کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
672660 | 1459447 | 2016 | 10 صفحه PDF | دانلود رایگان |
• Absorption affinity depends on interlayer cation charge.
• Acetylsalicylic acid readily undergoes hydrolysis with interlayer space water.
• Salicylic acid hydrolysis products adopt less thermal stable absorption sites.
• Salicylic acid molecules can persist until thermal decomposition to phenol.
• Salicylic acid decomposition-to-desorption ratios depend on interlayer cation charge.
Thermogravimetry-mass spectrometry is employed to characterize desorption and decomposition processes that occur when samples containing salicylic and acetylsalicylic acids absorbed to potassium, sodium, and calcium montmorillonites are heated. Whereas salicylic acid exhibits behavior similar to benzoic acid, in that the interlayer cation charge is the most important factor affecting desorption temperatures, acetylsalicylic acid decomposition is significantly affected by montmorillonite water content. When salicylic acid/clay samples are heated, desorption begins at temperatures slightly above 100 °C. At higher temperatures, decomposition produces phenol and carbon dioxide. Acetylsalicylic acid does not desorb. Instead, it reacts with water to produce salicylic and acetic acids. For both salicylic and acetylsalicylic acids, decomposition is favored for samples with low absorbate loadings, suggesting that initially absorbed molecules occupy more thermally stable environments than those subsequently incorporated into montmorillonite interlayer spaces.
Journal: Thermochimica Acta - Volume 639, 10 September 2016, Pages 120–129