Improved wet peroxide oxidation strategies for the treatment of chlorophenols

Muñoz, Macarena; Pedro, Zahara M. de; Casas, José A.; Rodrı́guez, Juan J.

doi:10.1016/j.cej.2013.05.057

Cited by 25 publications

(16 citation statements)

References 41 publications

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“…According to previous works, iron leaching from the catalysts during CWPO of organic pollutants is directly related to the formation of oxalic acid (27 mg L −1 in this work), which leads to the formation of a Fe–oxalate complex. In this respect, carbon‐based catalysts have proved to be less resistant than Al 2 O 3 ‐based catalysts . On the other hand, it has to be highlighted that the efficiency of the use of H 2 O 2 followed the same trend as the iron leaching, remaining almost unchanged from the second cycle for both catalysts.…”

Section: Resultssupporting

confidence: 92%

“…Accordingly, lower iron leaching after each run was detected and the hydrogen peroxide efficiency was almost entirely maintained. These results are consistent with previous work where Fe/Al 2 O 3 catalysts have proved to be fairly stable in both consecutive and long‐term continuous experiments . Moreover, it has to be pointed out that this catalyst, which exhibits magnetic properties (M S = 2.24 emu g −1 ), can be easily separated from the reaction system by applying an external magnetic field after being used.…”

Section: Resultsmentioning

confidence: 99%

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Degradation of imidazolium-based ionic liquids by catalytic wet peroxide oxidation with carbon and magnetic iron catalysts

Muñoz

Domı́nguez

Pedro

et al. 2016

J. Chem. Technol. Biotechnol.

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BACKCGROUND: The ‘green’ image of ionic liquids (ILs) has changed in the last few years since numerous works have evidenced their non-biodegradability, persistence and high ecotoxicity, particularly for the most common imidazolium-based ILs. In this work, the feasibility of catalytic wet peroxide oxidation for the degradation of imidazolium-based ILs of different alkyl chain lengths has been studied under selected operating conditions (1000 mg L−1 IL, stoichiometric H2O2 dose, 2 g L−1 catalyst, pH 3 and 90 Â°C temperature) using different catalysts such as magnetic iron (Fe3O4) supported on γ-Al2O3 and activated carbon (AC) as well as bare carbon materials (graphite, AC). The catalytic activity and stability and the efficiency of H2O2 consumption have been evaluated. RESULTS: Although both AC-based catalysts led to the conversion of the IL, they yielded a low H2O2 consumption efficiency (24% and 45% with AC and Fe3O4/AC, respectively) due to the fast decomposition of H2O2 and the recombination of radical species into H2O and O2, non-reactive species under the operating conditions. In contrast, graphite and Fe3O4/γ-Al2O3 showed high activity allowing complete conversion and relatively high mineralization degrees of all the ILs tested in 1 h reaction time. Among those catalysts, Fe3O4/γ-Al2O3 exhibited a considerably greater stability upon four successive uses where iron leaching was negligible and the magnetic properties were maintained. CONCLUSIONS: Catalytic wet peroxide oxidation has proved to be an interesting alternative for the treatment of imidazolium-based ILs in water. The application of Fe3O4/γ-Al2O3 is particularly promising due to its high activity, remarkable stability and easy magnetic recoveryThis research has been supported by the Spanish MINECO through the project CTQ2013-4196-R and by the CM through the project S2013/MAE-271

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Degradation of imidazolium-based ionic liquids by catalytic wet peroxide oxidation with carbon and magnetic iron catalysts

Muñoz

Domı́nguez

Pedro

et al. 2016

J. Chem. Technol. Biotechnol.

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“…The COD was determined by a microwave-assisted potassium dichromate method (Dharmadhikari et al 2005;Zhang et al 2012). The residual H 2 O 2 in the liquid phase was determined by colorimetric titration using a UV-vis spectrophotometer and the titanium sulfate method (Munoz et al 2013). The pH values were determined with a precision pH meter (pHS-3C).…”

Section: Catalytic Oxidation Experimentsmentioning

confidence: 99%

Continuous Treatment of Phenol over an Fe2O3/γ-Al2O3 Catalyst in a Fixed-Bed Reactor

Yao

Gao

et al. 2015

Water Air Soil Pollut

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Fe 2 O 3 /γ-Al 2 O 3 catalysts were prepared using the wet impregnation method and characterized by Xray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption-desorption. The continuous catalytic wet hydrogen peroxide oxidation of an aqueous phenol solution over Fe 2 O 3 /γ-Al 2 O 3 was studied in a fixedbed reactor. The effects of several factors, such as the weight hourly space velocity (WHSV), particle size, reaction temperature, H 2 O 2 concentration, and initial pH, were studied to optimize the operation conditions for phenol mineralization. For a 1 g L −1 phenolic aqueous solution, the phenol was nearly completely removed and chemical oxygen demand (COD) removal was approximately 92 % at steady-state conditions with a WHSV of 2.4×10 −2 g PhOH h −1 g cat −1 at 80°C with 5.1 g L −1 H 2 O 2 . The long-term stability of the Fe 2 O 3 / γ-Al 2 O 3 catalyst was also investigated for the continuous treatment of phenolic water. The removal of phenol and COD exhibited a slowly decreasing trend, which was primarily due to the complexation of active sites with acid organic compounds and the adsorption of intermediate products. The deposition of organic carbon and Fe leached from the catalyst had a small role in the partial deactivation of the catalyst. The Fe leached from the catalyst partially contributed to the phenol removal during a short run. However, this contribution could be neglected after 36 h because the Fe leached from the catalyst decreased to approximately 5 mg L −1 .

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“…However, the oxidation rates are still far below those obtained by conventional homogeneous Fenton oxidation under similar operating conditions. For the sake of improving the rate of the process, we have recently explored the effect of temperature within 50 to 90 °C [76]. The magnetic catalyst (1 g L -1 ) allowed complete degradation of chlorophenol (100 mg L -1 )…”

Section: Magnetic Catalysts Prepared By In-situ Synthesis Of Magnetitementioning

confidence: 99%

Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation – A review

Muñoz

Pedro

Casas

et al. 2015

Applied Catalysis B: Environmental

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274

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Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: AbstractThis study presents a critical review on the application of magnetite-based catalysts to industrial wastewater decontamination by heterogeneous Fenton oxidation. The use of magnetic materials in this field started only around 2008 and continues growing increasingly year by year. The potential of these materials derives from their higher ability for degradation of recalcitrant pollutants compared to the conventional iron-supported catalysts due to the presence of both Fe(II) and Fe(III) species. In addition, their magnetic properties allow their easy, fast and inexpensive separation from the reaction medium. The magnetic materials applied up to now can be classified in three general groups: magnetic natural minerals, in-situ-produced magnetic materials and ferromagnetic nanoparticles. A survey of the catalysts investigated so far is presented paying attention to their nature and competitive features in terms of activity and durability.2

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Improved wet peroxide oxidation strategies for the treatment of chlorophenols

Cited by 25 publications

References 41 publications

Degradation of imidazolium-based ionic liquids by catalytic wet peroxide oxidation with carbon and magnetic iron catalysts

Degradation of imidazolium-based ionic liquids by catalytic wet peroxide oxidation with carbon and magnetic iron catalysts

Continuous Treatment of Phenol over an Fe2O3/γ-Al2O3 Catalyst in a Fixed-Bed Reactor

Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation – A review

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