An environmental scanning electron microscopy study of aqueous gibbsite suspensions

Area of Science:

• Materials Science
• Colloid and Surface Chemistry

Background:

• Gibbsite is a key clay mineral with platelet-like structures.
• Understanding clay dispersion and aggregation is crucial in environmental science and materials engineering.

Purpose of the Study:

• To evaluate environmental scanning electron microscopy (ESEM) as a tool for studying clay dispersions.
• To investigate the aggregation behavior of synthetic gibbsite platelets under varying conditions.

Main Methods:

• Synthetic gibbsite dispersions were analyzed using ESEM.
• Imaging was performed after controlled water evaporation to visualize platelet surfaces.
• Experiments were conducted at different pH levels and with the addition of lithium chloride.

Main Results:

• ESEM successfully visualized platelet interactions and aggregation.
• At alkaline pH, face-edge contacts were minimal, aligning with known surface charges.
• Lower pH conditions showed increased face-edge contacts due to opposing surface charges.
• Lithium chloride addition at neutral pH induced face-face stacking.

Conclusions:

• ESEM is a valuable tool for studying clay platelet interactions and aggregation.
• Gibbsite platelet interactions are strongly influenced by pH-dependent surface charges.
• Salt concentration can promote different modes of platelet association, such as face-face stacking.