Depolymerization of waste nylon 6 in [Bmim]Cl/water mixture

Depolymerization of nylon 6 (PA 6) to obtain caprolactam in the mixture of water and ionic liquid ([Bmim]Cl) was a environmentally benign and high efficient method. There are two reasons for the using of ionic liquid: first is that high w- concentration in the mixture and the other is that anions of ionic liquid can break the hydrogen bonding of PA 6. The products of depolymerization are analyzed by mass spectrometry and high-performance liquid chromatography and the main is caprolactam. The optimal conditions to obtain caprolactam are determined of reaction temperature 170 degrees C, 1L/H2O (w/w) 13.4%, and reaction time 8 h, and thus the yield of caprolactam 30.7% and degradation of PA 6 94.1%.