Low-temperature Hg⁰ abatement by ionic liquid based on weak interaction

Area of Science:

• Environmental Chemistry
• Materials Science
• Chemical Engineering

Background:

• Low-temperature gaseous elemental mercury (Hg⁰) poses significant environmental risks and requires effective industrial flue gas treatment.
• Current methods for Hg⁰ abatement often face challenges at low temperatures, necessitating innovative solutions.

Purpose of the Study:

• To develop and evaluate novel ionic liquids for efficient Hg⁰ capture at low temperatures.
• To investigate the interaction mechanisms between ionic liquids and Hg⁰ to optimize mercury removal performance.

Main Methods:

• Design and synthesis of ionic liquids with varied anions: 1-butyl-3-methylimidazolium thioacetate ([Bmim][ThAc]), 1-butyl-3-methylimidazolium diethyldithiocarbamate ([Bmim][DTCR]), and 1-butyl-3-methylimidazolium ethylxanthate ([Bmim][EX]).
• Evaluation of Hg⁰ removal efficiency and adsorption capacity at low temperatures.
• Analysis of interaction energies, temperature effects, mercury temperature-programmed desorption (Hg-TPD), and X-ray photoelectron spectroscopy (XPS) to elucidate the adsorption mechanism.

Main Results:

• A strong positive correlation was observed between ionic liquid-Hg⁰ interaction energies and mercury removal efficiency.
• [Bmim][ThAc] demonstrated superior Hg⁰ abatement, achieving over 98% removal efficiency and an adsorption capacity of 10.66 mg/g at 50 °C.
• Physical adsorption, driven by anionic electrostatic interactions, was identified as the dominant mechanism for Hg⁰ capture.

Conclusions:

• Ionic liquids, particularly [Bmim][ThAc], offer a promising and efficient approach for low-temperature gaseous elemental mercury abatement.
• The study highlights the critical role of anionic electrostatic interactions in designing high-performance mercury sorbents.
• This research provides a new perspective for developing advanced materials for industrial flue gas purification.