Adsorption of congo red from aqueous solution using various TiO₂ nanoparticles

Abstract

In this work, TiO₂ nanopowder (TIP600) was prepared by a sol–gel method and titanium isopropoxide, glacial acetic acid, and deionized water were used as the starting materials. Adsorption of congo red (CR) on Degussa-P25 (P25), commercial TiO₂ (C-TiO₂), and TIP600 was investigated. But, photochemical and photocatalytic event were not used for this adsorption process. Adsorption of CR onto the adsorbents was studied at different temperatures (25.0, 40.0, and 50.0°C) and various adsorbent doses (0.1, 0.05, and 0.025 g). The kinetics of dye adsorption has been investigated in terms of pseudo-first order, pseudo-second order, and intra-particle diffusion rate. The results indicate that pseudo-second order plays a significant role in the adsorption mechanism. The adsorptive capacity of TIP600 is much higher than that of other adsorbents. The value of ∆H^# was obtained as positive, therefore the nature of adsorption was found endothermic. Equilibrium isotherm of CR was fitted to the Freundlich and Langmuir models. The equilibrium data of adsorbate were found to best fit the Langmuir model. For CR, TIP-600 was demonstrated as the best adsorption capacity (q_max 112 mg g⁻¹).

Keywords:

• TiO₂ nanopowder
• Congo red
• Adsorption
• Kinetic study
• Isotherms

Acknowledgments

This study was supported by the Scientific Research Project Fund of Istanbul University, project no: 12671. The author would like to thank Prof.Dr. Ayşe Zehra Aroğuz and associate professor Derya Dışpınar from Istanbul University for the editing of the manuscript in terms of grammar.