Calcium montmorillonite is a natural mineral with interlayer cations of calcium ions. Its appearance is mainly a 1-4mm white or light-yellow particles, and it also has gray, purple, and other colors due to different iron content. Montmorillonite adopts physical adsorption and can absorb more than 17% of its weight of water vapor at 25°C and RH40%. Montmorillonite particles can be reused after being reactivated. It is a natural, environmentally friendly, economical, and affordable adsorbent material.