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• Green synthesis of Mn 3 O 4 NPs was as a new Fenton catalyst. • The removal efficiency was 97.5% for E3 and 96.4% for EE2. • Various radicals were observed in the catalytic system. • A new mechanism was proposed. Manganese tetroxide (Mn 3 O 4) nanomaterials were prepared by green tea extract and applied to catalyze sodium peroxydisulfate (PDS) for the simultaneous degradation of estriol/17a-ethinylestradiol (E3/EE2) with removal efficiencies of 97.5 and 96.4% for E3 and EE2, respectively. XPS also showed that before and after the reaction the divalent manganese content decreased from 50.2 to 34.8%, indicating divalent manganese plays a major role in the catalytic process. EPR quenching and electrochemical studies showed that while initially singlet oxygen (1O 2), sulfate (SO 4 •-), superoxide (O 2 •-) and hydroxyl (•OH) radicals were all generated in the system, thereafter, the oxidation of E3/EE2 mainly depended on 1O 2 and O 2 •-, where O 2 •- intermediates participated in the generation of 1O 2 in the Fenton-like process. LC-MS analysis showed that degradation products of E3/EE2 were mainly produced via hydroxyl and sulfate degradation pathways. Finally, a mechanism of Fenton-like oxidation of E3/EE2 was proposed. [ABSTRACT FROM AUTHOR]

We report the synthesis of H 2 SO 4 -modified biochars (SBCs) as solid-acid catalysts to activate H 2 O 2 at circumneutral pH under visible light radiation. Spent coffee grinds were pyrolyzed with TiO 2 at 300, 500 and 600 °C followed by steeping in 5 M H 2 SO 4 and were used for the Fenton-like degradation of methyl orange (MO). The catalytic activity of SBC depended on the pyrolysis temperature and correlated well with the surface acidity and persistent free radical (PFR) concentration. Results showed that a complete MO removal and a TOC reduction of 70.2% can be achieved with SBC500 under photo-Fenton conditions. However, poisoning of the Lewis acid sites on SBC by PO 4 3- led to a dramatic decrease in the removal of MO with inhibition effects more pronounced than with radical scavengers, suggesting the key role played by acid-sites on the activation of H 2 O 2. Finally, electron paramagnetic resonance (EPR) studies identified •OH as the key transient in the degradation followed by •O 2 - and 1O 2. These findings suggest that H 2 O 2 was likely adsorbed on the surface oxygenated functional groups before being decomposed by accepting electrons from the PFRs on the SBC surface. [Display omitted] • Solid-acid biochar (SBC) was synthesized by sulphuric acid modification of catalytically pyrolyzed spent coffee grinds. • The prepared SBCs could activate H 2 O 2 under visible-light and degrade MO via a Fenton-like process. • The enhanced MO removal was ascribed to surface-bound PFRs and oxygenated functional groups. • EPR and scavenging studies showed •OH and •O 2 - were key for degradation of MO. [ABSTRACT FROM AUTHOR]

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/H2O2, 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 Fe0 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 (C8H14O9NS), and the mechanism for Fenton oxidation of AMX was proposed. Removal efficiency depended on the nZVI dosage, initial pH, initial H2O2 concentration and the temperature, where 86.5% of AMX was degraded and 71.2% of COD was removed after 25 min at conditions of H2O2 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 kobs 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%. [ABSTRACT FROM AUTHOR]

Highlights: [•] AlPO-5 molecular sieve is synthesized using new diol-substituted imidazolium template. [•] Effects of synthesis conditions on AlPO-5 crystallization are investigated. [•] AlPO-5 crystals with different morphologies and sizes are synthesized. [•] An efficient technique for template removal is presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-situ carbonization synthesis of Cu@N: C for the first time to activate H 2 O 2 for sewage treatment. • The formed carbon layers prevent the oxidation of Cu(0) to a certain extent. • 12% Cu@N: C catalyst showed good environmental stability. • 12% Cu@N: C catalyst exhibited excellent catalytic performance, especially in sea water. Low-valent transition metal catalysts show promising application in the catalytic degradation of organic pollutants in wastewater. However, the catalysts themselves are susceptible to be oxidized and easy to agglomerate, thus reducing the catalytic ability. Herein, a facile in-situ carbonization method is utilized to synthesize N-doped biochar encapsulated zero valent copper (Cu(0)) nanoparticles (Cu@N: C). The formed Cu(0) nanoparticles are uniformly dispersed in biochar. The carbon layers wrapped outside of Cu(0) nanoparticles can present the oxidation of Cu(0) to a certain extent. Therefore, the 12% Cu@N: C catalyst exhibits good environmental stability. The catalytic ability remains basically unchanged after directly exposing it to air for four months. In addition, the 12% Cu@N: C catalyst exhibits excellent catalytic performances for the degradation of various organic pollutants at near neutral pH range (pH = 4.0 ∼ 8.0). Low valent copper (Cu(0)/Cu(Ⅰ)) and pyridinic N both contribute to the excellent catalytic ability. Furthermore, the catalytic performances are less interfered in natural water matrices, and even obviously enhanced in sea water. Based on the experimental and characterization results, a possible catalytic mechanism is also proposed. [ABSTRACT FROM AUTHOR]

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 (C 32 H 22 N 6 Na 2 O 6 S 2) 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 (NH 4 +, 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(NH 4)ZSM-5 - exhibited excellent activity and stability at the end of the electrolysis (within 60 min), with a total dye degradation and an higher mineralization on Fe(H)ZSM-5 (64% of TOC), compared with Fe(Na)Y nano , which takes twice as long (120 min) 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 H 2 O 2 , at room temperature. [Display omitted] • Easy preparation of Fenton-like catalysts based on zeolites, MFI and FAU. • Highly effective Fe(III)-zeolite-modified electrodes to electro-Fenton oxidation. • Electrochemical method allows faster mineralization of dye without redox agents at RT. • Eco-friendly Fenton-like oxidation was achieved with MFI-zeolite catalysts. [ABSTRACT FROM AUTHOR]

Heterogeneous Fenton-like processes using green rusts (GRs) with hydrogen peroxide (H2O2) were studied to decolorize methyl orange (MO) in aqueous solution at an initial pH of 7.0. In this study, two types of crystal structure for GRs, the hydroxycarbonate GR(CO32-) (GR1) and the hydroxysulphate GR (SO42-) (GR2), were synthesized by partial oxidation of Fe(OH)2 suspension under light irradiation and distinguished by X-ray diffraction (XRD) due to different characteristic peaks. In oxidation reactions, decolorization rate of MO, bubbling air through the solution, was about 65% (experiment B), whereas, it was up to 95% in the presence of H2O2 (experiment C) within 60 min. The comparative tests of GR1 and GR2 show that the reduction capability of GR2 is stronger than GR1, which may be due to Fe(II) content and interlayer anions. XRD analysis and Fourier transform infrared spectroscopy revealed that the oxidation end products of GR2 were mainly a poorly crystallized mixture of magnetite (Fe3O4) and hydroxy ferric oxide (FeOOH). However, when GR was immediately oxidized, the weakly crystallized goethite (α-FeOOH) and lepidocrocite (γ-FeOOH) were formed for O2 and H2O2, respectively. Based on the intermediates obtained, a probable decolorization mechanism has been proposed. [ABSTRACT FROM AUTHOR]

