Environmental behaviour of the binuclear oxygen-bridged nitratonitrosylruthenium complex

The physico-chemical behaviour of prepared binuclear oxygen-bridged nitratonitrosylruthenium, [RuO2(NO)2(NO3)]2O, was investigated by filter paper electrophoresis, paper chromatography, and infrared absorption spectra of a decomposition product in fresh water. The binuclear (Ru-O-Ru) nitrate complex in aquatic systems was electrophoretically fractionated into at least four 'anionic' species, one 'neutral' species and one 'cationic' species, with aging, and about 75% of the total Ru was present in the anionic fractions. It was found that about 90% of the total Ru in the solution was taken up in the fraction with Rsub(f) less than 0.2, corresponding to the anionic mononitro-, mononitrato- and probably the polynuclear species from paper chromatography. The proportions of Rsub(f) 0-0.2 and Rsub(f) 0.2-1.0 to total Ru were scarcely altered by increasing the aging time more than one day. On the basis of infrared spectra of decomposition product by aging the (Ru-O-Ru) nitrate, it was confirmed that two oxide anions, nitrosyl, nitro, nitrato groups and water molecule are all coordinated to Ru metal, assuming [RuO2(NO)(NO2)(NO3)(H2O)]- as one of the possible chemical forms of the anionic species. RuNO-nitrato, RuNO-nitro and (Ru-O-Ru) nitrate complexes were entirely adsorbed by the addition of 500-700 ppm of activated carbon produced from coconut shell by batch equilibrium test. In spite of the high concentration of natural ion exchangers, the percentages of adsorption of these complexes were not observed to be very high. (author)