Sample preparation method for IR analysis of petroleum-contaminated soil: An innovative technology for ecological remediation using Miscanthus x giganteus

<i>Miscanthus x giganteus</i> phytoremediation of soil contaminated with petroleum was assessed in this study. A method of soil sample preparation for determining the total content of petroleum products by infrared spectrophotometry has been developed. It is a one-stage extraction method with minimal use of carbon tetrachloride as an extractant. This soil sample preparation method was environmentally friendly and cost-effective, as it required a significantly lower amount of extractant (15-30 ml of tetrachloromethane) compared to the commonly used threefold extraction method, which uses up to 150 ml of extractant. The extraction degree of petroleum products (PP) was determined to be from 81.78 % to 94.22 % after two days of extraction using the additive method of determining PP. It was observed that the presence of different fertilizer additives in the soil samples led to a reduction in the determined PP content in the following series: "without fertilizer" - "Biochar" additive - "Biohumus" additive. These results were compared with reference samples that did not involve the use of <i>Miscanthus x giganteus</i>. Furthermore, the main thermolysis stages of petroleum products sorbed by the soil matrix and the thermal behavior of an artificial soil sample spiked with PP were examined. Detailed interpretation of thermograms of laboratory soil samples was conducted at various phytoremediation stages.