Browsing by Author "Meichtry, Jorge Martín"
Now showing 1 - 15 of 15
- Results Per Page
- Sort Options
Item Análisis de los parámetros operativos de un proceso de remoción de contaminantes por electrocoagulación(2021-10-07) Marchisio, Bettina L.; Enrico Cuniolo, Agostina; Fioriti, Mariano; Belmonte, Micaela; Lan, Luis; De Seta, Elizabeth Graciela; Meichtry, Jorge MartínLa electrocoagulación es un proceso electroquímico con potencial como método versátil y económico para el tratamiento aguas y efluentes, ya que puede remover una gran variedad de contaminantes peligrosos y difíciles de tratar por otras tecnologías, como por ejemplo arsénico y colorantes. Trabajos previos en un sistema batch mostraron que la electrocoagulación con electrodos de hierro o aluminio es muy eficiente para remover As de aguas reales ([As(V)]0 = 2 mg L1, consumo eléctrico = 0,48 kWh m-3); por otro lado, estudios preliminares combinando electrocoagulación con electrodo de hierro y H2O2 (EC-Fenton) mostraron un gran potencial para degradar colorantes como azul de metileno (MB) y negro reactivo 5 (RB5) ([H2O2] = 5 mM, [MB] o [RB5] = 50 mg L-1, Consumo eléctrico = 5,1.10-3 kWh m-3) lo que permitiría reutilizar el agua en la industria textil para blanqueo y teñido. El objetivo de este trabajo es determinar los parámetros claves para escalar estos procesos de electrocoagulación a un proceso continuo. Para esto, se realizó una búsqueda sistemática de más de 100 artículos de investigación y patentes publicados en años recientes, pudiendo concluirse que las principales variables a considerar en el diseño y operación del proceso son: - Materiales de los electrodos. - Conductividad de la solución (cuanto más alta, menor consumo eléctrico). - Composición del electrolito (idealmente la relación molar nitrato/cloruro debe ser menor a 20). - Condiciones de operación: baja densidad de corriente, alto tiempo de residencia, régimen turbulento.Item Aplicación de procesos electroquímicos para el reúso de efluentes textiles: estudio preliminar con colorantes.(2024) Sánchez, Pablo C.V.; Vera, Noelia; Miranda Ruiz, Gladys; Aristi, María Elena; Marchisio, Bettina L.; Meichtry, Jorge Martín; De Seta, Elizabeth GracielaLa industria textil tiene una demanda intensiva de agua y sus vertidos se caracterizan por ser altamente contaminantes, principalmente debido a la presencia de colorantes sintéticos. La electrocoagulación sola (EC) o con adición de H2O2 (peroxicoagulación, PC) son tratamientos de aguas, simples y eficientes, posibilitando la descarga segura de los efluentes, pero también su reúso. En este trabajo se estudió el tratamiento de dos colorantes textiles, Negro reactivo 5 (RB5, un colorante reactivo) y Rojo Dianix (RD, un colorante disperso), y un agua real (AR) contaminada con colorantes, mediante EC y PC empleando ánodos de hierro; se analizó el tiempo de reacción (tr), el consumo eléctrico (CE) y el potencial reúso a partir de los requisitos de los distintos procesos textiles. Los resultados mostraron que PC es más eficiente para RB5 (tr = 1,5 min, CE 0.005 kWh m-3) y EC para RD (tr = 13 min, CE 0.5 kWh m-3), lográndose en ambos casos remociones ≥ 95%; por su parte, en el tratamiento de AR mediante PC se lograron remociones de 70% en turbidez y DQO (tr = 8 min, CE 0.31 kWh m-3). Se concluye que la elección de EC o PC depende de la naturaleza del contaminante, y que estos tratamientos posibilitarían el reúso parcial de agua en el proceso textil.Item Comparación de los procesos de electrocoagulación y electrocoagulación– Fenton para el tratamiento de colorantes textiles.