The aim of this work is to make a brief review of the adsorption of CO₂ on modified clay minerals. Previous researchers have used different clay modifications, either by making changes in the structure by a reaction with another product or by the addition of a catalyst to improve their CO₂ adsorption capacity. In order to obtain high values of CO₂ uptake, some researchers have been incorporated amines-speices such as (3-aminopropyl)triethoxysilane (APTES), tetraethylenepentamine (TEPA) and a branched polyethylenimine (PEI) by grafting or impregnation. The synthesis of an adsorbent from mineral clays can generate an increase in its porosity and in its textural properties. These investigations differ in a number of factors such as the kind of clay, the operating conditions, y and the nature of the impregnated compound. The role of these factors in the CO₂ adsorption capacity will be considered in detail in this review.

Factors influencing the degree of intercalation (‘reactivity’) of kaolinite group minerals have been investigated using six kaolin minerals, with variable crystallinity and particle size. Tests were performed to measure the degree of intercalation with potassium acetate, formamide, dimethylsulphoxide and hydrazine.These experiments indicate that intercalation degree depends on a number of factors, including particle size, degree of ordering, type of guest molecules, method of intercalation, and presence and types of impurities. Anew method for determination of the degree of intercalation is proposed, which is not dependent on the intensity of complex reflections. The results indicate that formamide is the most sensitive reagent to distinguish differently ordered kaolin minerals whereas hydrazine appears as the most appropriate reagent to differentiate kaolin minerals from other 7 Å phases.