Self-Constructing 100% Water-Resistant Metal Sulfides through In Situ Acid Etching for Effective Elemental Mercury...

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Metal sulfides (MSs) are effective sorbents for removing elemental mercury (Hg⁰) and other thiophilic pollutants.
• A major limitation for MSs application is their susceptibility to water (H₂O), which hinders their performance in humid environments.
• Developing water-resistant sorbents without complex preparation is crucial for practical environmental remediation.

Purpose of the Study:

• To develop a method for self-regulating the water resistance of metal sulfides (MSs).
• To enhance the adsorption selectivity of MSs towards elemental mercury (Hg⁰) in the presence of water.
• To enable efficient Hg⁰ removal from industrial flue gas.

Main Methods:

• An in situ acid-etching method was employed to modify the surface of MSs.
• The method engineered the interfacial interaction between MSs and Hg⁰/H₂O.
• Surface characterization focused on undercoordinated sulfur and polysulfur chains (S_n^2-).

Main Results:

• The acid-etching method introduced abundant undercoordinated sulfur, significantly improving MSs' water resistance.
• Polysulfur chains formed on the surface, stabilizing Hg⁰ and repelling H₂O due to favorable electron configurations.
• The modified MSs exhibited high hydrophobicity, 100% water resistance up to 20% H₂O, and increased Hg⁰ selectivity.

Conclusions:

• This study presents a scalable, simple method to create highly water-resistant MSs for Hg⁰ remediation.
• The self-regulating approach overcomes water's detrimental effects on MSs performance.
• The developed MSs are cost-effective and suitable for future applications in industrial flue gas treatment.