Abstract: The effectiveness of a two-stage reduction/subsequent oxidation (T-SRO) treatment of BDE-47, consisting of Fe–Ag reduction and Fenton-like oxidation, was investigated in this study. As an oxidation-resisting pollutant, BDE-47 (5mgL−1) was difficult to be degraded by homogeneous Fe–Ag/H2O2 system coupled with ultrasound (US) in 30min. However, when this solution was firstly treated with Fe–Ag/US, the final debrominated product could be rapidly oxidized by the succeeding Fenton-like reactions, resulting in an efficient debromination of BDE-47 and a 100% mineralization of diphenyl ether (DPE). To scrutinize the degradation mechanism, several analytical techniques including HPLC, LC-MS/MS and GC/MS, were employed to monitor the major intermediates and final products. Moreover, luminescent bacteria test showed that the acute toxicity of the original solution (before reduction) was evidently lower than that of Fe–Ag/US reduction-treated solution; no toxicity was detected after Fenton-like oxidation. Evidence for the significance of a T-SRO treatment to decompose BDE-47 was presented. [Copyright &y& Elsevier]

Abstract: The objective of this study was to evaluate the potential of applying acid/H2O2/basic oxygen furnace slag (BOF slag) and acid//BOF slag systems to enhance the chemical oxidation of trichloroethylene (TCE)-contaminated groundwater. Results from the bench-scale study indicate that TCE oxidation via the Fenton-like oxidation process can be enhanced with the addition of BOF slag at low pH (pH=2–5.2) and neutral (pH=7.1) conditions. Because the BOF slag has iron abundant properties (14% of FeO and 6% of Fe2O3), it can be sustainably reused for the supplement of iron minerals during the Fenton-like or persulfate oxidation processes. Results indicate that higher TCE removal efficiency (84%) was obtained with the addition of inorganic acid for the activation of Fenton-like reaction compared with the experiments with organic acids addition (with efficiency of 10–15% lower) (BOF slag=10gL−1; initial pH=5.2). This could be due to the fact that organic acids would compete with TCE for available oxidants. Results also indicate that the pH value had a linear correlation with the observed first-order decay constant of TCE, and thus, lower pH caused a higher TCE oxidation rate. [Copyright &y& Elsevier]

Abstract: A “two-stage reduction/subsequent oxidation” (T-SRO) process consists of Fe–Ag reduction and Fenton-like oxidation under ultrasound (US) radiation. Due to the refractory oxidation of brominated flame retardant, T-SRO was employed to remove Tetrabromobisphenol A (TBBPA) by the combination of first debromination and succeeding oxidation. It indicated that the T-SRO process resulted in a complete decrease in TBBPA concentration and a 99.2% decrease in BPA concentration. The T-SRO process for the removal of TBBPA is much effective than Fenton-like oxidation of TBBPA alone. The result showed that US radiation improved the Fenton-like oxidation rate of BPA solutions. The addition of dissolved iron into the Fenton-like oxidation system could accelerate the first 2 min reaction, but had little effect on the following process. The main intermediate products resulting from TBBPA reduction and BPA oxidation were identified by GC–MS and LC-MS/MS. On the basis of this analysis, reactions with •OH radical were identified as the major chemical pathways during BPA oxidation. [ABSTRACT FROM AUTHOR]

Abstract: Rapid decolourization of Methyl Orange by Fenton-like mesoporous Fe2O3–SiO2 catalyst has been reported. The effect of various parameters such as initial pH, initial H2O2 concentration, Fe content in the catalyst and initial dye concentration on decolourization process were studied. The results show that 20mg of mesoporous Fe2O3/SiO2 composite (with Si/Fe=10) was sufficient to decolourize 0.6mg/ml of Methyl Orange in presence of 2ml of H2O2 at an initial pH of 2.93 within 20min. The pH range for effective decolourization (≥90%) was found to be 1–3. Leaching tests indicated that the activity of the catalyst was almost unaffected up to three consecutive cycles although ≤0.2ppm of Fe ion was leached into treated water in each run. [ABSTRACT FROM AUTHOR]

Abstract: Decolorization of reactive azo dye, reactive black 5 (RB5), was conducted using Fe(III) immobilized on Montmorillonite K10 (MK10) as a catalyst in the presence of H2O2 using Fenton-like oxidation process. The effect of different parameters such as iron ions loading on supported catalyst, catalyst dosage, initial pH of dye solution, initial concentration of H2O2 and dye and reaction temperature on the decolorization efficiency of the process were studied. The results indicated that by using 12mM of H2O2 and 3.50gL−1 of the 0.11wt.% Fe(III) oxide on MK10 catalyst at pH of 2.5, 99% of decolorization efficiency was achieved within 150min in a batch process. [Copyright &y& Elsevier]

An advanced oxidation process (AOP) for degrading toxic contaminants, specifically polychlorinated dibenzo-p-dioxins (PCDDs), was developed to utilize steel dust, a steel industry by-product, as the heterogenous catalyst for a Fenton-like oxidation. The steel dust was treated using a chemical acid etchant (HCl) and ultrasound to remove surface anchored groups, reduce aggregation, and thereby increase the specific surface areas, resulting in increased access to catalytic sites. The removal of PCDD was optimized through various reaction conditions. The removal percentage of 1,2,3,4-tetrachlorintated dibenzo-p-dioxins (1,2,3,4-TCDD, 3.1μM) after 3h of Fenton-like oxidation under the conditions of 3g/L (88mM) H2O2 and pH 3 was ∼97% with 10g/L of steel dust, compared to ∼99% when 5g/L metallic iron was used as a control. When a PCDD mixture (0.5–0.7nM) was treated, 10g/L (92mM) steel dust achieved ∼88% removal, comparable to the removal with 5g/L (89mM) Fisher iron with 3g/L (88mM) H2O2. These results indicate that the steel dust is a potentially viable catalyst for removing PCDDs from contaminated water. [Copyright &y& Elsevier]

[Display omitted] • Mesoporous cobalt-silica (CoSi) catalyst was synthesized by soft-templating technique. • The Co atoms were incorporated into the SiO 2 network with high dispersion. • The textural properties were fine-tuned to improve the accessibility of the active sites. • Mesoporous CoSi catalyst displayed enhanced Fenton-like activity. • Thin-film CoSi/Al 2 O 3 foam catalyst demonstrated excellent operational stability. The narrow pore channels of cobalt-silica (CoSi) catalyst generated by conventional sol–gel process limited the active site accessibility. In this work, mesoporous CoSi catalysts containing highly dispersed Co sites were synthesized by a facile sol–gel derived soft-templating technique and tested for the Fenton-like oxidation of dyes and antibiotics. By controlling the concentration of triblock polymer Pluronic F127 template, the textural and chemical properties of CoSi catalysts were fine-tuned to improve the accessibility of their active sites. The CoSi catalyst achieved ∼ 96% removal of acid orange 7 (AO7) within 15 min using a low catalyst loading (50 mg L−1) and H 2 O 2 dosage (11 mM) at pH of 7–8. Moreover, thin-film CoSi coated on Al 2 O 3 foam, as a monolithic catalyst prepared by the washcoating method, maintained high oxidation activity (∼99% removal for AO7) over 10 days, demonstrating excellent operational stability and process intensification for practical wastewater treatment applications. [ABSTRACT FROM AUTHOR]

