Organoclay vs montmorillonite

When comparing organoclay vs montmorillonite, their relationship and differences lie in their properties and composition.

Montmorillonite, the primary component of bentonite, is defined by properties such as colloid index (a measure of dispersion and gel formation, with high-quality samples reaching 100%+), swelling volume (ml/g of water absorption expansion), and CEC (60 – 150 mmol/100g at pH = 7, a critical quality metric).

These properties are intrinsic to montmorillonite’s structure. Organoclay, however, is a modified form where montmorillonite’s interlayers are treated with organic cations. While it inherits the basic framework from montmorillonite, its swelling behavior in aqueous environments changes due to hydrophobic surface modification.

The CEC, originally a montmorillonite trait, enables the organic modification that creates organoclay. Both share physical properties like softness (Mohs hardness 1 – 2) and density (2 – 3 g/cm³ when dry), but organoclay’s functionality diverges based on its modified surface chemistry.

Organically modified bentonite — commercially known as organoclay — is the non-aqueous form of bentonite clay used as a rheology modifier and anti-settling agent in drilling fluids, coatings, and lubricating greases; full product specifications are at organoclay — the commercial form of organically modified bentonite. The natural bentonite clay properties, including swelling capacity, mineral composition, and industrial grades, are described in bentonite clay — natural properties and modified bentonite grades. To source organically modified bentonite or natural bentonite grades, see organoclay supplier — organically modified bentonite factory.