Multiscale evolution of VOC-loaded activated carbon during thermal regeneration: from contaminant desorption to carbon matrix reorganization.

Efficient regeneration of spent activated carbon (SAC) is critical for sustainable VOC abatement, yet the multiscale structural evolution during thermal treatment remains poorly understood. This study elucidates the multiscale structural evolution mechanism of SAC during thermal regeneration - from contaminant desorption to carbon matrix reorganization - through integrated multi-technique characterization (BET, SEM, TGA, XRD, FTIR). Key findings reveal a three-stage 'cleaning-reconstruction-degradation' mechanism: (i) Low-temperature treatment (300-400°C) removes surface contaminants and oxygen-containing groups, reopening blocked micropores; (ii) Optimal treatment at 400-500°C for 1-2 h achieves near-complete contaminant removal (>95%) while inducing controlled graphitization and beneficial mesoporosity development, restoring SBET to 965-1020 m²/g with well-preserved microporous architecture, indicating high potential for adsorption capacity recovery; (iii) Excessive treatment (≥600°C for 3 h) causes micropore collapse and sintering, reducing surface area. These findings establish a scientifically grounded optimal regeneration window (400-500°C, 1-2 h) that balances contaminant desorption efficiency with carbon matrix preservation, offering practical guidance for energy-efficient industrial regeneration of VOC-laden activated carbon from organic chemical manufacturing processes.