Clays play a catalytic role in pyrolytic treatment of crude-oil contaminated soils that is enhanced by ion-exchanged transition metals.

Autor: Denison SB; Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, United States., Da Silva PD; Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, United States., Koester CP; Department of Chemistry, Rice University, Houston, TX 77005, United States., Alvarez PJJ; Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, United States., Zygourakis K; Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, United States.
Jazyk: angličtina
Zdroj: Journal of hazardous materials [J Hazard Mater] 2022 Sep 05; Vol. 437, pp. 129295. Date of Electronic Publication: 2022 Jun 06.
DOI: 10.1016/j.jhazmat.2022.129295
Abstrakt: Pyrolytic treatment of crude-oil contaminated soils offers great potential for rapid remediation without destroying soil fertility with lower energy requirements than incineration. Here, we show that clays impregnated with non-toxic transition metals (iron or copper) can be used as an amendment to decrease the required pyrolytic treatment temperature and time. Amending a weathered crude-oil contaminated soil with 10 % (by weight) of bentonite modified via ion-exchange with Fe or Cu, achieved 99 % removal of residual total petroleum hydrocarbons (TPH) at a pyrolysis temperature of 370 °C with 15-min contact time. Pyrolytic treatment of amended soils at the unprecedentedly low pyrolysis temperature of 300 °C resulted in 87 % TPH removal efficiency with Cu-bentonite and a 93 % with Fe-bentonite. We postulate that the transition metals catalyzed the pyrolysis reactions at lower onset temperatures. This hypothesis is supported by thermogravimetric analysis coupled with mass spectrometry, which revealed the release of hydrogen, methyl and propyl ion fragments (markers of pyrolytic degradation products of crude oil) at lower temperatures than those observed for unamended soil. Overall, this work shows proof of concept that metal-impregnated clays can enhance rapid pyro-catalytic treatment of crude-oil contaminated soils and encourages further work to understand the detailed reaction mechanisms and inform process design.
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Databáze: MEDLINE
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