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Munoz M, Nieto-Sandoval J, Cirés S, de Pedro ZM, Quesada A, Casas JA. Degradation of widespread cyanotoxins with high impact in drinking water (microcystins, cylindrospermopsin, anatoxin-a and saxitoxin) by CWPO. WATER RESEARCH 2019; 163:114853. [PMID: 31310856 DOI: 10.1016/j.watres.2019.114853] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 07/08/2019] [Accepted: 07/09/2019] [Indexed: 06/10/2023]
Abstract
The occurrence of harmful cyanobacterial blooms has unabated increased over the last few decades, posing a significant risk for public health. In this work, we investigate the feasibility of catalytic wet peroxide oxidation (CWPO) promoted by modified natural magnetite (Fe3O4-R400/H2O2), as an inexpensive, simple-operation and environmentally-friendly process for the removal of the cyanotoxins that show the major impact on drinking water: microcystins (MC-LR and MC-RR), cylindrospermopsin (CYN), anatoxin-a (ATX) and saxitoxin (STX). The performance of the system was evaluated under ambient conditions and circumneutral pH (pH0 = 5) using relevant cyanotoxin concentrations (100-500 μg L-1). The nature of the cyanotoxins determined their reactivity towards CWPO, which decreased in the following order: MC-RR > CYN > MC-LR ≫ ATX > STX. In this sense, microcystins and CYN were completely removed in short reaction times (1-1.5 h) with a low catalyst concentration (0.2 g L-1) and the stoichiometric amount of H2O2 (2-2.6 mg L-1), while only 60-80% conversion was achieved with ATX and STX in 5 h. In these cases, an intensification of the operating conditions (1 g L-1 catalyst and up to 30 mg H2O2 L-1) was required to remove both toxins in 1 h. The impact of the main components of freshwaters i.e. natural organic matter (NOM) and several inorganic ions (HCO3-, HPO42-, SO42-) on the performance of the process was also investigated. Although the former led to a partial inhibition of the reaction due to HO· scavenging and catalyst coating, the latter did not show any remarkably effect, and the versatility of the process was finally confirmed in a real surface water. To further demonstrate the effectiveness of the catalytic system, the toxicity of both the initial cyanotoxins and the resulting CWPO effluents was measured with the brine shrimp Artemia salina. Remarkably, all CWPO effluents were non-toxic at the end of the treatment.
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Silveira JE, Zazo JA, Casas JA. Coupled heat-activated persulfate - Electrolysis for the abatement of organic matter and total nitrogen from landfill leachate. WASTE MANAGEMENT (NEW YORK, N.Y.) 2019; 97:47-51. [PMID: 31447026 DOI: 10.1016/j.wasman.2019.07.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/05/2019] [Accepted: 07/27/2019] [Indexed: 06/10/2023]
Abstract
This work analyzes the viability of a coupled heat-activated persulfate (PS) and electro-oxidation treatment toabatetheorganic matter and nitrogen from ahigh polluted landfill leachate (5500 mg L-1 TOC; 5849 mg L-1 TN, pH: 8.4). These characteristics makes PS as a suitable oxidant to deal with the recalcitrant organic matter. Under the optimal conditions (70 °C and 60% of the stoichiometric amount of PS), around 60% of the initial organic load was mineralized. On the contrary, the nitrogen removal was below 20%. A subsequent electrolytic stage using Ti/IrO2-TaO2 anode at 175 mA cm-2 and 0.42 M NaCl during 60 min, led to overall organic matter and nitrogen removal above 85% and 90%, respectively, with energy requirement of 38 kWh per kg of nitrogen removed. In this sense, the combined process achieves a significant reduction in terms of energy consumption, up to one fifth in relation to sole electrolysis. These results confirm the feasibility of this combined process to treat landfill leachate.
