Comparative (co-)pyrolytic performances and by-products of textile dyeing sludge and cattle manure: Deeper insights from Py-GC/MS, TG-FTIR, 2D-COS and PCA analyses.

Not only does pyrolysis recover energy and value-added by-products but also reduces waste stream volume. The low volatiles and high ash contents of textile dyeing sludge (TDS) limit its mono-pyrolysis performance. This study aimed to conduct an in-depth analysis of its co-pyrolytic performance with cattle manure (CM). The co-pyrolysis enhanced the volatiles emission from the early devolatilization stage whose reaction mechanism shifted from a diffusion model to a reaction-order model. The further cracking of macromolecular materials was mainly elucidated by the reaction-order model. The temperature dependency of the co-pyrolytic gases was of the following order: aliphatic hydrocarbons > CO > alcohols, phenols, ethers, aldehydes, ketones, and carboxylic acids. The main co-pyrolytic volatile products were coumaran and 4-vinylguaiacol. The relative content of guaiacol-type components could be enhanced by co-pyrolysis and lowering the operational temperature to 450 °C. The interaction of co-pyrolysis enriched the char aromaticity. Our findings provide practical insights into the control and application opportunities and limitations on the high value-added energy and products from the co-pyrolysis of TDS and CM.