Humic like substances for the treatment of scarcely soluble pollutants by mild photo-Fenton process

[EN] Humic-like substances (HLS) extracted from urban wastes have been tested as auxiliaries for the photo Fenton removal of thiabendazole (TBZ) under simulated sunlight. Experimental design methodology based on Doehlert matrices was employed to check the effects of hydrogen peroxide concentration, HLS amount as well as TBZ loading; this last parameter was studied in the range 25-100 mg/L, to include values below and above the limit of solubility at pH = 5. Very satisfactory results were reached when TBZ was above solubility if HLS and H2O2 amounts were high. This could be attributed to an interaction of HLS-TBZ that enhances the solubility of the pollutant. Additional evidence supporting the latter interaction was obtained by fluorescence measurements (excitation emission matrices) and parallel factor analysis (PARAFAC). (C) 2018 Elsevier Ltd. All rights reserved.Authors want to acknowledge the financial support of Spanish Ministerio de Economia y Competitividad (CTQ2015-69832-C04) and European Union (645551-RISE-2014, MAT4TREAT). The present work was partially supported by UNLP (11/X679), ANPCyT (PICT-2015-0374A) and CONICET (PIP: 12-2013-01-00236CO). B. Caram thank the CONICET for his research graduate grant. F. S. Garcia Einschlag is a research member of CONICET.Caram, B.; García-Ballesteros, S.; Santos-Juanes Jordá, L.; Arqués Sanz, A.; Garcia-Einschlag, FS. (2018). Humic like substances for the treatment of scarcely soluble pollutants by mild photo-Fenton process. Chemosphere. 198:139-146. https://doi.org/10.1016/j.chemosphere.2018.01.074S13914619

Humic-like substances from urban waste as auxiliaries for photo-Fenton treatment: a fluorescence EEM-PARAFAC study

In this work, analysis of excitation-emission-matrices (EEM) has been employed to gain further insight into the characterization of humic like substances (HLS) obtained from urban wastes (soluble bio-organic substances, SBOs). In particular, complexation of these substances with iron and changes along a photo-Fenton process have been studied. Recorded EEMs were decomposed by using parallel factor analysis (PARAFAC). Three fluorescent components were identified by PARAFAC modeling of the entire set of SBO solutions studied. The EEM peak locations (λex/λem) of these components were 310?330 nm/400?420 nm (C1), 340?360 nm/450?500 nm (C2), and 285 nm/335?380 nm (C3). Slight variations of the maximum position of each component with the solution pH were observed. The interaction of SBO with Fe(III) was characterized by determining the stability constants of the components with Fe(III) at different pH values, which were in the order of magnitude of the ones reported for humic substances and reached their highest values at pH = 5. Photochemical experiments employing SBO and Fe(III), with and without H2O2, showed pH-dependent trends for the evolution of the modeled components, which exhibited a strong correlation with the efficiency reported for the photo-Fenton processes in the presence of SBO at different pH values.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Caracterización de columnas reactivas rellenas con ZVI y diseño de prototipos para la eliminación de arsénico en agua

Se realizaron estudios de pequeña y mediana escala con columnas reactivas rellenas con hierro cero valente (ZVI) empleadas para la remoción continua de arsénico del agua de consumo. Los ensayos de corta duración en pequeña escala se utilizaron para estudiar el efecto de las variables operativas sobre la producción de Fe, consumo de oxígeno y protones. Los ensayos de en mediana escala permitieron observar la variación temporal de los parámetros hidráulicos de la columna reactiva. Los resultados obtenidos de ambos tipos de experimentos permiten optimizar el tiempo de operación y las condiciones operativas de un prototipo basado en esta técnica

Efecto del PH en la degradación de de derivados del ácido salicílico en sistemas TIPO-FENTON y FOTO-FENTON

