EFFECT OF NATURAL ORGANICS ON CS AND NP SORPTION

A batch sorption study was performed to investigate the effect of natu rally occurring organic materials on the sorption of Cd and Np on oxid es and tuff surfaces. Synthetic goethite, boehmite, amorphous Si oxide s and a crushed tuff material from Yucca Mountain, NV, were used as mo del sorbents. An amino acid, 3-(3,4-dihydroxyphenyl)-DL-alanine (DOPA) , and an aquatic originated fulvic material, nordic aquatic fulvic aci d (NAFA), were used as model organic chemicals. Sorption isotherm resu lts showed that DOPA sorption followed the order: Al oxide > Fe oxide > Si oxide. The amount of DOPA sorption for a given sorbent increased as the solution pH was raised. The sorption of Cd and Np on Fe oxide w as about ten times higher than that on Al oxide. The sorption of Cd an d Np on natural tuff material was much lower than that on Al and Fe ox ides. The sorption of Cd on Fe and Al oxides was found to be influence d by the presence of DOPA. Increasing DOPA coating resulted in higher Cd sorption on Al oxide. However, for Fe oxide, Cd sorption decreased with increasing DOPA concentration. The presence of model organic mate rials, DOPA and NAFA, did not affect the sorption of Np on tuff materi al or on Fe and Al oxides.