Synthesis and Characterization of γ-CD-Modified TiO₂ Nanoparticles and Its Adsorption Performance for Different Types of Organic Dyes

Abstract

In this work, γ-cyclodextrin-modified titanium dioxide nanoparticles (NPs) as an efficient nanoadsorbent were synthesized and used to remove methylene blue (MB), malachite green (MG), crystal violet (CV), disperse red 1 (DR1), acid blue 113 (AB113), and congo red (CR) dyes from synthetic wastewater. Characterization of cyclodextrin-functionalized TiO2 nanoparticles using Fourier transform infrared, field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller (BET) analysis revealed that the TiO2 NPs were effectively modified with γ-CD. Furthermore, synthesized adsorbent with a large BET specific surface area of 383.131 m2/g showed excellent adsorption performance toward organic dyes. The dye adsorption kinetics, isotherms, and thermodynamics using TiO2/γ-CD NPs were also investigated. The results showed that pseudo-second-order model and Freundlich isotherm model well describe the dye adsorption process on the TiO2/γCD NPs. Additionally, the maximum adsorption capacity of MB, MG, CV, DR1, AB113, and CR onto TiO2/γCD NPs was found to be 134, 244, 213, 238, 157, and 5000 mg/g, respectively. On the basis of the obtained RL values, which were less than 1.0, the adsorption of all tested dyes was favorable. Furthermore, the calculated thermodynamic parameters showed that the adsorption process of the studied dyes was endothermic.