Search

Refereed/Peer-reviewed Since ofloxacin (OFX) is one of many common antibiotics, which effluxes into aquatic environment in relatively high concentration, it has become of significant environmental concern due to the potential for increased antibiotic resistance. In this study, an innovative functional Fe/Ni@ZIF-8 composite was successfully used for the Fenton-like oxidation of OFX, with a OFX removal efficiency >98% under optimal conditions. FTIR analysis confirmed that OFX removal occurred via adsorption to Fe/Ni@ZIF-8 by a combination of π-π bond intercalation and electrostatic interaction, while XPS revealed that the Fe/Ni NPs in Fe/Ni@ZIF-8 were also involved in oxidation. Furthermore, LC-MS analysis identified the presence of several OFX degradation products post exposure, which indicted that Fe/Ni NPs in Fe/Ni@ZIF-8 reacted with H2O2 to form •OH, leading to Fenton-like oxidation of OFX. Thus overall, OFX removal by Fe/Ni@ZIF-8 involved both adsorption to ZIF-8 and Fenton-like oxidation by Fe/Ni NPs. A synergistic mechanism for OFX removal by Fe/Ni@ZIF-8 was thus proposed. The removal efficiency of the synthesized catalysts remained high (above 65%) even after a 5th reuse cycle, which reflected the high stability of Fe/Ni@ZIF-8. Overall, this study demonstrated that Fe/Ni@ZIF-8 had significant potential for the removal of OFX from wastewaters with a removal efficiency >90%.

Refereed/Peer-reviewed A green tea extract was used as a natural reducing agent to prepare three different manganese oxides (Mn3O4, Mn2O3 and MnO) which after carbonization in different atmospheres, were evaluated for their ability to degrade estriol (E3). Catalytic ability of the three manganese oxides varied in the order Mn2O3 > Mn3O4 > MnO; corresponding to E3 degradation efficiencies of 100, 100 and 92.5 % after 180 min. After calcination, no new functional groups were observed on the surface of three manganese oxides, except the corresponding spectra. The morphology of the manganese oxides was primarily olive-shaped, with numerous small cubic particles stacked at the nanoscale, with a uniform distribution of elements. Free radicals and Mn ion leaching was observed from the prepared manganese oxides where leaching of manganese ions was related to the intensity of singlet oxygen. Advanced material characterization showed while green synthesis resulted in materials being doped with a small amounts of elements such as C and S, the broad crystal structure of the three materials was still the main factor affecting the removal efficiency of E3; with Mn(III) playing a major role in the catalytic peroxydisulfate (PDS) process.

The effect of different parameters such as temperature, type of catalyst and hydrogen peroxide (H2O2) concentration on the degradation of pollutants in water by Fenton-like oxidation was studied by using the Box-Behnken design (BBD), an effective statistical model to design the experiments. Concerning the heterogeneous catalysts, three bimetallic catalysts with lanthanum (La) and iron (Fe) ion-exchanged into zeolites (NaY and ZSM5) and a natural clay from Morocco were prepared and used for Fenton-like oxidation of organic pollutants in water. Tartrazine (Tar, a food coloring compound known as E102) and caffeine (Caf, a stimulant drug present in popular beverages such as coffee and tea) were selected as pollutants due to their presence in several commercial products for daily consumption. The BBD model indicated that the optimum catalytic conditions for Fenton-like reaction with an initial pollutant concentration of 30ppm at pH 3.0 were T=40°C and 90mM of H2O2. The maximum conversion values achieved with the best catalyst, LaFeZSM5, were 96.6% for Tar after 180min and 51.0% for Caf after 300min of reaction. To increase the conversion of Caf, a modified zeolite electrode was used for electro Fenton-like oxidation without H2O2, at room temperature., O.A. thanks to ERASMUS + Program for the mobility Ph.D. grant and O.B. thanks to Fundação para Ciência e Tecnologia, Portugal (FCT) for his Ph.D. grant (SFRH/BD/140362/2018).This research work has been funded by national funds funded through FCT/MCTES (PIDDAC) over the projects: LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), UIDB/04469/2020 (CEB) and by LA/P/0029/2020 (LABBELS), Centre of Chemistry (UID/QUI/0686/2020) and project BioTecNorte (operation NORTE-01-0145-FEDER-000004), supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)., info:eu-repo/semantics/publishedVersion

