A Headspace‐Analysis Approach to Assess the Sorption of Fuel Volatile Compounds by Soils

Abstract

Sorption of volatile compounds from fuel by soils affects the final environmental fate of these contaminants and strongly determines the efficiency of decontamination techniques. The headspace‐analysis approach used in this study indirectly relates the sorption exerted by soils with the contaminant analytical recovery, which will be different according to the matrix effect of each particular sample. The aim of this study was to assess the sorption of benzene, toluene, ethylbenzene, and xylene (BTEX) and fuel oxygenates by a wide selection of soil components and soil samples and to determine the influence of the physicochemical properties of the sample and the contaminant, the contaminant concentration, the incubation time, and the temperature on sorption. For this purpose, the samples were spiked with BTEX and fuel oxygenates in hermetically sealed vials and later analyzed by headspace‐gas chromatography–mass spectrometry under several contaminant concentration, incubation time, and temperature conditions. The results were then compared to assess the sorption exerted by each sample under each scenario. Significant differences were found between the recovery of BTEX and fuel oxygenates, mainly due to the different mobility, polarity, and sorption mechanisms involved while interacting with soil surface charges. Furthermore, these interactions determined the kinetic and strength of sorption and had a strong influence on the recovery of BTEX and fuel oxygenates at different temperatures. The headspace analysis approach resulted in a quick, easy, simple, automatable, and environmentally friendly technique to obtain important information for understanding the behavior of fuel volatile compounds in soil under very different conditions. In addition, it establishes a good starting point for developing more sophisticated adsorption and soil remediation studies.