• Silver nanoparticles (Ag NPs) were biosynthesized by orange extract. • Ag NPs were used to simultaneous Fenton oxidation of estrone and β-estradiol. • Quenching and EPR highlighted the presence of ·OH and SO4•- radicals. • LC/Q-TOF-MS confirmed that major degraded products. Due to toxicity concerns, elevated levels of estrogens in the environment have attracted increasing interest in the development of efficient adsorbents for their removal. In this study, silver nanoparticles (Ag NPs) were biosynthesized using an orange extract for the simultaneous removal of estrone (E 1) and 17β-estradiol (β-E 2), where the removal efficiencies reached 100%. SEM-EDS and XRD analysis confirmed that Ag NPs with a diameter of 13 nm were successfully biosynthesized. FTIR and XPS confirmed Ag NPs surfaces were coated with organic components which enhanced stability. Quenching and EPR analysis detected the presence of both SO 4 •– and HO• radicals during oxidation, where SO 4 •– was the main radical facilitating the oxidative degradation of E 1 and β-E 2. LC-MS analysis confirmed at least 11 and 9 main degradation products for E 1 and β-E 2 , respectively, where the mechanism for E 1 and β-E 2 removal involved both adsorption and oxidative degradation. Furthermore, Ag NPs could be successfully reused for four cycles with removal efficiencies of 46.0 and 58.3% for E 1 and β-E 2 , respectively, suggesting that the proposed process could be used to efficiently remove E 1 and β-E 2 from both municipal wastewater and river water. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel metal–carbon nanocomposite (Cu-HAP/SiO 2 @carbon) was synthesized as a catalyst to remove 2,4-DCP. • Cu-HAP/SiO 2 @carbon surface has a rich pore structure and a high specific surface area. • The removal of 2,4-DCP conforms to first-order kinetics (k = 0.06331 mol/L∙min). • Cu-HAP/SiO 2 @carbon broadens the applicable pH range of H 2 O 2. • The removal rate of 93.73% can still be maintained after 5 times of reuse. Hydroxyapatite (HAP) has stable ion exchange capacity and is a potential environmental catalyst carrier. In this paper, a novel metal–carbon nanocomposite (Cu-HAP/SiO 2 @carbon) was synthesized as a catalyst to remove 2,4-DCP. The SEM, XRD, FT-IR, XPS and BET were used to characterize the synthesized catalyst materials, the results showed that Cu-HAP/SiO 2 @carbon has a rich pore structure and a high specific surface area, and the copper element is well dispersed on the surface of the carrier. The results of 2,4-DCP removal effect showed that almost 100 % of 2,4-DCP was removed under the optimal reaction conditions. In addition, the Cu-HAP/SiO 2 @carbon broaden the applicable pH range and has excellent performance in terms of reusability (93.73 % of removal rate after 5 cycles). Finally, based on the intermediate products identify by HPLC, the degradation mechanism and possible degradation pathway of 2,4-DCP was investigated, EPR was employed to confirm the effects of ·OH. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop a three-stage treatment train system to remediate fuel oil-contaminated soils. The treatment system included the first stage of biodegradable surfactant and groundwater flushing followed by the second stage of Fenton-like oxidation. The third stage was the application of enhanced bioremediation for the removal of residual total petroleum hydrocarbon (TPH) after the first two treatment processes. Three different surfactants [Simple Green™ (SG), Triton X-100, and Tween 80] were evaluated in batch experiments for their feasibility on TPH removal. Results from the surfactant biodegradation and microbial enumeration study indicate that SG was more biodegradable and enhanced the microbial activity of the intrinsic micro-organisms. Thus, SG was applied in the following column experiment. Results from the column study indicate that approximately 80% of TPH in soil (with initial concentration of 50,000 mg kg−1) could be removed after the SG [50 pore volumes (PVs)] followed by groundwater (30 PVs) flushing. The Fenton-like oxidation (with 6% of H2O2 addition) was able to remove another 15% of TPH. Observed first-order reaction rate constant of TPH oxidation was 2.74 × 10−2 min−1, and the half-life was 25 min during the first 40 min of reaction. The residual 5% of the TPH could be further remediated via the aerobic bioremediation process. Thus, complete TPH removal was obtained in this study using the three-stage treatment scheme. The proposed treatment system would be expected to provide a more efficient and cost-effective alternative to remediate fuel oil-contaminated sites. [ABSTRACT FROM AUTHOR]

Abstract: Three wastewater samples from a pharmaceutical plant formulating medical ointments were subjected to lab-scale treatment by a Fenton-like system in combination with lime coagulation. All samples were plant pre-treated by adsorption/flocculation/filtration processes with utilization of bentonite, but the quality of effluents did not comply with the regulations for wastewater discharged to local sewerage. The optimization of Fenton-like oxidation demonstrated the highest process efficacy at H2O2/COD weight ratio of 2:1, H2O2/Fe2+ molar ratio of 10:1 and 2h of treatment time. The fast pH decrease to acidic values ∼3 during first min of oxidation for all effluents suggested that pH adjustment was unnecessary. Combination of Fe(III) precipitation and lime coagulation proved feasible to improve considerably COD and residual iron concentration reduction in pharmaceutical effluents. Additionally, considerable BOD7 reduction and BOD7/COD ratio improvement of pharmaceutical wastewater samples was achieved by combined treatment. The application of Fenton-like oxidation with subsequent iron (III)/lime coagulation did not only enhance the quality of pharmaceutical effluents with different chemical characteristics and help to meet the requirements for wastewater discharged to sewage, but also improve the biodegradability of pharmaceutical effluents. [Copyright &y& Elsevier]

Abstract: Degradation of 2,4,6-trinitrotoluene (TNT) was investigated in presence of different oxidants (Fenton''s reagent, sodium persulfate, peroxymonosulfate and potassium permanganate) and different iron minerals (ferrihydrite, hematite, goethite, lepidocrocite, magnetite and pyrite) either in aqueous solution or in soil slurry systems. Fenton''s reagent was the only oxidant able to degrade TNT in solution (k app =0.0348 min−1). When using iron oxide as heterogeneous catalyst at pH 3, specific reaction rate constants per surface area were k surf =1.47.10−3 L min−1 m−2 and k surf =0.177 L min−1 m−2 for magnetite and pyrite, respectively while ferric iron minerals were inefficient for TNT degradation. The major asset of iron mineral catalyzed Fenton-like treatment has been the complete oxidation of the pollutant avoiding the accumulation of possible toxic by-products. In soil slurry systems, 38% abatement of the initial TNT concentration (2 g/kg) was reached after 24 h treatment time at neutral pH. Rate limiting steps were the availability of soluble iron at neutral pH together with desorption of the TNT fraction sorbed on the clay mineral surfaces. [Copyright &y& Elsevier]

Sonolysis, Fenton-like oxidation (FeOOH–H2O2), and a combination of the two processes were used to facilitate the degradation of para-chlorobenzoic acid (a model compound for free radical mediated reactions). The objective of this study was to investigate the effect of FeOOH and H2O2 dosages on the degradation of para-chlorobenzoic acid (p-CBA) using ultrasound/FeOOH–H2O2. The oxidation rate of p-CBA was measured at various concentrations of H2O2 and FeOOH particles and pH conditions. pH''s below the pKa of p-CBA (3.98), showed significantly better degradation of p-CBA than at higher values from 5 to 9. The rates of degradation of p-CBA by FeOOH–H2O2 were enhanced in the presence of ultrasound. The first-order rate constant, k, for p-CBA degradation by ultrasound was 4.5 × 10-3 min-1, and in the presence of FeOOH–H2O2 this was found to be substantially faster (1.54 × 10-2 min-1). The observed rate enhancements for the degradation of p-CBA can be attributed primarily to the continuous cleaning and chemical activation of the FeOOH surfaces by acoustic cavitation and the accelerated mass transport rates of reactants and products between the solution phase and the FeOOH surface. This new process provides a viable alternative to existing oxidation technologies. [Copyright &y& Elsevier]

