3,516 research outputs found
Photo-Fenton-Based Degradation of Methylene Blue Dye Using Hydroxyapatite Nanoparticles Doped with Fe3O4/γ-Fe2O3
No full textIn this study, we evaluated the catalytic properties of hydroxyapatite (HA) nanoparticles (NPs) doped with Fe3O4/γ-Fe2O3 for the degradation of methylene blue (MB) dye using a photo-Fenton process at pH 2.5, 7.0, and 9.0. The HA NPs were characterized using X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectrometry, Raman spectroscopy, thermogravimetric analysis, fluorescence spectrometry, and point of zero charge experiments. Upon using unmodified HA NPs, 1.33 mL of H2O2 30% (v/v), and ultraviolet radiation (125 W Hg lamp), the discoloration values achieved at pH 2.5, 7.0, and 9.0 were 88.4, 44.8, and 58.1%, respectively. For the HA NPs modified with Fe3O4/γ-Fe2O3, the composition Ca2.5FeII2.5FeIII5(PO4)6(OH)2 yielded the best results during the photo-Fenton-based process, and discolorations of 100, 100, and 95.2% were achieved at pH 2.5, 7.0, and 9.0, respectively. To confirm the effectiveness of the Ca2.5FeII2.5FeIII5(PO4)6(OH)2 NPs, the total organic carbon (TOC) and toxicity effects on Lactuca sativa L. were evaluated, and reproducibility tests were performed. The TOC removal of the Ca2.5FeII2.5FeIII5(PO4)6(OH)2 NPs was ca. 90% and the toxicity of the MB dye was eliminated after 120 min of reaction; moreover, the NPs retained their physical stability and activity and were reused for 11 consecutive degradation experiments.</div
Kinetic Study on Degradation of Methylene Blue by Fenton Reaction
No full textFenton\u27s reaction is an advanced treatment technology often used for the removal of hazardous and refractory organic compounds from industrial wastewaters. In the present project, Methylene Blue (MB) was selected as a model compound due to its readiness to be measured by visible spectrometer. The study was focused on the kinetic study of Fenton degradation of MB. The increase of [H2O2] and [Fe2+] increased the degradation rate of MB. The ratio of [H2O2]/[Fe2+] is a factor influencing the degradation rate of MB as well. According to the current experimental results, Fenton reaction was able to degrade MB rapidly while the ratio of [H2O2]/[Fe2+] was in the range of 1-20
Keterlibatan Reaksi Fenton pada Biodekolorisasi Metilen Biru oleh Gloeophyllum trabeum
No full textPada penelitian ini, keterlibatan reaksi Fenton pada biodegradasi metilen biru (MB) oleh jamur pelapuk coklat Gloeophyllum trabeum telah diteliti. Dekolorisasi MB (konsentrasi akhir 75 mg/L) dilakukan pada media garam mineral dengan dan tanpa FeSO4 dengan variasi inkubasi 0, 7, 14, 21 dan 28 hari. Analisa dekolorisasi dilakukan menggunakan instrumen UV-Vis. Persentase dekolorisasi tertinggi terjadi pada waktu inkubasi 28 hari sebesar 88,301% dan 91,937% dalam media tanpa dan dengan FeSO4. Hal ini mengindikasikan bahwa dekolorisasi MB dengan adanya FeSO4 lebih besar daripada tanpa FeSO4, menunjukkan bahwa reaksi Fenton terlibat dalam dekolorisasi MB oleh jamur G. trabeum.
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In this study, the involvement of Fenton reaction on biodegradation of methylene blue (MB) by Gloeophyllum trabeum was investigated. The decolorization of MB (final concentration 75 mg/L) was performed in mineral salt medium with and without FeSO4 during incubation period 0, 7, 14, 21 and 28 days. Decolorization analysist were determined using UV-Vis spectrophotometer. The highest MB decolorization was occurred during 28 days of incubation, which approximately 88,301% and 91,937% in media without and with FeSO4 respectively. These results indicated that decolorization of MB in media with FeSO4 was higher than in media without FeSO4, showing that Fenton reaction might be involved on MB decolorization by G.trabeum
Introducing saccharic acid as an efficient iron chelate to enhance photo-Fenton degradation of organic contaminants
No full textThe identification of iron chelates that can enhance photo-Fenton degradation is of great interest in the field of advanced oxidation process. Saccharic acid (SA) is a polyhydroxy carboxylic acid and completely non-toxic. Importantly, it can effectively bind Fe(III) as well as induce photoreduction of Fe(III). Despite having these interesting properties, the effect of SA on photo-Fenton degradation has not been studied. Herein, we demonstrate the first assessment of SA as an iron chelate in photo-Fenton process using methylene blue (MB) as a model organic contaminant. Our results demonstrate that SA has the ability to (i) enhance the photo-Fenton degradation of MB by about 11 times at pH 4.5 (ii) intensify photochemical reduction of Fe(III) to Fe(II) by about 17 times and (iii) accelerate the rate of consumption of H2O2 in photo-Fenton process by about 5 times (iv) increase the TOC reduction by about 2 times and (v) improve the photo-Fenton degradation of MB in the presence of a