Upcycling polyamide containing post-consumer Tetra Pak carton packaging to valuable chemicals and recyclable polymer. (15th July 2021)

• Record Type: Journal Article
• Authors: Chen, Xiaolin; Luo, Yixin; Bai, Xianglan
• Is Part Of: Waste management. Volume 131(2021)
• Page Start: 423
• Page End: 432
• Publication Date: 2021-07-15
• Subjects: Tetra Pak -- Recycling -- Levoglucosenone -- Furfural -- Caprolactam -- Polyethylene; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2021.06.031
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: Carton was converted in THF to selectively decompose paper fraction. Up to 19.2% of LGO and 8.6% furfural were produced in a single step. PE and PA in carton were not affected by the conversion in THF. High-quality PE was recovered by solvent dissolution. Caprolactam with high selectivity was produced by pyrolysis. Abstract: Billion tons of post-consumer Tetra Pak cartons are discarded annually as land and ocean wastes, creating significant environmental problems and resource losses. Recycling of the carton wastes is hindered by its multi-material compositions and low values of the recycled products. In this study, a novel upcycling of the cartons was investigated. A post-consumer carton consisting of paper, polyolefin, and polyamide was directly converted in 210–230 °C tetrahydrofuran containing 10–20 mM acid to produce up to 19.2% of levoglucosenone and 8.6% of furfural by selectively decomposing paper fraction. The remaining solids containing mostly intact polyethylene and polyamide but also a smaller fraction of paper-derived char were separated using a solvent-dissolution method. The xylene-soluble fraction was a recycled polymer similar to the original polyethylene, which was verified by its functional groups, the composition of the pyrolysis products, and the melt rheology results. The xylene-insoluble fraction was a mixture of polyamide and paper-derived char. Upon pyrolysis, caprolactam was produced as the only major vapor product. The remaining, thermally stable paper-derived char could be used as a high-quality solid fuel. Overall, the demonstrated recycling method could potentially maximize the values of the products recovered from carton wastes.