Metal species, aqueous, solubility environment

The very low concentrations of metal species in the aqueous environment preclude separations using ordinary methods which precipitate a relatively insoluble compound the minute amounts involved would mean large percentage losses due to significant solubility and to handling. One method of isolating the pollutants from their matrix is by coprecipitation or cocrystallization. This method of adding macroamounts of a substance which when precipitated will occlude, adsorb, absorb, or cocrystallize trace metals has been widely applied. 

Despite the extremely low concentrations of the transuranium elements in water, most of the environmental chemistry of these elements has been focused on their behavior in the aquatic environment. One notes that the neutrality of natural water (pH = 5-9) results in extensive hydrolysis of the highly charged ions except for Pu(V) and a very low solubility. In addition, natural waters contain organics as well as micro- and macroscopic concentrations of various inorganic species such as metals and anions that can compete with, complex, or react with the transuranium species. The final concentrations of the actinide elements in the environment are thus the result of a complex set of competing chemical reactions such as hydrolysis, complexation, redox reactions, and colloid formation. As a consequence, the aqueous environmental chemistry of the transuranium elements is significantly different from their ordinary solution chemistry in the laboratory. 

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