variety of common inorganic ions and organic matter. The influential properties of SA on photo-Fenton degradation is attributed to the efficient photochemical reduction of Fe(III) via LMCT (ligand to metal charge transfer reaction) to Fe(II), which then activated H2O2 to generate OH center dot and accelerated photo-Fenton degradation efficiency. Moreover, the effect of operational parameters such as oxidant: contaminant (H2O2: MB) ratio, catalyst: contaminant (Fe(III)SA: MB) ratio, Fe(III): SA stoichiometry and pH on the degradation of MB by photo-Fenton in the presence of SA is demonstrated. Importantly, SA assisted photo-Fenton caused effective degradation of MB and 4-Chiorophenol under natural sunlight irradiation in natural water matrix. The findings strongly support SA as a deserving iron chelate to enhance photo-Fenton degradation. (C) 2016 Elsevier Ltd. All rights reserved
Accelerated methylene blue (MB) degradation by Fenton reagent exposed to UV or VUV/UV light in an innovative micro photo-reactor
No full textThis study presents the accelerated discoloration/degradation of methylene blue (MB) in solution by Fenton reagent under exposure to ultraviolet (UV) or Vacuum-UV/UV (VUV/UV) light in an innovative micro photo-reactor. The MB degradation was kinetically faster when using VUV/UV light at 254/185 nm compared to UV-irradiation at 254 nm. Oxidative radicals produced by the photo-Fenton process were identified with appropriate scavengers. The addition of benzoquinone (BQ) at millimolar (mM) concentrations to MB solutions precluded completely the MB photo-induced bleaching, while tert-butanol hindered to a lesser extent the MB degradation suggesting that HO2 center dot was the predominant intermediate leading to MB degradation. The VUV/UV micro photo-reactor comprised mercury resonance lines at 185 and 254 nm. The photon percentages absorbed by water were estimated to be 16.8% at 254nm and 78.3% at 185 nm by water, while those absorbed by H2O2 were 0.9% and 2.2%, correspondingly. The solution parameters affecting the features of MB degradation, such as MB, Fe, and H2O2 concentrations, were explored and reaction mechanism was proposed. The lifetimes of (OH)-O-center dot and HO2 center dot were estimated to be 2 ns and 0.38 s under an optimized solution with 0.016 mM MB, 0.147 mM H2O2 and 0.05 mM Fe3+. Moreover, an estimation of the mean free paths of these radicals in solution provided the evidence that it was the radical lifetimes and mean-free paths, not their oxidation potentials that controlled the MB degradation kinetics. This study shows the potential of this VUV/UV assistant photo-Fenton process for the degradation of diluted organic compounds in aqueous solution. (C) 2016 Elsevier B.V. All rights reserved
Degradation of Methylene Blue with a Cu(II)–Quinoline Complex Immobilized on a Silica Support as a Photo-Fenton-Like Catalyst
No full textA Cu(II)–quinoline complex immobilized on a silica
support
was prepared to enhance the degradation of dyes. Mesoporous silica
functionalized with this Cu(II) complex was turned into a photo-Fenton-like
catalyst. Various techniques were used to characterize the resulting
material, and the catalytic activity was determined by the degradation
of methylene blue (MB) under UV light irradiation. The Cu(II) ion
was successfully coordinated to the quinoline ligand on a silica support.
The dye degradation investigation has shown that 95% of the dye was
degraded in 2.5 h. The active radical species involved in the reaction
were OH• and O2•–, suggesting that a peroxo complex intermediate might be formed during
degradation processes
Nano-PAA-CuCl2 Composite as Fenton-Like Reusable Catalyst to Enhanced Degrade Organic Pollutant MB/MO
No full textThe treatment of organic dye contaminants in wastewaters has now becoming more imperative. Fenton-like degradation of methylene blue (MB) and methyl orange (MO) in aqueous solution was investigated by using a nanostructure that a layer of CuCl2 nanoflake film grown on the top surface of nanoporus anodic alumina substrate (nano-PAA-CuCl2) as catalyst. The new nano-PAA-CuCl2 composite was fabricated with self-assembly approach, that is, a network porous structure film composed of CuCl2 nanoflake grown on the upper surface of nanoporous anodic alumina substrate, and the physical and chemical properties are characterized systematically with the X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HRTEM), Energy Dispersive Spectrometer (EDS), X-ray photoelectron spectroscopy (XPS). The experimental results showed that the nano-PAA-CuCl2 catalyst presented excellent properties for the degradation of two typical organic pollutants such as MB and MO, which were almost completely degraded with 8 × 10−4mol/L nano-PAA-CuCl2 catalyst after 46 min and 60 min at reaction conditions of H2O2 18 mM and 23 mM, respectively. The effects of different reaction parameters such as initial pH, H2O2 concentration, catalyst morphology and temperature were attentively studied. And more, the stability and reusability of nano-PAA-CuCl2 were examined. Finally, the mechanism of MB and MO degradation by the nano-PAA-CuCl2/H2O2 system was proposed, based on the experimental data of the BCA and the temperature-programmed reduction (H2-TPR) and theoretical analysis, the reaction kinetics belonged to the pseudo-first-order equation. This new nanoporous composite material and preparation technology, as well as its application in Fenton-like reaction, provide an effective alternative method with practical application significance for wastewater treatment
