RESUMEN
A hydrophobic Cu2O cathode (CuxO-L) was designed to solve the challenge of low oxidation ability in electro-Fenton (EF) for treating emerging pollutants. This fabrication process involved forming Cu(OH)2 nanorods by oxidizing copper foam (Cu-F) with (NH4)2S2O8, followed by coating them with glucose via hydrothermal treatment. Finally, a self-assembled monolayer of 1-octadecanethiol was introduced to create a low-surface-energy, functionalized CuxO-L cathode. Results exhibited an approximately 7.9-fold increase in hydroxyl radical (·OH) generation compared to the initial Cu-F. This enhancement was attributed to two key factors: (â ) the superior O2-capturing ability of CuxO-L cathode, which led to high H2O2 production due to a 2 nm thick hydrophobic gas layer facilitated O2-capturing; (â ¡) a relative high concentration of Cu+ at the CuxO-L cathode promoted the activation of H2O2 into·OH. In addition, the performance of EF with the CuxO-L cathode using sulfathiazole (STZ) as a model pollutant was evaluated. This study offers valuable insights into the design of O2-capturing cathodes in EF processes, particularly for treating emerging organic pollutants.
RESUMEN
Polyferric sulfate (PFS) and ferric chloride (FC) were compared for their efficiencies in capturing organic carbon and phosphorus, and their effects on the anaerobic fermentation process of sludge from a pilot-scale two-stage reactor were studied. Both PFS and FC promoted organic carbon and phosphorus capture. Further study revealed that PFS-based sludge with a dosage of 18 mg Fe/Lsewage showed a better volatile fatty acids (VFAs) production performance (202.97 ± 2.38 mg chemical oxygen demand (COD)/g volatile solids (VS)) than that of FC-based sludge (169.25 ± 1.56 mg COD/g VS). Besides, the high dosage of PFS effectively promoted the activities of the α-glucosidase and proteases. The dissimilatory iron reduction process enhanced sludge flocs disintegration and the conversion of carbohydrates and proteins to VFAs. Non-hydroxyapatite phosphorus predominated in the total phosphorus of all samples. This study contributes to developing strategies for optimizing iron-based sludge management and high-value product recovery.
Asunto(s)
Cloruros , Ácidos Grasos Volátiles , Fermentación , Compuestos Férricos , Fósforo , Aguas del Alcantarillado , Compuestos Férricos/química , Cloruros/farmacología , Anaerobiosis , Fósforo/farmacología , Reactores Biológicos , Análisis de la Demanda Biológica de Oxígeno , Carbono/farmacologíaRESUMEN
In the electro-Fenton process, there still suffers concern of low H2O2 generation caused by inadequate mass transfer of oxygen and low selectivity of oxygen reduction reaction (ORR). To solve it, in this study, various particle sizes (850 µm, 150 µm, and 75 µm) of granular activated carbon filled in a microporous titanium-foam substate was used to develop a gas diffusion electrode (AC@Ti-F GDE). This facile-prepared cathode has seen a 176.15% improvement in H2O2 formation compared to the conventional one. Aside from a much higher oxygen mass transfer by creating gas-liquid-solid three-phase interfaces coupled with much high dissolved oxygen, the filled AC played a significant role in H2O2 accumulation. Among these particle sizes of AC, the one in 850 µm has observed the highest H2O2 accumulation, reaching 1487 µM in 2 h electrolysis. Because there is a balance between chemical nature for H2O2 formation and micropore-dominant porous structure for H2O2 decomposition, resulting in an electron transfer of 2.12 and H2O2 selectivity of 96.79% during ORR. In a word, the facial AC@Ti-F GDE configuration is promising for H2O2 accumulation.
Asunto(s)
Carbón Orgánico , Contaminantes Químicos del Agua , Carbón Orgánico/química , Peróxido de Hidrógeno/química , Titanio , Oxidación-Reducción , Contaminantes Químicos del Agua/química , Electrodos , OxígenoRESUMEN
The sluggish kinetics of oxygen evolution reaction (OER) is the bottleneck of alkaline water electrolysis. The urea oxidation reaction (UOR) with much faster kinetics was to replace OER. To further promote UOR, a heterojunction structure assembled of CoSx and MoOx was established, and then its superior catalytic activity was predicted by DFT calculation. After that, an ultra-thin CoSx-MoOx@nickel foam (CoSx-MoOx@NF) electrode with a Mott-Schottky structure was prepared via a facile hydrothermal method, followed by a low-temperature vulcanization. Results highlighted CoSx-MoOx@NF electrode presented a superior performance toward UOR, OER, and H2 evolution reaction (HER). Notably, it exhibited excellent electrocatalytic performance for OER (1.32 V vs. RHE, 10 mA cm-2), UOR (1.305 V vs. RHE, 10 mA cm-2), and urea-assisted overall water splitting with a low voltage (1.38 V, 10 mA cm-2) when CoSx-MoOx@NF electrode served as both anode and cathode. It is promising to use CoSx-MoOx@NF in an electrochemical system integrated with H2 generation and urea-rich wastewater purification.
Asunto(s)
Electrólisis , Urea , Electrodos , Oxígeno , AguaRESUMEN
The sluggish kinetics of oxygen evolution reaction (OER) is the bottleneck of water splitting. Hence, we designed a nanowire Co3O4@nickel foam (Co3O4-NW@NF) electrode to boost OER utilizing the locally enhanced interfacial Joule heating and electric field within the diffusion layer. Results show that the morphology of Co3O4@NF could be regulated in nanowires, nanosheets, and nanoclusters by controlling the doping amount of fluoride ions (F-). F- served as a complexing agent to regulate the rate of crystal nucleus, and then morphologies could be tuned. compared to others, nanowire structures have a much lower potential (298 mV vs. RHE, 10 mA cm-2) and Tafel slope (48.11 mV dec-1). This better electrochemical performance was confirmed by the Density Functional Theory (DFT) that the (311) facet with oxygen vacancies of Co3O4 has a low onset potential (0.36 V) for the kinetic rate of OER. A much better mass transfer by the nanowire-enhanced interfacial Joule heating and electric field within the diffusion layer also accounted for superior OER activity, confirmed by COMSOL simulation. In a word, the design of the nanotip structure offers a novel way to boost the OER rate by enhancing electron transfer and mass transport simultaneously.