• A new functional based on FeNPs/rGO was biosynthesized. • Adsorption and Fenton-like oxidation enhanced 17α-estradiol removal. • The removal mechanism of αE 2 by FeNPs/rGO was proposed. • Degradation products were identified by HPLC-MS. Wastewater from sewage treatment plants containing 17α-estradiol (αE 2) has a high potential to cause environmental and human toxicity. Integration of adsorption and Fenton-like oxidation is one of the potential approaches to enhance αE 2 removal. In this study, one-step biosynthesized iron nanoparticles/reduced graphene oxide (FeNPs/rGO) by tea extract was successfully used for αE 2 removal. The results showed that the removal of αE 2 by FeNPs/rGO increased to 56.1%, being only 25.4% and 45.4% for rGO and FeNPs, respectively, indicating that both adsorption and Fenton-like oxidation enhanced the removal of αE 2 , where was confirmed by HPLC-UV. To understand the removal mechanism, characterizations, including ESR, SEM, EDS, FTIR and XPS were used to elucidate the specific roles of rGO and FeNPs in the adsorption and oxidation of αE 2 , and results showed that αE 2 was adsorbed as a monolayer on the surface of rGO via π–π bond interactions and that FeNPs underwent reactions with H 2 O 2 to generate ·OH for αE 2 degradation. Thereafter, a αE 2 degradation pathway was proposed via identification of degradation products (e.g., C 18 H 22 O 3) by HPLC-MS. Moreover, the removal of αE 2 by FeNPs/rGO conformed to the Langmuir isotherm with pseudo-first-order adsorption kinetics and pseudo-second-order degradation kinetics. Based on these evidences, the removal of αE 2 by FeNPs/rGO was presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel mesoporous carbon hybrid loaded zero-valent copper (Cu0/C) was prepared. • The performance of Cu0/C for the activation of molecular oxygen was evaluated. • Cu0/C composite showed high SMT removal efficiency over a broad pH range. • Cupryl species (Cu3+) rather than OH was major active species for SMT degradation. • The possible mechanism of Cu0/C activating oxygen was tentatively proposed. Zero-valent copper (ZVC) has shown potential as an oxygen activator for the degradation of organic pollutants from aqueous solution. Nevertheless, the high leaching of copper ions and the demand for acidic condition limited its application. In this study, a novel mesoporous carbon hybrid loaded zero-valent copper (Cu0/C) was successfully synthesized from Cu-based metal–organic framework (Cu 3 (BTC) 2) through a pyrolysis method and applied to efficiently degrade sulfamethazine (SMT) at neutral pH under aeration condition. The performance of Cu0/C composite for the activation of molecular oxygen was evaluated based on the effect of different reaction parameters, such as, initial SMT concentration, initial pH, activator dosage and reaction temperature. The results showed a high efficiency for SMT removal over a broad pH range (3.0–7.0). Moreover, the Cu0/C composite exhibited excellent stability and reusability for SMT degradation, and a 96.7% SMT removal and a 68.8% total organic carbon (TOC) conversion were achieved at pH 5.8 after continuous three cycles. Combined with the determination results of reactive oxidizing species and physical-chemical characterization, cupryl species (Cu3+) rather than OH produced by the reaction of the in-situ generated H 2 O 2 with Cu+ were the major reactive species. Additionally, the possible reaction mechanism of Cu0/C activated oxygen was tentatively proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • We used AlCP as the substitute for ZVAl to proceed Tl(I) oxidation. • 99.8% of Tl(I) in AlCP systems was removed via oxidation-precipitation processes. • Fe prompted the Tl(I) oxidation but exacerbated the Tl removal upon alkalinisation. • Tl 2 O 3 dominated the Tl inventory for solids removed from AlCP systems. • Labile Tl(III) sorbed on Al(hydr)oxides was main Tl species in AlCP/Fe systems. The emerging occurrence of thallium (Tl) in environments arouses the imposition of effective technology for its remediation. Due to the low solubility of Tl(III), the oxidation-precipitation of Tl(I) is considered as an promising removal method. Here, we recycled Al beverage can powder (AlCP) as the substitute for zero-valent Al to conduct the Fenton-like reaction for Tl(I) oxidation and subsequently induced the Tl(III) precipitation via the alkalinization at pH 9.5. The Tl(I) removal mechanisms in AlCP systems with amendments of Fe(III) or Fe(II) were determined in relation to its speciation for both dissolved and solid phases. Results showed that although additions of Fe(III)/Fe(II) prompted the Tl(I) oxidation as compared with the pure AlCP system, they were detrimental to the Tl removal upon the alkalinization. While the greatest removal efficiency was ~ 92% in AlCP/Fe(III)/Fe(II) systems, up to 99.8% of total Tl could be removed from the pure AlCP system. The Tl-XANES data indicated that although Tl(III) dominated the Tl inventory (92 – 95%) on all solids collected upon the alkalinization, it preferred to precipitate as stable Tl 2 O 3 in pure AlCP system but as labile Tl(III) in AlCP/Fe(III)/Fe(II) systems, which might sorb on precipitated Al (hydr)oxides. Such sorbed Tl(III) is subject to reduction and the further dissolution, accounting for the lower removal efficiency for Tl in the presence of Fe(III)/Fe(II). This study corroborated the comparable Tl(I) removal efficiency of AlCP to that of state-of-the-art (nano)composites, providing a niche opportunity to give consideration to both interests in hazard remediation and the waste reduction/reuse. [ABSTRACT FROM AUTHOR]

Iron-copper bimetals for Fenton-like catalysis were developed, due to efficient enhancement of catalytic activity by iron-copper synergy. However, deviation exists in mechanism analysis of multi-effect catalysis. In this study, a new in-situ strategy of shielding Fe(II) and Cu(I) from further reaction by trapping agents was developed, for analysis of iron catalysis alone, copper catalysis alone and synergistic effect in bimetallic catalyst systems. Inhibition efficiency and influence of trapping agents on Fe(II)/Cu(I) catalysis were quantitatively evaluated for reliability confirmation and method correction. The possible application scope was identified as pH of 4–6, and this strategy was available for analysis of five different groups of catalysts. The potential superiority and difference of the proposed strategy compared with current ex-situ strategy were also analyzed. The overestimation (12.1%–35.4%) of copper catalysis and biased analysis (0.1%–12.6%) of iron catalysis by ex-situ strategy can be alleviated, thereby improving accuracy for synergistic effect. In summary, this study proposed a new strategy to improve the understanding of iron-copper bimetallic catalysis, which can provide reference for other polymetallic catalysis analysis development. [Display omitted] • A strategy for in-situ analysis of Fe-Cu multi-effect catalysis was developed. • Different trapping agents were developed for Fe(II) or Cu(I) inhibition. • Inhibition and influence were evaluated for reliability confirmation and correction. • Overrated Cu catalysis and biased analysis of Fe catalysis were corrected. • Possible application scope was proposed with different catalysts and pH evaluation. [ABSTRACT FROM AUTHOR]