Heterogeneous fenton oxidation of methylene blue with Fe-impregnated biochar catalyst
No full textFe-impregnated biochar (Fe-BC) as high-efficiency heterogeneous Fenton catalyst was synthesized and evaluated in detail for its catalytic activity, stability and reusability under various conditions. The optimal conditions for the Fenton oxidation of methylene blue (MB) as model dye were determined as 0.075 g/L H2O2, 0.5 g/L Fe-BC for 0.1 g/L MB, which resulted in optimum Dye:Fecat:H2O2 ratio of 1:5:0.75 (on g/L basis) or [Dye]:[Fetotal]:[H2O2] molar ratio of 1:6.2:7.0 respectively. The effective degradation of MB was identified over a wider pH range, and even after four consecutive runs Fe-BC maintained above 95% MB removal rate within 3 min of treatment with low Fe release, indicating strong stability and reusability. Under the optimum Dye:Fecat:H2O2 (g/L) condition at initial pH 4, the Fe-BC achieved 99.9% removal efficiency of MB within 3 min in heterogeneous Fenton reaction (HEFR) with much less H2O2 concentration and low catalyst dosage, demonstrating its efficiency and cost-effectiveness compared to other Fenton reaction catalysts. The removal velocity of MB showed two rate steps: a fast first stage followed by a slow stage with the rate in the order of H2O2/Fe-BC ⋙ H2O2/biochar \u3e biochar \u3e H2O2. Overall, the developed Fe-BC is more economical with strong stability and recyclability for use in HEFR for treating recalcitrant pollutants
Synergetic adsorption and photo-Fenton degradation of methylene blue by ZnFe<sub>2</sub>O<sub>4</sub>/SiO<sub>2</sub> magnetic double-mesoporous-shelled hollow spheres
No full textAdsorption and Fenton technologies have been widely employed to deal with wastewater. ZnFe2O4/SiO2 magnetic double-mesoporous-shelled hollow spheres (MDSHSs) were feasibly synthesized by a solvothermal method. The as-synthesized MDSHSs show excellent adsorption and selectivity for methylene blue (MB), which it took about only 1 min to reach the adsorption equilibrium. About 50% MB was removed by adsorption, and other 50% MB was degraded under further photo-Fenton process. Effects of experimental conditions on the adsorption and photo-Fenton process were investigated. The mechanisms of MDSHSs formation and photo-Fenton process were proposed. Total organic carbon (TOC) reduction reached as high as 90% with 60 mg/L of MB for 90 min. The experimental results indicated that MDSHSs exhibit a remarkable adsorption and catalytic activity for photo-Fenton process in a wide pH range of 3.3–11.0. Simultaneously, the composite shows an excellent stability and reusability.</p
Optimization of Fenton Technology for Recalcitrant Compounds and Bacteria Inactivation
No full textIn this work, the Fenton technology was applied to decolorize methylene blue (MB) and to inactivate Escherichia coli K12, used as recalcitrant compound and bacteria models respectively, in order to provide an approach into single and combinative effects of the main process variables influencing the Fenton technology. First, Box–Behnken design (BBD) was applied to evaluate and optimize the individual and interactive effects of three process parameters, namely Fe2+ concentration (6.0 × 10−4, 8.0 × 10−4 and 1.0 × 10−3 mol/L), molar ratio between H2O2 and Fe2+ (1:1, 2:1 and 3:1) and pH (3.0, 4.0 and 5.0) for Fenton technology. The responses studied in these models were the degree of MB decolorization (D%MB), rate constant of MB decolorization (kappMB) and E. coli K12 inactivation in uLog units (IuLogEC). According to the results of analysis of variances all of the proposed models were adequate with a high regression coefficient (R2 from 0.9911 to 0.9994). BBD results suggest that [H2O2]/[Fe2+] values had a significant effect only on D%MB response, [Fe2+] had a significant effect on all the responses, whereas pH had a significant effect on D%MB and IuLogEC. The optimum conditions obtained from response surface methodology for D%MB ([H2O2]/[Fe2+] = 2.9, [Fe2+] = 1.0 × 10−3 mol/L and pH = 3.2), kappMB ([H2O2]/[Fe2+] = 1.7, [Fe2+] = 1.0 × 10−3 mol/L and PH = 3.7) and IuLogEC ([H2O2]/[Fe2+] = 2.9, [Fe2+] = 7.6 × 10−4 mol/L and pH= 3.2) were in good agreement with the values predicted by the model
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