Valorization potential of dried tannery fleshing wastes (TFW) through pyrolysis in the leather industry: Kinetic and thermodynamic investigations

Since the moisture content of the tannery fleshing waste (TFW) of the leather industry is too high, this paper evaluates the effects of open air and greenhouse drying pretreatment on the valori-zation potential of these wastes by pyrolysis. The pyrolysis behavior and kinetics were studied using KAS and Starink model-free methods and the reaction mechanisms of both dried TFW samples were established by the Coats-Redfern model. The activation energy (E & alpha;) calculated by KAS and Starink methods were similar for both samples, resulting in 121.71, 149.32 and 169.80 kJ mol-1 for TFW-OD and 155.41, 203.33 and 175.19 kJ mol-1 for TFW-GD in the first, second and third stages respectively. Moreover, the performance of two drying approaches on the behavior of TFW slow pyrolysis was studied at 500 degrees C and focused on biochar production to improve the feasibility of the TFW pyrolysis process, with the main goal of moving towards circular economy in the leather industry. The obtained results revealed that produced biochars are not suitable for either subsequent energetic valorization as fuels (H/C > 0.7). However, they showed a great potential for soil amendment (R50 = 0.11-0.12), long-term carbon storage (O/C < 0.4), fertilizers or sorbent for tannery wastewater treatment where adsorption of dyes is essential. Amongst the drying pretreatments, the open-air drying method proved to be the most suitable for industrial scale unit to convert TFW into economic value biochar.