Kinetics and thermodymics studies for the removal of bromocresol purple using raw bentonite clay and activated carbon from Vachellia nilotica pod as adsorbents

Abstract

The adsorption of Bromocresol purple (BCP) onto Raw Bentonite Clay (RBC) and activated carbon from Vachellia nilotica (AVNP) was investigated using batch adsorption process. The adsorbents were characterized using Fourier transform spectrometer (FTIR) and Scanning Electron Microscope (SEM). The study of adsorption Kinetics and Thermodynamics were carried out. The pseudo –second order kinetic exhibits the best fit with the experimental data with R² values close to 1 and experimental values q_e (mg/g) 7.197 and 5.169 for RBC and AVNP are more closer to the calculated q_e 7.246 and 5.263.The negative values of Gibbs free energ change, ΔG of -5.98 to -7.75 and -2.77 to -4.36kJ/mol for RBC and AVNP respectively shows the process to be spontaneous. Positive values of enthalpy, ΔH, confirm the endothermic character of the adsorption process. Lower ΔH values of 11.01 and 11.98kJ/mol for adsorption of dye onto raw bentonite clay and activated carbon respectively, suggests that the adsorption is physical in nature..

Keywords: Bromocresol purple, Raw Bentonite clay, activated Vachellia nilotica pods kinetics, thermodynamic