Nickel (II) & Copper (II), Surrogates for Uranyl Nitrate Sorption Studies

Uranium is dangerous, so an analytical surrogate is needed for safety and testing in remote areas.  Uranium is considered a toxic heavy metal; 99.3% of uranium’s natural abundance is chemically toxic and 0.72% is radioactive.  Uranium is an alpha emitter, and when consumed may result in DNA translocation which leads to cancer, mutations and ultimately death.  Anthropogenic activity, e.g. mining in the Four Corners area, disrupts nature’s equilibrium.  As a result of this disruption, uranium exposure has increased through leaching and run-off; thus, inhalation and ingestion are problematic.  The ultimate objective is to eliminate uranium from potential portable water.  Our specific goal is to avoid uranium contact in analytical, field experimentation; therefore, a surrogate is needed for uranium.  In addition, colorimetry is an inexpensive rapid, portable, and safe technique which may be employed in the field to assess sorption of the uranium surrogates.  We plan to use soil sorbents for uranium abatement at the contaminated site of which there are too many for safety reasons.  Nickel and copper nitrates exhibit sorption potential and dissociate to introduce Met⁺² ions. They are similar to uranyl ions in this respect.  Ni²⁺ and Cu²⁺ ions exhibit sorption with dry and pre-soaked pellets.  In fact, the pre-soaked pellets sorb Ni faster than Cu and reduce the Ni concentration levels below the detection limit. The Cu concentration abatement rate is slower.  Nickel and copper do not sorb at the same rate; therefore, one of these is a better surrogate for uranium.