Kinetics of Hydrolytic Depolymerization of Textile Waste Containing Polyester

Abstract

Textile products comprise approximately 10% of the total global carbon footprint. Standard practice is to discard apparel textile waste after use, which pollutes the environment. There are professional collectors, charity organizations, and municipalities that collect used apparel and either resell or donate them. Non-reusable apparel is partially recycled, mainly through incineration or processed as solid waste during landfilling. More than 60 million tons of textiles are burnt or disposed of in landfills annually. The main aim of this paper is to model the heterogeneous kinetics of hydrolysis of multicomponent textile waste containing polyester (polyethylene terephthalate (PET) fibers), by using water without special catalytic agents or hazardous and costly chemicals. This study aims to contribute to the use of closed-loop technology in this field, which will reduce the associated negative environmental impact. The polyester part of waste is depolymerized into primary materials, namely monomers and intermediates. Reaction kinetic models are developed for two mechanisms: (i) the surface reaction rate controlling the hydrolysis and (ii) the penetrant in terms of the solid phase rate controlling the hydrolysis. A suitable kinetic model for mono- and multicomponent fibrous blends hydrolyzed in neutral and acidic conditions is chosen by using a regression approach. This approach can also be useful for the separation of cotton/polyester or wool/polyester blends in textile waste using the acid hydrolysis reaction, as well as the application of high pressure and the neutral hydrolysis of polyester to recover primary monomeric constituents.