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Razaviarani V, Zazo JA, Casas JA, Jaffé PR. Coupled fenton-denitrification process for the removal of organic matter and total nitrogen from coke plant wastewater. CHEMOSPHERE 2019; 224:653-657. [PMID: 30849626 DOI: 10.1016/j.chemosphere.2019.02.178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/23/2019] [Accepted: 02/25/2019] [Indexed: 06/09/2023]
Abstract
This work assesses the feasibility of applying a Coupled Fenton-Denitrification (CFD) process for the treatment of wastewater from a coking plant. This highly toxic effluent is characterized by comparable carbon and nitrogen contents and it is usually released into the treatment system at well above room temperature. Recalcitrant organic matter can be easily removed in a first step using Fenton treatment. Working at 50 °C, pH0: 3, and a wastewater obtained from a coking plant, the stoichiometric amount of H2O2 relative to COD and a H2O2/Fe2+ weight ratio of 50, around 60% of carbon load was mineralized whereas H2O2 was completely depleted. However, no changes were observed in the total nitrogen content. A subsequent denitrification stage led to an additional 80% TOC (overall above 90%) and 75% Total Nitrogen removal. This was done in a batch bioreactor at room temperature over 72 h, using a 40-day pre-acclimated denitrifying biomass. These results point to the possibility of designing a combined chemical oxidation and biological treatment to deal with complex effluents containing refractory organic matter including high concentrations of nitrogen species.
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García-Muñoz P, Zussblatt NP, Pliego G, Zazo JA, Fresno F, Chmelka BF, Casas JA. Evaluation of photoassisted treatments for norfloxacin removal in water using mesoporous Fe 2O 3-TiO 2 materials. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 238:243-250. [PMID: 30852400 DOI: 10.1016/j.jenvman.2019.02.109] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/03/2019] [Accepted: 02/22/2019] [Indexed: 06/09/2023]
Abstract
We report the synthesis of mesoporous TiO2 and mesoporous Fe2O3-TiO2 catalysts by using a structure-directing-surfactant method, their characterization and their employment as photocatalysts for norfloxacin degradation in aqueous solution. The main findings show that in the presence of both O2 and H2O2, Fe-containing mesoporous titania (Fe2O3-TiO2), with iron percentages between 1 and 3 wt%, exhibited norfloxacin degradation rates more than 60% greater than otherwise identical mesoporous titania without iron. Furthermore, the activity of the mesoporous composite catalysts also exceeds that of titania when illuminated with 405 nm light-emitting diodes. Iron loading improved the photocatalytic activity for norfloxacin degradation with values of apparent reaction rate constants of 0.037 min-1 and 0.076 min-1 with 1 and 3 surface wt.% of iron, respectively. An optimum of activity was found with the 3 wt% Fe2O3-TiO2 catalyst. Under these conditions, 10 mg/L of norfloxacin is reacted essentially to completion and 90% of total organic carbon conversion was obtained within 120 min of reaction. This higher organic carbon conversion degree was reached due to the photo-oxidation of short-chain organic acids. The high activity of the as-synthesized mesoporous composites is attributed to the additional iron phase which led to the different reactions for H2O2 decomposition, but also due to the improvement in light absorbance. Finally, the activity of the most active catalyst was found to be stable over multiple sequential runs, which was related to a negligible amount of iron leaching (<0.1%) from these materials.
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Garcia-Costa AL, Zazo JA, Casas JA. Microwave-assisted catalytic wet peroxide oxidation: Energy optimization. Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2019.01.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Garcia-Costa AL, Zazo JA, Rodriguez JJ, Casas JA. Intensification of catalytic wet peroxide oxidation with microwave radiation: Activity and stability of carbon materials. Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2018.07.054] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Domínguez CM, Munoz M, Quintanilla A, de Pedro ZM, Casas JA. Kinetics of imidazolium-based ionic liquids degradation in aqueous solution by Fenton oxidation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:34811-34817. [PMID: 29034425 DOI: 10.1007/s11356-017-0459-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 10/09/2017] [Indexed: 06/07/2023]
Abstract
In the last few years, several works dealing with Fenton oxidation of ionic liquids (ILs) have proved the capability of this technology for their degradation, achieving complete ILs removal and non-toxic effluents. Nevertheless, very little is known about the kinetics of this process, crucial for its potential application. In this work, the effect of several operating conditions, including reaction temperature (50-90 °C), catalyst load (10-50 mg L-1 Fe3+), initial IL concentration (100-2000 mg L-1), and hydrogen peroxide dose (10-200% of the stoichiometric amount for the complete IL mineralization) on 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) oxidation has been investigated. Under the optimum operating conditions (T = 90 °C; [Fe3+]0 = 50 mg L-1; [H2O2]0 = 100% of the stoichiometric amount), the complete removal of [C4mim]Cl (1000 mg L-1) was achieved at 1.5-min reaction time. From the experimental results, a potential kinetic model capable to describe the removal of imidazolium-based ILs by Fenton oxidation has been developed. By fitting the proposed model to the experimental data, the orders of the reaction with respect to IL initial concentration, Fe3+ amount and H2O2 dose were found to be close to 1, with an apparent activation energy of 43.3 kJ mol-1. The model resulted in a reasonable fit within the wide range of operating conditions tested in this work.
