Dear Santosh Kumar Paul, acid treatment is an activation process leading to an increase in pososity and thus increase in specific surface area.

The noticed decrease in surface area may be due to either (or both) octadecylamine intercalation and/or pore blocking. My Regards

Dear Santosh Kumar Paul, acid treatment is an activation process leading to an increase in pososity and thus increase in specific surface area.

The noticed decrease in surface area may be due to either (or both) octadecylamine intercalation and/or pore blocking. My Regards

Hi;

The effect of acid attack on the physicochemical characteristics of clays is highly dependent on the treatment conditions (acid concentration, temperature, contact time, etc.). The use of concentrated acid solution at relatively high temperatures for long periods of time generally leads to a deep destruction of the crystalline network of the clay with the formation of large quantities of amorphous silica. The attack of the clay by the acid takes place according to a well determined mechanism which starts with the adsorption of the acid on the surface of the solid to lead to the substitution of the exchangeable ions by protons. The exchanged protons then diffuse towards the active sites of the activated solid where the chemical reactions take place (breaking of existing chemical bonds and formation of other bonds). The soluble products of these chemical reactions are then desorbed in the liquid phase. The chemical attack is accompanied by a progressive dissolution of the solid which can then lead to the dislocation, or even the collapse, under severe attack conditions, of the crystal lattice and the formation of amorphous silica. The structural cations of the clay (Al3+, Mg2+, Fe3+) are replaced, during acid attack, by H+ protons to lead to a substantial increase in the surface acidity of the clay.

With my best regards