High-performance and regenerable poly(2-aminothiazole)-modified montmorillonite for textile dye removal

Adsorption is a cost-effective and environmentally friendly method for removing organic pollutants from water. In this study, cetyltrimethylammonium bromide-modified montmorillonite (OMt) and a poly(2-aminothiazole) nanocomposite (OMt|PAT) were synthesized and evaluated for removing Bemacid Blue dye from aqueous solutions. BET analysis showed that PAT incorporation restructured the clay, reducing the microporous surface area from 3.41 to 0.51 m² g^- 1, indicating that the polymer chains effectively occupied the original micropores. Structural modifications were confirmed after BB-Dye uptake via FTIR, XRD, SEM, and EDX. Batch experiments showed that optimal adsorption occurs at pH 5.5-6.0. Kinetic studies revealed that OMt followed a pseudo-second-order model, while OMt|PAt followed a pseudo-first-order model, achieving equilibrium within 60-90 min. Isotherm modeling indicated that OMt|PAT follows the Langmuir model (q_m = 18.86 mg g^- 1, R² ≈ 0.994), while OMt adsorption is better described by the Hill de Boer model (R² ≈ 0.989), suggesting cooperative interactions. Thermodynamic analysis confirmed a spontaneous (ΔG° < 0) and endothermic adsorption process. The enthalpy changes (ΔH° = 15.83 and 12.48 kJ mol^- 1 for OMt and OMt|PAT, respectively) indicate a physisorption mechanism, while positive entropy values (ΔS° = 140.59 and 132.03 35 J.mol^- 1.K^- 1) reflect an entropy-driven process for both adsorbents. Regeneration studies using acetic acid demonstrated > 90% desorption, with the nanocomposite maintaining > 80% efficiency after four cycles. These findings highlight OMt|PAT as a robust, high-affinity, and recyclable material for sustainable dye removal.