Photo-Fenton oxidation of phenolic compounds catalyzed by iron-PILC (original) (raw)
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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 Clay Science, 2012
Clay pillared with Al-Fe was synthesized as a catalyst for (photo)-Fenton oxidation of 4-chlorophenol. The catalyst was characterized by X-ray diffraction, nitrogen physisorption, diffuse reflectance UV-VIS spectroscopy and temperature-programmed reduction. The chemical composition, indicating the incorporation of Al and Fe within the clay structure, was determined by ICP-OES. The oxidation of 4-chlorophenol was faster in the UV-A assisted process, followed by VIS-light assisted and "dark" processes. All the processes begin with an induction period, followed by a fast oxidation step. Iron leaching is observed for all the systems and was mainly attributed to proton and reductive dissolution processes. Proton dissolution is very slow and could be responsible for the induction period. The reductive dissolution is induced in the presence of 4-chlorocatechol, the main reaction intermediate. The dissolved iron ions are able to catalyze the homogeneous Fenton-like process. All the experimental findings suggest that a combined heterogeneous-homogeneous mechanism could be envisaged for the studied reaction system.
Chemical degradation of chlorophenols with Fenton's reagent (Fe2+ + H2O2)
Chemosphere, 1987
Aqueous solutions of Fenton's reagent (Fe 2+ + H202) have been used to e[ fect the total decomposition of the chlorophenols: 2-chlorophenol, 3-chlorophe nol, 4-chlorophenol, 3,4-dichlorophenol and 2,4,5-trichlorophenol. The mlnerallzatlon of these chlorinated aromatic substrates to CO 2 and free C1 has been
Photo-Fenton Degradation of Pentachlorophenol: Competition between Additives and Photolysis
Nanomaterials
In the present work, the photo-Fenton degradation of pentachlorophenol (PCP, 1 mg/L) has been studied under simulated and natural solar irradiation; moreover, the effect on the process efficiency of urban waste-derived soluble bio-based substances (SBO), structurally comparable to humic acids, has been investigated. Experiments showed a crucial role of PCP photolysis, present in the solar pilot plant and hindered by the Pyrex® filter present in the solar simulator. Indeed, the SBO screen negatively affects PCP degradation when working under natural solar light, where the photolysis of PCP is relevant. In contrast, in the absence of PCP photolysis, a significant improvement of the photo-Fenton process was observed when added to SBO. Furthermore, SBO were able to extend the application of the photo-Fenton process at circumneutral pH values, due to their ability to complex iron, avoiding its precipitation as oxides or hydroxides. This positive effect has been observed at higher concent...
Journal of Hazardous Materials, 2006
This study reports the photodegradation of 4-chlorophenol (4-CP) in aqueous solution by the photo-Fenton process using solar irradiation. The influence of solution path length, and Fe(NO3)3 and H2O2 concentrations on the degradation of 4-CP is evaluated by response surface methodology. The degradation process was monitored by the removal of total organic carbon (TOC) and the release of chloride ion. The results showed a very important role of iron concentration either for TOC removal or dechlorination. On the other hand, a negative effect of increasing solution path length on mineralization was observed, which can be compensated by increasing the iron concentration. This permits an adjustment of the iron concentration according to the irradiation exposure area and path length (depth of a tank reactor). Under optimum conditions of 1.5 mM Fe(NO3)3, 20.0 mM H2O2 and 4.5 cm solution path length, 17 min irradiation under solar light were sufficient to reduce a 72 mg C L−1 solution of 4-CP by 91%.
Advanced oxidation of catechol: A comparison among photocatalysis, Fenton and photo-Fenton processes
Desalination, 2009
The aim of this work was to compare the behaviour of Fenton, photo-Fenton and photocatalysis processes to treat catechol solutions which are pollutants occurring in wastewaters from many industries. The effect of different process parameters, such as initial catechol concentration, H 2 O 2 /FeSO 4 ratio in Fenton and photo-Fenton oxidation, TiO 2 loadings in photocatalysis and irradiation times has been studied. Fenton and photo-Fenton (H 2 O 2 /FeSO 4 = 600/500 (w/w) and 30 min reaction time) processes allowed us to achieve a high efficiency in the mineralization of catechol (COD removals up to 83% and 96% respectively), and removal of aromaticity (UV 280 ) (up to 93% and 98% respectively), for an initial catechol concentration of 110 mg/l. On the opposite, photocatalysis was not effective in the removal of higher catechol concentrations (110 and 200 mg/l), whereas a significant removal of aromaticity versus time was observed for 50 mg/l. Gas chromatography-mass spectrometry analysis, performed under selected treatment conditions, showed that total removal of catechol can occur after Fenton (2000/500 w/w; 30 min), photo-Fenton (600/500 w/w; 30 min), and photocatalysis (3 g TiO 2 /l; 240 min) treatments.
