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 (qm = 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.