Surfactant-modifications of Na+-beidellite for the preparation of TiO2-Bd supported photocatalysts: I-organobeidellite precursor for nanocomposites

• Effects of alkyl chain length and amount of surfactants on organobeidellite development.
• Longer the alkyl chain length or higher the amount of surfactants, more expanded beidellite galleries.
• CTA+ species in the form of monolayer, paraffin monolayer, paraffin bilayer as the CTAB amount increases.

This study aims at determining suitable conditions for the preparation of the best organobeidellite starting material used for the development of efficient mesoporous TiO2 supported beidellite (Bd) photocatalysts. For this purpose, organo-modifications of natural Bd from Agadir Basin (Morocco) were achieved. The influence of (i) the length of alkyl chains Cn (n = 8, 12, 14 and 16) of n-alkyl ammonium surfactants CH3(CH2)n-1NH3+ and (ii) the amount of C16 surfactant ranging from 1 to 5 times the smectite (Sm) cation exchange capacity (CEC) on the structure of organo- Bd was studied. XRD, TEM, TG-DTA and FTIR results are consistent with the intercalation of cationic surfactants species in Bd interlayer spaces according to different conformations yielding to their expansion. The interlayer expansion magnitude increased both with the length of alkyl chain and the amount of C16 surfactant. Organomodification with increasing surfactant load beyond 1CEC besides yielded to the adsorption of increasing excess on external surfaces of Bd particles. These controlled structural modifications will be used further in the functionalization of this Bd by TiO2 nanoparticles to produce efficient supported TiO2-Bd photocatalysts.