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Fe3O4 nanospheres (Fe3O4-S) synthesized via a facile one-pot solvothermal method were used for H2O2 activation and tetracycline (TC) elimination from aqueous solutions. It can be found that more than 80% of TC was degraded in the Fe3O4-S/H2O2 system. Besides, batch experiments were conducted to investigate the effects of different parameters such as catalyst dosages, H2O2 concentration, pH values and temperature on the degradation of TC, and these experimental results were also described by the pseudo-first-order model. Radical quenching experiments and an electron paramagnetic resonance (EPR) technique revealed that ˙OH and ˙O2−/˙HO2 were involved and ˙OH generated on the surface of Fe3O4-S played a main role in TC degradation. The XPS observations demonstrated that the surface FeII participated in the H2O2 activation through the redox reactions. Moreover, thirteen intermediate products were monitored by the LC–MS and possible degradation pathways of TC were accordingly proposed. The Fe3O4-S catalyst exhibited good reusability and the catalytic performance of it did not show any significant decrease even after five trials. It was worth noting that the optimal pH for TC degradation was expanded to neutral pH conditions by using the Fe3O4-S/H2O2 system. Additionally, Fe3O4-S was easily separated from the reaction solutions by virtue of its magnetism (66.8 emu g−1), which is beneficial for reuse of the catalysts. [ABSTRACT FROM AUTHOR]

Fenton system is one of the most popular methods to eliminate antibiotics and dyes in aquatic environment. However, the existed Fenton system is limited by various factors such as potential second pollution and narrow pH range. In this study, we report that the bottlenecks for high strength antibiotics and dyes wastewater treatment at a wide pH range can be well tackled by the nanoscale "yarn ball"-like Mo/W-containing heteropoly blue (HPB) catalyst Mg 2 Ti 6 Mo 23 O 119 SiW 12 (1). This novel catalyst displayed extremely efficient elimination for several typical organic contaminants such as malachite green (MG), tetracycline (TC) and methyl orange (MO). Compared with other materials reported in previous papers, the catalytic performance of 1 in degradation of the organic contaminants of high concentrations increased several times. More than 90% of antibiotics and dyes are degraded within 60 min. Electron spin resonance (ESR) experiments and UV–vis spectra confirmed that the catalytic mechanisms of 1 could mainly ascribe to the 1 /H 2 O 2 process and the possible photocatalytic oxidation of adsorbed H 2 O by holes (h+) in the valence band (VB) of 1 surface generated · OH for extremely efficient degradation of organic contaminants. This work widens the optimal pH values up to neutral condition and it's significant for the expansion of the heterogeneous Fenton-like catalyst family and its application in the field of water treatment. Image 1 • A HPB Fenton-like catalyst for degradation of antibiotics and dyes. • More than 90% of antibiotics and dyes are degraded within 60 min. • Widening the optimal pH values up to neutral condition. • Expanding the Fenton-like catalyst family and its application in the field of water treatment. [ABSTRACT FROM AUTHOR]

Abstract Industrial waste, urban sewage and aquaculture have led to severely increased grades of environment pollutants such as dyes, pesticides and fertilizer. The use of technologies for purifying contaminated waters can be difficult and toxic due to the anti-photolysis, anti-oxidation and anti-bio-oxidation characteristics of organic pollutants, and there is therefore a significant need for new approaches. Here, we report methods of Fenton oxidation and EDTA-Fe(III) Fenton-like oxidation which can be used to degrade malachite green (MG: a dye and antibiotic-like substance) from contaminated water. Compared with the degradation rate (59.34%) of the Fe(III)/H 2 O 2 Fenton process, the EDTA-Fe(III) Fenton-like oxidation got a better degradation rate (92.7%) at neutral pH conditions. By conducting a series of parallel controlled experiments (changing parameters such as the reactant concentration, temperature, and pH), we report the relationships between the degradation effect and different parameters, and we fitted their pseudo first order kinetic curves. Furthermore, we repeated to adjustment of the concentrations of MG in solutions to test the cycle performance and catalytic activities of EDTA-Fe(III)/H 2 O 2 system and it showed good repeatability in the first five rounds and all of them keep the degradation efficiencies greater than 80%. By conducting comparative spin-trapping electron paramagnetic resonance (EPR) experiments, we showed indirectly that the OH contributes to the degradation of MG. Additionally, the results of the EPR experiments showed that EDTA contributes to the generation of OH in the EDTA-Fe(III)/H 2 O 2 Fenton-like system. By conducting total organic carbon (TOC) analysis experiments, we found that EDTA was also oxidized to some extent during the degradation of MG. In all, the findings of this work widen the range of the optimal pH values up to neutral condition for degradation of MG by use of EDTA-Fe(III) Fenton-like system. And this system could be used as one approach for the degradation of organic pollutants at neutral conditions and provide some initial information regarding EDTA-Fe(III) Fenton-like oxidations. It's significant for the expansion of the homogenous Fenton-like family and its application in the field of water treatment. Graphical abstract Image 1 Highlights • The feasibility of the Fenton-like system for MG degradation at neutral condition. • Self-degradation possibility of EDTA in EDTA-Fe(III)/H 2 O 2 Fenton-like system. • EDTA was contributed to the generation of OH in the Fenton-like oxidation. • The mechanisms of EDTA-Fe(III)/H 2 O 2 Fenton-like oxidation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical Fe 3 O 4 /Co 3 S 4 nanosheets were prepared via one step phase transformation. • Fe 3 O 4 /Co 3 S 4 /PMS system achieved a great degradation on 200 mg/L of RhB. • SO 4 •− was the dominated reactive oxygen species in this Fenton-like process. • The introduction of S promoted the electron cycle of Co3+/Co2+ and Fe3+/Fe2+. • Fukui function based DFT did help to precisely predict the radical reactive sites on RhB. Fenton-like catalysts have usually superior catalytic activities, however, some drawbacks of ion leaching and difficult-to-recovery limit their applications. In this work, a hierarchical porous Fe 3 O 4 /Co 3 S 4 catalyst was fabricated via a simple phase change reaction to overcome these shortcomings. The introduced iron cooperates with cobalt achieving high-efficiency activation of peroxymonosulfate (PMS) to eliminate Rhodamine B (RhB). The results showed that 0.05 g/L Fe 3 O 4 /Co 3 S 4 and 1 mM PMS could quickly remove 100% of 200 mg/L RhB within 20 min, and the removal rate of RhB remained above 82% after 5 cycles. Moreover, the as-prepared Fe 3 O 4 /Co 3 S 4 possessed a great magnetic separation capacity and good stability of low metal leaching dose. Radical quenching experiments and electron paramagnetic resonance (EPR) techniques proved that sulfate radicals (SO 4 •−) were the dominant reactive oxygen species responding for RhB degradation. X-ray photoelectron spectroscopy (XPS) pointed out that the synergism of sulfur promoted the cycling of Co3+/Co2+ and Fe3+/Fe2+, boosting the electron transfer between Fe 3 O 4 /Co 3 S 4 and PMS. Moreover, the degradation pathways of RhB were deduced by combining liquid chromatography-mass spectrometry (LC-MS) analysis and density functional theory (DFT) calculations. The toxicities of RhB and its intermediates were evaluated as well, which provided significant assistance in the exploration of their ecological risks. [ABSTRACT FROM AUTHOR]

