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Author: search.filters.author.Chaiyasith, PachernchaipatSubject: search.filters.subject.Thermodynamic properties

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    A new synthesis of BaHPO4 precipitated by BaCO3-H4PO4-NaOH system at room temperature
    (2013-08-30)
    Boonchom, Banjong
    ;
    Ruttanapun, Chesta
    ;
    Thongkam, Montree
    ;
    Chaiyasith, Pachernchaipat
    ;
    Woramongkonchai, Somsak
    Barium hydrogenphosphate, BaHPO<inf>4</inf> was synthesized for the first time through simple and rapid method using BaCO<inf>3</inf>-H<inf>3</inf>PO<inf>4</inf>-NaOH, pH =9.0 at room temperature for 30 min. The studied BaHPO<inf>4</inf> decomposed in a single well-defined stage via deprotonated hydrogenphosphate reactions, revealed by TG/DTG and DSC techniques. The calculated wavenumbers based on DSC peak were comparable with FTIR results, which support the breaking bonds of P-OH (HPO<inf>4</inf><sup>2-</sup>) in the deprotonated hydrogenphosphate reactions. The thermodynamic functions (ΔH*, ΔG*, and ΔS*) for the deprotonated hydrogenphosphate reactions calculated from DSC data indicate that the deprotonated HPO<inf>4</inf><sup>2-</sup> reaction occur a lower-energy pathway and spontaneous process. The FTIR, XRD and SEM data of the studied BaHPO<inf>4</inf> and its decomposed product Ba<inf>4</inf>P<inf>2</inf>O<inf>7</inf> are also reported. © (2013) Trans Tech Publications, Switzerland.