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Effect of complex ionic liquid additives on the formation kinetics and separation efficiency of binary gas mixture hydrates
Rising carbon emissions worldwide have necessitated the discovery of efficient CO2 separation and capture technologies. Owing to their good CO2 selectivity, imidazolium-based ionic liquids (ILs) have been used as additives in hydrate-based gas separation (HBGS) technologies. Sodium dodecyl sulfate (SDS) can notably improve the rate of hydrate formation when used as a surfactant. However, the synergistic effect of imidazolium-based ILs and SDS remains unknown. This study aimed at investigating the synergistic effect of imidazolium-based ILs and SDS on the hydrate formation kinetics of binary gas mixtures of CO2/N2 at different temperatures. The carbon capture and storage capacity was determined, and HBGS was evaluated using pure imidazolium-based IL 1-butyl3-methylimidazolium octyl sulfate ([BMIM] [OS]) and composites of IL and SDS as additives. Compared with pure water, [BMIM] [OS] effectively promoted gas hydrate formation and increased CO2 consumption by 107.9 %. The maximum CO2 separation factor was obtained at 273.15 K, and the mixed additive significantly enhanced gas consumption by 11.1 %. X-ray diffraction and Raman spectroscopy analysis indicated that the hydrate samples were type I structural hydrates and that [BMIM] [OS] improved the mass transfer process. The results of this study provide a theoretical basis for CO2 gas separation and capture
Ultrasonic assisted in-situ synthesis of photocatalytic ZnO on PVDF membrane surface for fouling degradation
Animal carcasses can be harmlessly treated through high-temperature and high-pressure hydrolysis, resulting in the production of bioactive polypeptides. The polypeptides can be effectively separated from other impurities by ultrafiltration (UF) membranes technology. However, membrane fouling is inevitable during filtrating process, which significantly impacts their lifespan and economic efficiency. In this study, the photocatalyst ZnO nanoparticles on the PVDF membrane surface (PVDF/Zn) were fabricated to degrade foulant. Firstly, tannic acid (TA) was blended into the membrane to provide coordination sites to fix Zn2+. Then, ZnO nanoparticles was synthesized exclusively on the membrane surface under ultrasonic assistance, where the ultrasonic energy generated by the cavitation bubbles was excluded by the pore size. Chemical composition and morphology characterization were conducted to prove the successful synthesis of ZnO on the membrane surface. The PVDF/Zn membrane demonstrated a flux of 42 L m- 2h- 1 and a rejection of 97 % when filtering BSA solution, with a flux recovery rate (FRR) of 80 % after photocatalytic degradation. During the treatment of high-temperature and high-pressure hydrolyzed animal carcass solution (HHAS), the FRR exceeded 90 %, effectively separating impurities from polypeptides. This work provides a novel approach to enhancing the efficiency of treating HHAS and offers new insights into the preparation of photocatalytic membranes
Electric syntrophy-driven modulation of Fe<SUP>0</SUP>-dependent microbial denitrification
In natural or engineered anaerobic environments, iron oxidation-driven microbial denitrification plays a critical role in the water or wastewater treatment. Herein, we report a previously unidentified metallic iron (Fe0)dependent denitrification mode driven by the electro-syntrophic interaction between electroactive microorganism and denitrifier. In a model denitrifying consortium of Shewanella oneidensis and Pseudomonas aeruginosa, we find that P. aeruginosa can accept electrons for nitrate reduction via the constructed electron transfer system of Fe0-S. oneidensis-P. aeruginosa. In the electro-syntrophic consortium, the membrane-bound CymA-OmcA-MtrC protein complexes of S. oneidensis drive the generation, transfer and consumption of electrons, thus enabling modulation of microbial metabolic activity. Specially, using Fe0 as the sole electron donor, S. oneidensis can act as a bio-engine to harvest electrons and conserve energy from Fe0 biocorrosion. Electrons released by S. oneidensis are utilized by P. aeruginosa for accomplishing microbial denitrification. Metatranscriptomics analysis demonstrated that the direct electron cross-feeding process facilitates the expression of genes encoding for denitrification enzymes, intracellular electron transfer proteins, and quorum sensing of P. aeruginosa. The Fe0dependent electronic syntrophy in this work could provide a metabolic window for the growth of denitrifiers that is a new insight into nitrate removal or global nitrogen cycle
