Photonic efficiency of the photodegradation of paracetamol in water by the photo-Fenton process (original) (raw)
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Water Research, 2012
The photo-Fenton degradation of paracetamol (PCT) was evaluated using FeSO 4 and the iron complex potassium ferrioxalate (FeOx) as iron source under simulated solar light. The efficiency of the degradation process was evaluated considering the decay of PCT and total organic carbon concentration and the generation of carboxylic acids, ammonium and nitrate, expressed as total nitrogen. The results showed that the degradation was favored in the presence of FeSO 4 in relation to FeOx. The higher concentration of hydroxylated intermediates generated in the presence of FeSO 4 in relation to FeOx probably enhanced the reduction of Fe(III) to Fe(II) improving the degradation efficiency. The degradation products were determined using liquid chromatography electrospray time-of-flight mass spectrometry. Although at different concentrations, the same intermediates were generated using either FeSO 4 or FeOx, which were mainly products of hydroxylation reactions and acetamide. The toxicity of the sample for Vibrio fischeri and Daphnia magna decreased from 100% to less than 40% during photo-Fenton treatment in the presence of both iron species, except for D. magna in the presence of FeOx due to the toxicity of oxalate to this organism. The considerable decrease of the sample toxicity during photo-Fenton treatment using FeSO 4 indicates a safe application of the process for the removal of this pharmaceutical.
A kinetic study for the Fenton and photo-Fenton paracetamol degradation in an annular photoreactor
Environmental Science and Pollution Research
A 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−1 and varying the initial concentrations of H2O2 and 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...
Applied Catalysis B: Environmental, 2015
A new model is proposed for the photo-Fenton oxidation of water contaminants including the effect of photon absorption (volumetric rate of photon absorption, VRPA), the effect of the geometry of the reactor and the illuminated volume to total volume ratio (R i) in the reaction system. Fe(III) was found to be the main species in the aqueous solution responsible for photon absorption provided that hydrogen peroxide was not totally consumed. Paracetamol was used as model pollutant at a concentration of 1 mM to validate the model. The illuminated part of the raceway reactor configuration (total length of 80 cm) was operated at two liquid depths (5.0 and 2.5 cm) equivalent to two irradiated reactor volumes (2 and 1 L) and using R i ratios in the range 0.30-0.65, which changed the dark reactor volume. These values are commonly found in photo-Fenton pilot plants for water treatment and purification. The model successfully fitted the temporal evolution of the dissolved oxygen (O 2) and the hydrogen peroxide (H 2 O 2) concentrations and the evolution of the total organic carbon (TOC) in solution in both reactor geometries and for different illuminated volume to total volume ratios. The model can be easily extended to model other water contaminants and provides a robust method for process design, process control and optimization.
Simultaneous degradation of pharmaceuticals by classic and modified photo-Fenton process
Journal of Environmental Chemical Engineering, 2018
Pharmaceutical compounds are known to be persistent. Their presence after conventional treatments in sewage treatment plants may harm aquatic environments. The simultaneous degradation of the pharmaceuticals gemfibrozil, hydrochlorothiazide and naproxen involving photo-Fenton processes was evaluated using different sources and concentrations of iron (Fe 2+ , Fe 3+ and the iron complexes of oxalate-FeOx), initial pH (2.6, 5.0 and 7.0) and concentrations of H2O2. The classic photo-Fenton reaction (at initial pH 2.6, using Fe 2+ and Fe 3+) showed a limited efficiency in promoting gemfibrozil degradation, which, based on evidence provided by LC-MS measurements, is related to the formation of associations between this compound and iron ions. The simultaneous degradation of gemfibrozil and the other compounds was improved using FeOx (1.0 mg L-1 in iron) at an initial pH of 2.6 and 2.0 mg L-1 H2O2. In addition, using this catalyst it was possible to efficiently degrade the pharmaceuticals at an initial pH of 5.0, reaching complete degradation of these compounds with a treatment time varying between 20 and 60 min and generating a low toxicity effluent. These results highlight the potential applicability of ferrioxalate as a photocatalyst in the photo-Fenton process as an alternative method to degrade this kind of pollutant at a pH near neutrality.
Revista de Chimie, 2008
An experimental study on 4-chlorophenol (4-CP) degradation in aqueous solutions by advanced oxidation process photo-Fenton type is presented. The efficiency of the oxidation process is determined by the very high oxidative potential of the OH. radicals generated by catalytic and photo-catalytic processes. The presence of the inorganic species inside the reaction medium influences the rate of the oxidation process as function of their nature and concentration. The inorganic anionic species reduce drastically the 4-CP oxidation efficiency by Fe2+/3+ complexing processes, HO. radicals scavenging effect or iron precipitate forming. The decrease of the 4-CP oxidation degree is correlated with the nature of the anions as following: Cl- ] PO43- ] SO42- ]] NO3-. The presence of the insoluble inorganic species (bentonite) modifies the oxidation efficiency by additional 4-CP and UV sorption processes, especially at high solution turbidity values.
