Maghnite grafting with (3-Mercaptopropyl) triethoxysilane and its influence on the interlamellar distance blocking value

• Montmorillonite was successfully grafted with (3-Mercaptopropyl) triethoxysilane. • Grafting stabilized the interlayer spacing at 21.47 Å, preventing excessive swelling. • TGA confirmed increased hydrophobicity with reduced water loss from 11.36 % to 6.73 %. • FTIR analysis validated the grafting with characteristic -CH₂ and SH absorption bands. • Controlled interlayer fixation enables the design of stable organophilic clay materials. Maghnite (Algerian Montmorillonite) was grafted with (3-Mercaptopropyl)triethoxysilane in a water/ethanol mixture. The intercalation phenomenon of the grafted product was investigated following a modification with trimethyltetradecylammonium chloride at different cation exchange capacities (CEC). XRD results revealed a fixation of the d 001 value at 21.47 Å after the grafting reaction, caused by the condensation of silane molecules with the two adjacent clay layers. This effect was not observed during the modification of non-grafted montmorillonite with the same surfactant, as the d001 value increased with higher concentrations of trimethyltetradecylammonium chloride. TGA analysis revealed the hydrophobic nature of the modified material, initially hydrophilic, with a reduction in the loss of physisorbed and chemisorbed water from 11.36 % to 6.73 %, thus limiting the swelling phenomenon. The absorption bands at 2954.4 cm⁻¹, 2854.4 cm⁻¹, and 2569 cm⁻¹, assigned to -CH₂ (symmetric), -CH₂ (asymmetric), and SH groups, respectively, confirm the successful grafting and intercalation. Controlling the fixation of the interlayer spacing of a clay grafted with an alkoxysilane can lead to the development of an organophilic material with immobilized reactive organic groups and controlled swelling.