Evaluation of an air-breathing anion-exchange membrane fuel cell based on Pd0.9-Cu0.1/rGO anode catalyst for low ethanol sensing
Breath alcohol analyzers (BrAAs) can utilize anion exchange membrane fuel cells (AEMFCs) as an alternative to proton exchange membrane ones, allowing non-platinum catalysts in BrAA structure. In this respect, an anode catalyst consisting of Pd0.9-Cu0.1/rGO is used in the AEMFC catalyst layer to sense low ethanol concentration solution in the presence of carbonate. In addition to catalyst structural analysis, the performance of the prepared AEMFC is evaluated using the electrochemical tests. Polarization curves of the air-breathing passive ethanol fuel cell show a high power density output of 189 mWcm-2 at 2 M of ethanol. To assess the sensitivity of the AEMFC, the polarization and V-t curves are investigated at low ethanol concentrations of 5-50 mmolL-1. According to the obtained results, the sensor's highest sensitivity is achieved at 300 mV, indicating that voltage can be used for sensitivity control. In addition, the separation of the anode and cathode polarization curves shows that the anode current density increases with ethanol concentration, whereas the cathode current density remains constant. Overall, the sensitivity and repeatability evaluations represent Pd0.9-Cu0.1/rGO as an appropriate anode catalyst in the new generation of breath alcohol analyzers based on AEMFC
Enhanced electrochemical performance of ZrTe-Mn<sub>2</sub>O<sub>3</sub> nanocomposite electrocatalyst for HER and OER in alkaline medium
Electrochemical energy conversion in renewable-energy technologies relies on the OER and HER towards next-generation fuels. Herein, we have coupled zirconia telluride (ZrTe) and manganese oxide (Mn2O3) nanosheets heterointerfaces by a facile hydrothermal method, which are engineered on stainless steel substrate (ZrTe-Mn2O3/SS). The physical properties, including crystallinity, phase purity, morphology, conductivity, and chemical interacted states of the developed composite, are systematically investigated by XRD, HRTEM, I-V, and XPS. The XPS observation showed unique redox properties of hydrogen peroxide species on the ZrTe-Mn2O3 catalyst and the oxidation state of Zr and Mn that was more easily changed in the ZrTe-Mn2O3 electrocatalyst compared with the pristine catalysts. The very decent electrochemical performance of the catalyst activation step (Mn3+-> Mn4+ and Zr2+-> Zr4+ oxidations) observed from electrochemical cyclic voltammetry (CV) and linear sweep voltammetry (LSV) studies that are tested in the alkaline environment. Concerning higher bifunctional activity for ZrTe-Mn2O3, the current density of 10 mA cm(-2) is revealed only at a lower overpotential of 244 mV and Tafel slope of 48 mV/dec toward better OER. At the same time, composite material also exhibited a minimal overpotential of 61 mV toward HER to attain 100 mA/cm(2). It was also found that introducing a connection of ZrTe with Mn2O3 improves the precise surface area and exposes more multi-active sites for easy transfer of electrons. In addition, it maintains excellent long-term stability for almost 110 hrs through chronoamperometry, which leads to no activity loss and further represents higher OER/HER activity in industrial applications. We conclusively demonstrate that the first-time reported research provides valuable insights attributed to the defective structure, porous nature, and covalently bridging between atomic-level heterogeneous interfaces, favouring rapid electron transfer process activation for continuously produced O-2 and H-2 gas bubbles