Search

[Display omitted] • Cobalt doped Fe 2 O 3 nanospheres were synthesised via a solvothermal route. • 3% cobalt doping was most efficient for peroxymonosulfate activation in degradation of p-hydroxybenzoic acid. • Identification of free radicals was done by quenching tests and electron paramagnetic resonance spectra. • Detailed mechanistic studies on peroxymonosulfate activation and degradation pathways were performed. Environmental remediation has become more effective when using nanotechnologies. In this study, iron oxide (α-Fe 2 O 3) nanospheres with different cobalt doping levels (xCo-Fe 2 O 3) were synthesised and applied in the heterogeneous activation of peroxymonosulfate (PMS) for the degradation of p-hydroxybenzoic acid (p-HBA). The catalyst (3Co-Fe 2 O 3) with 3% Co doping exhibits the best performance for PMS activation, possibly because of the larger specific surface area and the tailored catalyst surface as confirmed by X-ray photoelectron spectroscopy (XPS). Reaction parameters were investigated to optimise the degradation efficiency. The metal ions leaching tests confirmed the higher stability of the catalyst, thanks to the leaching suppression by the doping of Co2+. The main contribution of free radicals (SO 4 •- and •OH) was confirmed by electron paramagnetic resonance (EPR) spectra, whereas partial contribution of oxygen anions and singlet oxygen (O 2 •-, 1O 2) was observed during the quenching tests. Finally, a radical based degradation mechanism was proposed for the removal of p-HBA. It is expected to open up a novel perspective for the application of iron oxide as a potential catalyst for the removal of emerging contaminants. [ABSTRACT FROM AUTHOR]

[Display omitted] • A perforated CuFe 2 O 4 /Fe 2 O 3 composite was designed by a MOF-derived solid-state process. • The composite shows efficient PMS activation for sulfamethoxazole degradation. • Both radical and non-radical degradation contributed to SMX remediation. • Possible degradation mechanisms were proposed. • The catalyst shows excellent stability and reusability via magnetic recovery. Design of metal–organic framework (MOF) derived metal oxides is an effective approach for environmental remediation. The current study describes the fabrication of MIL-53-derived perforated CuFe 2 O 4 /Fe 2 O 3 using a facile, one-step, post-thermal solid-state approach by varying Cu/Fe ratios. Herein, the release of CO 2 and H 2 O during the thermal treatment facilitates the incorporation of Cu2+ onto the Fe 2 O 3 structure, forming a perforated hollow CuFe 2 O 4 /Fe 2 O 3 composite via an in-situ ion-exchange mechanism. The optimised catalyst CF-0.5 displays a high degradation efficiency for the removal of sulfamethoxazole (SMX) by heterogeneous activation of peroxymonsulfate (PMS), ascribing to the better textural, morphological, and elemental properties of the novel catalyst. Important reaction parameters such as pH, catalyst loading, PMS dosage, pollutant kind and concentration, and reaction temperature are further optimised to develop a cost-effective catalytic system. The magnetically recoverable catalyst outlines a high stability rate, and only a 9 % efficiency loss is observed even after the fourth cycle. Reactive oxygen species (ROS) are identified by electron paramagnetic resonance spectroscopy (EPR) and their roles are determined by performing quenching experiments. In the end, a detailed study of the mineralisation ability and reaction intermediates is performed and possible pathways for the degradation mechanism are proposed. This study not only introduces a facile approach for the fabrication of MOF-driven nanomaterials but provides insights into the removal of emerging contaminants such as SMX. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel g-C 3 N 4 /Fe 2 O 3 /rGO ternary composite was synthesised using a hydrothermal process. • The catalyst exhibits a high photocatalytic oxidation efficiency for the removal of sulfamethoxazole. • Reactive oxygen species were identified by quenching tests and electron paramagnetic resonance spectra. • Detailed mechanistic studies were performed to deduce the radical and non-radical degradation pathways. Rational design of semiconductor photocatalysts is an effective way to achieve efficient visible-light-driven environmental remediation. Herein, a series of graphitic carbon nitride (g-C 3 N 4) engineered hematite (Fe 2 O 3)/reduced graphene oxide (rGO) photocatalysts were synthesised and employed in visible-light-driven photo-Fenton-like degradation of sulfamethoxazole (SMX). The exceptional performance of the optimal photocatalyst (0.4-FerGCN-3) was achieved because of the successful structural integration of g-C 3 N 4 /Fe 2 O 3 /rGO for efficient separation and migration of photoinduced charge carriers (e−/h+). Photochemical decomposition efficiency was also optimised by analysing the important reaction parameters such as initial catalyst loading, initial H 2 O 2 dosage, pH, and reaction temperature. Detailed studies on the generation of reactive species and degradation intermediates were performed to propose a possible mechanism for SMX degradation. The findings may provide not only a strategy for nanostructure engineering of semiconductor photocatalysts but also insights into the effective remediation of emerging contaminants such as SMX. [ABSTRACT FROM AUTHOR]