A non-destructive, environment-friendly method for separating and recycling polyamide 6 from waste and scrap polyamide 6 blended textiles

Abstract

Recycling their trash has garnered significant scientific interest as the use of waste and scrap (Was) polyamide 6 (PA6) blended textiles rises. Based on the complexation and decomplexation of PA6 with Ca2+, an investigation was conducted into the possibility of selectively and nondestructively dissolving and recovering PA6 and separating another component from Was PA6 blended models using CaCl2/ethanol/water (CEW) solvents. It was found through experiments that the dissolution of PA6 in CEW was related to temperature and stirring speed; the optimum conditions were chosen to be 75°C, 2 h, and 300 r/min, under which 94.80 wt% of Was PA6 textiles could be dissolved. Results also revealed that PA6 could be reprecipitated by simply adding water, whereas Ca2+ could be significantly removed by washing. The PA6 may be separated without degradation by controlled complexation and decomplexation, and the performance of Recycled PA6 (RPA6) was nearly identical to Was PA6 textiles. In addition, the two-component blended models experience non-destructive separation and recovery, and CEW treatment has little impact on the other components (except PA6). In this study, it is demonstrated that different types of Was PA6 blended textiles could be successfully separated via CEW treatment. Furthermore, the solvent system comprises easily accessible, low-cost materials that are widely used in industrial-scale processes. Thus, the concept will make a significant contribution to a green textile recycling strategy.