Pyrolysis Behaviors, Kinetics and Gaseous Products Evolution of Dye-Adsorbed Leather Shavings Hao Wang, Mingrui Zhang, Zonghui Zhang, Fang Wang, Mădălina Georgiana Albu Kaya, Xiumin Li, Keyong Tanga and Jie Liua,

Abstract

Chrome-tanned leather shavings (CLS), a challenging solid waste from tannery industry, are difficult to dispose of due to their small size and high chromium content. At the same time, CLS shows great potential as an adsorbent for toxic dyes due to its abundant functional groups and large surface area. To fully exploit this capability, this study proposes a novel waste-to-treat-waste strategy for the utilization and disposal of CLS. This approach involves using CLS as adsorbents for toxic dye removal, followed by pyrolyzing the dye-adsorbed CLS into less harmful substances or useful products. 
The pyrolysis behaviors and kinetics of three CLS samples, each adsorbed with a different dye (Congo red, reactive blue, and acid red), were investigated using thermogravimetric analysis and iso- conversional methods. The pyrolysis process was further analyzed using the generalized master plots method, revealing that the reaction model remained consistent with the A2 mechanism, despite significant variations in the average activation energy. The influence of adsorbed dyes on volatile products emissions during pyrolysis was analyzed using thermogravimetry coupled with Fourier transform infrared spectroscopy and mass spectroscopy.  Main gaseous products identified include CH4, H2O, CO, CO2, and trace amounts of sulfur- and nitrogen-containing compounds.