(2023-05-05) De Seta, Elizabeth Graciela; Meichtry, Jorge Martín; Marchisio, Bettina L.; Sánchez, Pablo C.V.; Enrico Cuniolo, Agostina; Vera, Noelia; Coelho, JeffersonEn el presente trabajo se evaluó la eficiencia de la electrocoagulación con ánodo de hierro, solo (RC) o combinada con la adición de H2O2 (EC-Fenton), para el tratamiento de soluciones acuosas de un colorante textil reactivo (negro de Synozol, NS) y un colorante textil disperso (rojo Dianix, RD), analizándose los tiempos de reacción y el consumo eléctrico (CE). Los resultados muestran que, bajo las condiciones experimentales ensayadas, la EC y la EC-Fenton son eficientes para tratar efluentes que contengan estos contaminantes tóxicos y persistentes, siendo EC más eficiente para RD (CE 0.5 kWh m-3) y EC-Fenton para NS (CE 0.005 kWh m-3), lo cual permitiría su acoplamiento a un proceso biológico para reducir así la DQO, habilitando el reuso parcial del agua en el proceso textil.Item Comparison between Electrocoagulation, Electrochemical Fenton and Fenton processes for the treatment of dyes.(2023-06-08) Vera, Noelia; Enrico Cuniolo, Agostina; Di Fraia, Guido; Sánchez, Pablo C.V.; Marchisio, Bettina L.; De Seta, Elizabeth Graciela; Reina, Fernando; Halac, Emilia; Meichtry, Jorge MartínElectrocoagulation with an iron anode, alone (EC) and combined with H2O2 (ECF), and the Fenton reaction, were studied as alternative treatments for the removal of two dyes, methylene blue (MB) and reactive black 5 (RB5), from aqueous solution. The effect of pH, [H2O2]0 and [Fe(II)] on the degradation rate (r) was analyzed, and both the electrical energy consumed (EEC) and the amount of final wastes generated (ENC, kg of Fe per kg of dye removed) were calculated.Item Contaminación, tratamiento y reúso de efluentes de la industria textil.(2023-10-20) Vera, Noelia; Miranda Ruiz, Gladys; Aristi, María Elena; Sánchez, Pablo C.V.; Russo, Analía V.; Marchisio, Bettina L.; Meichtry, Jorge Martín; De Seta, Elizabeth GracielaSe estudia la eficiencia de la electrocoagulación (EC) con ánodo de hierro y la adición de H2O2 (EC-Fenton) para la degradación de negro de Synozol (NS), un colorante reactivo, y de rojo Dianix, un colorante disperso.Item Degradación de los colorantes por procesos avanzados y evaluación de reúso del agua en la industria textil.(2022-03-11) Belmonte, Micaela; Golubickas, Ariel; Di Fraia, Guido; Lan, Luis; Russo, Analía V.; Sánchez, Pablo C.V.; Marchisio, Bettina L.; Meichtry, Jorge Martín; De Seta, Elizabeth GracielaEn este trabajo se estudiaron dos Procesos Avanzados (PAs), la reacción de Fenton (Fe2+ y H2O2) y la electrocoagulación con ánodo de hierro y adición de H2O2 (EC-Fenton), para la degradación de azul de metileno (AM) y el negro de Synozol (NS). Se utilizó una celda de 250 ml para EC-Fenton con electrodos de hierro SAE 1010 de 19,5 cm2 y 9 cm de separación, y agitación a 250 rpm. Se estudió el efecto del pH y de [H2O2]0 en la velocidad de degradación (r) de AM y NS; además, para AM se estudió el efecto de [AM]0.Item Effect of different gases on the sonochemical Cr(VI) reduction in the presence of citric acid(2020-12-01) Meichtry, Jorge Martín; Cancelada, Lucía; Destaillats, Hugo; Litter, Marta IreneThe sonochemical (850 kHz) Cr(VI) reduction (0.30 mM, pH 2) in the presence of citric acid (Cit, 2 mM) was analyzed under different working atmospheres: reactor open to air without sparging (ROAWS), and Ar, O2, air and N2 sparging. Hydrogen peroxide formation in pure water at pH 2 and KI dosimetry were also measured. Zero-order kinetics was observed in all cases. A complete Cr(VI) reduction after 180 min insonation was obtained with the ROAWS and under Ar, while a lower Cr(VI) reduction efficiency was achieved under the other conditions. The Cr(VI) reduction and H2O2 formation rates followed the order ROAWS ?° Ar > air ?° O2 >> N2, while for KI dosimetry the order was ROAWS >> O2 ?