Suchergebnisse

AbstractThe removal of biological phosphorus (P) removal along with chemical P removal additions is significantly important role in removing P at full‐scale wastewater treatment plants (WWTPs). Few research groups have recently reported the use of P forms in these WWTPs. The current study mainly presents the varied forms of morphological phosphorus and the fate of chemical P removal agents in a full‐scale WWTP that has adopted the A2O + MBR process. With time, the TP concentration in the liquid phase and the solid phase reaches the minimum (0.27 mg/L) and maximum values (1.75 mg/g), respectively. At this point, the TP concentration at the end of the aerobic and membrane pool becomes nearly constant. This indicates the complete removal of effluent TP from in the system. The heavy chemical P removal and addition dosing result in Al–P being the predominant P form in the solid phase. The fate of the chemical P removal and agents was determined by investigating the valences of the surface elements in freeze‐dried MLSS at the membrane pool.

AbstractDemethoxylation was kinetically and spectroscopically studied over three catalysts with different Ru0/Ruδ+ ratios. In-situ spectroscopic tests demonstrated that the synergy between Ru0 and Ruδ+ was crucial, and Ru0 was in charge of H2 activation and adsorption of aromatic ring while Ruδ+ adsorbed with O in methoxyl. A Langmuir–Hinshelwood kinetic model was proposed, and ratio of Ru0/Ruδ+ was the key in deciding the rate-determining step (RDS): i) desorption of toluene was RDS over catalyst with high Ru0 ratio; ii) dissociation of H2 was RDS over Ruδ+ enriched catalyst; iii) demethoxylation was rate-determined by CO water–gas shift (WGS) when Ru0/Ruδ+ approached ~ 1. The best performance was obtained over Ru/NiAl2O4-200, which effectively enabled both C-O bond activation and rapid recovery of adsorption sites for aromatic rings. Finally, in-situ DRIFT studies on methoxy decomposition and CO-WGS unraveled that the electronic composition of Ru was more stable in Ru/NiAl2O4-200 which contributes to its excellence.

Copper-based materials are promising electrocatalysts for CO2 reduction. Prior studies show that the mixture of copper (I) and copper (0) at the catalyst surface enhances multi-carbon products from CO2 reduction; however, the stable presence of copper (I) remains the subject of debate. Here we report a copper on copper (I) composite that stabilizes copper (I) during CO2 reduction through the use of copper nitride as an underlying copper (I) species. We synthesize a copper-on-nitride catalyst that exhibits a Faradaic efficiency of 64 ± 2% for C2+ products. We achieve a 40-fold enhancement in the ratio of C2+ to the competing CH4 compared to the case of pure copper. We further show that the copper-on-nitride catalyst performs stable CO2 reduction over 30 h. Mechanistic studies suggest that the use of copper nitride contributes to reducing the CO dimerization energy barrier-a rate-limiting step in CO2 reduction to multi-carbon products. ; This work was supported financially by the Ontario Research Fund Research-Excellence Program, the Natural Sciences and Engineering Research Council (NSERC) of Canada, and the CIFAR Bio-Inspired Solar Energy program. Computations were performed on the SOSCIP Consortium's Blue Gene/Q computing platform. SOSCIP is funded by the Federal Economic Development Agency of Southern Ontario, the Province of Ontario, IBM Canada Ltd., Ontario Centres of Excellence, Mitacs and 15 Ontario academic member institutions. X-ray absorption spectra were performed on SXRMB beamlines at the Canadian Light Source (CLS), which is supported by the Canada Foundation for Innovation, Natural Sciences and Engineering Research Council of Canada, the University of Saskatchewan, the Government of Saskatchewan, Western Economic Diversification Canada, the National Research Council Canada, and the Canadian Institutes of Health Research. Z.L. acknowledges a scholarship from the China Scholarship Council (CSC) (201607090041) and Basic and Innovation Program, Beijing Jiaotong University (KSJB17016536). A.S. acknowledges Fonds de Recherche du Quebec-Nature et Technologies (FRQNT) for the postdoctoral fellowship award. P.D.L. acknowledges support from NSERC in the form of the Canada Graduate Scholarship. H.T. acknowledges the Netherlands Organisation for Scientific Research (NWO) for a Rubicon grant (680-50-1511) to support his postdoctoral research at University of Toronto. The authors thank C. Q. Zou, M. X. Liu, F. F. Fan, J. Xing and L. Gao from University of Toronto for fruitful discussions.