Investigation into the removal of persistent organic pollutants from soil using infrared thermal desorption apparatus

Abstract The rapid accumulation of electronic waste has led to severe soil contamination with persistent organic pollutants (POPs), particularly polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), posing significant environmental and health risks. Consequently, this study developed and evaluated a vacuum-infrared thermal desorption system for the efficient remediation of POPs-contaminated soil. A comprehensive investigation was conducted to determine the critical operating factors governing the desorption process. The results identified temperature, pressure, and residence time as the dominant factors affecting POPs removal, whereas moisture content and particle size exhibited minimal influence. Furthermore, a second-order polynomial prediction model for POPs removal was established using response surface methodology based on a box-behnken design, achieving an R 2 of 0.9921. It is noteworthy that the synergistic interaction between high temperature (400°C) and low pressure (100 Pa) significantly enhanced the contaminant removal rate of POPs to levels exceeding 90%. Moreover, an increase in heating rates substantially accelerated the removal of POPs independent of system pressure, progressing from a rapid initial spike to a subsequent phase of steady enhancement. Throughout this process, PBDEs consistently exhibited higher removal efficiencies than PCBs due to their lower thermal decomposition thresholds. In conclusion, these findings not only validate the feasibility of the integrated vacuum-infrared technology but also provide crucial theoretical guidance and technical support for the energy-efficient remediation of POPs-contaminated soil.