Combining Fenton-like oxidation with ultrafiltration by membranes seems promising for wastewater treatment, while it still has defects in comprehensive comparison of different combinations for industrial wastewater treatment. To fill in these gaps, mixed matrix Fe 3 O 4 /polyvinylidene fluoride membranes were used for setting up three combined systems, i.e., sequential oxidation and filtration (Seq-O&F), simultaneous oxidation and filtration (Sim-O&F), and sequential filtration and oxidation (Seq-F&O) systems. Performance on industrial wastewater decontamination was evaluated, and anti-fouling property of membranes was measured by flux decline and recovery efficiency. Characterizations of membranes and change of molecular weight distribution were also investigated for auxiliary analysis. Furthermore, the stability of membrane matrix and catalyst was investigated for time-equivalent of 10,000 L/m2 wastewater treatment. The results indicate that Seq-O&F system shows the best decontamination and anti-fouling performance, but with multi-units and low stability of the catalyst. Sim-O&F system shows acceptable decontamination and anti-fouling performance, yet the stability for long-term operation needs to be further improved. Seq-F&O can effectively save the oxidant and prolong operational life, but performs worse in decontamination and anti-fouling. We believe this study gives a new understanding of Fenton-like oxidation and ultrafiltration combined systems for industrial wastewater treatment, and provides guidance for further application. [Display omitted] • Different combined systems with Fenton-like and ultrafiltration were developed. • Potential for practical application was identified by industrial wastewater treatment. • Decontamination efficiency, membrane fouling and stability were evaluated. • Possible application scenarios of different combinations were proposed. [ABSTRACT FROM AUTHOR]

At present, the use of conventional wastewater processes is becoming increasingly challenging, mainly due to the presence of biorecalcitrant organic matter. Advanced oxidation processes such as Fenton, Fenton-like and hybrid processes have been successfully employed for the treatment of highly concentrated and toxic non-biodegradable pollutants. Here, a series of bimetallic catalysts, based on Cu/Fe supported over ZrO2, were investigated for the mineralization of ibuprofen with a heterogeneous Fenton-like reaction. The materials were prepared by incipient wetness impregnation and characterized by standard techniques. Temperature-programmed experiments highlighted the promotion of the reduction in CuO due to the synergistic effects of the coupled redox cycles of copper (Cu2+/Cu+) and iron (Fe+3/Fe+2). 5%Cu-5%Fe/ZrO2 not only displays the highest ibuprofen mineralization (83%) under optimum conditions but also exploits its activity in a wider range of pH (3–5) with extremely low metal leaching. The recycling of bimetallic catalysts reveals that only the 5%Cu-5%Fe/ZrO2 system is able to provide sustainable activity in heterogeneous Fenton process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-embedded coffee biochar catalysts were synthesized at high pyrolysis temperatures. • Improving catalytic properties was most pronounced for Fe@HCBC prepared at 700 °C. • Fe@HCBC700/H 2 O 2 system showed the highest degradation of synthetic food dyes. • ESR study demonstrated a significant role of •OH in degradation of synthetic food dyes. • Heterogeneous Fenton-like reaction governed the degradation of synthetic food dyes. Fe-embedded biochar catalysts originating from waste coffee grounds (Fe@HCBCs) were developed at different pyrolysis temperatures (500, 600, and 700 °C) for the Fenton oxidation of synthetic food dyes: amaranth (AM) and sunset yellow (SY). Increasing the pyrolysis temperature significantly improved the physicochemical properties of the Fe@HCBCs (i.e., surface area, total pore volume, and Fe content), which led to the highest AM and SY removal in the Fe@HCBC700/H 2 O 2 system. The Fe@HCBC700/H 2 O 2 system showed 19.0 and 14.6 mg(dyes)/g(catalysts)·h of catalytic reaction rate for AM and SY, respectively. The results of the scavenging experiment and electron spin resonance revealed that hydroxyl radicals (•OH) were the dominant reactive oxygen species for the oxidation of AM and SY by the Fe@HCBCs/H 2 O 2 system. The heterogeneous Fenton-like reaction between the Fe content of the Fe@HCBC surfaces and H 2 O 2 was the main contributor to the oxidation of AM and SY compared with the homogeneous Fenton reaction caused by aqueous Fe with H 2 O 2. The effects of catalyst dosage (0.1–0.5 g/L), H 2 O 2 concentration (0.0–12.5 mM), pH (3.0–9.0), and solution temperature (15–35 °C) on the oxidation of AM and SY by the Fe@HCBCs/H 2 O 2 systems at pH 3.0 were also investigated. The opposite result was obtained in a suspension with pH > 5.0; that is, the removal efficiency gradually increased as the pyrolysis temperature decreased (500 °C > 600 °C > 700 °C) because of the abundance of O-containing functional groups on the surface of the Fe@HCBC500. These observations imply that pyrolysis temperatures might have a strong impact on the catalytic degradation of synthetic food dyes using the Fe@HCBCs/H 2 O 2 systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Trade-off of activity and stability of MILs(Fe) catalyzed Fenton-like was evaluated. • Catalytic activity decline was determined by decontamination and OH formation. • Structural change and possible negative effects during operation were investigated. • Weak acid condition seems acceptable for MILs(Fe) based systems development. In this study, three typical MILs(Fe) catalysts were used for Fenton-like catalysis to investigate their stability and catalytic activity within 20-cycle used. Catalytic activity with various oxidants was evaluated by bisphenol S removal and OH generation. Possible negative effects were determined, and structural changes were characterized. The results indicate catalytic activity and stability of these three MILs(Fe) catalysts showed similar regularities under different conditions. At pH 3, MILs exhibited high catalytic activity initially, while the catalytic activity declined sharply prolonging operational time, due to the deactivation of surface active sites and decomposition of structure. Organics leaching and acute toxicity were relatively high in the effluent as well. Under weak acid condition, initial catalytic activity of MILs(Fe) was lower, while the decline of activity was much slower, that OH generation only declined 15.2%-27.1% within 20-cycle used. The leaching and acute toxicity were much lower as well. Under neutral condition, MILs(Fe) were stable, while the catalytic activity was unsatisfactory even in 1st cycle. The trade-off of catalytic activity and structural stability exists in some degree in MILs(Fe) based Fenton-like processes, and only comprehensively considering the trade-off is feasible to investigate them for wastewater treatment. [ABSTRACT FROM AUTHOR]

This study investigated the applicability of waste antivirus copper film (CF) as a Fenton-like catalyst. The reaction activity of H 2 O 2 and CF in combination was significantly enhanced by ultrasound (US) irradiation, and the synergy factor calculated from bisphenol A (BPA) degradation using CF-H 2 O 2 -US was 9.64 compare to that of dual factors. Photoluminescence analyses were conducted to compare the generation of hydroxyl radicals during both processes. In this sono-Fenton-like process, BPA degradation was affected by solution pH, temperature, ultrasound power, CF size, H 2 O 2 dose, and initial BPA concentration. The BPA degradation curves showed an induction period (first stage) and a rapid degradation period (second stage). Process efficiency was totally and partially enhanced in the presence of chloride and carbonate ions, respectively. Chemical scavenger tests showed that both free and surface-bound hydroxyl radicals participate in BPA degradation under the sono-Fenton-like process using CF. The functional groups and copper crystals on the CF surface remained unchanged after five consecutive reuses, and the BPA degradation efficiency of CF was maintained over 80% during the reuse processes as a sono-Fenton-like catalyst. [Display omitted] • Copper films used in epidemic prevention can be reused as Fenton-like catalysts. • Catalytic efficiency of copper film was enhanced via ultrasound. • Sono-Fenton-like process provides excellent bisphenol A removal at neutral pH. • Chloride and carbonate can improve process efficiency. • Free and surface-bounded hydroxyl radicals participate in bisphenol A degradation. [ABSTRACT FROM AUTHOR]