° air > Ar >> N2. This indicates that H2O2 formation rate is a better measure of the system reactivity for Cr(VI) reduction. For air, O2 and N2, once the sparging was stopped, Cr(VI) reduction rate increased up to approximately the same value obtained for the ROAWS, suggesting that the sparging decreased the generation of reactive species and, thus, the Cr(VI) reduction rate. Nitrate production was measured at low concentrations (micromolar range) in the ROAWS, air and N2 systems. Formic and acetic acids were detected as Cit degradation products. Reaction mechanisms were proposed. It can be concluded that the best conditions for Cr(VI) removal are with the ROAWS because of a higher Cr(VI) reduction rate, no atmosphere control is required, and it is a less expensive system.Item New insights on the UV/TiO2 photocatalytic treatment of thiomersal and its 2-sulfobenzoic acid product(2021-06-28) de la Fourniere, Emmanuel; Meichtry, Jorge Martín; Gautier, Eduardo Amilcar; Custo, Graciela; Litter, Marta IreneAbstract: Background: Thiomersal (TM), a complex between 2-mercaptobenzoic acid (2-MBA) and ethylmercury (C2H5Hg+), is an antimicrobial preservative used in immunological, ophthalmic, cosmetic products, and vaccines. Objective: TM has been treated by UV/TiO2 photocatalysis in the presence or absence of oxygen at acidic pH. C2H5Hg+, 2-MBA, and 2-sulfobenzoic acid (2-SBA) were found as products. A 2-SBA photocatalytic treatment was undertaken to study sulfur evolution. Methods: Photocatalytic runs were performed using a UVA lamp (λmax = 352 nm), open to air or under N2. A suspension of the corresponding TM or 2-SBA salt and TiO2 was prepared, and pH was adjusted. Suspensions were stirred in the dark for 30 min and then irradiated. TM, 2-MBA, 2-SBA, and C2H5Hg+ were quantified by HPLC, sulfur by TXRF, and the deposits on the photocatalyst were analyzed by chemical reactions. The mineralization degree was followed by TOC. Sulfate was determined using BaCl2 at 580 nm. Results: Photocatalytic destruction of TM and total C2H5Hg+ was complete under N2 and air, but TM degradation was much faster in air. The evolution of TM and the products followed a pseudo-first order kinetics. Conclusion: TiO2-photocatalytic degradation is a suitable technique for the treatment of TM and its degradation products. In contrast to other organomercurial compounds, TM degradation is faster in the presence of O2, indicating that the oxidative mechanism is the preferred pathway. A significant TM mineralization (> 60%, NPOC and total S) was obtained. TM was more easily degraded than 2-SBA. Sulfate was the final productItem Photocatalytic activity of TiO2 films prepared by cathodic arc deposition: dependence on thickness and reuse of the photocatalysts(2020-01-25) Meichtry, Jorge Martín; Vega, Daniel; Kleiman, Ariel; Litter, Marta Irene; Márquez, AdrianaIn this work, the photocatalytic activity of anatase films with thicknesses up to 1100 nm prepared by cathodic arc deposition (CAD) on glass substrates is reported. The photocatalytic activity under UV?Vis irradiation (λ > 330 nm) was evaluated through the efficiency in the reduction of 0.80 mM Cr(VI) in the presence of 1 mM ethylenediaminetetraacetic acid (EDTA) at pH 2, and compared with the performance of samples obtained by dip-coating using commercial P25. The CAD films were optically transparent, with visible light transmittance ≥ 50% even for the thickest samples. The photocatalytic efficiency of the films increased as the thickness increased. The possibility of obtaining thicker films allowed cathodic arc films reaching better performance than P25 samples. For the most active films obtained by CAD, complete Cr(VI) reduction could be obtained in <300 min under a 28 W m−2 UV-A irradiance. The photocatalytic reaction for all the studied TiO2 films obeyed pseudo-first order kinetics. A decrease of the reaction rate constant was observed for both types of films after reusing the photocatalysts. The fate of the reduced Cr(VI) was also analyzed.Item Preliminary results of photocatalytic Cr(VI) reduction using TiO2 films