Co-pyrolysis of textile dyeing sludge and four typical lignocellulosic biomasses: Thermal conversion characteristics, synergetic effects and reaction kinetics

In this work, the thermal conversion characteristics, interactive effects and reaction kinetics during co-pyrolysis of textile dyeing sludge (TDS) and four typical lignocellulosic biomasses (peanut vine – PV, wheat straw – WS, cotton stalks – CS and sawdust – SD) were comparatively investigated based on thermogravimetric analysis. The results indicated that the more contents of cellulose and hemicelluloses in the raw materials, the larger pyrolysis characteristic index D was. Meanwhile, the type of biomass played an important role on the interactive effect during co-pyrolysis process, which could be inhibitive and accelerative. Moreover, CS pyrolysis with the simulation ash showed that the metallic oxide in TDS ash would react with the residue carbon to increase the mass loss at the final stage. According to kinetic analysis result, the reaction mechanism of TDS, biomasses and their blends can be well predicted by the reaction order model and the diffusion models, i.e. 0, 3rd and 1-D model. The kinetic analysis also suggests TDS co-pyrolysis with biomass could reduce the theoretical activation energy for thermochemical conversion. About 50% CS content was turned out to be the optimal additive for the co-pyrolysis.