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Nieto-Sandoval J, Munoz M, de Pedro ZM, Casas JA. Fast degradation of diclofenac by catalytic hydrodechlorination. CHEMOSPHERE 2018; 213:141-148. [PMID: 30216814 DOI: 10.1016/j.chemosphere.2018.09.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 08/29/2018] [Accepted: 09/04/2018] [Indexed: 06/08/2023]
Abstract
Aqueous-phase catalytic hydrodechlorination (HDC) has been scarcely explored in the literature for the removal of chlorinated micropollutants. The aim of this work is to prove the feasibility of this technology for the fast and environmentally-friendly degradation of such kind of compounds. Diclofenac (DCF), a highly consumed anti-inflammatory drug, has been selected as the target pollutant given its toxicity and low biodegradability. The commercial Pd/Al2O3 (1% wt.) catalyst has been used due to its prominent role on this field. Complete degradation of DCF was achieved in a short reaction time (20 min) under ambient conditions (25 °C, 1 atm) at [DCF]0 = 68 μM; [Pd/Al2O3]0 = 0.5 g L-1 and H2 flow rate of 50 N mL min-1. Remarkably, the chlorinated intermediate (2-(2-chloroanilino)-phenylacetate (Cl-APA)) generated along reaction was completely removed at the same time, being the chlorine-free compound 2-anilinophenylacetate (APA) the only final product. A reaction scheme based on this consecutive pathway and a pseudo-first-order kinetic model have been proposed. An apparent activation energy of 43 kJ mol-1 was obtained, a comparable value to those previously reported for conventional organochlorinated pollutants. Remarkably, the catalyst exhibited a reasonable stability upon three successive uses, achieving the complete degradation of the drug and obtaining APA as the final product in 30 min. The evolution of ecotoxicity was intimately related to the disappearance of the chlorinated organic compounds and thus, the final HDC effluents were non-toxic. The versatility of the system was finally demonstrated in different environmentally-relevant matrices (wastewater treatment plant effluent and surface water).
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Silveira JE, Zazo JA, Pliego G, Casas JA. Landfill leachate treatment by sequential combination of activated persulfate and Fenton oxidation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2018; 81:220-225. [PMID: 30527039 DOI: 10.1016/j.wasman.2018.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/26/2018] [Accepted: 10/04/2018] [Indexed: 05/21/2023]
Abstract
This work assesses the feasibility of sequential persulfate and Fenton oxidation for the decolorization and mineralization of landfill leachate (5600 mg L-1 TOC; pH0: 8.6) in a continuous batch-recirculation system. Firstly, it was analyzed the role of the operational conditions upon the persulfate activation evaluating the effects of electrolysis, ilmenite (FeTiO3) as a source of Fe(II) and UV-LED (at 365 nm). The studied variables include current density (j) (50-200 mA cm-2), persulfate dose (46.8-234 mM) and mineral concentration (500-1500 mg L-1). The increase in j enhanced the hypochlorite generation and PS conversion to SO4- and, consequently, decolorization efficiency increasing the penetration of light through the solution and the photoreduction of Fe(III) to Fe(II) in the FeTiO3 surface. The combined electrolysis/FeTiO3/UV-LED showed synergetic effect compared to the individual processes, achieving mineralization around 53% under the optimum operating conditions (1 g L-1 of FeTiO3, using 234 mM of PS at 200 mA cm-2 under UV-LED radiation). The subsequent Fenton oxidation once the pH decreased up to around 3, led to overall mineralization above 90% after 480 min, confirming the suitability of this combined treatment to deal with recalcitrant and highly colored effluents.
