We investigated the ammonium removal abilities of natural and synthetic zeolites with distinct Si/Al ratios and various surface areas to study how adsorption and ion exchange processes in zeolites perform under different ammonium concentrations and different temperatures. Five zeolites—natural mordenite, chabazite, erionite, clinoptilolite, and synthetic merlinoite—were immersed in 20, 50, and 100 mg/kg ammonium solutions. The results demonstrate that zeolites under high ammonium concentrations (100 mg/kg) possess higher physical adsorption capacity (0.398–0.468 meq/g), whereas those under lower ammonium concentrations (20 mg/kg) possess greater ion exchange properties (64–99%). The ion exchange ability of zeolites is extremely dependent on the cation content of the zeolites, and the cation content is affected by the Si/Al ratio. The surface area of zeolites also has a partial influence on its physical adsorption ability. When the surface area is less than 100 m2/g, the adsorption ability of zeolite increases obviously with surface area; however, adsorption ability is saturated as the surface area becomes larger than this critical value of 100 m2/g. When we placed the zeolites in 50 mg/kg ammonium concentration at different temperatures (5–50 °C), we found that the zeolites exhibited the highest ammonium removal ability at 30 °C and the potassium release was enhanced at 30–40 °C.
304 stainless steels (SS) were considered as the materials for a dry storage canister. In this study, ER (Electrode Rod) 308L was utilized as the filler metal for the groove and overlay welds of a 304L stainless steel substrate, which was prepared via a gas tungsten arc-welding process in multiple passes. The electron backscatter diffraction (EBSD) map was used to identify the inherent microstructures in distinct specimens. U-bend and weight-loss tests were conducted by testing the 304L substrates and welds in a salt spray containing 5 wt % NaCl at 80 °C to evaluate their susceptibility to stress corrosion cracking (SCC). Generally, the weight loss of the ER 308L deposit was higher than that of the 304L substrate in a salt spray in the same sample-prepared condition. The dissolution of the skeletal structure in the fusion zone (FZ) was responsible for a greater weight loss of the 308L deposit, especially for the cold-rolled and sensitized specimen. Cold rolling was detrimental and sensitization after cold rolling was very harmful to the SCC resistance of the 304L substrate and 308L deposit. Overall, the SCC susceptibility of each specimen was correlated with its weight loss in each group.
The increased thermal efficiency of fossil power plants calls for the development of advanced creep-resistant alloy steels like T92. In this study, microstructures found in the heat-affected zone (HAZ) of a T92 steel weld were simulated to evaluate their creep-rupture-life at elevated temperatures. An infrared heating system was used to heat the samples to 860 °C (around AC1), 900 °C (slightly below AC3), and 940 °C (moderately above AC3) for one minute, before cooling to room temperature. The simulated specimens were then subjected to a conventional post-weld heat treatment (PWHT) at 750 °C for two hours, where both the 900 °C and 940 °C simulated specimens had fine grain sizes. In the as-treated condition, the 900 °C simulated specimen consisted of fine lath martensite, ferrite subgrains, and undissolved carbides, while residual carbides and fresh martensite were found in the 940 °C simulated specimen. The results of short-term creep tests indicated that the creep resistance of the 900 °C and 940 °C simulated specimens was poorer than that of the 860 °C simulated specimens and the base metal. Moreover, simulated T92 steel samples had higher creep strength than the T91 counterpart specimens.
11 September 2024 in International Journal of Food Microbiology
The surface behavior of ZnO-based films can be modulated via the postannealing and ultraviolet (UV) illumination of different strengths and durations, respectively. The present results could provide the basis for modulating their microstructures with respect to the grain-size distribution and photocatalytic behavior, and act as a potential guide in the field of wide-bandgap semiconducting oxides. ZnO films were prepared at room temperature onto Corning-1737 glass substrates by applying radio-frequency magnetron sputtering without supplying an oxygen source. With the purpose of obtaining modulational grain microstructures, the as-prepared ZnO films (Z0) were treated via a postannealing modification in a vacuum furnace at 300 °C for 30 min after deposition (Z300), accompanied by adjustable internal stress. The contact angle (CA) value of the ZnO films was reduced from 95° to 68°, owing to the different grain microstructure accompanied by a change in the size variation. In addition, UV light with different illumination strengths could be used to improve the hydrophilicity, which varied from a hydrophobic status to a superhydrophilic status due to the desirable surface characteristics of its photocatalytic action. In addition, the photocatalytic activity of the ZnO films exhibited an effectual photodegradation of methylene blue (MB) under UV illumination, with a chemical reaction constant of 2.93 × 10−3 min−1. In this present work, we demonstrated that the CA value of the ZnO films not only caused a change from a hydrophobic to hydrophilic status, accompanied by a change in grain size combined with internal stress, but also, induced by the UV light illumination, was combined with photocatalytic activity simultaneously. On the other hand, an enhanced surface plasmonic resonance was observed, which was due to couple oscillations between the electrons and photons and was generated from the interface by using a flat, continuous Pt capping nanolayer. This designed structure may also be considered as a Pt electrode pattern onto ZnO (metal Pt/ceramic ZnO) for multifunctional, heterostructured sensors and devices in the near future.
The surface plasmonic resonance, surface wettability, and related mechanical nanohardness and of face-centered-cubic (fcc) chromium nitride (CrN) films have been successfully manipulated via the simple method of tuning nitrogen-containing gas with different nitrogen-to-argon ratios, varying from 3.5 (N35), to 4.0 (N40), to 4.5 (N45), which is directly proportional to argon. All of the obtained CrN films showed that the surface wettability was due to hydrophilicity. All of the characteristics were mainly confirmed and explained by using X-ray diffraction (XRD) patterns, including plan-view and cross-section SEM images, with calculations of the average grain size performed via histograms accompanied by different preferred grain orientations. In the present work, not only the surface plasmonic resonance, but also the surface wettability and the related mechanical nanohardness of CrN films were found to be tunable via a simple method of introducing adjustable nitrogen-reactive-containing gas during the deposition process, while the authors suggest that the crystal orientation transition from the (111) to the (200) crystalline plane changed significantly with the nitrogen-containing gas. So the transition of the preferred orientation of CrN’s cubic close-packed from (111) to (200) varied at this composite, caused and found by the nitrogen-containing gas, which can be tuned by the nitrogen-to-argon ratio. The surface plasmonic resonance and photoluminescence quenching effects were coupled photon and electron oscillations, which could be observed, and which existed at the interface between the CrN and Au metals in the designed heterostructures.