Effect and mechanisms of red mud catalyst on pyrolysis remediation of heavy hydrocarbons in weathered petroleum-contaminated soil. Issue 5 (October 2021)

• Record Type: Journal Article
• Authors: Liu, Yuqin; Li, Xiaodong; Zhang, Wenwen; Dou, Junfeng; Zhang, Qian; Ma, Fujun; Gu, Qingbao
• Is Part Of: Journal of environmental chemical engineering. Volume 9:Issue 5(2021)
• Publication Date: 2021-10
• Subjects: Contaminated soil -- Heavy hydrocarbons -- Red mud -- Catalytic pyrolysis -- Removal mechanism; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2021.106090
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: In this study, industrial waste red mud (RM)-assisted pyrolysis of weathered petroleum-contaminated soil (WPCS) was developed based on the principle of "Treating the wastes with wastes". In contrast with WPCS treated without RM at 400 °C for 30 min, the total petroleum hydrocarbons content reduced by 23.93% in the WPCS treated with 5% RM, and the contents of saturates, aromatics, resins, and asphaltenes decreased by 6.39%, 66.79%, 37.78%, and 64.95%, respectively. X-ray photoelectron spectroscopy results showed that the percentages of pyridinic−N and thiophene compounds on the surface of soil treated with 5% RM decreased significantly. The binding of metal oxides in RM with oxygen-containing groups and deposition of graphitic C increased the CO and O−CO groups. The activation energy at petroleum hydrocarbon thermal degradation stages of WPCS pyrolyzed with 5% RM reduced by 13.53% (lighter petroleum) and 16.40% (heavier petroleum), suggesting the strong catalytic action between RM and petroleum hydrocarbons. The catalytic mechanisms of RM for the removal of heavy hydrocarbons include (1) producing Brønsted/protonic acid in the absence of water vapor; (2) producing lattice oxygen [O] in the presence of water vapor; and (3) transforming metal oxides in RM into more active forms with a higher specific surface area. Our results suggest that the RM-assisted pyrolysis of WPCS is a cost-effective and energy-saving method that can not only promote heavy hydrocarbon removal but also relieve the environmental burden by converting industrial waste to a value-added product. Graphical Abstract: ga1 Highlights: Red mud-assisted pyrolysis of weathered petroleum-contaminated soil was conducted. TPH removal efficiency increased by 23.93%in the soil treated with 5% red mud. Red mud significantly promoted the removal of aromatics, resins, and asphaltenes. Ea of heavy hydrocarbons pyrolysis in soil was reduced significantly by red mud. Removal mechanisms of heavy hydrocarbons by red mud during pyrolysis were explored.