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The increasing discharge of antibiotic wastewater leads to increasing water pollution. Most of these antibiotic wastewaters are persistent, strongly carcinogenic, easy to bioaccumulate, and have other similar characteristics, seriously jeopardizing human health and the ecological environment. As a commonly used wastewater treatment technology, non-homogeneous electro-Fenton technology avoids the hazards of H₂O₂ storage and transportation as well as the loss of desorption and reabsorption. It also facilitates electron transfer on the electrodes and the reduction of Fe³⁺ on the catalysts, thereby reducing sludge production. However, the low selectivity and poor activity of electro-synthesized H₂O₂, along with the low concentration of its products, combined with the insufficient activity of electrically activated H₂O₂, results in a low ∙OH yield. To address the above problems, composites of layered bimetallic hydroxides and carbon materials were designed and prepared in this paper to enhance the performance of electro-synthesized H₂O₂ and non-homogeneous electro-Fenton by changing the composite mode of the materials. Three composites, NiFe layered double hydroxides (LDHs)/reduced graphene oxide (rGO), NiMn LDHs/rGO, and NiMnFe LDHs/rGO, were constructed by the electrostatic self-assembly of exfoliated LDHs with few-layer graphene. The LDHs/rGO was loaded on carbon mats to construct the electro-Fenton cathode materials, and the non-homogeneous electro-Fenton oxidative degradation of organic pollutants was realized by the in situ electrocatalytic reduction of O₂ to ∙OH. Meanwhile, the effects of solution pH, applied voltage, and initial concentration on the performance of non-homogeneous electro-Fenton were investigated with ceftazidime as the target pollutant, which proved that the cathode materials have an excellent electro-Fenton degradation effect. Full article

Clean water is a precious and limited resource that plays a crucial role in supporting life on our planet. However, the industrial sector, especially the pharmaceutical industry, significantly contributes to water consumption, and this can lead to water body pollution. Fenton’s reagent was introduced in the current investigation to oxidize acetaminophen as an emerging pollutant in such effluents. Therefore, we employed a straightforward co-precipitation method to fabricate chitosan-coated magnetic iron oxide, which is referred to in this study as Chit@Fe₃O₄. X-ray diffraction spectroscopy (XRD), Fourier transform infrared (FTIR), diffuse reflectance spectra (DRS), scanning electron microscopy (TEM), and transmission electron microscopy (TEM) were utilized to characterize the sample. It is crucial to treat such effluents due to the rapid increase in emerging pollutants. In this study, a photo-Fenton system was introduced as a combination of a Chit@Fe₃O₄ catalyst augmented with hydrogen peroxide under ultraviolet (UV) illumination conditions. The results reveal that only 1 h of irradiance time is efficient in oxidizing acetaminophen molecules. Doses of 20 and 200 mg/L of Chit@Fe₃O₄ and H₂O₂, respectively, and a pH of 2.0 were recorded as the optimal operational conditions that correspondingly oxidize 20 mg/L of acetaminophen to a 95% removal rate. An increase in the reaction temperature results in a decline in the reaction rate, and this, in turn, confirms that the reaction system is exothermic in nature. The sustainability of the catalyst was verified and deemed adequate in treating and oxidizing acetaminophen, even up to the fourth cycle, achieving a 69% removal rate. A kinetic modeling approach is applied to the experimental results, and the kinetic data reveal that the oxidation system conforms to second-order kinetics, with rate constants ranging from 0.0157 to 0.0036 L/mg·min. Furthermore, an analysis of the thermodynamic parameters reveals that the reaction is exothermic and non-spontaneous, predicting an activation energy of 36.35 kJ/mol. Therefore, the proposed system can address the limitations associated with the homogeneous Fenton system. Full article

The catalytic treatment of wastewater serves as an effective way to solve the problem of water pollution, in which non-homogeneous Fenton catalysts are widely used. However, the activity enhancement of non-homogeneous Fenton catalysts still remains a great challenge. Herein, self-assembled BiFeO₃/CeO₂ nanocatalytic materials with different molar ratios were successfully fabricated by a suspension blending method, following which the structure evolution was determined by various characterizations. The catalytic degradation of methylene blue (MB), rhodamine B (RhB), and saffron T (ST) were performed over the BiFeO₃/CeO₂ nanocatalytic materials. It was found that the 0.2BiFeO₃:0.8CeO₂ nanocatalytic materials exhibited an 80.8% degradation efficiency for RhB. The 0.6BiFeO₃:0.4CeO₂ nanocatalytic materials reached 81.1% and 48.7% for ST and MB, respectively. The BiFeO₃/CeO₂ nanocatalytic materials also showed a good stability during several cycles. The combination of CeO₂ with BiFeO₃ led to an enhanced activity for dye degradation, probably due to the electron transfer from ≡Fe²⁺ to ≡Ce⁴⁺. This study provides a new approach to dye degradation by using Fenton catalytic systems. Full article