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Author: search.filters.author.Boonchom, BanjongSubject: search.filters.subject.Thermodynamics

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    Simple synthesis, kinetics and thermodynamics of rod-like Cu2(OH)PO4 microparticles and rod-like Cu4O(PO4)2 nanoparticles
    (2020-08-01)
    Kullyakool, Saifon
    ;
    Boonchom, Banjong
    ;
    Chaiseeda, Kittichai
    Rod-like Cu<inf>2</inf>(OH)PO<inf>4</inf> microparticles were synthesized via a simple wet chemical reaction by mixing the solutions of CuSO<inf>4</inf>·5H<inf>2</inf>O and Na<inf>3</inf>PO<inf>4</inf>·12H<inf>2</inf>O at 90 °C for 24 h. Thermal transformation of the prepared Cu<inf>2</inf>(OH)PO<inf>4</inf> microparticles were related to endothermic dehydroxylation and its final decomposed product rod-like Cu<inf>4</inf>O(PO<inf>4</inf>)<inf>2</inf> nanoparticles were obtained. The XRD results indicated that Cu<inf>2</inf>(OH)PO<inf>4</inf> and Cu<inf>4</inf>O(PO<inf>4</inf>)<inf>2</inf> crystallize orthorhombic (space group Pnnm, D<inf>2h</inf> <sup>12</sup>) and triclinic (space group P1‾, C<inf>i</inf> <sup>1</sup>) phases, respectively. The thermal transformation mechanisms from Cu<inf>2</inf>(OH)PO<inf>4</inf> to Cu<inf>4</inf>O(PO<inf>4</inf>)<inf>2</inf> were expressed thought the relation of the graphical shape of isothermal combined with the non-isothermal multi-heating rate equation and kinetic models (P<inf>3/2</inf> and R<inf>2</inf>) to discuss the change of morphologies from microparticles to nanoparticles. Kinetic parameters and triplet thermodynamic functions of activated compound were determined and fully discussed. The obtained data will be useful for academic scientists and industrial researchers to apply these copper phosphates for special applications.
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    Study of kinetics and thermodynamics of the dehydration reaction of AlPO4 . H2O
    (2010-02-01)
    Boonchom, Banjong
    ;
    Kongtaweelert, Samart
    The kinetics and thermodynamics of the thermal dehydration of aluminum phosphate monohydrate, AlPO<inf>4</inf> . H<inf>2</inf>O were studied using thermogravimetry (TG-DTG-DTA) at four heating rates in dry air atmosphere. The activation energies of the dehydration step of AlPO<inf>4</inf> . H<inf>2</inf>O were calculated through the methods of Friedman (FR) and Flynn-Wall-Ozawa (FWO) and the possible conversion function has been estimated through the Achar and Li-Tang equations. The independent activation energies on extent of conversions and the better kinetic model of the dehydration reaction for AlPO<inf>4</inf> . H<inf>2</inf>O indicate single kinetic mechanism and the F<inf>2.05</inf> model as a simple n-order reaction of "chemical process or mechanism no-invoking equation", respectively. The positive values of ΔH<sup>#</sup> and ΔG<sup>#</sup> for the dehydration reaction show that it is endothermic and non-spontaneous process and it is connected with the introduction of heat. The kinetic and thermodynamic functions calculated for the dehydration reaction by different techniques and methods were found to be consistent. © Akadémiai Kiadó, Budapest, Hungary 2009.
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    Rapid synthesis, kinetics and thermodynamics of binary Mn 0.5Ca0.5(H2PO4)2 • H2O
    (2009-12-01)
    Boonchom, Banjong
    ;
    Danvirutai, Chanaiporn
    The binary manganese and calcium dihydrogen phosphate monohydrate Mn <inf>0.5</inf>Ca<inf>0.5</inf>(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf> • H<inf>2</inf>O was synthesized by a rapid and simple co-precipitation method using phosphoric acid, manganese metal, and calcium carbonate at ambient temperature. Thermal transformation shows complex processes and the final decomposed product was the binary manganese calcium cyclotetraphosphate MnCaP<inf>4</inf>O<inf>12</inf>. The activation energies of some decomposed steps were calculated by Kissinger method. Activated complex theory has been applied to each step of the reactions and the thermodynamic functions are calculated. These values for transformation stages showed that they are non-spontaneous processes without the introduction of heat. The differences of physical and chemical properties of the synthesized compound and its decomposed product are compared with M(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf> • H<inf>2</inf>O and M<inf>2</inf>P<inf>4</inf>O<inf>12</inf> (M = Mn and Ca), which indicate the effects of the presence of Ca ions in substitution of Mn ions and confirm the formation of solid solution. © 2009 Akadémiai Kiadó, Budapest, Hungary.