Investigation of the adsorption behaviors of thymol blue, crystal violet and rhodamine B on lichen-derived activated carbon Scientific paper

Abstract

Since thymol blue (TB), crystal violet (CV) and rhodamine B (RB) are frequently used in various industries, they cause environmental pollution owing to the wastewater treatment process. The current study focused on the removal of TB, CV and RB from aqueous media with lichen-derived activated carbon (LDAC) and comparing their adsorption behavior. The maximum Lang­muir adsorption capacity for TB, CV and RB was found to be 400, 213 and 345 mg g^-1, respectively. The removal (%) of TB, CV and RB was found to be 86.38, 79.02 and 82.73 % at the same condit­ions, respectively. Experimental data were interpreted with some commonly used kinetic and isotherm models. Calculated activation energies, D-R model energies, enthalpy changes and eva­luation of FT-IR, XRD and SEM/EDX images taken before and after dye load­ing showed that the adsorption of TB, CV and RB on the LDAC are physical processes. The pseudo-second-order kinetic model better described the adsorp­tion behavior of TB, CV and RB on the LDAC. The boundary layer thickness value for all the dyes studied incr­eased with increasing initial dye concentration and temperature, and CV also had a larger boundary layer thickness value than that of TB and RB.