Palladium Chemistry in Seawater

The solution chemistry of palladium has been examined directly in seawater by ultraviolet absorbance spectroscopy. Our results indicate that chloride complexation strongly suppresses the hydrolysis of Pd²⁺ in seawater. At 25 °C and salinity equal to 36, hydroxy complexes account for ~18% of the total palladium and the remainder is present principally as PdCl₄^2-. Strong similarities previously reported for Pd and Ni distributions in seawater appear to have dissimilar origins at the molecular level. The enormous reactivity of Pd²⁺ relative to Ni²⁺ appears to be moderated, in seawater, by extensive complexation of Pd²⁺ with chloride ions.