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Garcia-Costa AL, Lopez-Perela L, Xu X, Zazo JA, Rodriguez JJ, Casas JA. Activated carbon as catalyst for microwave-assisted wet peroxide oxidation of aromatic hydrocarbons. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:27748-27755. [PMID: 29785599 DOI: 10.1007/s11356-018-2291-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 05/09/2018] [Indexed: 06/08/2023]
Abstract
This paper addresses the removal of four aromatic hydrocarbons typically found in petrochemical wastewater: benzene (B), toluene (T), o-xylene (X), and naphthalene (N), by microwave-assisted catalytic wet peroxide oxidation (MW-CWPO) using activated carbon (AC) as catalyst. Under the studied conditions, complete pollutant elimination (B, 1.28 mM; T, 1.09 mM; X, 0.94 mM; and N, 0.78 mM) was achieved, with more than 90% TOC removal after only 15-min reaction time, working at 120 °C, pH0 = 3, AC at 1 g L-1, and H2O2 at the stoichiometric dose. Furthermore, in the case of toluene, naphthalene, and xylene, the hydroxylation and breakdown of the ring is very rapid and toxic intermediates were not detected. The process follows two steps: (i) pollutant adsorption onto AC followed by (ii) adsorbed compounds oxidation. Thus, MW-CWPO with AC as catalyst appears a promising way for a fast and effective process for B, T, X, and N removal in aqueous phase.
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Munoz M, Conde J, de Pedro ZM, Casas JA. Antibiotics abatement in synthetic and real aqueous matrices by H2O2/natural magnetite. Catal Today 2018. [DOI: 10.1016/j.cattod.2017.10.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Silveira JE, Claro EMT, Paz WS, Oliveira AS, Zazo JA, Casas JA. Optimization of Disperse Blue 3 mineralization by UV-LED/FeTiO3 activated persulfate using response surface methodology. J Taiwan Inst Chem Eng 2018. [DOI: 10.1016/j.jtice.2017.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Silveira JE, Garcia-Costa AL, Cardoso TO, Zazo JA, Casas JA. Indirect decolorization of azo dye Disperse Blue 3 by electro-activated persulfate. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.11.143] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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García-Muñoz P, Pliego G, Zazo JA, Bahamonde A, Casas JA. Sulfonamides photoassisted oxidation treatments catalyzed by ilmenite. CHEMOSPHERE 2017; 180:523-530. [PMID: 28431390 DOI: 10.1016/j.chemosphere.2017.04.047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/24/2017] [Accepted: 04/11/2017] [Indexed: 06/07/2023]
Abstract
This work assesses the feasibility of several advanced oxidation processes (CWPO Catalytic Wet Peroxide Oxidation), Photocatalysis and their combination (CWPO-Photoassisted process) for sulfonamide antibiotic degradation. Raw ilmenite was used as catalyst in both processes, because of the presence of iron and titanium in its structure. Despite both treatments allowed reaching a total starting antibiotic depletion working at pH0 = 3 and T0 = 30 °C within 30 min reaction time, significant differences were observed in terms of mineralization. Thus, whereas photocatalytic process just reduced 35% of initial TOC after 120 min, a 85% of mineralization was reached in the presence of H2O2 (CWPO-Photoassisted process) which was related to the oxidation pathway. Only a 35% of mineralization was reached in case of CWPO. In this sense, the degradation route under CWPO-Photoassisted process displayed a mechanism based on the hydroxylation that led to lower molecular weight intermediates. On the contrary, under photocatalysis conditions, the appearance of higher molecular weight intermediates due to organic radical recombination indicates the prevailing of a condensation mechanism.
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Munoz M, Mora FJ, de Pedro ZM, Alvarez-Torrellas S, Casas JA, Rodriguez JJ. Application of CWPO to the treatment of pharmaceutical emerging pollutants in different water matrices with a ferromagnetic catalyst. JOURNAL OF HAZARDOUS MATERIALS 2017; 331:45-54. [PMID: 28242528 DOI: 10.1016/j.jhazmat.2017.02.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 02/08/2017] [Accepted: 02/12/2017] [Indexed: 06/06/2023]
Abstract
CWPO has proved to be effective for the treatment of representative pharmaceuticals (sulfamethoxazole, atenolol, metronidazole, diltiazem, trimethoprim and ranitidine) in different water matrices (ultrapure water, surface water, WWTP effluent and hospital wastewater). Complete removal of the pollutants and the aromatic intermediates was achieved using the stoichiometric dose of H2O2, a catalyst (Fe3O4/γ-Al2O3) load of 2gL-1, pH 3 and temperature of 50-75°C. Accordingly, the ecotoxicity was reduced to negligible values. The degradation was faster when the pharmaceuticals were together, being the reaction time for the elimination of the most refractory species (metronidazole) shortened from 4h to 1h. The mineralization of the drugs was fairly different, being the most reactive species those containing several aromatic rings (XTOC∼80%) and the most refractory that bearing an imidazolium ring (XTOC∼35%). The water matrix affected the kinetics of the process but in all cases complete conversion of the drugs was reached within 1h. The presence of dissolved organic matter (surface water) seemed to promote drugs degradation while the occurrence of inorganic ions (real WTTP and hospital effluents) partially inhibited it due to scavenging effects. Remarkably, the process was successfully operated at the typical concentrations of main micropollutant sources (μgL-1).
