Environmental Fluid Mechanics - Bed-load transport is a complex process exhibiting anomalous dynamics, which cannot be efficiently described using the traditional advection–diffusion... 相似文献
• Strong metal-support interaction exists on Pt/Fe3O4 catalysts.• Pt metal particles facilitate the formation of oxygen vacancies on Fe3O4.• Fe3O4 supports enhance the strength of CO adsorption on Pt metal particles. The self-inhibition behavior due to CO poisoning on Pt metal particles strongly impairs the performance of CO oxidation. It is an effective method to use reducible metal oxides for supporting Pt metal particles to avoid self-inhibition and to improve catalytic performance. In this work, we used in situ reductions of chloroplatinic acid on commercial Fe3O4 powder to prepare heterogeneous-structured Pt/Fe3O4 catalysts in the solution of ethylene glycol. The heterogeneous Pt/Fe3O4 catalysts achieved a better catalytic performance of CO oxidation compared with the Fe3O4 powder. The temperatures of 50% and 90% CO conversion were achieved above 260°C and 290°C at Pt/Fe3O4, respectively. However, they are accomplished on Fe3O4 at temperatures higher than 310°C. XRD, XPS, and H2-TPR results confirmed that the metallic Pt atoms have a strong synergistic interaction with the Fe3O4 supports. TGA results and transient DRIFTS results proved that the Pt metal particles facilitate the release of lattice oxygen and the formation of oxygen vacancies on Fe3O4. The combined results of O2-TPD and DRIFTS indicated that the activation step of oxygen molecules at surface oxygen vacancies could potentially be the rate-determining step of the catalytic CO oxidation at Pt/Fe3O4 catalysts. The reaction pathway involves a Pt-assisted Mars-van Krevelen (MvK) mechanism. 相似文献
• Fe(III) accepted the most electrons from organics, followed by NO3‒, SO42‒, and O2.• The electrons accepted by SO42‒ could be stored in the solid AVS, FeS2-S, and S0.• The autotrophic denitrification driven by solid S had two-phase characteristics.• A conceptual model involving electron acceptance, storage, and donation was built.• S cycle transferred electrons between organics and NO3‒ with an efficiency of 15%. A constructed wetland microcosm was employed to investigate the sulfur cycle-mediated electron transfer between carbon and nitrate. Sulfate accepted electrons from organics at the average rate of 0.84 mol/(m3·d) through sulfate reduction, which accounted for 20.0% of the electron input rate. The remainder of the electrons derived from organics were accepted by dissolved oxygen (2.6%), nitrate (26.8%), and iron(III) (39.9%). The sulfide produced from sulfate reduction was transformed into acid-volatile sulfide, pyrite, and elemental sulfur, which were deposited in the substratum, storing electrons in the microcosm at the average rate of 0.52 mol/(m3·d). In the presence of nitrate, the acid-volatile and elemental sulfur were oxidized to sulfate, donating electrons at the average rate of 0.14 mol/(m3·d) and driving autotrophic denitrification at the average rate of 0.30 g N/(m3·d). The overall electron transfer efficiency of the sulfur cycle for autotrophic denitrification was 15.3%. A mass balance assessment indicated that approximately 50% of the input sulfur was discharged from the microcosm, and the remainder was removed through deposition (49%) and plant uptake (1%). Dominant sulfate-reducing (i.e., Desulfovirga, Desulforhopalus, Desulfatitalea, and Desulfatirhabdium) and sulfur-oxidizing bacteria (i.e., Thiohalobacter, Thiobacillus, Sulfuritalea, and Sulfurisoma), which jointly fulfilled a sustainable sulfur cycle, were identified. These results improved understanding of electron transfers among carbon, nitrogen, and sulfur cycles in constructed wetlands, and are of engineering significance. 相似文献
• Physical and chemical properties and application of peracetic acid solution.• Determination method of high concentration peracetic acid.• Determination method of residual peracetic acid (low concentration). Peroxyacetic acid has been widely used in food, medical, and synthetic chemical fields for the past several decades. Recently, peroxyacetic acid has gradually become an effective alternative disinfectant in wastewater disinfection and has strong redox capacity for removing micro-pollutants from drinking water. However, commercial peroxyacetic acid solutions are primarily multi-component mixtures of peroxyacetic acid, acetic acid, hydrogen peroxide, and water. During the process of water treatment, peroxyacetic acid and hydrogen peroxide (H2O2) often coexist, which limits further investigation on the properties of peroxyacetic acid. Therefore, analytical methods need to achieve a certain level of selectivity, particularly when peroxyacetic acid and hydrogen peroxide coexist. This review summarizes the measurement and detection methods of peroxyacetic acid, comparing the principle, adaptability, and relative merits of these methods. 相似文献
• Selective molecularly imprinted polymer (MIP) binding gel was prepared.• MIP-DGT showed excellent uptake performance for antibiotics.• In situ measurement of antibiotics in wastewaters via MIP-DGT was developed.• The MIP-DGT method was robust, reliable, and highly sensitive. Urban wastewater is one of main sources for the introduction of antibiotics into the environment. Monitoring the concentrations of antibiotics in wastewater is necessary for estimating the amount of antibiotics discharged into the environment through urban wastewater treatment systems. In this study, we report a novel diffusive gradient in thin films (DGT) method based on molecularly imprinted polymers (MIPs) for in situ measurement of two typical antibiotics, fluoroquinolones (FQs) and sulfonamides (SAs) in urban wastewater. MIPs show specific adsorption toward their templates and their structural analogs, resulting in the selective uptake of the two target antibiotics during MIP-DGT deployment. The uptake performance of the MIP-DGTs was evaluated in the laboratory and was relatively independent of solution pH (4.0–9.0), ionic strength (1–750 mmol/L), and dissolved organic matter (DOM, 0–20 mg/L). MIP-DGT samplers were tested in the effluent of an urban wastewater treatment plant for field trials, where three SA (sulfamethoxazole, sulfapyridine, and trimethoprim) and one FQ (ofloxacin) antibiotics were detected, with concentrations ranging from 25.50 to 117.58 ng/L, which are consistent with the results measured by grab sampling. The total removal efficiency of the antibiotics was 80.1% by the treatment plant. This study demonstrates that MIP-DGT is an effective tool for in situ monitoring of trace antibiotics in complex urban wastewaters. 相似文献
Environmental Science and Pollution Research - Currently, sustainable utilization, including recycling and valorization, is becoming increasingly popular in waste management. Black soldier fly... 相似文献