Hydrolytic depolymerization of major fibrous wastes

Abstract Sustainability is one of the main issues of today’s research and development. One aspect of sustainability is also the efficient treatment of waste. Fibrous-based wastes have quite different reasons. They are in different stages of degradation and are more or less chemically complex or contain nonfibrous materials (such as zippers, buttons, membranes, etc.). There are, therefore, plenty of various combinations of mechanical and chemical methods for processing them. The main aim of this work was to describe a proven practical strategy for depolymerization of mixed fibrous wastes to their submicron particles and monomeric components. High-pressure neutral and acid hydrolysis kinetics of cotton, wool, and polyester (PET) fibers and their 50/50 blends representing common components of textile wastes were investigated. High-pressure water-neutral hydrolysis and acid (strong and weak) hydrolysis were used for both pure-component and bicomponent fiber blends. Hydrolysis was conducted in a newly designed high-pressure reactor. Parameters of mechanistic models for the kinetics of heterogeneous solid–liquid degradation were evaluated by nonlinear least squares regression. Model characteristics were basic parameters for efficient selection of suitable decomposition of basic types of individual and mixture fibrous waste including time factor. Hydrolysis agents and conditions of decomposition were selected as optimal based on our previous experimental findings and modeling. Two pure, untreated raw materials were used for the experiments on the decomposition of natural fibers: raw cotton yarn and wool fibers. Two multicomponent mixtures, cotton and PET (weight ratio, 50:50) and wool and PET (weight ratio, 50:50), prepared from the materials described above, were selected.