Low-temperature treatment optimization for diesel-contaminated kaolin: Mutual impacts of generated pyrolytic carbon and particle agglomeration.

Environ Pollut

State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China; IRSM-CAS/HK Poly U Joint Laboratory on Solid Waste Science, Wuhan, 430071, China; Hubei province Key Laboratory of Contaminated Sludge and Soil Science and Engineering, Wuhan, 430071, China.

Published: December 2024

AI Article Synopsis

  • Efficiency improvements in low-temperature treatments for diesel-contaminated soil are necessary because of changes in soil properties and new substances created during the remediation process.* -
  • The study examines how pyrolytic carbon and kaolin aggregation interact, finding that the ideal temperature for mass loss occurs between 100 and 150 °C, while higher temperatures (over 200 °C) show minimal mass loss.* -
  • Results indicate that diesel contamination alters the fractal dimension of kaolin aggregates, affecting the adhesion forces and the formation of liquid bridges, ultimately influencing the decline rates of pollutant gas concentrations during thermal treatment.*

Article Abstract

Efficiency improvement in low-temperature treatment for diesel-contaminated sites is urgent because changes in soil properties and the generation of new substance during the remediation process can influence the duration and energy utilization. This paper focuses on low-temperature treatment optimization based on the mutual impacts of pyrolytic carbon and kaolin aggregation. Results reveal that the peak mass loss rate occurred between 100 and 150 °C, with minimal loss beyond 200 °C. Samples thermally treated at 150-200 °C exhibited darker colors, indicating pyrolytic carbon formation, corroborated by x-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), and three-dimensional fluorescence spectrum (3D-EEM) analyses. Additionally, diesel contamination influenced the fractal dimension of aggregates by influencing adhesion forces (<10000 mg/kg) and forming liquid bridges (≥10000 mg/kg) in untreated kaolin, resulting in an initial increase and subsequent fall in fractal dimension with increasing concentration. Decline rates of pollutant gas concentration were closely correlated with fractal dimension changes under thermal conditions due to pollutant volatilization and pyrolytic carbon formation. Based on the consistency between fractal dimension and decline rate, two critical remediation concentrations (C) and temperatures (T) indices were identified to optimize the low-temperature remediation.

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Source
http://dx.doi.org/10.1016/j.envpol.2024.125196DOI Listing

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