[Display omitted] • CuO particles were encapsulated by an irregular polyhedral carbon framework (CuO@C). • Synthesis of the stable and recyclable CuO@C was via a one-pot polymerization method. • CuO@C exhibited an excellent performance in the activation of peroxymonosulfate. • Tetracycline elimination was completely achieved within 40 min. • The reaction mechanism and catalytic cycle were investigated. CuO particles encapsulated by an irregular polyhedral carbon framework (CuO@C) were prepared via a one-pot polymerization method. The prepared CuO@C exhibited a highly enhanced performance in the activation of peroxymonosulfate (PMS). Our results indicated that the rate constant of tetracycline (TC) degradation was significantly increased by more than 85%, i.e., from 0.021 to 0.147 min−1, compared with the corresponding value for the bare CuO. TC elimination was completely achieved within 40 min, with the mineralization rate reaching 75.3% in 1 h. In addition, the CuO@C/PMS system exhibited an excellent performance in complex water matrixes containing various inorganic ions. Based on the use of scavengers and spin-trapping electron paramagnetic resonance technology, reactive species including OH, SO 4 −, and 1O 2 were proposed to be the main oxidants of the CuO@C/PMS system, and the possible intermediates were also fully investigated. Moreover, a catalytic cycle involving Cu+/Cu2+/Cu3+ was proposed. It was also demonstrated that the highly stable CuO@C can be easily recycled and reused. The present study therefore embodies the conceptual design of an excellent catalyst with a persistent stability for the activation of PMS, which may serve as a versatile platform for wider environmental applications. [ABSTRACT FROM AUTHOR]

• Novel catalyst CoFe-ONSs were prepared to activate H 2 O 2 for TC degradation. • 83.5% of TC could be removed at neutral conditions by CoFe-ONSs/H 2 O 2 system. • Hydroxyl (OH) radicals were responsible for TC degradation. • Catalytic mechanism was comprehensively discussed. • Intermediate compounds and possible transformation pathways were proved. Ultrathin iron-cobalt oxide nanosheets (CoFe-ONSs) synthesized via a facile one-step routine by using NaBH 4 as the reductant were used for H 2 O 2 activation and tetracycline (TC) elimination. The CoFe-ONSs realized 83.5% removal of TC under the neutral conditions after 50 min with 0.3 g/L catalyst, 20 mM H 2 O 2 and 50 mg/L TC. The effects of catalyst dosage, H 2 O 2 concentration, initial pH, temperature, initial TC concentration, anions and water sources on TC degradation were studied. Hydroxyl (OH) radicals were the main active species in the entire reaction, which was demonstrated by quenching experiments, fluorescence detection and the electron paramagnetic resonance (EPR) technology. Additionally, the redox cycles of FeII/FeIII and CoII/CoIII were participated in OH generation. What's more, the plausible degradation pathways were put forward followed with detected intermediates. The CoFe-ONSs displayed negligible iron ions leaching and held high TC elimination performance even after five trials. Therefore, the CoFe-ONSs may expand the heterogeneous Fenton-like catalysts family and display great potential in eliminating antibiotic contaminants from wastewater. [ABSTRACT FROM AUTHOR]