En los sistemas tipo-Fenton el pH del medio juega un rol muy importante debido a que por encima de pH ~ 3.2 la solubilidad del Fe(III)aq decrece notablemente resultando en la pérdida de actividad catalítica. Una estrategia para evitar lo antedicho consiste en emplear sustratos capaces de complejar al Fe(III) a pHs cercanos a la neutralidad. En este contexto, se pudieron obtener las funciones de distribución de los complejos formados entre el Fe(III) y diferentes ligandos derivados del ácido salicílico y se comprobó el efecto del pH en los tiempos medios de degradación de los complejos, donde a pH=7 en presencia de luz se observaron cambios interesantes y los complejos estudiados tienen una potencial aplicación para su uso en la técnica foto-Fenton a pHs cercanos a la neutralidad

Caracterización de columnas reactivas rellenas con ZVI y diseño de prototipos para la eliminación de arsénico en agua

Se realizaron estudios de pequeña y mediana escala con columnas reactivas rellenas con hierro cero valente (ZVI) empleadas para la remoción continua de arsénico del agua de consumo. Los ensayos de corta duración en pequeña escala se utilizaron para estudiar el efecto de las variables operativas sobre la producción de Fe, consumo de oxígeno y protones. Los ensayos de en mediana escala permitieron observar la variación temporal de los parámetros hidráulicos de la columna reactiva. Los resultados obtenidos de ambos tipos de experimentos permiten optimizar el tiempo de operación y las condiciones operativas de un prototipo basado en esta técnica

Recent Advances in the Development of Novel Iron–Copper Bimetallic Photo Fenton Catalysts

Advanced oxidation processes (AOPs) have been postulated as viable, innovative, and efficient technologies for the removal of pollutants from water bodies. Among AOPs, photo-Fenton processes have been shown to be effective for the degradation of various types of organic compounds in industrial wastewater. Monometallic iron catalysts are limited in practical applications due to their low catalytic activity, poor stability, and recyclability. On the other hand, the development of catalysts based on copper oxides has become a current research topic due to their advantages such as strong light absorption, high mobility of charge carriers, low environmental toxicity, long-term stability, and low production cost. For these reasons, great efforts have been made to improve the practical applications of heterogeneous catalysts, and the bimetallic iron–copper materials have become a focus of research. In this context, this review focuses on the compilation of the most relevant studies on the recent progress in the application of bimetallic iron–copper materials in heterogeneous photo–Fenton-like reactions for the degradation of pollutants in wastewater. Special attention is paid to the removal efficiencies obtained and the reaction mechanisms involved in the photo–Fenton treatments with the different catalysts

May a natural lake behave as an efficient Fenton reactor under dark conditions

Phenol degradation experiments were performed to study the potential behavior of the acidic Lake Caviahue (LC) as a dark Fenton reactor under natural conditions and upon H₂O₂ addition at doses typically used for technological applications. In both cases, to assess the influence of dissolved organic matter present in the lake, control experiments were carried out under identical initial conditions (pH, concentrations of phenol, iron, and H₂O₂), but in the absence of organic matter. A first set of experiments was performed to test the feasibility of dark Fenton processes under environmental conditions. Lake water samples were used as reaction matrix and catalyst source, whereas phenol and H₂O₂ were added as model pollutant and oxidant, respectively. H₂O₂ concentrations used were similar to those reported for rainwater. Results show that phenol can be degraded under all conditions studied and that the amount of phenol consumed depends on both the H₂O₂ concentration added and the matrix composition LC A second set of experiments was designed to characterize the lake behavior as a natural Fenton reactor upon the addition of H₂O₂ concentrations typically used for technological applications. Although phenol concentration profiles obtained for LC and the artificial solution show the characteristic behavior of Fenton-like systems, the trends are rather different, since for LC, the lag phase is much longer than that for the artificial matrix. Overall, the results suggest that the Fe(III)-chelating effect of the organic matter present in LC slows down reaction rates, but it does not block phenol degradation through Fenton-like processes.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada