In situ synthesis of TiO2 nanofiller in preparation of carrageenan-based nanocomposites and its application in the adsorption of copper(ІI) from aqueous solution

In this study, new kappa-carrageenan-based nanocomposites (CG/TiO₂) were synthesized using in situ generated TiO₂ inorganic nanofiller, which were utilized for Cu²⁺ ions adsorption from aqueous media. The physicochemical properties of the nanocomposites were studied using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning and transmission electron microscopies (SEM and TEM). Data from TGA experiments indicate that nanocomposites have improved thermal properties. Also, morphological investigations and particle size distribution diagrams show the uniform distribution of nanoparticles within the polymer matrix. The effects of pH, contact time, and initial concentration on the adsorption properties of the synthesized nanocomposites were investigated. CG/TiO₂ demonstrated efficient adsorption for Cu²⁺ cations from aqueous solutions, achieving > 80% removal at optimal conditions and reduced Cu²⁺ levels from 10 to < 1.7 mg/L (below the WHO limit). Kinetic studies of copper cation adsorption showed pseudo-second-order kinetics, and the equilibrium isothermal models for this nanocomposite agreed with the Langmuir isotherm model.