Suchergebnisse

Solar Energy and Photochemistry Laboratory, Department of Chemistry, University College of Science, M. L. Sukhadia University, Udaipur-313 002, Rajasthan, India E-mail : ameta_sc@yahoo.com, vaishnave.prahlad@gmail.com Department of Chemistry, M.P. Government P.G. College, Chittorgarh-312 001, Rajasthan, India Manuscript received 06 May 2010, revised 19 May 2010, accepted 27 July 2010 The oxidation using sono-photo-Fenton has been found to be a promising treatment for the effective decolorization and degradation of dye. The degradation of methylene blue was investigated using photo-Fenton and sono-photoFenton processes. The effect of different variables like the concentration of ferric ion, concentration of dye, pH, hydrogen peroxide, light Intensity etc. on the reaction rate has been observed and optimal conditions determined. The methylene blue dye degradation was found to depend on these variables. The progress of dye degradation was observed spectrophotometrically. The sono-photo-Fenton reaction showed higher degradation rate of the dye as compared to photoFenton process. The results showed that the dye was completely oxidized and degraded Into C02 and H20. A suitable tentative mechanism for degradation of methylene blue by sono-photo-Fenton's reaction bas been proposed.

AbstractA kinetic model describing Fenton and photo-Fenton degradation of paracetamol (PCT) and consumption of hydrogen peroxide (H2O2) was proposed. A set of Fenton and photo-Fenton experiments (18 runs in total) was performed by fixing the initial concentration of PCT to 40 mg L−1and varying the initial concentrations of H2O2and ferrous ion, Fe2+. The experimental set-up was a well-stirred annular photoreactor equipped with an actinic BL TL-DK 36 W/10 1SL lamp. Experimental results highlighted that PCT is no more detected by HPLC analysis within a minimum reaction time of 2.5 and a maximum reaction time of 15.0 min. Besides, a maximum conversion of total organic carbon (TOC) of 68.5% was observed after 75 min of reaction in case of using UV radiation and the highest concentrations of the Fenton reagents. The experimental data were used to fit the kinetic model. The radiation field inside the reactor was taken into account through the local volumetric rate of photon absorption, evaluated by assuming a line source model with spherical and isotropic emission. The kinetic parameters were estimated by using a non-linear least-squares regression procedure and root mean square errors (RMSE) were calculated in order to validate the feasibility of the proposed model. A good agreement between experimental and predicted data was observed and the lowest values of RMSE resulted in 5.84 and 9.59% for PCT and H2O2normalized concentrations, respectively.

AbstractCylindrospermopsin (CYN) is a potent cyanobacterial toxin found in freshwaters worldwide. In this work, the feasibility of the photo-Fenton process under neutral pH using light emitting diodes as irradiation source for the removal of this hazardous cyanotoxin from freshwater was investigated. The impact of the kind of iron chelating agent (ethylenediamine-N, N′-disuccinic acid vs. ethylenedinitrilotetraacetic acid) as well as the effect of the main operating conditions viz. H2O2 dose, Fe(III) load, initial CYN concentration, and Fe(III):EDDS molar ratio on the performance of the process was systematically evaluated. EDDS was selected as the most appropriate iron chelating agent considering the kinetics of the process and the environmental impact (Vibrio fischeri and Artemia salina). Under optimized conditions ([H2O2] = 30 mg L−1; [Fe(III)] = 5 mg L−1; Fe(III):ligand = 1:0.5 (molar ratio)), complete removal of CYN was achieved in 15-min reaction time. Furthermore, the catalytic system showed to be effective in real water matrices (river and reservoir waters) spiked with CYN. Although the presence of inorganic ions (mainly HCO3−/CO32−) and dissolved organic carbon decreased the oxidation rate of CYN due to scavenging reactions and iron coordination, respectively, complete elimination of the cyanotoxin was achieved in all cases. The fate of EDDS along the process was also evaluated to demonstrate that the catalytic system investigated, apart from its effectiveness, warrants the complete absence of residues after reaction. Therefore, the proposed system constitutes a promising method for cyanotoxin treatment either as a drinking water treatment step in conventional plants or as a potential remediation strategy in the natural environment.

The present work investigates the conjugation of flotation and photo-Fenton techniques on oil removal performance from oilfield produced water. The experiments were conducted in a column flotation and annular lamp reactor for induced air flotation and photodegradation steps, respectively. A nonionic surfactant was used as a flotation agent. The flotation experimental data were analyzed in terms of a first-order kinetic rate model. Two experimental designs were employed to evaluate the oil removal efficiency: fractional experimental design and central composite rotational design (CCRD). Overall oil removal of 99% was reached in the optimum experimental condition after 10 min of flotation followed by 45 min of photo-Fenton. The results of the conjugation of induced air flotation and photo-Fenton processes allowed meeting the wastewater limits established by the legislations for disposal

[EN] An iron-based photochemical process able to act via reductive and oxidative stages by tuning experimental conditions has been explored. In a first step, zero-valent iron (ZVI), added as steel wool, was used to reduce those pollutants reluctant to oxidative processes. Then, the iron released in the solution was employed, upon addition of hydrogen peroxide, to drive a photo-Fenton process. This procedure has been checked with a mixture of five chemicals, namely p-toluenesulfonic acid, benzoic acid, p-nitrobenzoic acid, acetaminophen and caffeic. p-Nitrobenzoic acid resulted to be the most reluctant against oxidation but it was reduced in the absence of H2O2 to form 4-aminobenzoic acid; the presence of salts (e.g. tap water) was required and best results were reached at neutral pH. As p-aminobenzoic acid can be more easily oxidized than p-nitrobenzoic, combination of both stages is meaningful: a ZVI-based reduction followed by a photo-Fenton like-oxidation was employed to remove this pollutant from tested solutions. (C) 2016 Elsevier B.V. All rights reserved. ; Authors want to acknowledge the financial support of Spanish Ministerio de Economia y Competitividad (CTQ2015-69832-C4-4-R), European Union (645551-RISE-2014, MAT4TREAT), Argentinean CONICET Project (PIP: #112-2013-01-00236CO) and Argentinean UNLP (Project No. I174). F.S. Garcia Einschlag is a research member of CONICET. ; Santos-Juanes Jordá, L.; Garcia Einschlag, FS.; Amat Payá, AM.; Arqués Sanz, A. (2017). Combining ZVI reduction with photo-Fenton process for the removal of persistent pollutants. Chemical Engineering Journal. 310:484-490. https://doi.org/10.1016/j.cej.2016.04.114 ; S ; 484 ; 490 ; 310

The application of the photo-Fenton process for the treatment of wastewaters contaminated with diesel oil was investigated. This particular process has been widely studied for the photochemical degradation of highly toxic organic pollutants. Experiments were performed according to a factorial experimental design at two levels and two variables: H2O2 concentration (5–200 mM) and Fe2+ concentration (0.01–1 mM). Experimental results demonstrated that the photo-Fenton process is technically feasible for the treatment of wastewaters containing diesel oil constituents, with total mineralization. A combination of factorial experimental design and gradient descent techniques was employed to optimize the amount of the Fenton reagents, resulting in Fe2+ (0.1 mM) and H2O2 (50 mM). These optimized levels did not exceed the limit for disposal of ferrous ions (0.27 mM) proposed at the local environmental legislation