Adsorption kinetics, mechanism, isotherm, and thermodynamic analysis of copper ions onto the surface modified agricultural waste

The adsorption of copper ions onto the surface modified Strychnos potatorum seeds ( SMSP ) in a batch adsorption system has been studied. Kinetics, mechanism, isotherm, and thermodynamic parameters have been estimated. Adsorption kinetics of copper ions onto the SMSP follows a pseudo‐second order kinetic model. Adsorption mechanism was explained with the intraparticle diffusion model, Boyd kinetic model ( BKM ), and Shrinking core model ( SCM ). Adsorption process was found to be controlled by both intraparticle diffusion and film diffusion. The diffusivity values were estimated from the BKM and SCM . Adsorption isotherm data agreed well with the Freundlich adsorption isotherm model, which indicates the multilayer adsorption of copper ions onto the SMSP . The maximum monolayer adsorption capacity of the SMSP was found to be 248 mg of copper ions/g of SMSP . Adsorption thermodynamic studies show that the adsorption of copper ions onto the SMSP was spontaneous and exothermic in nature. © 2012 American Institute of Chemical Engineers Environ Prog, 33: 28–37, 2014