grown by cathodic arc deposition: effect of the film thickness and the N-doping(2023-06-08) Kleiman, Ariel; Meichtry, Jorge Martín; Xaubet, M.; Grondona, D.; Litter, Marta Irene; Márquez, AdrianaTiO2 is the most studied photocatalyst for the treatment of pollutants; however, its rather large band gap and the need for a removal step when used as a suspension hinder the wide application of this technology. Immobilized TiO2 films grown by cathodic arc deposition (CAD) have shown superior adhesion to the substrate and activities similar to that of P-25 TiO2 films, the reference photocatalyst, but they still require UV light to be excited [1]. N-doping is a strategy frequently used to extend the TiO2 band gap to the visible range [2], but it has a scarce application on CAD-grown films. In this work, TiO2 CAD films, with and without N-doping, were prepared and tested on the photocatalytic removal of Cr(VI), a priority water pollutant, in the presence of ethylenediaminetetraacetic acid (EDTA) as an organic donor. TiO2 films of different thicknesses: (290 ± 40 nm), (440 ± 40) nm, and (850 ± 70) nm, were deposited by CAD according to a reported method [1]. The doping of the films was performed by plasma immersion ion implantation in a N2 environment. For comparison, P-25 TiO2 films of (280 ± 20) nm and (480 ± 30) nm thicknesses were prepared by dip-coating; thicker P-25 films were not stable. All films were grown over a borosilicate glass substrate. Photocatalytic experiments were performed in thermostatted cylindrical glass cells (T = 25 °C) magnetically stirred and irradiated from the top with a HPA 400S lamp (λ > 320 nm, mean UV irradiance 28 W m-2), equipped with an IR filter. 10 mL of a 0.8 mM Cr(VI) and 1 mM EDTA solution at pH 2 (HClO4) were poured into each cell, and 0.25 mL samples were periodically taken for Cr(VI) quantification by the diphenylcarbazide method; at the end of the experiments, a Cr(III)-EDTA complex in solution was determined by direct spectrophotometry [1]. After 5 h of irradiation, Cr(VI) removals of 58% and 85% were obtained with pure and N-doped 290 nm CAD films, respectively, while for pure and N-doped 440 nm CAD films the corresponding removals were 70% and 85%; with the 280 nm and 480 nm P-25 films, Cr(VI) removals were 81% and 88%, respectively. Although thicker CAD films were more efficient (99% of Cr(VI) removal with 850 nm films), no difference could be appreciated between N-doped and undoped films. Cr(VI) evolution could be adjusted to a pseudo-first-order kinetics. In all cases, Cr(III)-EDTA represented 75% of the reduced Cr(VI), the remaining Cr(III) being retained on the TiO2 surface, [1]. The photocatalytic efficiency increased with the thickness of the films. Although P-25 films showed a higher photoactivity than the CAD films of similar thickness, thicker and more active CAD films can be surely obtained in future works. N-doping increased slightly the photocatalytic activity of the thinnest films.Item Remoción de arsénico en agua mediante materiales de bajo costo y segura disposición final(2015-10-01) Meichtry, Jorge Martín; De Seta, Elizabeth Graciela; Reina, Fernando Damián; Mugrabi, Fernando Isaac; Domingo, Esteban JoséSe estudió la capacidad de remoción de arsénico mediante adsorción y/o co-precipitación empleando materiales económicos como arcilla natural y hierro cerovalente (Fe(0)) comercial, microparticulado y como viruta. Se realizaron experimentos de remoción de As(III) y As(V) presente en soluciones acuosas ([As]0 = 5 mg L -1 , pH 7), empleando concentraciones variables de arcilla y Fe(0); para el caso de la arcilla, se estudió la cinética de remoción y el efecto del pH (5,5 ≤ pH ≤ 8,5). También se estudió la lixiviación del As retenido en los residuos generados, los cuales fueron sometidos previamente a distintos tratamientos térmicos. Se determinó