Thermal decomposition pathways of extracellular polymeric substances recovered from wastewater sludge using TG-FTIR with Gaussian deconvolution and 2D-COS analysis

, and HNCO). PC2 (210-450 °C, AE = 160-175 kJ/mol), represent the transition stage dominated by proteinaceous and lipid cross-linking, which produces nitrogenous species essential for promoting condensed-phase char development. PC3 (290-600 °C, AE > 180 kJ/mol) corresponds to the decomposition of humic-like substances and subsequent aromatic condensation of stable residues. Furthermore, comparative analysis reveals that EPS extracted from activated sludge exhibits higher thermal stability and a significantly increased char yield (33.5 %) than aerobic counterpart, attributed to higher AE during the middle decomposition stage. The persistent detection of C-O-C/P-O-C and aromatic C=C vibrations up to 700 °C confirms the formation of a phosphorus-rich aromatic char structure. This multi-dimensional analytical framework moves beyond conventional TG-based pseudo-component fitting, providing high resolution interpretation of the sequential evolution of volatile species and early-stage charring mechanisms of EPS.