Wormhole Mesoporous Silica Framework with Enhanced Thiol Loading for Improved Hg²⁺ Sequestration.

Area of Science:

• Materials Science
• Nanotechnology
• Environmental Chemistry

Background:

• Mesoporous silica materials, like KIT-6, are versatile platforms for various applications including catalysis and adsorption.
• Thiol functionalization is crucial for enhancing the adsorption capabilities of silica-based materials, particularly for heavy metals.
• Existing functionalization methods may have limitations in efficiency and structural integrity.

Purpose of the Study:

• To develop a novel and efficient synthesis route for thiol-functionalized mesoporous silica (KIT-6) using 3-methacryloxypropyl trimethoxy silane (MPTMS).
• To characterize the structural and chemical modifications of the functionalized material.
• To evaluate the mercury (Hg²⁺) adsorption performance of the novel thiol-functionalized KIT-6.

Main Methods:

• Synthesis of MPTMS-functionalized KIT-6.
• Characterization using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, Fourier-Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, ²⁹Si Solid-State Nuclear Magnetic Resonance (NMR), X-ray Photoelectron Spectroscopy (XPS), and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES).
• Mercury adsorption experiments and analysis of adsorption capacity.

Main Results:

• Achieved a 71.5% enhancement in thiol functionalization on KIT-6 surfaces.
• Confirmed the stable three-dimensional wormhole chain structural framework (WCSF) with ~4 nm pores and a surface area of 1451 m²/g.
• Demonstrated a high mercury adsorption capacity of 3199.6 mg/g with an optimal Hg²⁺/S ratio of 1.8.
• XPS and NMR confirmed enhanced and homogeneous thiol functionalization and siloxane network formation.

Conclusions:

• The new MPTMS functionalization route significantly improves thiol loading on KIT-6.
• The resulting thiol-functionalized KIT-6 exhibits a stable WCSF structure ideal for heavy metal adsorption.
• The material demonstrates exceptional mercury adsorption capacity, indicating its potential for environmental remediation of mercury-contaminated sources.