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 H+ 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 °C, IL/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%.

Hydrolysis of corn residue, one of major by-products after the extraction of starch, in sub-critical water to produce amino acids was conducted in this paper. The quality and quantity analysis of amino acids in hydrolysate were carried out by Amino Acid Analyzer (Biological Liquid Chromatography), and the main amino acid of arginine were obtained. The effects of Solid-water ratio, reaction temperature and time on the yield of the arginine were investigated. It was found that the optimum hydrolysis conditions for arginine preparation from the corn residue in sub-critical water are as follows: solid-water ratio 0.05, reaction temperature 473K and reaction time 1h, and the yield of arginine 10.23%. The results show that the sub-critical water hydrolysis process has the advantages of high efficiency, simple process and friendly to environment.