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 much as 40%, depending on the metal studied. These findings suggest that carboxylate groups are important in metal ion adsorption to this biomaterial. Base hydrolysis of the native plant material resulted in a slight increase in metal ion uptake for Cu2+ and Sr2+ and a decrease in uptake for Cd2+. These results are attributed to the hydrolysis of esters native to the plant material, which increases the carboxylate content but also results in conformational changes in the macromolecules that comprise the cell fragments. Both the esterified product and the hydrolyzed material were examined via infrared spectroscopy. A peak occuring at 1735 cm(-1) (attributed to the carbonyl stretch) confirmed the esterification process. The infrared spectra of the hydrolyzed samples indicate further ionization of carboxylate groups or hydrolysis of esters native to D. innoxia.