Delving into textile fast pyrolysis: A holistic study on the effects of feedstock and temperature variability

• Published in: Journal of cleaner production 2024-12, Vol.484, p.144278, Article 144278
• Main Authors: Cheng, Yoke Wang, Huang, Jiaqing, Tang, Xueying, Fu, Wenming, Xu, Dequan, Wang, Chi-Hwa
• Format: Article
• Language: English
• Subjects: Pollutant emission; Product applications; Pyrolysis products; Textile types; Thermochemical conversion
• ISSN: 0959-6526
• DOI: 10.1016/j.jclepro.2024.144278

Perpetual fast fashion wave, dismal global recycling rate, and poor circularity of textiles urged sustainable textile waste disposal solution in lieu of incineration and landfilling. Herein, textile fast pyrolysis was mooted as a promising solution by dint of its fast disposal rate, mild pollutant emission, and multiple value-added products formation. Following ill-defined thermochemical behaviour of individual textiles, in-depth experimental exploration on textile fast pyrolysis was supplemented by feedstock characterization, product distribution, and product characterization to unravel the effects of feedstock (natural/synthetic) and temperature (500–900oC) variability on pyrolysis products. Textile fast pyrolysis harnessed pyrogas with two variable products, viz. retrievable chars and oils [natural textiles: cotton (C), denim (D), & cashmere/plant fibre (CP)] or non-retrievable chars and waxes [synthetic textiles: polyester (P), P/acrylic (PA), & P/cotton (PC)]. Melting and high aromaticity of polyethylene terephthalate (PET) rendered the synthesis of non-retrievable chars and waxes, separately. Given monotonic char yields (7.31–24.19 wt%) reduction with temperature, the oil/wax (53.19–75.19/60.46–70.52 wt%) and gas (13.44–33.67 wt%) yields were negatively correlated to each other. Twill-woven network of D contributed to exclusively high BET surface area of D chars (132.64–217.10 m2/g). All natural textile chars (28.56–32.88 MJ) exhibited comparable higher heating value (HHV) to commercial coals/coke (14.77–34.39 MJ/kg) and biochars (7.26–33.37 MJ/kg). Compared to the commercial fuels, raw textile oils (incombustible-10.14 MJ/kg) and textile waxes (15.88–23.18 MJ/kg) were inferior fuels with low HHV. Nonetheless, cotton (C & D) oils, CP oils, and P-based textile waxes had respective enriched content of levoglucosan (6.85–34.38 area%), triacetoneamine (6.22–21.09 area%), and benzoic acid (16.37–46.55 area%). Considering noteworthy H2 formation data sets (700–900oC; C700 only), natural textile pyrogas (62.75–79.02%) had greater syngas (H2 & CO) composition than synthetic textile pyrogas (62.48–68.23%). At optimal temperature of 900oC, textile fast pyrolysis generated pyrogas with H2:CO ratios (1.30–3.49 ≈ 2) that nearly ideal for Fischer-Tropsch synthesis. Conversely, textile fast pyrolysis also emitted pollutant gases that differ between natural (NH3, N2O, NO, & SO2) and synthetic [NH3 (excluding P), N2O, & NO2] textiles. [Display omitted] •Fast pyrolysi