In this paper, a sensitive atomic emission spectrometer (AES) based on a new low power and low argon consumption (<8 W, 100 mL min) miniature direct current (dc) atmospheric pressure glow discharge (APGD) plasma (3 mm × 5 mm) excitation source was developed for the determination of arsenic in water samples. In this method, arsenic in water was reduced to AsH by hydride generation (HG), which was then transported to the APGD source for excitation and detected by a compact CCD (charge-coupled device) microspectrometer. Different parameters affecting the APGD and the hydride generation reactions were investigated. The detection limit for arsenic with the proposed APGD-AES was 0.25 μg L, and the calibration curves were found to be linear up to 3 orders of magnitude. The proposed method was successfully applied to the determination of certified reference material (GBW08605), tap water, pond water, groundwater, and hot spring samples. Measurements from the APGD analyzer showed good agreement with the certified value/values obtained with well-established hydride generation atomic fluorescence spectrometry (HG-AFS). These results suggest that the developed robust, cost-effective, and fast analyzer can be used for field based arsenic determination and may provide an important tool for arsenic contamination and remediation programs.
Removing the interferences such as Ce on Nd isotopes during column chemistry is hardly achieved due to their similar properties. In this study, we established a simple but efficient Nd...
In
the context of current energy and environmental crises, dry
reforming of methane (DRM) is an important reaction. While non-noble
metal catalysts are highly promising for real-world DRM applications,
they often suffer from deactivation due to sintering and carbon deposition.
In this study, ultrafine bimetallic NiCo nanoparticles encapsulated
in silicalite-2 (S-2) were prepared via an in situ growth method. Density functional theory in combination with microkinetic
modeling was used to understand the influence of the alloy on reaction
kinetics and the resistance to carbon deposition. Elemental segregation
was observed during the activation stage, wherein the Ni and Co atoms
migrated toward the outer surface and center of the NiCo alloy, respectively.
Subsequently, the Ni0.2Co0.3@S-2 catalyst prepared
using the optimized Ni/Co ratio showed stable and high CH4 and CO2 conversions for 100 h with no carbon deposition.
The confinement effect together with precisely balancing the carbon
and oxygen content on the surface of the catalyst contributed to its
high catalyst performance. This work is expected to provide relevant
guidance for studying the evolution of catalyst structures via material
dynamics elucidation.
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