Removal of rhodamine b and alizarin red from aqueous solutions by oxidized carbon nanotubes: kinetics and isotherm Study

Abstract

Alizarin Red and Rhodamine B are widely used dyes in the textile, paper, and plastic industries. However, the disposal or release of these dyes into the environment can negatively impact on both the environment and human health. In the present study, oxidized carbon nanotubes (OCNT) were used to eliminate Alizarin Red and Rhodamine B from contaminated water in batch adsorption experiments. The adsorption outcomes suggested that OCNT has the potential to be an effective material for the removal of these dyes from contaminated water. The kinetics modeling revealed that the adsorption process of both dyes onto OCNT follows the pseudo-second-order model, indicating a chemisorption process. Moreover, the OCNT has indicated fast kinetics in which the equilibrium was achieved in 4 h. The isotherm study demonstrated that the Freundlich isotherm model best fits the experimental data, suggesting that dyes’ adsorption onto OCNT is a monolayer adsorption process. The maximum adsorption capacities were 124.7 and 614.7 mg/g for Rhodamine B and Alizarin Red, respectively. The adsorption of these dyes was found to be more efficient at pH values of 6-8. This study suggests that OCNT can be an effective adsorbent for removing Alizarin Red and Rhodamine B from contaminated water.