Muanghlua, Rangson

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Muanghlua, Rangson
Alternative Name
Muanghlua, R.
Muanghlua, Rangsan
Main Affiliation
Email
rangson.mu@kmitl.ac.th

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    Item type:Publication,
    Surface phosphatization of cerium-lanthanum oxides for catalytically inert white pigments
    (2025-11-01)
    Onoda, Hiroaki
    ;
    Wada, Takuma
    ;
    Charoonsuk, Thitirat
    ;
    Pulphol, Phieraya
    ;
    Muanghlua, Rangson
    Cerium dioxide (CeO<inf>2</inf>) is a UV-scattering agent commonly employed in sunscreens but suffers from oxidative catalytic activity, raising concerns for dermal applications. To address this issue, surface passivation via phosphatization has been explored, although prior attempts with CeO<inf>2</inf> alone failed to eliminate its intrinsic yellow hue due to low reactivity with phosphoric acid. In this study, we introduce a novel white pigment synthesized via the phosphoric acid-mediated treatment of CeO<inf>2</inf>–La<inf>2</inf>O<inf>3</inf> mixtures. By co-utilizing lanthanum oxide, which readily forms lanthanum phosphate—a white, inert compound—we achieved enhanced suppression of oxidative activity alongside improved whiteness. The composite materials were systematically characterized via X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), particle size analysis, colorimetry (Lab*), and catalytic activity assays. The results reveal that phosphatization preferentially proceeds at lanthanum sites, forming phosphate-rich surface layers that diminish redox activity while maintaining favorable dispersion and smoothness properties. The pigment shows high acid resistance and negligible photocatalytic activity, indicating its potential as a safe, non-reactive alternative for cosmetic formulations. This work advances the development of rare-earth-based functional pigments via a scalable, low-temperature route.
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    Item type:Publication,
    Acidic dynamics: Unveiling mechanistic insights for improved performance in chitosan triboelectric nanogenerators
    (2024-07-01)
    Charoonsuk, Thitirat
    ;
    Ukasi, Sirinya
    ;
    Mokthaisong, Panadta
    ;
    Khuntakaew, Pawita
    ;
    Hajra, Sugato
    In recent years, there has been a surge in interest surrounding the development of chitosan (CS)-based triboelectric nanogenerators (TENG) for powering attachable/portable devices. Despite numerous strategies aimed at enhancing their efficiency, the selection of acid solvent has remained largely unexplored. In this study, various acids, including acetic (CH<inf>3</inf>COOH), succinic (C<inf>4</inf>H<inf>6</inf>O<inf>4</inf>), and citric (C<inf>6</inf>H<inf>8</inf>O<inf>7</inf>) acids, were investigated for their impact on mechanical and electrical output signals. Remarkably, the choice and concentration of acid were found to significantly influence performance. Specifically, employing citric acid rendered the CS solid film more pliable and yielded the highest output signal at optimal concentration levels. Under optimized conditions, the CS-TENG exhibited an open-circuit voltage output (V<inf>OC</inf>) of 157 V and short-circuit current output (I<inf>SC</inf>) of 53 µA—more than triple that of pristine CS-TENG. Mechanistic insights into electrical generation have been elucidated, underscoring the importance of solvent selection in CS TENG fabrication. These findings underscore the potential for tailored acid solvent selection to advance specialized applications in the field.
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