que son necesarias concentraciones de 2,5% m/v de arcilla o 0,05% m/v de Fe(0) para lograr una remoción ≥ 95% para ambas especies de As. Los estudios de remoción con arcilla indicaron que la cinética de adsorción de As(III) y As(V) respondió a un comportamiento bi-exponencial y que la remoción de As(V) por arcilla es mayor a valores ácidos, mientras que la presencia de materia orgánica (ácido cítrico) disminuye la remoción. En todos los casos, se observó una lixiviación despreciable para As(V), mientras que para As(III) es inferior al 3% del As total removido.Item Reúso del agua en el proceso de teñido textil(2022-11-08) De Seta, Elizabeth Graciela; Marchisio, Bettina L.; Sánchez, Pablo C.V.; Meichtry, Jorge Martín; Di Fraia, Guido; Enrico Cuniolo, Agostina; Belmonte, Micaela; Vera, NoeliaEl agua es el recurso central para el desarrollo sostenible, se trata de un recurso limitado e insustituible; sin embargo, algunas estimaciones muestran que más del 80% de las aguas residuales se vierten a los cursos de agua sin tratamiento. Existen casos testigos con avances prometedores en la buena administración del agua para la industria textil, que demostraron la capacidad de reciclar y reutilizar el agua para lograr una disminución del consumo. La industria textil descarga entre el 10 y el 15 % de los colorantes utilizados en sus efluentes, poniendo en riesgo la seguridad hídrica de las comunidades, los colorantes sintéticos utilizados suelen ser tóxicos y su biodegradación lenta. Este trabajo se inscribe en un proceso de tratamiento para efluentes textiles aplicando la reacción de Fenton, para reducir la elevada carga de colorante en el efluente, posteriormente un tratamiento biológico y evaluar el reuso como agua del proceso de teñido. Los experimentos de EC-Fenton se realizaron en una celda de 250 mL con electrodos de hierro SAE 1010 de 19,5 cm2, 9 cm de separación interelectródica, y agitación magnética a 250 rpm. El estudio compara la eficiencia de la reacción de Fenton (Fe2+ y H2O2) y la electrocoagulación con ánodo de hierro y adición de H2O2 (EC-Fenton). Se estudió el efecto del pH y de la [H2O2]0 en la velocidad de degradación. Los resultados muestran, para todas las condiciones ensayadas, que EC-Fenton es más eficiente que Fenton tanto a pH 3 como 6, su acoplamiento a un proceso biológico permitiría reducir el valor de DQO a valores inferiores a 50 mg L-1, por lo que el agua tratada, combinada con un cierto % de alimentación fresca, podría reutilizarse como agua de proceso, reduciendo significativamente el consumo neto del recurso hídrico.Item Synergetic combination of nano zero-valent iron, ultrasound and carboxylic acids for the removal of aqueous Cr(VI)(2023-06-08) Cancelada, Lucía; Meichtry, Jorge Martín; Destaillats, Hugo; Litter, Marta IreneCr(VI) is a priority pollutant present in wastewater of several industrial processes such as electroplating and leather tanning; it can be also naturally present in groundwater. The usual treatment of Cr(VI) involves its reduction to Cr(III), a far less toxic and mobile species, which can be precipitated from the solution at circumneutral pH values [1]. However, conventional Cr(VI) chemical reductants, such as Fe(II) salts, require large Fe:Cr molar ratios to be efficient, generating the disposal of large amounts of dangerous sludge. Thus, more efficient Cr(VI) reduction treatments are required. In this work, the efficiency of commercial zero-valent iron nanoparticles (nZVI), ultrasound (US), and carboxylic acids (CAs) for Cr(VI) reduction was evaluated. The CAs used were citric acid (Cit) or ethylenediaminetetraacetic acid (EDTA). The experiments were performed with 200 mL of a 0.3 mM Cr(VI) solution at pH 3 and under air bubbling (0.5 L min-1) at 30 °C for 180 min in an ultrasonic reactor (850 kHz, total power input 35 W L-1). NSTAR (Nanoiron®) was used