A novel composite (CNTs-Fe 3 O 4) was synthesized by a ball-milling strategy and characterized by BET, SEM, FTIR, XRD and VSM. The as-fabricated CNTs-Fe 3 O 4 was used to remove six sulfonamides by a Fenton degradation process, including sulfanilamide (SAM), sulfamerazine (SMR), sulfadimethoxine (SMX), sulfadiazine (SDZ), sulfamethazine (SMT) and sulfametoxydiazine (SMD). The degradation behaviors of six sulfonamides in CNTs-Fe 3 O 4 /H 2 O 2 system and the relationship between molecular structure of sulfonamides and their degradation behaviors were investigated systematically. Batch experimental results showed that the as-fabricated CNTs-Fe 3 O 4 had excellent Fenton catalytic activity for the degradation of sulfonamides due to its unique porous structure and the good combination mode of CNTs with Fe 3 O 4 particles. The first-order kinetic mode could better describe the degradation behaviors of six sulfonamides in CNTs-Fe 3 O 4 /H 2 O 2 system, and the degradation rate constant could be ordered as: SAM < SMT < SDZ < SMR < SMD < SMX. The quantitative relationship between the Mulliken charge of sulfonamides (x) and their degradation rate constant (y) in CNTs-Fe 3 O 4 /H 2 O 2 system could be described as: y = - 28.719x + 15.67 (R2 = 0.957). Finally, the possible synthesis mechanisms of CNTs-Fe 3 O 4 and the degradation mechanisms of sulfonamides in CNTs-Fe 3 O 4 /H 2 O 2 system was proposed. • A novel composite (CNTs-Fe 3 O 4) was synthesized by a ball-milling strategy. • CNTs-Fe 3 O 4 had high catalytic activity for Fenton-like oxidation of sulfonamides. • Relationships between Mulliken charge and degradation rate constant were obtained. [ABSTRACT FROM AUTHOR]

The long term catalytic activity of pyrite in advanced oxidation for wastewater treatment is vital for the practical application. In this work, the efficacy of pyrite catalyzed Fenton-like oxidation for tertiary treatment of dyeing wastewater was investigated for a period of two years. The influence of pyrite oxidation and dissolution on the catalytic activity was studied based on surface characterizations and chemistry studies. Experimental results demonstrated that pyrite can effectively catalyze H 2 O 2 to oxidize recalcitrant pollutants in the biological effluent of dyeing wastewater. At initial pH 3–6, H 2 O 2 of 10 mM and pyrite of 24 g L−1, COD and color removals reached 76.67% and 97.09% in 180 min of reaction time. The higher treatment efficacy of pyrite catalyzed Fenton-like oxidation was due to appropriate conversion rate of H 2 O 2 to hydroxyl radicals compared with the classic Fenton oxidation. Heterogeneous catalysis by Fe(II) on the pyrite surface was much more significant than Homogeneous catalysis by dissolved iron ions of pyrite. The latter contributed only 28.25% abatement of COD at pH 3 and can be negligible at wastewater initial pH > 5. The oxidation of pyrite resulted in acidic pH environment for recalcitrant organic compound destruction even if the initial pH of wastewater was 6.5. It was found that the catalytic activity of pyrite can maintain at least two years, as the surface regeneration of pyrite in that period of time occurred spontaneously due to the slow dissolution of oxidation products. [Display omitted] • Long term catalytic activity of pyrite in Fenton-like systems was investigated. • Removal kinetics of COD and H 2 O 2 decomposition rates were correlated. • Catalytic activity and surface oxidation and dissolution of pyrite were examined. • Pyrite catalyzed Fenton-like oxidation can effectively treat dyeing wastewater. • Fe(II) on surface played more important part than dissolved iron ions in catalysis. [ABSTRACT FROM AUTHOR]

In this study, a comparative activity assessment of several activated carbon (AC) and AC-Fe 3 O 4 composites was performed to evaluate their efficiency and versatility as Fenton-like catalysts. Although many studies have demonstrated the advantages of AC-based materials as Fenton-like catalysts, most have been developed using only one oxidant and/or one pollutant. Here, untreated (AC 0) and acid-treated AC (AC A) iron-oxide composites were synthesized, characterized, and compared in terms of activity to bare AC using several oxidants and pollutants, the activation efficiency of hydrogen peroxide (H 2 O 2) and ammonium persulfate ((NH 4) 2 S 2 O 8), and the subsequent oxidation extent and kinetics of bisphenol-A, atrazine, and carbamazepine by the AC-based materials were studied in depth. The persulfate-based systems showed considerably higher pollutant removal in the presence of the catalysts, despite lower persulfate decomposition rates: atrazine and carbamazepine were partially degraded, mainly through a radical-dependent pathway; the highest removal of atrazine was achieved with the AC A -iron composite, whereas carbamazepine was best removed by the AC 0 -iron composite. In contrast, bisphenol A was completely mineralized, probably via a non-radical pathway, in the presence of all AC-based composites, even at very low persulfate concentrations. Furthermore, bisphenol A removal remained high for several consecutive cycles, with the most efficient removal and stability observed in the presence of AC A. These findings reveal the high complexity of AC-based systems, with multiple binding sites and degradation pathways unique to each combination of pollutants, catalysts, and oxidants. In general, the composition of the waste stream governs the applicability of these materials. Thus, the structure-function correlations and degradation mechanisms revealed here are crucial for improving sorbent-catalyst design and accelerating the implementation of low-cost remediation and in situ regeneration technologies. [Display omitted] • Activated carbon (AC)-Fe 3 O 4 composites were synthesized to catalyze oxidation of pollutants. • Persulfate decomposition was lower than H 2 O 2 , but degradation of the model pollutants was higher. • ATZ and CBZ degradation was via a radical pathway, BPA was degraded via a non-radical pathway. • Complete BPA removal and to 94% mineralization was achieved by the persulfate/AC systems. • Continuous long-term use of the persulfate/AC system was demonstrated. [ABSTRACT FROM AUTHOR]

