Structural characterization and adsorptive performance of polyaniline‐based nanocomposite reinforced with TiO 2 ‐modified montmorillonite for malachite green dye removal: kinetic, isothermal and thermodynamic analysis

Abstract The increasing presence of contaminants from aqueous solutions involves significant environmental and public health risks, necessitating the development of efficient adsorbents for their removal. This study explores the potential of polyaniline‐embedded montmorillonite‐type clay modified titanium dioxide which was designed via an in situ polymerization technique for removal of malachite green (MG) dye from water. Characterization was conducted using XRD, Fourier transform infrared spectroscopy, X‐ray fluorescence, X‐ray photoelectron spectroscopy, TEM, SEM coupled with energy dispersive X‐ray spectroscopy and a Brunauer–Emmett–Teller study. Significant findings for optimal conditions for MG adsorption were identified as pH 6.0, 50 mg adsorbent mass, 120 min contact time, 200 mg L −1 initial concentration and 298 K, achieving an adsorption capacity of 172.69 and 238.32 mg g −1 for Mt‐TiO 2 (Mt, natural montmorillonite‐type clay) and PAni@Mt‐TiO 2 (PAni, polyaniline), respectively. Kinetic studies followed a pseudo second order model, and equilibrium data best fitted the Langmuir isotherm for PAni@Mt‐TiO 2 ( R 2 = 0.924) and the Freundlich model for Mt‐TiO 2 ( R 2 = 0.817). The Gibbs free energy (Δ G 0 ) was negative for the adsorption process in the range 298–328 K, indicating that the process was spontaneous. In addition, the enthalpy parameter (Δ H 0 ) was determined for the adsorption process using PAni@Mt‐TiO 2 and Mt‐TiO 2 at 1.906 kJ mol −1 and 4.506 kJ mol −1 , respectively. A positive Δ H 0 indicates that the process is endothermic in the range 298–328 K using both adsorbents. The potential reusability of the adsorbent materials was confirmed for five adsorption–desorption cycles. These results highlight the potential of a conducting polymer matrix as a strategy to develop high‐performance, sustainable clay‐modified adsorbents for environmental uses, especially water treatment. © 2026 Society of Chemical Industry.