Propylene glycol-mixed steam enhanced extraction for an efficient and sustainable remediation of PAHs-contaminated soil

Rui Yue; Zhikang Chen; Likun Zhao; Xin Song; Chaoqi Chen; Jin Qi; Xuhui Mao

doi:10.1016/j.jhazmat.2023.132029

Propylene glycol-mixed steam enhanced extraction for an efficient and sustainable remediation of PAHs-contaminated soil

J Hazard Mater. 2023 Oct 5:459:132029. doi: 10.1016/j.jhazmat.2023.132029. Epub 2023 Jul 13.

Authors

Rui Yue¹, Zhikang Chen¹, Likun Zhao¹, Xin Song², Chaoqi Chen¹, Jin Qi¹, Xuhui Mao³

Affiliations

¹ School of Resources and Environmental Science, Wuhan University, Wuhan 430079, China.
² Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
³ School of Resources and Environmental Science, Wuhan University, Wuhan 430079, China. Electronic address: clab@whu.edu.cn.

PMID: 37499501
DOI: 10.1016/j.jhazmat.2023.132029

Abstract

An innovative thermal desorption method, propylene glycol (PG)-mixed steam enhanced extraction, is proposed for a highly efficient remediation of polycyclic aromatic hydrocarbons (PAHs)-contaminated soil. It is found that injecting PG-mixed steam into soil column could obtain > 99% removal efficiencies of PAHs either for the pyrene-spiked soil, or for the contaminated field soil with high-molecular-weight PAHs. PG is a safe and low-cost dihydric alcohol with a boiling point higher than water. When the PG-mixed steam penetrated the contaminated soil, the PG vapor preferentially condensed to form a hot liquid with concentrated PG (e.g., from 30 wt% PG in gas phase to 90 wt% PG in the liquid phase), which would significantly solubilize the PAHs and enhance their desorption from soils. The results also revealed that the effluents derived from the PG-mixed steam could be purified by removing the desorbed PAHs using a simple coagulation treatment, and the recovered PG solution could be reused. The plant assay using wheat seeds showed that the remediated soil had a good regreening potential. Our results demonstrate that PG-mixed steam injection is a promising thermal desorption method for an efficient and sustainable remediation of PAHs-contaminated soil.

Keywords: PAHs-contaminated soil; Soil flushing; Soil remediation; Solvent-mixed steam; Steam enhanced extraction (SEE).