Thermochemical conversion of textile waste to useful commodities and fuel

Abstract

The quantity of textile waste has been increased significantly in the recent years and a considerable portion of this waste has been sent to landfills, causing environmental issues. This research has been carried out to address this issue and propose a method for textile waste conversion to useful commodities such as chemicals or biofuels with potential of application in a commercial scale. Wool was selected as feedstock while gasification and pyrolysis were selected as the technologies with potential to facilitate the achievement of the objectives. Pyrolysis and gasification were carried out in bench-scale fixed bed reactor to check the feasibility of the pyrolysis for textile waste conversion. Furthermore, model compounds representing textile waste were pyrolysed with and without catalysts to evaluate if the properties of products could be modified. 5 different catalysts were used for pyrolysis of lignin, cellulose, and phenylalanine. The results indicated that Al-KIL2 and 20-ZSM5 had the potential to modify the properties of wool pyrolysis by-products and were used in wool pyrolysis in fixed bed. This decision was based on the increase in quantity of aromatics obtained in the oil products in based on the GC-MS analysis results. High CO content of gas, char product properties and marketable products such as phenols in the oil obtained in pyrolysisand gasification using fixed bed reactor proved that these technologies were promising. Therefore, a novel scaled-up system (auger reactor) for textile waste pyrolysis was designed, built, and modified. Comparing the findings of the gasification/pyrolysis of wool in the fixed bed and auger reactor, the conversion of feedstock to volatiles seemed to be more efficient in fixed bed while the properties of the char did not vary significantly. Regarding the oil products, while phenols and indoles were the prominent product in the fixed bed, ketones, nitriles and quinolines were the main products in the auger reactor. Overall, the results indicated that up to 2 kg/h of textile waste feedstock on its own (without mixing with other material) can be pyrolysed/gasified in this system and by-products could be collected successfully. Furthermore, it was observed that residence time, heating rate and product collection method have been the main contributor for the difference between the small scale and scaled-up tests.