An effective thermal treatment of toluene-contaminated soil by uniform heating from microwave coupled infrared radiation (MCIR)

Thermal treatment technologies are generally very effective for the remediation of soils contaminated. For the traditional thermal treatment method of contaminated soil, the heating method from the outside to the inside will inevitably cause a waste of energy, and it may be expensive due to the energy costs. Therefore, it is necessary to find a new heating technology to improve the thermal treatment. In this study, a novel microwave coupled infrared radiation (MCIR) technology was used to achieve uniform heating treatment of contaminated soil. A mathematical model was established and applied to simulate the electric field and temperature induced by microwave radiation and MCIR. The model results showed that MCIR heating produces well uniformity of thermal field distribution. Then, the influence of infrared in the MCIR treatment of soil was investigated by the lab experiment. The lab experimental results indicated that infrared could efficiently improve the microwave treatment of soil. A toluene removal efficiency of 92.8% could be achieved at 500 W microwave coupled with 300 W infrared radiation for 300 s, retaining 9.2% soil moisture. In addition, it exhibited a high cost-benefit. Furthermore, MCIR did not destroy the structure of toluene by infrared spectrum analysis. The results show that this MCIR treatment has the advantages of uniform heating, high efficiency, and low damage, which indicates the application prospect of MCIR in soil remediation.