Carboxymethyl Guar Gum–TiO ₂ Nanocomposite Films for Combined Dye Adsorption and Photocatalytic Degradation

ABSTRACT The increasing presence of synthetic dyes in industrial wastewater poses major environmental concerns due to their stability, toxicity, and resistance to conventional treatments. In this study, carboxymethyl guar gum (CMGG) based nanocomposite films incorporated with varying concentrations of titanium dioxide (TiO 2 ) nanoparticles were synthesized using an ex situ sol‐gel approach. Structural and functional properties of the nanocomposites were characterized using Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), UV–vis, thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and Dynamic light scattering (DLS). The optical band gap decreased from 3.56 eV for TiO 2 nanoparticles to 2.22 eV for the film F4 (1.5 TiO 2 ). The resulting films exhibited dual functionalities: CMGG enabled dye adsorption through electrostatic and hydrogen‐bonding interactions, while Titanium Dioxide Nanoparticles contributed to photocatalytic degradation by generating reactive species under irradiation. The film F4 showed the highest dye removal efficiencies, achieving 92.38% for methylene blue, 72.06% for bromothymol blue, and 67.33% for methyl orange. The maximum adsorption capacity ( q e ) was observed for bromothymol blue (1.23 mg/g), whereas the highest removal efficiency was obtained for methylene blue. Kinetic studies revealed pseudo‐first‐order adsorption and Langmuir‐Hinshelwood photocatalytic degradation, indicating a surface reaction‐controlled process, with the maximum rate constant ( k ) of 0.0225 min −1 for the film F4 towards methylene blue.