Removal of an anionic reactive dye from aqueous solution using functionalized multi-walled carbon nanotubes: isotherm and kinetic studies

Abstract

AbstractIn this research, the adsorption process of Reactive Blue 19 (RB19) as an anionic dye onto functionalized multi-walled carbon nanotubes (f-MWCNTs) was studied. For this purpose, four parameters including agitation time, adsorbent dose, initial dye concentration, and pH were examined. N2 adsorption isotherms and Fourier transform infrared spectroscopy were used to characterize f-MWCNTs. Four isotherm and four kinetic models including two diffusion models were applied to comprehensively investigate the RB19 adsorption using f-MWCNTs. It was found that the adsorption follows Langmuir and Temkin equilibrium models with a maximum adsorption capacity of 217.39 mg g−1. The adsorption process best fitted to pseudo-second-order kinetic model and by applying diffusion models, the predominant rate-limiting step was found to be physisorption during the liquid film diffusion.