Removal of basic red 5 on calcined kaolinite - Characterization and adsorption kinetics

Indigenous kaolin was collected from Swat district and then activated. The samples were characterized by BET surface area, FTIR, XRD, SEM, EDS, TGA/DTA, zeta potential and particle size analysis. Adsorption of basic red 5 on each sample was studied by adsorption kinetics at 20 °C, 30 °C and 40 °C. The residual concentration of the dye was determined by using UV-Vis spectrophotometer. The removal of basic red 5 from water solution was studied with respect to dye concentrations and equilibration time. Adsorption kinetics on kaolinite surface were analyzed by using parabolic diffusion, Elovich and Bangham models. Thermodynamic parameters like δE^#, δH^# and δS^# were calculated from the adsorption kinetics data. The results show that the adsorption is a spontaneous and endothermic process. The negative value of entropy shows that the dye molecules take a proper position on the surface.