Thermochemistry and kinetics of the aspect of diammonium hydrogen phosphate precipitation in phosphoric acid solution
| Autor: | Khemaies Brahim, Amira Soussi-Baatout, Ismail Khattech, Khalil Rouissi |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Isothermal microcalorimetry
Precipitation (chemistry) Kinetics Inorganic chemistry 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics Kinetic energy 01 natural sciences Ammonium dihydrogen phosphate 010406 physical chemistry 0104 chemical sciences Ammonia chemistry.chemical_compound chemistry Thermochemistry Physical and Theoretical Chemistry 0210 nano-technology Phosphoric acid |
| Zdroj: | Journal of Thermal Analysis and Calorimetry. 143:3173-3179 |
| ISSN: | 1588-2926 1388-6150 |
| DOI: | 10.1007/s10973-020-09399-z |
| Popis: | The thermochemical and kinetic studies of diammonium hydrogen phosphate precipitation in phosphoric acid with ammonia were followed using a microcalorimetry at 25 °C. The calculated thermogenesis curves for various molar ratios show one, two, or three peaks. The plot of the amount of heat measured by integrating the raw signal of the acid–basic reaction presents four domains labeled as ‘a,’ ‘b,’ ‘c,’ and ‘d.’ In ‘a’ and ‘b’ domains, no solid was observed. From the slopes of line segments, it was possible to determine the enthalpies of the first and second neutralization of phosphoric acid (− 57 kJ mol−1 and − 28 kJ mol−1, respectively). However, domains ‘d’ and ‘c’ correspond to precipitation of ammonium dihydrogen phosphate and diammonium hydrogen phosphate. The presence of these compounds was checked by X-ray diffraction analysis performed on the solid precipitated in these domains. The TG, DTG and DTA curves confirm, also, the existence of these solids. The partial order rate with respect to NH3 and to H3PO4 is equal to 1 and 0.5, respectively. |
| Databáze: | OpenAIRE |
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