Cesium removal using acid- and base-activated biotite and illite.

Area of Science:

• Geochemistry
• Environmental Science
• Materials Science

Background:

• Biotite and illite possess significant cesium (Cs) adsorption capabilities due to inherent negative charges and various adsorption sites.
• Understanding mineralogical characteristics is crucial for optimizing Cs adsorption processes.

Purpose of the Study:

• To investigate the cesium adsorption capacity of acid- and base-activated biotite and illite.
• To correlate Cs adsorption performance with mineralogical property changes induced by activation treatments.

Main Methods:

• Acid and base activation treatments were applied to biotite and illite samples.
• Cesium adsorption efficiency was evaluated using deionized (DI) water and artificial seawater.
• Mineralogical characteristics, including specific surface area (SSA), Fe(III)/Fe(II) ratio, d-spacing, and zeta potential, were analyzed.

Main Results:

• Acid-activated biotite and base-activated illite showed high Cs removal efficiency (>97%) in low-level Cs-containing DI water.
• Acid activation of biotite increased SSA, Fe(III)/Fe(II) ratio, and d-spacing, while decreasing zeta potential.
• Base activation of illite decreased SSA, zeta potential, and Fe(III)/Fe(II) ratio.
• Acid-activated biotite demonstrated superior Cs adsorption capacity (73.9%) in Cs-containing seawater compared to base-activated illite (26.1%).

Conclusions:

• Acid-activated biotite exhibits a higher capacity for cesium adsorption, particularly in challenging matrices like seawater.
• The frayed edge sites (FES) of acid-activated biotite are more effective for Cs adsorption than the pH-dependent charges of base-activated illite.