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

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 process wastewater. 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 mg g^-1, 212.766 mg g^-1, and 344.828 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 values, and evaluation of FT-IR, XRD, and SEM/EDX images taken before and after dye loading showed that the adsorption mechanisms of TB, CV, and RB on the LDAC physically occur. 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.