Fluorinated Fe3O4 microspheres with 7.1 ± 1.4 wt% of fluoride (F-Fe3O4-1) were prepared via glycothermal synthesis. Fluorination significantly enhanced the activity of F-Fe3O4-1 in catalytic wet peroxide oxidation of anionic dyes (including orange G (OG) and congo red) at pH ~7. However, the promotional effect of fluorination became less obvious for amphoteric rhodamine B and was not observed for cationic methylene blue. After reacting with H2O2 (40 mM) for 2 h at pH 6.5 and 40 °C, the decolorization rates of OG (0.1 mM) and the pseudo-first-order rate constant were 96.8% and 0.0284 min−1 over F-Fe3O4-1 versus 17.6% and 0.0011 min−1 over unmodified Fe3O4. The effects of reaction parameters (initial H2O2 concentration and pH value and reaction temperature) on OG decolorization with H2O2 over F-Fe3O4-1 were investigated. The reusability of F-Fe3O4-1 was demonstrated by OG decolorization in eight consecutive runs. Fluorination increased the isoelectric point of F-Fe3O4-1 to 8.7 and facilitated the adsorption and degradation of anionic dyes on the surface of F-Fe3O4-1 at pH ~7. Scavenging tests and EPR spectra supported that hydroxyl radicals were the main reactive species for the OG decolorization over F-Fe3O4-1.

Electrochemical oxidation, a powerful tool for the conversion of several of organic dye compounds using metal-exchanged zeolite modified electrodes, has shown great potential due to its capability of high efficiency degradation, a global priority for a sustainable environment. In this study, the role of the Fe(III)-exchanged-zeolite-modified electrodes using two different zeolite structures (such as FAU (Y) and MFI (ZSM-5)) on the Fenton-like oxidation of Congo Red dye (C32H22N6Na2O6S2) was investigated at room temperature. To clarify the electrocatalytic trend observed by constant potential electrolysis, the surface acidity of the catalysts prepared by ion-exchange method was determined by microcalorimetric measurements of ammonia adsorption. The different acid properties deriving from the presence of different cations (NH4+, H+ and Na+) in the case of MFI structure were found to enhance the ion-exchange capacity as well as the oxidation reaction. MFI catalysts - Fe(Na)ZSM-5, Fe(H)ZSM-5 and Fe(NH4)ZSM-5 - exhibited excellent activity and stability at the end of the electrolysis (within 60min), with a total dye degradation and an higher mineralization on Fe(H)ZSM-5 (64% of TOC), compared with Fe(Na)Ynano, which takes twice as long (120min) for total degradation, with 19% of TOC removal. This work provides an effective route for the development of stable Fe(III)-zeolite-modified electrodes for electro-Fenton oxidation, with a better stabilization of Fe3+ ions within the framework, without the aggregation of iron and the addition of H2O2, at room temperature., Z.B. thanks to ERASMUS+ Program for the mobility PhD grant. This research work has been funded by national funds funded through FCT/MCTES (PIDDAC), (Fundação para Ciência e Tecnologia, FCT) over the projects: LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), Centre of Chemistry (UID/QUI/0686/2020) and project BioTecNorte (operation NORTE-01-0145-FEDER 000004), supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)., info:eu-repo/semantics/publishedVersion

Effluent arising from kraft or soda pulping section of a pulp and paper mill is difficult to treat due to the presence of recalcitrant organics such as lignin. In this study, FeCl3 pretreated pulping effluent was subjected to Fenton-like oxidation. Residual dissolved iron from pretreatment step and H2O2 were utilized as catalyst and oxidant, respectively while the initial wastewater pH was 4.0 (unadjusted). The maximum lignin and total organic carbon (TOC) removals of 85% and 48% could be achieved within 2 h of reaction. The oxidation reaction was mediated by hydroxyl radicals (HO center dot) which were detected by electron spin resonance (ESR) spectroscopy. Moreover, the addition of tertiary butyl alcohol and chloroform (both radical scavengers) as well hydroxyl amine (a ferrous ion recycler) affected TOC removal significantly. The TOC degradation data could adequately be fit in a lumped kinetic model (LKM) and the activation energy was calculated as 50.85 kJ/mol. The nature of chemical compounds in treated wastewater was also predicted using Fourier transforms infrared (FTIR) spectroscopy. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Large amounts of wastewater containing hydroxypropyl guar gum (HPGG), polyacrylamide (PAM) and carboxymethyl cellulose (CMC) are produced in the process of fracturing. In the work, a Fentonlike system in the presence of H2O2 was employed to degrade wastewater. The effects of oxidant concentration, catalyst dosage, the temperature and pH on the degradation efficiency of the polymer were studied in detail. Results showed that the prepared complex (Cu(II)L) exhibited a great catalytic effects in the range of pH 7-12. It was also found that under the conditions of 45℃ and pH=10, when the amount of H2O2 was 5.0% (mass ratio to hydroxypropyl guar gum) and the amount of Cu (II)L complex was 10%, HPGG had a great reduction rate, and its viscosity value can be reduced from 18 to 6.47.

