Kinetic and thermodynamic studies of Indigo adsorption on some activated bio-solids

The performances of five activated bio-solids adsorbents on adsorption of indigo from its dyeing effluent were studied using their thermo-kinetics equilibrium data. the results were compared with the commercial powder carbon as standard. the adsorbents were prepared from cattle bone carbon,algae carbon,water lettuce carbon,elephant grass carbon and crab shell carbon. the activated cattle bone has the highest monolayer adsorption capacity among the bio-solids. the adsorption kinetics of all the adsorbents conformed to the pseudo-second order kinetics,with good correlation. also,the thermodynamics parameters of the adsorption process fitted very well with the experimental data. the standard gibb's free energy change (δg°) for all the adsorption reaction was negative,indicating the spontaneity of the proces.