Toward halal-compliant organoclay from plant-based surfactants: a green approach for food-grade montmorillonite modification

Sodium montmorillonite (Na-MMT) serves as a popular nanofiller in polymer-based materials; however, its inherent hydrophilicity restricts its interaction with hydrophobic polymer matrices. To improve compatibility, surface treatment with organic surfactants is commonly performed. Traditional methods typically rely on animal-derived surfactants such as hydrogenated tallow, which can be problematic for halal-sensitive applications like food packaging. This study focuses on modifying Na-MMT using plant-based quaternary ammonium compounds – specifically, myristyltrimethylammonium bromide (MTAB) and cetyltrimethylammonium bromide (CTAB) – to promote sustainability and potential religious compliance. Ion-exchange reactions were used to intercalate these surfactants into Na-MMT at concentrations of 0.5–2.0 times the cation exchange capacity (CEC). Structural and morphological changes were examined using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), CHNS elemental analysis, thermogravimetric analysis (TGA) and water contact angle measurements. FTIR spectra verified surfactant inclusion, and XRD revealed expanded basal spacing, more pronounced in samples modified with longer alkyl chains. Thermal behavior, as assessed by TGA, varied depending on surfactant type and loading. Increased hydrophobicity was demonstrated through contact angle testing, especially for CTAB- and MTAB-treated clays. The findings highlight the effectiveness of MTAB and CTAB as plant-derived modifiers, offering a reliable, plant-based alternative with halal-compliant potential for enhancing Na-MMT in nanocomposite formulations intended for food packaging applications.