as nZVI, with a 3:1 Fe:Cr molar ratio (the optimal ratio as determined before for N25 nZVI [2]), Cit (0 or 2 mM) or EDTA (0 or 1 mM). In the absence of Cit or EDTA (nZVI alone or nZVI + US), or with Cit or EDTA alone (neither nZVI nor US), Cr(VI) reduction was negligible (≤ 5% of the initial [Cr(VI)]). US + Cit showed a reduction of 49% of the initial [Cr(VI)], while US + EDTA showed a 32% of reduction. On the other hand, nZVI + US + Cit yielded an 88% of Cr(VI) reduction, which was 60% with nZVI + US + EDTA. This indicates a clear synergy within the ternary system (nZVI + US + CAs). In all cases, the evolution of Cr(VI) could be fitted to a zero-order kinetic model , with R2 values higher than 0.94. NSTAR nZVI particles are composed of a zerovalent Fe core surrounded by a protective shield of iron oxides that inhibits Cr(VI) reduction; thus, only the combination of US and CAs can remove this protective shield and enhance Cr(VI) reduction, being Cit more efficient than EDTA. This was reinforced by the monitoring of the evolution of the total Fe concentration in solution, with final values of 0.076, 0.26, and 0.18 mM for the systems nZVI + US, nZVI + US + Cit and nZVI + US + EDTA, respectively, indicating that Cit and EDTA promote the formation of soluble Fe complexes. Besides, in the previous experiments of US without nZVI, Cit also proved to be a better donor than EDTA, probably because it can stabilize to a higher extent intermediate peroxo-Cr(V) compounds [1]. Summarizing, there is a synergy for Cr(VI) reduction in the ternary system nZVI + US + CAs, being Cit more efficient than EDTA.Item Tratamiento de colorantes por procesos avanzados, y análisis de reúso del agua en la industria textil.(2022-04-08) Banfi, Candela; Galasso, Victoria; Belmonte, Micaela; Golubickas, Ariel; Di Fraia, Guido; Lan, Luis; Russo, Analía V.; Sánchez, Pablo C.V.; Marchisio, Bettina L.; Reina, Fernando; De Seta, Elizabeth Graciela; Meichtry, Jorge MartínEn este trabajo, se estudia usar la reacción de Fenton (Fe2+ y H2O2), luego la electrocoagulación con ánodo de hierro y la electrocoagulación con ánodo de hierro y adición de H2O2 (EC-Fenton), para lograr una remoción de color que permita el reuso de agua en la industria textil, empleando azul de metileno (AM) y de negro de Synozol (NS) como colorantes modelo. Los experimentos de EC-Fenton se realizaron en una celda de 250 mL con electrodos de hierro SAE 1010 de 19,5 cm2, 9 cm de separación interelectródica, y agitación magnética a 250 rpm. Se estudió el efecto del pH, la intensidad de corriente y la [H2O2]0 en la velocidad de degradación (r) de AM y NS; además, para AM se estudió el efecto de [AM]0Item Treatment of ethylmercury chloride by heterogeneous photocatalysis over TiO2(2021-04-15) de la Fourniere, Emmanuel; Meichtry, Jorge Martín; Gautier, Eduardo Amilcar; Leyva, Ana Gabriela; Litter, Marta IreneEthylmercury chloride (C2H5HgCl) was treated by UV/TiO2 photocatalysis in the presence of O2 and under N2 at pH 4.2. No report exists on C2H5Hg+ degradation by heterogeneous photocatalysis. The adsorption of C2H5Hg+ over TiO2 (no irradiation) was studied and fitted to the Freundlich isotherm. The photocatalytic evolution of C2H5Hg+ was adjusted to a two parameter Langmuir-Hinshelwood model, modified to include a third parameter attributed to the deactivation caused by the deposition of Hg(0). Hg(II) in solution, Hg(0) and Hg2Cl2 (detected only under N2) were the products of the photocatalytic degradation; the organic moiety was degraded but no organic by-product could be detected. Experiments in the absence of O2 showed a higher conversion rate, indicating that C2H5Hg+ is removed both by oxidative and reductive pathways, being this last step partially inhibited by O2. A degradation mechanism considering both oxidative and reductive one-electron transfer steps is proposed.