Single‐walled carbon nanotubes (SWCNTs) as an efficient adsorbent for removal of reactive dyes from water solution: Equilibrium, kinetic, and thermodynamic

Abstract

Dyes are water-soluble aromatic compounds that are widely used in the industry today. Among the industries, the textile and leather industries rank first in the use of dyes. Common methods for removing of dyes often lead to the production of large volumes of sludge, which finally leads to problems with the treatment and disposal of sludge. This study aimed to investigate the efficiency of single-walled carbon nanotubes (SWCNTs) in the removal of reactive yellow dye 15 (RY15) and reactive yellow dye 42 (RY42). This study was performed experimentally and on a laboratory scale and batch system. The effect of various parameters such as pH, initial dye concentration, the adsorption capacity of SWCNTs and reaction time in the removal of RY15 and RY42 were investigated, and finally, thermodynamics, isotherm, and adsorbent kinetics were investigated. Various analyses showed that the maximum adsorption capacity occurs at pH = 3, initial dyes concentration = 50 mg/L, and adsorption mass of 0.2 g/L. The data obtained from this study for the adsorption of RY15 and RY42 effectively comply with Freundlich and Langmuir isotherms. Also, the adsorption kinetics of the mentioned dyes was better described by the pseudo-second-order kinetic model. The adsorption process of RY15 was endothermic, while this process for RY42 was exothermic. Regarding that carbon nanotubes are available and economically viable, and according to the present study, SWCNTs have a high efficiency in removing dyes, it can be used as an efficient adsorbent in the removal of dyes from water solutions.