• The structure of Fe-MOFs can be reasonably tuned by partial Fe(II) substitution. • The Fe(II) center promotes Fe(II)→Fe(III) reaction to rapidly activate H 2 O 2. • Fe(II) substitution improves the density of Fe(III) CUICs and 4-NP diffusion rate. • The increased Fe(III) CUICs favor Fe(III)→Fe(II) reaction and Fe(III)/Fe(II) cycle. • The enhanced mechanism of FeII-MIL-53(Fe) for Fenton-like oxidation is elucidated. Metal-organic frameworks (MOFs), especially iron-based MOFs (Fe-MOFs), are deemed as promising Fenton-like catalysts due to their well-developed pores and accessible active sites. However, the Fenton-like performance of Fe-MOFs is limited by the relatively low redox rate of Fe(Ⅲ)/Fe(Ⅱ) couples and density of coordinatively unsaturated iron centers (CUICs), which depend on the intrinsic structure of iron-oxo nodes in Fe-MOFs. Herein, we manipulated the structure of iron-oxo nodes in MIL-53(Fe) via a Fe(Ⅱ) substitution method, affording a mixed-valence (i.e., Fe(Ⅱ)/Fe(Ⅲ)) material (denoted as FeⅡ-MIL-53(Fe)) with highly improved Fenton-like performance. The substituted Fe(Ⅱ) centers could serve as stronger active sites, where Fe(Ⅱ)→Fe(Ⅲ) half-reaction occurs, over original Fe(Ⅲ) centers to rapidly activate H 2 O 2 for efficient destruction of 4-nitrophenol (4-NP). Meanwhile, Fe(Ⅱ) substitution induced the formation of a larger amount of Fe(Ⅲ) CUICs, which was proven by the increased Lewis acidity of MIL-53(Fe). The increased density of Fe(Ⅲ) CUICs promoted the interaction between Fe(Ⅲ) centers and H 2 O 2 and thus rendered another half-reaction, Fe(Ⅲ)→Fe(Ⅱ), with a greater rate. Accordingly, the accelerated cycle of Fe(Ⅲ)/Fe(Ⅱ) couples favored OH generation for improving 4-NP degradation. As a result, the 4-NP degradation and rate on FeⅡ-MIL-53(Fe) were 1.39 and 9.48 times higher than that on pristine MIL-53(Fe). Moreover, FeⅡ-MIL-53(Fe) showed a good stability and reusability over multiple cycles. Our work provides insights into the rational design of Fe-MOFs as promising Fenton-like catalysts for advanced water/wastewater treatment. [ABSTRACT FROM AUTHOR]

• Fenton-like treatment of fresh IRN-150 & simulated 14C spent resin were compared. • Reaction conditions were optimized as 0.35 M Cu2+, 30 % H 2 O 2 , pH 2, 90 °C for 4 h. • Fresh IRN-150 showed 91.26 % weight loss & 85 % TOC removal at optimized conditions. • Simulated 14C spent resin exhibited reduction in weight loss up to 87.34 %. Spent resins with 14C are enlisted among the most problematic radioactive wastes. In current study, we successfully prepared the simulated 14C-loaded spent resins using HCO 3 −, and for the first time the Fenton-like treatment of simulated 14C-loaded spent resins were compared with fresh Amberlite IRN-150 resin (without simulated 14C loading) by optimizing the influential reaction parameters. The experimental results revealed that 91.26 % weight loss and 85.47 % in TOC removal were achieved for fresh Amberlite IRN-150 resin (without simulated 14C loading) using 0.35 M Cu(II) catalyst, 30 % H 2 O 2 as oxidant at pH 2, and 90 ± 3 °C temperature for 4 h reaction time. However, the simulated 14C-loaded spent resin using HCO 3 − exhibited 87.34 % weight loss under the similar reaction conditions. The reduction in weight loss (%) of simulated 14C-loaded spent resin was attributed to the presence of HCO 3 − on the resins, which could produce the carbonate radical (CO 3 -∙) of lower oxidation capability as compared to hydroxyl radical and in turn affect the efficacy of Fenton-like treatment for simulated 14C-loaded spent resin. Scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FT-IR) analyses were used to characterize and the results also supported the resin's degradation. [ABSTRACT FROM AUTHOR]

• A dual-layer membrane was used for performance enhancement of Fenton-like oxidation. • Sequential decontamination was achieved by a UF layer above a catalysis layer. • BPS and macromolecular substances removal were enhanced in multicomponent wastewater. • The enhancement mechanisms by sequential interception-oxidation were proposed. Fenton-like oxidation for multicomponent wastewater treatment suffers from a low efficiency due to non-selective nature of produced reactive species. In this study, a multifunctional dual-layer ultrafiltration membrane (Seq-ICM) was synthesized for multiple pollutants decontamination. Characterizations of the membranes indicate that Seq-ICM comprises a skin layer for ultrafiltration, and a porous support layer loaded with ∼50% MIL-53(Fe) for catalysis. With bovine serum albumin coexisting, Seq-ICM can remove 75.7% bisphenol S (BPS), which is much higher than that of a simultaneous interception-catalysis membrane (44.2 %). For multicomponent wastewater treatment, Seq-ICM system can save ∼59%-67% oxidant dosage as well compared with catalysis alone membrane system to achieve 50% BPS removal. Furthermore, the decontamination mechanisms were investigated to explain the advantages of Seq-ICM. Sequential interception and oxidation process by Seq-ICM leads to the interception of macromolecular substances first, following by catalytic oxidation of low-molecular-weight organics. This process prevents macromolecular substances from competing for active species with low-molecular-weight organics, thereby enhancing selectivity and oxidation efficiency. Meanwhile, Seq-ICM shows satisfactory BPS removal efficiency for treatment of 2865 L/m2 synthetic solution, as well as in real wastewater matrix. We believe the proposed technology based on a composite membrane is promising for the removal of multicomponent substances from wastewater. [ABSTRACT FROM AUTHOR]

• Bimetallic Cu0/Zn0 particle was prepared and used for activate oxygen to form H 2 O 2. • O 2 − was the dominant reactive species in Cu0/Zn0-air system for SMX degradation. • The main reactive oxidant species (ROSs) were affected by oxygen concentration. • The possible mechanism and pathway of SMX degradation were proposed. In this study, a bimetallic Cu0/Zn0 particles were prepared, characterized and used as Fenton-like catalyst for the degradation of sulfamethoxazole (SMX). The results showed that Cu0/Zn0 particles were capable of converting O 2 to H 2 O 2 , O 2 − and OH radicals. In bimetallic Cu0/Zn0 particles, Cu0/Zn0 corrosion cells were formed through the direct contact of Zn0 and Cu0, which not only accelerated the electron transfer from Zn0 to O 2 , leading to the promotion of H 2 O 2 generation, but also enhanced the conversion of Cu2+ to Cu+/Cu0, facilitating the catalytic decomposition of H 2 O 2 to produce O 2 − and OH radicals. SMX could be efficiently degraded in Cu0/Zn0-air system over a broad pH range from 3 to 9, the removal efficiency of SMX and TOC was 87.8% and 45.5%, respectively at following condition: SMX concentration, 20 mg/L; dosage of bimetallic Cu0/Zn0 particles (mole ratio of Zn to Cu was 1:2), 2 g/L; air flow rate, 1.8 L/min; reaction temperature, 25℃ and without adjusting pH. The recycling use of bimetallic Cu0/Zn0 particles leaded to the enhanced degradation of SMX due to the newly formed cuprous oxide (Cu 2 O), which could further catalytically activate O 2. The quenching experiment showed that the concentration of dissolved oxygen could significantly affect the main reactive oxidant species (ROSs). Additionally, the intermediate products of SMX degradation were detected and a possible pathway of SMX degradation as well as the catalytic mechanism of Cu0/Zn0-air system were proposed. [ABSTRACT FROM AUTHOR]

Here we discuss the role of heterogeneous Fenton oxidation and persulfate oxidation for the treatment of hazardous landfill leachate that readers should consider in addition to the advanced oxidation processes described by Gautam et al. (2019). • Heterogeneous Fenton and persulfate are viable oxidants to treat landfill leachate. • They can address the limitations associated with traditional oxidation processes. • Oxidation efficiency is mainly dictated by catalyst type and reaction conditions. [ABSTRACT FROM AUTHOR]