Heterogeneous Fenton-like catalysts with the activation of peroxymonosulfate (PMS), which offer the advantages of fast reaction rate, wide functional pH range and cost efficiency, have attracted great interest in wastewater treatment. In this study, a novel magnetic MnO2/Fe3O4/diatomite nanocomposite is synthesized and then used as heterogeneous Fenton-like catalyst to degrade the organic pollutant methylene blue (MB) with the activation of PMS. The characterization results show that the Fe3O4 nanoparticles and nanoflower-like MnO2 are evenly distributed layer-by-layer on the surface of diatomite, which can be readily magnetically separated from the solution. The as-prepared catalyst, compared with other Fenton-like catalysts, shows a superb MB degradation rate of nearly 100% in 45 min in the pH range of 4 to 8 and temperature range of 25 to 55 °C. Moreover, the nanocomposite shows a good mineralization rate of about 60% in 60 min and great recyclability with a recycle efficiency of 86.78% after five runs for MB. The probable mechanism of this catalytic system is also proposed as a synergistic effect between MnO2 and Fe3O4.

Degradation of carbamazepine (CBZ) upon Fenton-like oxidation has been investigated analyzing the effect of H2O2 dose and temperature at a very low catalyst concentration (2mgL-1 of Fe3+). Fenton-like oxidation allowed complete conversion of CBZ, the oxidation rate depending on the amount of H2O2 used. The addition of the theoretical stoichiometric amount of H2O2 led to the complete conversion of CBZ in 1h reaction time. The reduction of the H2O2 initial concentration down to 10% of the stoichiometric led to a significant increase of that time up to 3h. The mineralization efficiency of H2O2 was considerably increased by increasing the temperature (from 21 to 131mgTOC/gH2O2 at 35 and 50°C, respectively). Beyond 50°C no significant effect was observed in the extension of reaction although it proceeded at significantly higher rate. The toxicity and biodegradability of the resulting effluents from Fenton-like oxidation were evaluated by respirometric tests using non-acclimated activated sludge. CBZ strongly inhibits the microbial activity (EC50=1.8mgL-1) being essentially non-biodegradable. Fenton-like oxidation of CBZ (10mgL-1) at 50°C with the theoretical stoichiometric H2O2 amount for complete mineralization (5.6mgH2O2/mgCBZ) allowed obtaining an easily biodegradable effluent The Spanish MCI through the project CTM2013-43803-P and CTQ2013-41963-R, and by the CM through the project S-2013/MAE-2716.

Nanoscale zero-valent iron (nZVI) was used as the catalyst to remove amoxicillin (AMX) using a heterogeneous Fenton-like system, where 86.5% of AMX was oxidized using nZVI/H 2 O 2 , while only 25.2% of AMX was removed when nZVI was used. The surface change in nZVI before and after reaction was characterized by various techniques. Scanning electron microscopy (SEM) showed that aggregation and corrosion of nZVI had occurred. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) confirmed the existence of Fe 0 and the presence of iron oxide and iron oxohydroxide Fe(II), Fe(III), as well as UV–visible demonstrated that the absorption peak of AMX had disappeared after the reaction. To understand the degradation mechanism, LC–MS analysis of the degraded products shows that the LC–MS spectra found a new peak at m/z 301 (C 8 H 14 O 9 NS), and the mechanism for Fenton oxidation of AMX was proposed. Removal efficiency depended on the nZVI dosage, initial pH, initial H 2 O 2 concentration and the temperature, where 86.5% of AMX was degraded and 71.2% of COD was removed after 25 min at conditions of H 2 O 2 6.6 mM, nZVI 500 mg/L, AMX 50 mg/L, pH 3.0 and temperature 30 °C. Kinetics for the oxidation of AMX fitted well to the pseudo first-order model and the rate constant k obs increased as temperature increased with an apparent activation energy of 30.1 kJ/mol. Finally, nZVI demonstrated its capacity as a catalyst for heterogeneous Fenton oxidation of AMX from wastewater, and the removal percentage was 80.5%.

This paper is built on the Fenton-like oxidation of p-hydroxybenzoic acid (p–HBZ) in the presence of H2O2 and 3%Fe supported on CeO2-TiO2 aerogels under mild conditions. These catalysts were deeply characterized by X-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy (XPS). The effect of thermal treatment, pH (2–3, 5, 7), H2O2/p–HBZ molar ratio (5, 15, 20, 25) and reaction temperature (25 °C, 40 °C and 60 °C) on the catalytic properties of supported Fe catalysts are studied. Our results highlight the role of CeO2 and the calcination of the catalyst to obtain the highest catalytic properties after 10 min: 73% of p–HBZ conversion and 52% of total organic carbon (TOC) abatement.