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Pliego G, Garcia-Muñoz P, Zazo JA, Casas JA, Rodriguez JJ. Improving the Fenton process by visible LED irradiation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:23449-23455. [PMID: 27613628 DOI: 10.1007/s11356-016-7543-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/26/2016] [Indexed: 06/06/2023]
Abstract
The effect of irradiation with visible light-emitting diode (LED) light on the efficiency of Fenton oxidation is investigated using phenol as the target compound (100 mg/L). The H2O2 dose and temperature are tested as operating variables with the aim of minimizing consumption of the reagents. At 50 °C, 10 mg/L Fe2+, and 60 % of the stoichiometric H2O2 amount, phenol was completely oxidized into CO2, H2O, and short chain organic acids, with oxalic acid completely degraded. Up to 95 % mineralization was achieved. This high efficiency can be attributed to the effect of LED radiation on the quinones/Fe2+/Fe3+/H2O2 cycle, which significantly increases the reaction rate, as well as on the photodecomposition of the iron complexes formed along the oxidation process, which also enhanced mineralization.
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Álvarez-Torrellas S, Muñoz M, Zazo JA, Casas JA, García J. Synthesis of high surface area carbon adsorbents prepared from pine sawdust-Onopordum acanthium L. for nonsteroidal anti-inflammatory drugs adsorption. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2016; 183:294-305. [PMID: 27604753 DOI: 10.1016/j.jenvman.2016.08.077] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/28/2016] [Accepted: 08/29/2016] [Indexed: 06/06/2023]
Abstract
Chemically activated carbon materials prepared from pine sawdust-Onopordum acanthium L. were studied for the removal of diclofenac and naproxen from aqueous solution. Several carbons, using different proportions of precursors were obtained (carbon C1 to carbon C5) and the chemical modification by liquid acid and basic treatments of C1 were carried out. The textural properties of the carbons, evaluated by N2 adsorption-desorption isotherms, revealed that the treatments with nitric acid and potassium hydroxide dramatically reduced the specific surface area and the pore volume of the carbon samples. The surface chemistry characterization, made by thermal programmed decomposition studies, determination of isoelectric point and Boehm's titration, showed the major presence of lactone and phenol groups on the activated carbons surface, being higher the content when the acidic strength of the carbon increased. Diclofenac and naproxen kinetic data onto C1 carbon followed pseudo-second order model. The adsorption equilibrium isotherms of C1 and the modified carbons were well described by both Sips and GAB isotherm equations. The highest adsorption capacity was found for naproxen onto C1 activated carbon, 325 mg g(-1), since the liquid acid and basic functionalization of the carbon led to a severe decreasing in the adsorption removal of the target compounds.
