Enhanced catalytic performance of CuFeS2 chalcogenide prepared by microwave-assisted route for photo-Fenton oxidation of emerging pollutant in water

In this work, CuFeS2 chalcogenide powders were easily produced by conventional and microwave methods, and for the first time, the influence of synthesis route on their properties and consequent catalytic activity in the photo-Fenton reaction was investigated. X-ray diffraction, N2 adsorption–desorption isotherms, Fourier-transform infrared spectroscopy, transmission and scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were employed to characterize and point out the main properties and differences among samples. The CuFeS2 particles were used as catalysts for tartrazine dye degradation by the photo-Fenton reaction under visible irradiation. The results showed that the CuFeS2 prepared by microwave-assisted method (CuFeS2–MW) present higher crystallinity, higher concentration of Fe2+ on its surface and remarkable catalytic activity, reaching 99.1% of tartrazine decolorization and 87.3% of mineralization, at a rate twice as fast as CuFeS2 prepared by the conventional method. The catalyst showed high catalytic efficiency and stability during the reaction after five recycles. The hydroxyl radical was revealed to be the reactive species responsible for tartrazine degradation. A mechanism was proposed to elucidate how these free radicals are generated from the catalytic decomposition of H2O2 by CuFeS2–MW

Obesity associated with coal ash inhalation triggers systemic inflammation and oxidative damage in the hippocampus of rats

People with large amounts of adipose tissue are more vulnerable and more likely to develop diseases where oxidative stress and inflammation play a pivotal role, than persons with a healthy weight. Atmospheric contamination is a reality to which a large part of the worldwide population is exposed. Half of today's global electrical energy is derived from coal. Each organism, in its complexity, responds in different ways to dietary compounds and air pollution. The objective of this study was to investigate the effects of obesity and coal ash inhalation within the parameters of oxidative damage and inflammation in different regions of the brain of rats. A diet containing high-fat concentration was administered chronically to rats, along with exposure to coal ash, simulating the contamination that occurs daily throughout human life. High-resolution transmission electron microscopy was performed to identify the particles present in coal ash samples. Our results demonstrated that obese rats exposed to coal ash inhalation were more affected by oxidative damage with subsequent systemic inflammation in the hippocampus. Since there is an inflammatory predisposition caused by obesity, the inhalation of nanoparticles increases the levels of free radicals, resulting in systemic inflammation and oxidative damage, which can lead to chronic neurodegeneration

Synthesis of citrate–modified cufes2 catalyst with significant effect on the photo–fenton degradation efficiency of bisphenol a under visible light and near–neutral PH

In this study, for the first time, citric acid was employed as a chelating agent in CuFeS2 synthesis in order to accelerate the regeneration of Fe2+ during the photo–Fenton reaction, promoting a faster production of •OH radicals. The novel CuFeS2 material showed remarkable catalytic efficiency for bisphenol A (BPA) degradation during the photo–Fenton process under visible light and near–natural pH, with a rate 10 times faster than that of CuFeS2 prepared without citrate. Furthermore, CuFeS2 promoted rapid generation of •OH radicals and showed efficient H2O2 consumption, sustaining the catalytic efficiency and stability even after 4 consecutive cycles of use. CuFeS2 was also efficient for BPA degradation from a municipal wastewater treatment plant effluent. BPA by–products were identified and a mechanism for BPA degradation was proposed. After the photo–Fenton process, no Fe3+ species were identified on the catalyst surface by X–ray photoelectron spectroscopy (XPS), indicating that citric acid accelerated the conversion of Fe3+/Fe2+, thus increasing the generation of •OH and the process efficiency

Improved catalytic activity of EDTA–modified BiFeO3 powders for remarkable degradation of procion red by heterogeneous photo–Fenton process

For the first time, heterogeneous photo–Fenton degradation of Procion Red dye under visible irradiation was investigated using ferrite bismuth (BiFeO3) catalysts synthesized by hydrothermal method with and without EDTA. The results and analysis revealed that the presence of EDTA affected the crystallinity degree and morphology of BiFeO3 particles, but almost not changed their specific surface area and band–gap energy values. The BiFeO3 catalyst prepared with EDTA exhibited superior catalytic activity, reaching 99% of degradation in 120 min, when compared to the BiFeO3 prepared without EDTA, which obtained 70% degradation under the same conditions. This result may be associated with the synergistic enhancement effects between the morphology and the degree of crystallinity of the particles. In addition, the EDTA–modified catalyst showed high reusability and stability even after five cycles. Radical scavenger experiments were developed to determine that •OH and •O2− were the main active species involved on the dye degradation. A possible simplified mechanism for the photo–Fenton reaction was also proposed coupled with the identification of reaction intermediates