Investigation of lead ion binding to an immobilized Datura innoxia biomass using affinity distributions

The biomass, immobilized cell fragments cultured from the plant, Datura innoxia, has been targeted as a potential sorbent for the application of heavy metal remediation and reclamation from wastewater and water resources.; Great complexity of the biomass results in the unpredictability of metal binding properties. The determination of physico-chemical parameters (binding capacities, affinities or affinity distributions) and the investigation of metal sorption processes are therefore the focus of this dissertation.; To overcome problems encountered in the measurement of binding isotherms by the conventional batch and titration technique, an application of frontal affinity chromatography was first explored with an on-line flame atomic absorption spectrometric detection. A modified mode of such frontal analysis was further developed to broaden isotherm concentration ranges, particularly with extended lower concentration limits.; A procedure (or algorithm) for determining sound physico-chemical parameters from the experimental data was pursued and investigated. The QUASI program based on regularized least-square method was determined to be the most appropriate and was therefore adapted for the derivation of lead affinity distributions on the biomass under various solution compositions. These results suggested that for the two existing classes of binding sites, the low affinity sites (mean affinity constant, K, {dollar}sim{dollar}10{dollar}sp2{dollar} M{dollar}sp{lcub}-1{rcub}){dollar} involved sulfonates and carboxylates in an ion exchange process, while the high affinity sites (K {dollar}sim{dollar} 10{dollar}sp5{dollar} M{dollar}sp{lcub}-1{rcub}){dollar} resulted from the coordination (or chelation) of carboxylates to lead ions.; The approach of chemical modifications of functionality on the biomass was further employed to verify and confirm this hypothesis. Results from FT-IR and {dollar}sp{lcub}13{rcub}{dollar}C NMR studies of the modified material confirmed those modification reactions. Comparison of the affinity distributions between the immobilized unmodified and modified biomasses indicated that at conditions of 0.01M of a pH 5.5 buffer solution, Pb low affinity sites included approximately 43 {dollar}mu{dollar}mol/g of sulfonates and 147 {dollar}mu{dollar}mol/g of carboxylates. High affinity sites of Pb binding were similarly determined to nearly exclusively involve carboxylates and exhibit a lead binding capacity of {dollar}sim{dollar}106 {dollar}mu{dollar}mol/g under the same conditions.