Elimination of ethanethiol released from municipal wastes by absorption sequencing electrochemical oxidation

ABSTRACT

As a typical municipal waste landfill gas, ethanethiol can become an air pollutant because of its low odor threshold concentration and toxicity to human beings. A hybrid process of absorption combined with electrochemical oxidation to degrade ethanethiol was investigated. The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF₄) was employed as an absorbent to capture ethanethiol from the air stream. Electrochemical oxidation demonstrated that ethanethiol could be oxidized on a β-PbO₂ anode modified with fluoride, while [BMIM]BF₄ was used as an electrolyte. After a reaction time of 90 min under a current density of 50 mA/cm², ethanethiol could be thoroughly destructed by the successive attack of hydroxyl radicals (·OH) electrogenerated on the surface of the β-PbO₂ anode, while the sulfur atoms in ethanethiol were ultimately converted to sulfate ions . The reaction mechanism is proposed, and the operating condition is also estimated with a kinetic model. This hybrid process could be a promising way to remove thiol compounds from municipal waste landfill gases.

KEYWORDS:

• Ethanethiol absorption
• electrochemical oxidation
• hydroxyl radical
• sulfur conversion
• kinetic model

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is financially supported by the NSFC [grant numbers 21473158, 21173188] and the 863 program of China [grant number 2013AA065900].