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Author: search.filters.author.Chansai, Sarayute

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    Smartphone-based disposable cotton-swab sensor loaded with creatinine/Cu–chlorophyllin–stabilized AuNPs for ultrasensitive RGB colorimetric detection of mercury (II) ions in aquatic environments
    (2026-05-01)
    Lerdpiriyaskulkij, Natee
    ;
    Detsri, Ekarat
    ;
    Teerasong, Saowapak
    ;
    Chansai, Sarayute
    ;
    Mathaweesansurn, Arjnarong
    A simple, rapid, selective, and sensitive colorimetric sensor based on a disposable cotton swab loaded with Au nanoparticle–modified Cu-chlorophyllin (Au<sup>0</sup>–NPs<inf>CHL</inf>) and creatinine was developed for mercury (II) detection in aquatic environments using smartphone–based RGB analysis. Au<sup>0</sup>–NPs<inf>CHL</inf> were synthesized by ultrasonic-assisted chemical reduction, employing Cu-chlorophyllin as a stabilizing and NaBH<inf>4</inf> as a reducing agent. A vivid red Au<sup>0</sup>–NPs<inf>CHL</inf> colloidal (7.96 ± 0.29 nm) with a sharp SPR peak at 515 nm was successfully obtained. An aliquot of 75 µL of Au<sup>0</sup>-NPs<inf>CHL</inf> (0.103 ± 0.03 nmol L<sup>−1</sup>) and 25 µL of creatinine solution (40 mg L<sup>−1</sup>) were sequentially loaded into an 8.0 × 0.5 cm cotton swab, separated by a 0.5 cm air gap. Detection began by immersing the swab into Hg<sup>2+</sup>–contaminated samples for 3 min, allowing Hg<sup>2+</sup> adsorption. Breaking the swab generated pressure differential, which, along with gravity, drove the Au<sup>0</sup>–NPs<inf>CHL</inf> to mix with creatinine. The resulting mixture migrated toward the swab tip by capillary action and reacted with adsorbed Hg<sup>2+</sup> through metallophilic 5d<sup>10</sup>–5d<sup>10</sup> interactions. Creatinine acted as a bridging ligand, inducing Au<sup>0</sup>–NPs<inf>CHL</inf> aggregation and shifting the SPR to 620 nm, causing a visible red-to-blue transition. This sensor enables rapid and visual detection and quantitative evaluation via smartphone RGB analysis. The system demonstrated excellent linearity from 1 to 100 µg L<sup>−1</sup> with a low LOD of 0.82 µg L<sup>−1</sup>. Recoveries of 97.6–101.8 % confirmed high accuracy and minimal matrix interference. The disposable cotton swab RGB sensor provides a rapid, portable, and practical tool for on-site primary assessment of Hg<sup>2+</sup> contamination in environmental samples.
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    Effect of metal dispersion and support structure of Ni/silicalite-1 catalysts on non-thermal plasma (NTP) activated CO2 hydrogenation
    (2020-09-05)
    Chen, Huanhao
    ;
    Goodarzi, Farnoosh
    ;
    Mu, Yibing
    ;
    Chansai, Sarayute
    ;
    Mielby, Jerrik Jørgen
    Non-thermal plasma (NTP) activated heterogeneous catalysis is a promising alternative to thermal catalysis for enabling many challenging reactions (e.g. catalytic CO<inf>2</inf> hydrogenation) under mild conditions. However, the mechanistic insight into the interaction between highly energetic electrons and vibrationally-exited reactive species with metal catalyst is still lacking. Here, catalytically active Ni nanoparticles supported on silicalite-1 zeolites with different configurations regarding the location of Ni active sites and support pore structures were comparably investigated using catalytic CO<inf>2</inf> hydrogenation under the thermal and NTP conditions. Experimental results revealed that the performance of the NTP-catalysis depends on the configuration of the catalysts significantly. Specifically, catalysts with Ni active sites sit on the outer surface of zeolite crystals (i.e. microporous Ni/S1 and Ni/M-S1@Shell with steam-assisted recrystallised micro-meso-porous structure) showed relatively good catalytic performance at a low applied voltage of 6.0 kV. Conversely, the encapsulated catalyst with hierarchical meso-micro-porous structure (i.e. Ni/D-S1) which has relatively small (i.e. average Ni particle sizes of 2.8±0.7 nm) and dispersed Ni nanoparticles (i.e. Ni dispersion of ca. 2.5 %) demonstrated comparatively the best catalytic performance (i.e. CO<inf>2</inf> conversion of ca. 75 %) at 7.5 kV. Additionally, under the NTP conditions studied, Ni on carbon-templated mesoporous silicalite-1 (Ni/M-S1) showed the worst selectivity to CH<inf>4</inf>, which was attributed to the poor accessibility of Ni active sites encapsulated in the enclosed mesopores. This study demonstrated the crucial role of catalyst design in NTP activated catalysis.