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

Biotite and illite have excellent cesium (Cs) adsorption capacity due to their negative charges in addition to adsorption sites of the planar, interlayer, and frayed edge sites (FES). The aim of this study is to investigate the Cs adsorption capacity using acid- and base-activated biotite and illite based on their mineralogical characteristics. The acid-activated biotite and base-activated illite exhibited high Cs removal efficiency from the low-level Cs-containing DI water (97.5 % and 97.3 %, respectively). The acid-activation of biotite increased the specific surface area (SSA, 12.08 -> 43.04 m(2)/g), Fe(III)/Fe(II) ratio (0.56 -> 0.76), and wedge zone d-spacing (1.017 -> 1.065 nm), while the zeta potential (-4.06 -> -4.82 mV) decreased. The base-activation of illite resulted to a decrease in the SSA (22.14 -> 18.49 m(2)/g), zeta potential (-7.68 -> 31.64 mV), and Fe(III)/Fe(II) ratio (0.92 -> 0.79). However, only acid-activated biotite appeared to have a high capacity of Cs removal from Cs-containing seawater (73.9 %; base-activated illite: 26.1 %). These results indicate that the FES of biotite owing to acidactivation showed better results in regards to Cs adsorption as compared to the pH-dependent negative charges of the base-activated illite.

Automated summary

Biotite and illite have excellent cesium adsorption capacities due to their negative charges and various adsorption sites, but the acid-activated biotite showed higher Cs removal efficiency compared to base-activated illite. Acid activation increased specific surface area and Fe(III)/Fe(II) ratio of biotite, while decreasing zeta potential, while base activation decreased specific surface area, zeta potential, and Fe(III)/Fe(II) ratio of illite. Acid-activated biotite also showed higher Cs removal capacity from seawater compared to base-activated illite.