Synthesis, Characterization and Efficiency of 1-Ethyl-3-methylimidazolium tetrafluoroborate ([emim]BF4) for Degradation of Waste Nylon-66

Ionic liquid 1-ethyl-3-methylimidazoliumtetrfluoroborate ([emim]BF4) has shown efficient degradation of waste nylon-66 (polyamide) into its useful monomers. The degradation of nylon-66 was carried out in two different ways. In the first method, [emim]BF4 provides the reaction medium as a solvent where N, N-dimethylaminopyridine (DMAP) works as a catalyst, which promotes the degradation of nylon-66 effectively. The reaction was executed at 290–300 °C for 1 hour. After benzoylation, the benzoyl derivative of hexamethylenediamine (BDHMD) was obtained with maximum yield, and adipic acid was obtained by repeatedly extracting with ethyl acetate from the reaction mixture. The second method involves hydrolysis, in which 0.5 g of waste nylon-66, 0.1 mole [emim]BF4 as catalyst, and 5N HCl were refluxed at around 100–120 °C for 12-15 hours. After cooling the reaction mixture, it was neutralized by 5N NaOH to make a slightly alkaline solution, followed by benzoylation by using benzoyl chloride to yield DBHMD. Following filtration and extracting the filtrate using ethyl acetate multiple times to obtain adipic acid, it was recrystallized with methanol. The obtained monomers were characterized with FT-IR. At the end of the reaction, the ionic liquid can be regenerated without changing its efficiency.