining photogenerated ROS. A comparison of the BZ and OT photooxidative-rate with those of the archetypal surface-water-contaminants aniline and phenol indicates that BZ-C degradation occurs in a moderately slower fashion than the reference contaminants, within a common overall time-scale. The primary photoprocesses initiating the Rf-sensitized degradation seems to be quite similar for the four compounds, with the simultaneous operation of Type I and Type II photoprocesses. In conclusion: the natural Rf- photosensitized degradation of BZ-C appears as a plausible process, as evaluated under simulated environmental conditions.
Author affiliation: Morales, María Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina
Author affiliation: Pajares, Adriana Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Departamento de Ciencias Exactas y Naturales; Argentina
Author affiliation: Natera, Jose Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Escalada, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Departamento de Ciencias Exactas y Naturales; Argentina
Author affiliation: Massad, Walter Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Author affiliation: Garcia, Norman Andino. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas