Drying Kinetics and Pollutant release Characteristics of Organic Contaminated Soil

Abstract

ABSTRACT The non-isothermal drying behavior of organic contaminated soil was studied via thermogravimetric analysis. The contaminated soil demonstrated a preheating period and two falling-rate periods during the drying process, while a constant-rate period was absent. An increased heating rate during non-isothermal drying helped reduce the critical moisture content and increase the rate of the entire drying process. The optimal mechanism function of the two falling-rate periods was determined, and the reaction mechanism represented by it is three-dimensional diffusion with the spherical symmetric. The kinetic parameters at different heating rates were calculated, the apparent activation energy of the first falling-rate periods is between 20.8 kJ mol−1 and 64.8 kJ mol−1, while the apparent activation energy of the second falling-rate periods is between 13.6 kJ mol−1 and 20.8 kJ mol−1. The Midilli drying model was found to be the most suitable for describing the drying process of the contaminated soil. The pollutant precipitation characteristics during the drying process were observed through thermogravimetric mass spectrometry. At a drying temperature higher than 80–100°C, the concentration of benzene and other volatile organic compounds in the drying tail gas increased rapidly.