| The purpose of this research was to evaluate the influence of a hydrocarbon, such as toluene, on heavy metal adsorption, estimate the adsorption kinetics of mixtures, and apply that information to treatment of mixtures. In this research, toluene and Cu(II) were mixed to represent a mixture of hydrocarbon and metal for the study of interfacial reactions between adsorbates and granular activated carbon (GAC) because they are prevalent in most DOE waste sites.; A series of isotherm tests showed that Cu(II) uptake onto the GAC surface was relatively slower when toluene was present and toluene did not influence Cu(II) surface equilibrium loading on GAC. Toluene did not compete with Cu(II) for the same surface sites; that is, no site competition occurred between Cu(II) and toluene. Results from testing Cu(II) uptake rate in the presence of toluene in a batch reactor showed that more toluene caused more reduction of Cu(II) uptake rate. Modeling results from these kinetic tests demonstrated that the estimated effective diffusivity of Cu(II) varied with toluene surface loading on GAC.; Toluene also slowed uptake of Cd(II) and Pb(II). Toluene had more impact on those metals which had better affinity to GAC. The effect of toluene on metal adsorption followed the sequence: Pb(II) > Cu(II) > Cd(II). In conclusion, there is no site competition involving toluene and metals. Toluene has an insignificant influence on adsorption of the metals with a weak affinity to the sorbent, but plays an important role on the removal of those metals with a relatively higher affinity to the GAC. |
