Probing interaction forces associated with calcite scaling in aqueous solutions by atomic force microscopy

Area of Science:

• Environmental Science
• Materials Science
• Nanotechnology

Background:

• Calcite aggregation and scaling pose significant challenges in aqueous systems.
• Microscopic mechanisms for aggregation control are known, but nanoscale experimental data is scarce.

Purpose of the Study:

• To investigate the nanoscale topographic features of calcite during aggregation.
• To elucidate the role of intermolecular and surface forces in calcite aggregation.
• To explore strategies for preventing calcite scaling and deposition.

Main Methods:

• Atomic force microscopy (AFM) was used to measure forces between calcite/silica particles and a calcite surface.
• Scanning electron microscopy (SEM) visualized nanoscale structural changes.
• Experiments were conducted in aqueous solutions under varying pH, salinity, and inhibitor concentrations.

Main Results:

• Higher pH, inhibitor concentration, and lower salinity promoted stronger repulsion and weaker adhesion, reducing aggregation.
• Magnesium ions (Mg2+) exhibited pH-dependent roles in aggregation prevention.
• Calcite crystal size depended on calcite-calcite and calcite-silica interactions at the nanoscale.

Conclusions:

• Nanoscale topographic features and intermolecular forces are key determinants of calcite aggregation.
• The findings provide a generalized framework for understanding calcite aggregation mechanisms.
• This research offers a basis for developing effective anti-aggregation strategies for industrial and environmental applications.