CHEMICAL MODIFICATION AND METAL-BINDING STUDIES OF DATURA-INNOXIA

The esterification of carboxylate functionalities present in the cell walls of Datura innoxia results in a decrease in metal uptake by as mu ch as 40%, depending on the metal studied. These findings suggest that carboxylate groups are important in metal ion adsorption to this biom aterial. Base hydrolysis of the native plant material resulted in a sl ight increase in metal ion uptake for Cu2+ and Sr2+ and a decrease in uptake for Cd2+. These results are attributed to the hydrolysis of est ers native to the plant material, which increases the carboxylate cont ent but also results in conformational changes in the macromolecules t hat comprise the cell fragments. Both the esterified product and the h ydrolyzed material were examined via infrared spectroscopy. A peak occ uring at 1735 cm(-1) (attributed to the carbonyl stretch) confirmed th e esterification process. The infrared spectra of the hydrolyzed sampl es indicate further ionization of carboxylate groups or hydrolysis of esters native to D. innoxia.