Study on Pyrolysis Characteristics of Tannery Sludge based on Distributed Activation Energy Model and TG-FTIR-MS Method

There are a large amount of inorganic and organic matter and a variety of heavy metal compounds in the tannery sludge. The reasonable treatment and resource utilization of this type of hazardous waste is one of the key issues for the sustainable development of leather industry. Thermogravimetric analysis was performed to study the pyrolysis behavior of tannery sludge under different heating rates, and the relationship between pyrolysis activation energy and conversion was calculated using the distributed activation energy model (DAEM). Thermogravimetry-Fourier transform infrared spectrometry-Mass spectroscopy (TG-FTIR-MS) technology was used to investigate the composition of evolved gaseous products, and the pyrolysis characteristics of tannery sludge were analyzed. Results showed that the thermal weight loss process of tannery sludge can be divided into three stages, with the main weight loss at 200-600 ℃. The activation energy of the tannery sludge pyrolysis process presented a staged distribution, mainly concentrated in the lower activation energy area. TG-FTIR-MS analysis indicated that the main components of the gas released during the pyrolysis process of the tannery sludge were CO₂, H₂O, CH₄ and CO, which is resulted from the thermal decomposition of protein macromolecules and inorganic substances such as calcium carbonate.