Co-pyrolysis of chrome-tanned leather shavings with wheat straw: thermal behavior, kinetics and pyrolysis products

The thermal behavior and kinetics of chrome-tanned leather shavings (CLS)/wheat straw (WS) blends at different mass ratios during co-pyrolysis were investigated, and the pyrolysis products were characterized. Model-free isoconversional and master-plots methods were applied to determine kinetic triplet of the pyrolysis/co-pyrolysis of CLS, WS and their blends based on thermogravimetric (TG) analysis. Results showed that the activation energy for CLS pyrolysis was reduced by the addition of WS, and a synergistic promoting effect predominated across the majority of temperature ranges and feedstock compositions during the co-pyrolysis process. TG-Fourier transform infrared spectrometry-Mass spectrometry analysis showed the changes in evolution profiles of H2O, CO, CO2, HNCO and pyrrole during pyrolysis. The pyrolysis solid residues were characterized and results indicated that the addition of WS to CLS can increase solid residue yield and potentially inhibit the formation of hexavalent chromium during pyrolysis. This study helps to foster a promising solution for the valorization and safe disposal of chromium-containing solid wastes from leather industry.