Applied Catalysis B-environmental, 2007
Iron-containing catalysts have been prepared following different synthesis routes and silica supports (amorphous, zeolitic and mesostructured materials). Activity and stability of these materials were assessed on the photo-Fenton degradation of phenolic aqueous solutions using near UV irradiation (higher than 313 nm) at room temperature and initial neutral pH. Their catalytic performance was monitored in terms of phenol and total organic carbon (TOC) conversions. Aromatic compounds and carboxylic acids as by-products coming from incomplete mineralization of phenol as well as the efficiency of each catalytic system in the use of the oxidant were also studied. Stability of the materials throughout the photo-Fenton reaction was evaluated in terms of metal leachibility. Activity and stability depend on the environment of iron species and features of silica support. The evolution of pH with the reaction time and their relationship with TOC degradation and leaching degree has been discussed. A nanocomposite material of crystalline iron oxides supported over mesostructured SBA-15 material is shown the most successful catalyst for degradation of phenolic aqueous solutions by photo-Fenton processes, achieving an outstanding overall catalytic performance accompanied with a noteworthy stability.
CLEAN - Soil, Air, Water, 2017
The present work demonstrates the applicability of ferrites as photo-Fenton catalysts for deterioration of different phenolic derivatives. To analyze optimal reaction conditions, experiments were performed with four magnetic spinel ferrites MFe2O4 (M = Co, Cu, Ni and Zn) and two inorganic oxidants i.e. hydrogen peroxide (HP) and potassium peroxymonosulfate (PMS). The reactions were performed using p-nitrophenol as phenolic probe. CuFe2O4 and CoFe2O4 possessed excellent ability to activate HP and PMS, respectively, among all four synthesized catalysts. Noteworthy aspect of two oxidizing agents is that the concentration of PMS used during the reaction was four times less than HP. Further the broad pH activity of PMS provides a significant advantage over HP. The optimal reaction conditions, when HP was the oxidant in the photo-Fenton degradation, are: 0.50 g/L MFe2O4, pH 2.5 and 8.8 mM HP. Although PMS was active in a wide pH range (2-10), adequate reaction conditions were: 0.50 g/L MFe2O4, natural pH and 2.2 mM PMS. The photo-Fenton activity of ferrites was extended to the degradation of different nitro-and chloro-analogs of phenol (2-nitrophenol, 3-nitrophenol, 4nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,4dichlorophenol) with only two ferrites (CuFe2O4 and CoFe2O4). A comparative study was performed with the two oxidants (HP and PMS) with positive results. Finally, stability and reusability of magnetic ferrites as catalysts were also studied to prove their use in phenolic solution treatment.
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
Journal of Environmental Management, 2012
A highly concentrated aqueous saline-containing solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) was treated by the photo-Fenton process in a system composed of an annular reactor with a quartz immersion well and a medium-pressure mercury lamp (450 W). The study was conducted under special conditions to minimize the costs of acidification and neutralization, which are usual steps in this type of process. Photochemical reactions were carried out to investigate the influence of some process variables such as the initial concentration of Fe 2+ ([Fe 2+ ] 0 ) from 1.0 up to 2.5 mM, the rate in mmol of H 2 O 2 fed into the system (F H2O2, in ) from 3.67 up to 7.33 mmol of H 2 O 2 /min during 120 min of reaction time, and the initial pH (pH 0 ) from 3.0 up to 9.0 in the presence and absence of NaCl (60 g.L -1 ). Although the optimum pH for the photo-Fenton process is about 3.0, this particular system performed well in experimental conditions starting at alkaline and neutral pH. The results obtained here are promising for industrial applications, particularly in view of the high concentration of chloride, a known hydroxyl radical scavenger and the main oxidant present in photo-Fenton processes.