• Fe 3 O 4 /rGO was successfully prepared by one-step hydrothermal method. • Hydrophobic, electrostatic, hydrogen bridging and π-π interactions are involved. • The utilization efficiency of free radicals increased with increasing OBS adsorption. • Fe 3 O 4 /rGO can be successfully regenerated and stably reused in Fenton-like oxidation system. The catalytic performance of Fe 3 O 4 /reduced graphene oxide (Fe 3 O 4 /rGO) nanocomposite makes it attractive for the removal of emerging pollutants from water, but the combination of its efficient adsorption and degradation of per- and polyfluoroalkyl substances has not been studied. Here we report the optimal granular Fe 3 O 4 /rGO with high thermal and acid resistance stability through controlling its self-assembly for the adsorption and degradation of sodium p -perfluorous nonenoxybenzene sulfonate (OBS) from water. The maximum adsorption capacity for OBS was calculated to be 362.4 μmol/g according to Langmuir fitting. Electrostatic, π-π and hydrogen bonding interactions were involved in OBS adsorption, and the quaternary N in Fe 3 O 4 /rGO was a key adsorption site. The efficiency of the utilization of free radicals generated in Fenton-like and persulfate (PS) systems increased with the increase of OBS adsorbed onto the Fe 3 O 4 /rGO, while the increase of OBS amount adsorbed on Fe 3 O 4 /rGO would casue a slow OBS removal in the adsorption-degradation process due to the slow adsorption process. The Fenton-like oxidation was more efficient for OBS removal than PS oxidation. The spent Fe 3 O 4 /rGO was able to be reused in the Fenton-like system at least ten times, while the OBS removal in the PS reaction system was reduced to 47.8 % after six reuse cycles. [ABSTRACT FROM AUTHOR]

Catalytic advanced oxidation processes (AOPs) utilising UV irradiation have been reported to be highly efficient for the degradation of recalcitrant compounds. The focus of present study was to evaluate the potential of steel industry waste as an alternative to homogenous iron salts often used in AOPs. Iron rich sludge from effluent treatment plant (ETP) of a steel industry was subjected to acid washing and acid washing followed by calcination before using as catalyst for the oxidative removal of chlorinated organics present in synthetic and simulated bleaching effluents. The maximum total organic carbon removals of 64% and 25% from 4-chlorophenol solution and simulated pulp bleaching effluent, respectively were observed during photo-catalytic oxidation with acid washed steel sludge at stoichiometric H 2 O 2 dose after 2 h reaction (catalyst dose = 1 g/L, and pH = 4.4). Low iron leaching (<2%) was observed from the catalyst even in acidic conditions and it could be reused twice without significant loss of catalytic activity. Image 1 • Potential of steel industry waste as heterogeneous Fenton-type catalysts. • Evaluation of catalysts for advanced oxidation of chlorinated organics. • Catalyst displayed 64% mineralisation during 4-CP photo-Fenton oxidation. • Catalyst contained 40–50% but showed less than 3% iron leaching during treatment. [ABSTRACT FROM AUTHOR]

The integration of two different advanced oxidation processes can not only avoid their individual shortcomings but also utilize the synergistic effects between them. Herein, CoFe 2 O 4 modified g -C 3 N 4 composite (CoFe 2 O 4 @ g -C 3 N 4 ) was synthesized and used for building a novel coupled system, in which two processes of visible light-activated photocatalysis and sulfate radical-based Fenton-like oxidation have been combined together to provide a synergistic reaction path for the removal of rhodamine B. The coupled system exhibited a drastically enhanced catalytic efficiency compared with the photocatalytic or Fenton-like process alone. It also showed a significantly enhanced catalytic activity compared with g -C 3 N 4 , CoFe 2 O 4 or their simple mixture. The improved catalytic performance can be ascribed to the efficient separation of photogenerated carriers as well as more available catalytic reactive sites for peroxymonosulfate (PMS) activation due to the synergistic effects between the photocatalytic and Fenton-like processes. In 30 min, 96% RhB was degraded using PMS activated by a CoFe 2 O 4 @ g -C 3 N 4 composite with 3% CoFe 2 O 4 loading under visible light irradiation, and the synergistic index in such system reached as high as 3.07. Such system can be used at a wide pH range of 3.0-10.0. The composite also showed good stability for its practical applications.

Sludge-based activated carbon (ZAC) was successfully employed as both adsorbent and catalyst for the oxidation process of reactive yellow 86 (RY86) and reactive black 5 (RB5). Physicochemical properties of the prepared sewage sludge-derived activated carbon were evaluated by N 2 adsorption/desorption, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The effects of parameters such as initial pH, H 2 O 2 concentrations, ZAC dosages, dye concentrations and temperature on the removal of RY86 and RB5 were investigated. Kinetics results showed that the adsorption rates of RY86 and RB5 by ZAC can be approximated by the pseudo-first order model, and that the oxidation rates by Behnajady-Modirshahla-Ghanbery (BMG) model. Under the optimum conditions in the experiment, i.e. pH = 6.0, T  = 303 K, [H 2 O 2 ] = 49.5 mmol/L, [ZAC] = 4 g/L, [dyes] = 300 mg/L and t  = 150 min, 99%, 88% and 84% of colour, COD and TOC were removed by Fenton -like oxidation for RY86, while for RB5, the three removal rates were 90%, 70% and 62%, respectively, indicating that sludge-based activated carbon can be used as an effective catalyst to oxidation of dyes by H 2 O 2 from coloured wastewater.

• Green Fe NPs simultaneously removed OFL and ENR via sequential Fenton-like oxidation. • High removal efficiencies for both OFL (91.8%) and ENR (90.7%) were achieved. • The removal mechanism involved pre-adsorption and Fenton oxidation. • Pre-adsorption with Fenton oxidation was an efficient strategy for treatment of FQ contaminated wastewaters. Due to the widespread use of antibiotics worldwide in both medicine and agribusiness, many wastewaters often contain a range of different fluoroquinolone antibiotics such as ofloxacin (OFL) and enrofloxacin (ENR) in elevated concentrations. Simultaneous removal of such mixed antibiotics is a major challenge where the utility of using nanomaterials for such purposes is unknown. In this study, pre-adsorption followed by Fenton-like oxidation (sequential Fenton-like oxidation) was developed and shown to be useful for the simultaneous removal of OFL and ENR, with removal efficiencies of 91.8 and 90.7%, respectively. Changes in the surface of Fe NPs, before and after exposure to both FQs, were characterized by field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM), Fourier-transform infrared (FTIR), X-ray diffraction pattern (XRD) and X-ray photoelectron spectroscopy (XPS). This comparative characterization revealed that both OFL and ENR were initially adsorbed on to the surface of Fe NPs, and then Fe NPs were corroded to form Fe 3 O 4 via sequential Fenton-like oxidation. Initial kinetic adsorption data best fit a pseudo-second-order kinetic model (R2 ≥ 0.913), while the subsequent Fenton-like oxidation process best fit a pseudo first-order model (R2 ≥ 0.964). Oxidation products detected by the high performance liquid chromatography mass spectrometry (HPLC-MS) confirmed that overall removal mechanism of both OFL and ENR involved oxidative degradation. Finally, the recycling and application in real wastewaters of sequential Fenton-like oxidation of the Fe/H 2 O 2 system was evaluated. [ABSTRACT FROM AUTHOR]