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Xu X, Pliego G, Zazo JA, Casas JA, Rodriguez JJ. Mineralization of naphtenic acids with thermally-activated persulfate: The important role of oxygen. JOURNAL OF HAZARDOUS MATERIALS 2016; 318:355-362. [PMID: 27442986 DOI: 10.1016/j.jhazmat.2016.07.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 07/03/2016] [Accepted: 07/05/2016] [Indexed: 06/06/2023]
Abstract
This study reports on the mineralization of model naphtenic acids (NAs) in aqueous solution by catalyst-free thermally-activated persulfate (PS) oxidation. These species are found to be pollutants in oil sands process-affected waters. The NAs tested include saturated-ring (cyclohexanecarboxylic and cyclohexanebutyric acids) and aromatic (2-naphthoic and 1,2,3,4-tetrahydro-2-naphthoic acids) structures, at 50mgL(-1)starting concentration. The effect of PS dose within a wide range (10-100% of the theoretical stoichiometric) and working temperature (40-97°C) was investigated. At 80°C and intitial pH=8 complete mineralization of the four NAs was achieved with 40-60% of the stoichiometric PS dose. This is explained because of the important contribution of oxygen, which was experimentally verified and was found to be more effective toward the NAs with a single cyclohexane ring than for the bicyclic aromatic-ring-bearing ones. The effect of chloride and bicarbonate was also checked. The former showed negative effect on the degradation rate of NAs whereas it was negligible or even positive for bicarbonate. The rate of mineralization was well described by simple pseudo-first order kinetics with values of the rate constants normalized to the PS dose within the range of 0.062-0.099h(-1). Apparent activation energy values between 93.7-105.3kJmol(-1) were obtained.
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Diaz E, Cebrian M, Bahamonde A, Faraldos M, Mohedano AF, Casas JA, Rodriguez JJ. Degradation of organochlorinated pollutants in water by catalytic hydrodechlorination and photocatalysis. Catal Today 2016. [DOI: 10.1016/j.cattod.2015.08.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Munoz M, Domínguez CM, de Pedro ZM, Quintanilla A, Casas JA, Ventura SP, Coutinho JA. Role of the chemical structure of ionic liquids in their ecotoxicity and reactivity towards Fenton oxidation. Sep Purif Technol 2015. [DOI: 10.1016/j.seppur.2015.07.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Munoz M, Domínguez CM, de Pedro ZM, Quintanilla A, Casas JA, Rodriguez JJ. Ionic liquids breakdown by Fenton oxidation. Catal Today 2015. [DOI: 10.1016/j.cattod.2014.03.028] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Munoz M, Pliego G, de Pedro ZM, Casas JA, Rodriguez JJ. Application of intensified Fenton oxidation to the treatment of sawmill wastewater. CHEMOSPHERE 2014; 109:34-41. [PMID: 24873704 DOI: 10.1016/j.chemosphere.2014.02.062] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 02/24/2014] [Accepted: 02/25/2014] [Indexed: 06/03/2023]
Abstract
The application of the Fenton process for the treatment of sawmill wastewater has been investigated. The sawmill wastewater was characterized by a moderate COD load (≈3gL(-1)), high ecotoxicity (≈ 40 toxicity units) and almost negligible BOD/COD ratio (5×10(-3)) due to the presence of different fungicides such as propiconazole and 3-iodo-2-propynyl butyl carbamate, being the wastewater classified as non-biodegradable. The effect of the key Fenton variables (temperature (50-120°C), catalyst concentration (25-100 mg L(-1) Fe(3+)), H2O2 dose (1 and 2 times the stoichiometric dose) and the mode of H2O2 addition) on COD reduction and mineralization was investigated in order to fulfill the allowable local limits for industrial wastewater discharge and achieve an efficient consumption of H2O2 in short reaction times (1h). Increasing the temperature clearly improved the oxidation rate and mineralization degree, achieving 60% COD reduction and 50% mineralization at 120°C after 1h with the stoichiometric H2O2 dose and 25 mg L(-1) Fe(3+). The distribution of H2O2 in multiple additions throughout the reaction time was clearly beneficial avoiding competitive scavenging reactions and thus, achieving higher efficiencies of H2O2 consumption (XCOD ≈ 80%). The main by-products were non-toxic short-chain organic acids (acetic, oxalic and formic). Thus, the application of the Fenton process allowed reaching the local limits for industrial wastewater discharge into local sewer system at a relatively low cost.
