Microscopic Mechanism of Coal Wetting-Dissolution under Surfactant-Assisted Acidification Conditions.

Area of Science:

• Geochemistry
• Materials Science

Background:

• Coal wetting-acidification is a key technique for improving coal dust control and gas permeability.
• Understanding the internal transformation during coal wetting-dissolution is crucial for optimizing this process.

Purpose of the Study:

• To investigate the wetting characteristics and pore structure changes in coal after treatment with acid and surfactant composite reagents.
• To explore the interaction mechanisms between mineral dissolution and wetting-dissolution properties.
• To elucidate the microscopic mechanisms of coal wetting-dissolution and the inhibitory effects of ionic liquids.

Main Methods:

• Contact angle measurements to assess wettability.
• Low-temperature nitrogen adsorption to analyze pore structure changes.
• Scanning electron microscopy (SEM) and X-ray diffraction (XRD) for material characterization.
• Fractal theory to analyze surface roughness and pore connectivity.

Main Results:

• Surfactant-assisted acidification reduced the coal contact angle by ~60%, enhancing wettability.
• Composite reagent treatment increased total pore volume by 2.0 times and average pore diameter by 1.5 times.
• Fractal dimensions (D1 and D2) decreased by 24.1% and 10.3%, respectively, indicating improved pore connectivity.
• [BMIM]BF4 ionic liquid addition inhibited surfactant activity, increasing contact angle and reducing pore size.

Conclusions:

• Coal wettability is positively correlated with dissolution, leading to increased pore volume and size.
• The study elucidates the microscopic mechanisms of coal wetting-dissolution and the impact of ionic liquids.
• Optimized coal wetting-acidification enhances coal properties for improved dust control and gas permeability.