A novel heterogeneous Co(II)-Fenton-like catalyst for efficient photodegradation by visible light over extended pH

Visible Fenton Degradation of Bisphenol A by Boron-Doped, Graphene-Oxide-Coated Nano-Fe3O4

Phenolic pollutants in industrial wastewater are considered to be harmful aromatic compounds. With the development of industry and pharmaceuticals, phenolic pollutants and their derivatives have gradually started to affect people’s daily lives. Therefore, it is necessary to strictly control the content of phenolic pollutants in industrial wastewater, not only for the natural environment but also for human life. The research optimized the existing treatment methods for classified pollutants, and successfully prepared a heterogeneous photo-Fenton catalyst Fe3O4@B-rGO (9.3%). The characterization results of the catalyst showed that the synthesis of the catalyst was successful, and its specific surface area was 11.28 (m2/g), and the pore volume area was 0.137 (m3/g), respectively, which were larger than those of the other two comparative catalysts. In addition, the research conclusion also showed that the catalyst prepared during the research had good catalytic activity, the treatment efficiency of Fe3O4@B-rGO (9.3%) to bisphenol A could reach 100%, and the mineralization rate could reach 67.4%. In the reaction, the main active radicals are generated, and catalyst Fe3O4@B-rGO (9.3%) can produce more active free radicals compared with Fe3O4 and Fe3O4@rGO.

Reactive Oxygen Species Formed by Metal and Metal Oxide Nanoparticles in Physiological Media—A Review of Reactions of Importance to Nanotoxicity and Proposal for Categorization

Diffusely dispersed metal and metal oxide nanoparticles (NPs) can adversely affect living organisms through various mechanisms and exposure routes. One mechanism behind their toxic potency is their ability to generate reactive oxygen species (ROS) directly or indirectly to an extent that depends on the dose, metal speciation, and exposure route. This review provides an overview of the mechanisms of ROS formation associated with metal and metal oxide NPs and proposes a possible way forward for their future categorization. Metal and metal oxide NPs can form ROS via processes related to corrosion, photochemistry, and surface defects, as well as via Fenton, Fenton-like, and Haber–Weiss reactions. Regular ligands such as biomolecules can interact with metallic NP surfaces and influence their properties and thus their capabilities of generating ROS by changing characteristics such as surface charge, surface composition, dissolution behavior, and colloidal stability. Interactions between metallic NPs and cells and their organelles can indirectly induce ROS formation via different biological responses. H₂O₂ can also be generated by a cell due to inflammation, induced by interactions with metallic NPs or released metal species that can initiate Fenton(-like) and Haber–Weiss reactions forming various radicals. This review discusses these different pathways and, in addition, nano-specific aspects such as shifts in the band gaps of metal oxides and how these shifts at biologically relevant energies (similar to activation energies of biological reactions) can be linked to ROS production and indicate which radical species forms. The influences of kinetic aspects, interactions with biomolecules, solution chemistry (e.g., Cl⁻ and pH), and NP characteristics (e.g., size and surface defects) on ROS mechanisms and formation are discussed. Categorization via four tiers is suggested as a way forward to group metal and metal oxide NPs based on the ROS reaction pathways that they may undergo, an approach that does not include kinetics or environmental variations. The criteria for the four tiers are based on the ability of the metallic NPs to induce Fenton(-like) and Haber–Weiss reactions, corrode, and interact with biomolecules and their surface catalytic properties. The importance of considering kinetic data to improve the proposed categorization is highlighted.

The crystal structure of cobalt cadmium bis(hydrogenphosphate) bis(phosphate(V)) tetrahydrate, H10O20P4Co3.14Cd1.86

H10O20P4Co3.14Cd1.86, monoclinic, C2/c (no. 15), a = 17.5779(6) Å, b = 9.0747(3) Å, c = 9.4946(3) Å, β = 96.636(3)°, V = 1504.38(9) Å3, Z = 1, R gt (F) = 0.0273, wR ref (F 2) = 0.0646, T = 293(2) K.

Revealing the enhancing mechanisms of Fe-Cu bimetallic catalysts for the Fenton-like degradation of phenol

To develop a heterogeneous Fenton-like catalyst with desirable activity and reusability remains a great challenge for the practical degradation of environmental remediation. Herein, we demonstrate a dendritic Fe-Cu bimetallic catalyst consisted of a Cu/Fe₃O₄ shell and a FeCu core (E100). In comparisons of single Cu, Fe and Fe₃O₄, E100 performs far better performance for the Fenton-like degradation of phenol, and its dominant Fenton-like active centers are Fe species under acidic pH or Cu species under neutral pH. Particularly, Cu-based Fenton-like reactions are greatly accelerated by galvanic micro-cells effects that come from the special co-existence of Cu/Fe₃O₄ shell, and subsequently, owing to the Cu leaching from the shell, the inner FeCu core of E100 is able to be exposed and further strengthen Fe-based Fenton-like reactions. Overall, the appropriate synergistic effects endow E100 with superior catalytic activity and reusability than other catalysts. Our work pushes forward a step for understanding the catalytic mechanism of Fe-Cu bimetallic catalysts and provides new sights for fabricating efficient Fenton-like catalysts for environmental remediation.

Ferroin in dyes degradation by Fenton-like process: a chemical waste recycling perspective

Published literature describes the formation of the Fe (II)-phenanthroline complex (ferroin) as a stop way for Fenton processes, reducing radical yield. By contrast, this study presents evidence that ferroin can be activated by UVA in mildly acidic media in a photo-Fenton-like process. Because ferroin is the main waste from total iron determination in environmental samples, a recycling approach is suggested. Based on the best practices of waste management planning, an application of the proposed method for treating another chemical waste is presented. Titrimetric ammonia determination waste containing 2.67 mg L^-1 methyl red azo dye and 1.33 mg L^-1 methylene blue was degraded using the optimized experimental conditions: pH = 5.2-5.4; [H₂O₂] = 310 mg L^-1; [ferroin] = 1.4 mg L^-1; temperature = 36 ± 1 °C; reaction time = 165 min under UVA irradiation. Attenuation of most intense spectroscopic bands for the dyes achieved 94% (510 nm) and 96% (665 nm) reduction for methyl red and methylene blue, respectively, with degradation of ferroin itself. The present work brings empirical evidence that is possible to recycle ferroin as photo-Fenton-like process catalyst, as well as determine the best conditions for providing less acidic treated effluents with negligible suspended solid concentration, better than that obtained from classical photo-Fenton processes.