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Bautista P, Casas JA, Zazo JA, Rodriguez JJ, Mohedano AF. Comparison of Fenton and Fenton-like oxidation for the treatment of cosmetic wastewater. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2014; 70:472-478. [PMID: 25098877 DOI: 10.2166/wst.2014.246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The treatment of cosmetic wastewaters by Fenton (Fe²⁺/H₂O₂) and Fenton-like (Fe³⁺/H₂O₂) oxidation has been studied. From batch and continuous experiments it has been proved that both versions of the Fenton process lead to quite similar results in terms of chemical oxygen demand (COD) and total organic carbon reduction although the COD shows a slightly higher rate in the early stages of reaction. COD reductions of around 55% after 2 h reaction time and 75-80% with 4 h residence time were reached in batch and continuous experiments, respectively, conducted at pH around 3, ambient temperature (20 °C), with 200 mg/L of Fe dose and an initial H₂O₂/COD weight ratio corresponding to the theoretical stoichiometric value. Achieving the locally allowable limit of COD for industrial wastewater discharge into the municipal sewer system takes no more than 30 min reaction time under those conditions by both Fenton systems. However, the Fenton-like process, where iron is fed as Fe(3+), would be preferable for industrial applications since the ferric sludge resulting upon final neutralization of the effluent can be recycled to the process. A second-order kinetic equation with respect to COD fitted fairly well the experimental results at different temperatures, thus providing a simple practical tool for design purposes.
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Munoz M, de Pedro ZM, Casas JA, Rodriguez JJ. Chlorophenols breakdown by a sequential hydrodechlorination-oxidation treatment with a magnetic Pd-Fe/γ-Al2O3 catalyst. WATER RESEARCH 2013; 47:3070-3080. [PMID: 23561499 DOI: 10.1016/j.watres.2013.03.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 02/26/2013] [Accepted: 03/08/2013] [Indexed: 06/02/2023]
Abstract
Degradation of chlorophenols by a sequential combination of hydrodechlorination (HDC) and catalytic wet peroxide oxidation (CWPO) using a new magnetic Pd-Fe/γ-Al2O3 catalyst has been studied. This catalyst is active in both hydrodechlorination of chlorophenols and decomposition of H2O2 for the oxidation of organic compounds. The sequential combination of HDC and CWPO allows overcoming some of the drawbacks of both treatments applied independently. The HDC step achieves the complete dechlorination of chlorophenols, so that the subsequent CWPO does not lead to the formation of highly toxic chlorinated by-products and reduces significantly the organic load of the effluent. The results showed that the presence of iron in the Pd catalyst improved significantly its hydrodechlorination rate, achieving the complete dechlorination of chlorophenols in a short reaction time (≈ 15 min), giving rise to phenol and cyclohexanone. The CWPO of synthetic mixtures of phenol and cyclohexanone showed that a high phenol concentration promotes the oxidation of all the organic species, but the presence of cyclohexanone seems to hinder the formation of aromatic radicals limiting the effectiveness of the CWPO step. Therefore, the effective combination of HDC and CWPO requires that the HDC step achieves the complete dechlorination of chlorophenols but no further hydrogenation is needed. The Pd-Fe/γ-Al2O3 catalyst showed a high activity in both HDC and subsequent CWPO of chlorophenols being easily separated and recovered from the reaction medium due to its ferromagnetic properties. In spite of a moderate loss of activity, the complete dechlorination of chlorophenol and a negligible ecotoxicity of the final effluents were maintained upon successive applications of HDC + CWPO in a four-cycles test.
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Pliego G, Zazo JA, Casas JA, Rodriguez JJ. Case study of the application of Fenton process to highly polluted wastewater from power plant. JOURNAL OF HAZARDOUS MATERIALS 2013; 252-253:180-185. [PMID: 23523909 DOI: 10.1016/j.jhazmat.2013.02.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 02/22/2013] [Accepted: 02/24/2013] [Indexed: 06/02/2023]
Abstract
This work investigates the application of Fenton process to the treatment of a highly polluted industrial wastewater resulting from the pipeline cleaning in a power plant. This effluent is characterized by a high chemical oxygen demand (COD>40 g/L), low biodegradability and quite a high iron concentration (around 3g/L) this coming from pipeline corrosion. The effect of the initial reaction temperature (between 50 and 90 °C) and the way of feeding H2O2 on the mineralization percentage and the efficiency of H2O2 consumption has been analyzed. With the stoichiometric amount of H2O2 relative to initial COD, fed in continuous mode, more than 90% COD reduction was achieved at 90 °C. That was accompanied by a dramatic improvement of the biodegradability. Thus, a combined treatment based on semicontinuous high-temperature Fenton oxidation (SHTF) and conventional aerobic biological treatment would allow fulfilling the COD and ecotoxicity regional limits for industrial wastewaters into de municipal sewer system. For the sake of comparison, catalytic wet air oxidation was also tested with poor results (less than 30% COD removal at 140 °C and 8 atm oxygen pressure).
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