Antisolvent crystallization of aqueous ammonium dihydrogen phosphate solutions by addition of methanol
| Autor: | Keshra Sangwal, Ewa Mielniczek-Brzóska |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Exothermic reaction
Aqueous solution Inorganic chemistry Analytical chemistry 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Chemical reaction Ammonium dihydrogen phosphate Endothermic process 0104 chemical sciences law.invention Inorganic Chemistry chemistry.chemical_compound chemistry law Metastability Materials Chemistry Methanol Crystallization 0210 nano-technology |
| Zdroj: | Journal of Crystal Growth. 451:139-149 |
| ISSN: | 0022-0248 |
| DOI: | 10.1016/j.jcrysgro.2016.07.027 |
| Popis: | Experimental results of antisolvent crystallization of ammonium dihydrogen phosphate from their aqueous solutions saturated at 30 °C by addition of methanol at preselected feeding rate R A , studied by in situ measurements of laser beam intensity I transmitted through solutions and their temperature T as functions of feeding time t for methanol at rate R A , are described and discussed. It was found that (1) measurement of temperature of solutions during antisolvent feeding is more informative and is more reliable than transmitted laser beam intensity measurements, (2) there are two regions of methanol feeding durations involving endothermic reactions and one region involving exothermic reactions, (3) the data of metastable zone width determined from the values of maximum antisolvent content Δ x max calculated from methanol feeding duration are reliable when the temperature difference Δ T = T s − T w , where T s and T w are temperatures of solution and water, respectively, for theoretical analysis, (4) rates Δ T /Δ t of linear changes in temperatures of solution and water with methanol feeding time t increases with feeding rate R A , and (5) the maximum changes Δ T max in the temperature of solution and water are related to antisolvent content Δ x associated with their appearance. It is argued that feeding of antisolvent methanol to saturated solutions or water leads to chemical reactions with evolution of heat. |
| Databáze: | OpenAIRE |
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