Pyrolysis of Denim Jeans Waste: Pyrolytic Product Modification by the Addition of Sodium Carbonate

Quickly changing fashion trends generate tremendous amounts of textile waste globally. The inhomogeneity and complicated nature of textile waste make its recycling challenging. Hence, it is urgent to develop a feasible method to extract value from textile waste. Pyrolysis is an effective waste-to-energy option to processing waste feedstocks having an inhomogeneous and complicated nature. Herein, pyrolysis of denim jeans waste (DJW; a textile waste surrogate) was performed in a continuous flow pyrolyser. The effects of adding sodium carbonate (Na(2)CO(3); feedstock/Na(2)CO(3) = 10, weight basis) to the DJW pyrolysis on the yield and composition of pyrolysates were explored. For the DJW pyrolysis, using Na(2)CO(3) as an additive increased the yields of gas and solid phase pyrolysates and decreased the yield of liquid phase pyrolysate. The highest yield of the gas phase pyrolysate was 34.1 wt% at 800 °C in the presence of Na(2)CO(3). The addition of Na(2)CO(3) could increase the contents of combustible gases such as H(2) and CO in the gas phase pyrolysate in comparison with the DJW pyrolysis without Na(2)CO(3). The maximum yield of the liquid phase pyrolysate obtained with Na(2)CO(3) was 62.5 wt% at 400 °C. The composition of the liquid phase pyrolysate indicated that the Na(2)CO(3) additive decreased the contents of organic acids, which potentially improve its fuel property by reducing acid value. The results indicated that Na(2)CO(3) can be a potential additive to pyrolysis to enhance energy recovery from DJW.