Using CO2 in pyrolysis to neutralise toxic aromatic compounds derived from blended textile waste

Abstract

Blended textiles are favoured for their enhanced properties, combining the strengths of constituent fibres (typically synthetic fibres integrated with natural cellulosic fibres). However, the presence of aromatic components in blended textile waste (BTW) complicates its disposal and raises environmental concerns due to the release of toxic chemicals. To resolve this issue, this study suggests a pyrolysis system as a strategy to neutralise toxic aromatic compounds derived from BTW. Carbon dioxide (CO₂) was used as the partial oxidative reagent. The characterisation of BTW revealed its composition, containing rayon and polyester. The complex composition of BTW, particularly the recalcitrant nature of polyester, leads to the massive generation of toxic aromatic chemicals, such as terephthalic acid and its analogues, during thermolysis. However, introducing CO₂ to pyrolysis facilitates interacting with these toxic compounds, converting them into carbon monoxide (CO). The effectiveness of CO₂ for the suppression of toxic aromatic formations was further enhanced when adopting a nickel-based catalyst. CO₂-assisted catalytic pyrolysis achieved a 64.87 % reduction in toxic aromatic chemicals and an 11.36-fold increase in CO production compared with conventional pyrolysis. This study presents a promising approach for the sustainable disposal of BTW, emphasising the oxidative functionality of CO₂ in neutralising toxic aromatic chemicals into detoxified products, especially CO.