Pyrolysis as\na Remediation Strategy for Weathered\nOil-Contaminated Soil: The Role of Minerals and Native Organic Matter

Soil contaminated by weathered oil\n(WO) is the most challenging\nand toxic type of oily sludge (OS) to remediate. Its pyrolysis behavior\nis significantly affected by soil composition, including minerals\nand natural organic matter, yet the interaction mechanism remains\nunclear. This study systematically investigates the influence of natural\nminerals and organic matter on the pyrolysis behavior of WO-contaminated\nsoil, with a particular focus on the mechanisms of key minerals (e.g.,\nSiO<sub>2</sub>, CaO, MgO, Fe<sub>2</sub>O<sub>3</sub>, and Al<sub>2</sub>O<sub>3</sub>) and natural organic matter, represented by\nhumic acid (HA). The findings reveal substantial differences in the\ncatalytic performance of various minerals during pyrolysis. MgO and\nCaO exhibit exceptional catalytic cracking capabilities in the mid-\nto high-temperature range, significantly enhancing the quality of\npyrolysis-derived oil and gas fuels. Fe<sub>2</sub>O<sub>3</sub> demonstrates\nsuperior performance at elevated temperatures by promoting aromatic\nstability and hydrogen production. Moreover, HA, in synergy with minerals,\noptimizes pyrolysis pathways, improves hydrocarbon fuel yields, and\nrefines the characteristics of the residual materials. This study\nfurther elucidates the distribution patterns of pyrolysis products\nand their intricate interactions with minerals and organic matter,\nproviding critical insights for the efficient remediation of WO-contaminated\nsoil. These findings offer a novel perspective on the restoration\nand resource utilization of WO-contaminated soil while delivering\nvaluable guidance for advancing catalytic pyrolysis technologies.