Heavy metal adsorption by Ligand loaded granular activated carbon: Thermodynamics and kinetics

This paper describes the adsorption of Cu metal ions from aqueous solutions by IQSA, [7iodo-8-hydroxyquinoline-5-sulphonic acid] an adsorbed chelating species on F-400 granular activated carbon [GAC]. The optimum shaking speed, adsorbent mass, contact time and pH were determined and adsorption isotherms were obtained for Cu metal ions ranging from 25mg/l to 120mg/l. The adsorption process follows pseudo second order reaction kinetics as well as validated to Freundlich, Langmuir and D-R adsorption isotherms. The paper discusses the thermodynamic parameters of the adsorption process like Gibb's free energy, entropy and enthalpy. Our results demonstrate that the adsorption process was spontaneous and slightly exothermic under natural conditions. The maximum removal efficiency was found to be 95% for Cu [II] at pH 5.5.