Applied Catalysis B: Environmental, 2011
The degradation of 10 L of 157 mg L −1 paracetamol solutions in 0.05 M Na 2 SO 4 has been studied by the solar photoelectro-Fenton (SPEF) method. A solar flow plant with a Pt/air-diffusion electrochemical cell and a compound parabolic collector (CPC) photoreactor was used operating under recirculation mode at a liquid flow of 180 L h −1 with an average UV irradiation intensity of about 32 W m −2. A central composite rotatable design coupled with response surface methodology was applied to optimize the experimental variables. Optimum SPEF treatment was achieved by applying a current of 5 A, 0.40 mM Fe 2+ and pH 3.0 at 120 min of electrolysis, being reduced total organic carbon (TOC) by 75%, with an energy cost of 93 kWh kg −1 TOC (7.0 kWh m −3) and a mineralization current efficiency of 71%. Initial N was partially converted into NH 4 + ion. Under these optimized conditions, paracetamol decays followed a pseudo first-order kinetics. HPLC analysis of the electrolyzed solution allowed the detection of hydroquinone, p-benzoquinone, 1,2,4-trihydroxybenzene, 2,5-dihydroxy-p-benzoquinone and tetrahydroxy-p-benzoquinone. All aromatics were destroyed by the attack of • OH. Maleic, fumaric, succinic, lactic, oxalic, formic and oxamic acids were identified as generated carboxylic acids, which form Fe(III) complexes that are quickly photodecarboxylated under UV irradiation of sunlight. A reaction sequence involving all the detected byproducts was proposed for the SPEF degradation of paracetamol.
Degradation of organic effluents containing wastewater by photo-Fenton oxidation process
RESEARCH STATEMENT TOPIC OF Ph.D THESIS : “USE OF PHOTOFENTONS REAGENT AS AN OXIDANT” YEAR OF SUBMITION : 2004 YEAR OF AWARD : 2006 PAPER PUBLICATION:02 (ONE NATIONAL AND ONE INTERNATIONAL LEVELIJC-A Vol.47A(11) [November 2008] Photooxidation of some organic pollutants (p-nitroaniline, p-aminophenols and acetanilide) has been carried out in the presence of photo-Fenton reagent. The effect of various parameters like pH, concentrations of organic compounds, ferric ions and hydrogen peroxide and light intensity, etc. on the reaction rate has been studied. The degradation is found to be pseudo first order. The optimum pHs for the degradation of p-aminophenol, p-nitroaniline and acetanilide are found to be 3.0, 3.5 and 2.5, respectively while the rate degradations of the three compounds are found to be comparable. The study shows that the photo-Fenton process are more effective and faster than Fenton's reagent in oxidation of organic compounds, and that the organic compounds are completely oxidized and degraded into CO2 and H2O. A tentative mechanism has been proposed. Excellent removal has been obtained using photo-Fenton process assisted with artificial irradiation. This study demonstrates that the use of photo-Fenton process on organic effluents wastewater treatment is very promising, especially when solar light is used.
Applied Catalysis B: Environmental, 1994
Photo-Fenton, Fenton and biodegradation reactions have been mveshgated m &tat1 dunng the degradation of 2 and 4-mtrophenols Fenton-type reactions accelerated mtrophenols degradation in companson with duect photolysls using pyrex flasks (A > 290 nm) The mfluence of Fe'+, H,Oz. hght, temperature, reactant concentration and gas atmosphere was systematically studied Expenmental techniques used involved total orgamc carbon determmatlon (TOC), high pressure liquid chromatography ( zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA HPLC) , nuclear magnetic resonance (NMR) and spectroscopy (OD) A solution contammg 3 6 10e3 M of 2-mtrophenol was degraded in ca 3 h (30°C) m the dark and in ca 1 h (30°C) under hght where contmuous photoproduchon of the Fenton reagent IS achieved This study shows that the hydroxylahon of the phenol nng IS fast as compared to the slower conconutant decrease m DOC m dark or light processes Using NMR an explanation IS proposed m terms of pathways mvolvmg direct oxidation of the mtrophenols under study by hydroxy type radicals Chenucal insight IS provided why the photo-Fenton degradation observed for 2-mtrophenol proceeds at ahout half the rate than his homologue 4-mtrophenol Blodegradabllity of 2-mtrophenol was monitored before and after photo-Fenton treatment by hochenucal oxygen demand (BOD) and dissolved organic carbon (JIOC) and m&cated the formation of substances which are non-biodegradable dunng photo-Fenton pretreatment Key words hochenucal oxygen demand, dissolved organic carbon, nitrophenols, organic carbon, photo-Fenton, water treatment zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
Latin American Applied Research - An international journal, 2016
Environmental hazards are a consequence of the massive use of synthetic chemicals that are prevalent in nearly every aspect of modern life. The outburst of the so-called “emerging pollutants” (pharmaceuticals and pesticides among others) generates an additional problem due to the scarce available information on their impact on the environment or their interferences with the biological processes. Among them, paracetamol is one of the drugs the most widely found in hospital effluents, in the effluents of wastewater treatment plants, as well as in rivers. In this work, the feasibility of paracetamol degradation by different processes based on ultraviolet radiation is discussed: photolysis, photo-oxidation with hydrogen peroxide, photo-Fenton reaction, and heterogeneous photocatalysis with TiO2 are evaluated. The best results are obtained with the photoFenton process, for which more than 99% of the pharmaceutical is degraded within 5 minutes. At best experimental conditions the minerali...