Factors influencing the luminescence intensity of europium(III) complexes prepared via synergistic extraction.

The excitation and luminescence spectra of Eu(III) extracted with pivaloyltrifluoroacetone (HA) and/or 2,2'-bipyridyl (B) into CHCl3 were measured. The data were compared to those obtained in an HA/CHCl3 solution into which EuA3 or EuA3B was dissolved. The results are summarized as follows: (1) The degree of HA influence on the luminescence intensity differs in the two systems; in the HA/CHCl3-dissolved EuA3, the intensity abruptly decreases when the HA concentration exceeds approximately 10(-2)M, depending on EuA3 concentration. The data measuring the size of the dominant species in the CHCl3 containing EuA3 and HA via DLS indicate that the abrupt concentration quenching is due to the formation of aggregate consisting of EuA3 and HA. However, in the solvent-extracted sample, the luminescence intensity is not influenced by the HA concentration, even at 0.1M HA. This difference can be explained by the difference in water content. (2) In the synergistic extraction of Eu(III) with HA and B, the intensity is not substantially influenced by HA. The effect of HA on the luminescence intensity in the B/CHCl3-dissolved EuA3 is larger than that obtained via solvent extraction. These results suggest that synergistic extraction could be an efficient method for preparing the phosphor in solution and that, when using luminescence intensity to determine Eu(III) concentration, one should be careful for the other materials, such as HA, that are involved in the solution and serve as reference materials.

Selective separation of samarium(III) by synergistic extraction with ß-diketone and methylphenylphenanthroline carboxamide.

Synergistic extraction of trivalent lanthanides (Lns(III)) with pivaloyltrifluoroacetone (HA) and N-methyl-N-phenyl-1,10-phenanthroline-2-carboxamide (MePhPTA) was evaluated across the Ln series. The distribution ratio (D) of Sm(III) under an identical condition was the largest among all Lns(III). The separation factor (SF) between Sm(III) and Nd(III) (SF=D(Sm)/D(Nd)) was 2.0 and SF between Sm(III) and Eu(III), (D(Sm)/D(Eu)) was 1.4. Upon analyzing the extraction data in detail on the basis of mass balance, it was found that the dominant extracted species of light Lns(III) was a stable ternary complex consisting of Ln(III), HA, and MePhPTA (B), namely, LnA(3)B, while the dominant extracted species of heavy Lns(III) was the ion pair, [LnA(2)B](+)ClO(4)(-). The complex for Pr(III) was very stable (the stability constant, ߯, denoted as [LnA(3)B](o)[LnA(3)](o)(-1)[B](o)(-1), was 10(8.3)). It suggests that LnA(3) can form two 5-membered rings with MePhPTA, and the size of Pr(III) matches to the distance between the donor atoms in MePhPTA. Although the stability constant decreased with increasing Ln atomic number, the synergistic extraction constant (K(ex31)=[LnA(3)B](o)[H(+)](3)[Ln(3+)](-1)[HA](o)(-3)[B](o)(-1)) was the largest for Sm(III). Since the constant, K(ex31,) is given by K(ex31)=K(ex30)×߯ where K(ex30)=[LnA(3)](o)[H(+)](3)[Ln(3+)](-1)[HA](o)(-3), the largest K(ex31) of Sm(III) is attributable to the difference of the degree of the variation of K(ex30) between the light and the heavy Lns(III); the increment of extraction constant of LnA(3) (logK(ex30)) for light Lns is larger than the decrement of the stability constant of LnA(3)B (log߯), while the increment of logK(ex30) of post-Sm lessens than the decrement of log߯. From these results, it is concluded that selective separation of a particular Ln(III) among all Lns(III) is possible using synergistic extraction with a suitable combination of a multidentate ß-diketone and a Lewis base.

The succession of microbial community in the organic rich fish-farm sediment during bioremediation by introducing artificially mass-cultured colonies of a small polychaete, Capitella sp. I.

We monitored seasonal changes of the abundance and composition of microorganisms in the fish-farm sediment in Kusuura Bay, Amakusa, Japan, using the quinone profiling technique, during bioremediation by introducing cultured colonies of polychaete, Capitella sp. I. In November 2004, approximately 9.2 million cultured worms were transferred to the fish-farm sediment, which increased rapidly, and reached 458.5 gWW/m(2) (528,000 indiv./m(2)) in March 2005. During this fast-increasing period of Capitella, the microbial quinone content of the surface sediment (0-2 cm) also increased markedly, and reached 237 micromol/m(2) in January 2005, although the water temperature decreased to the lowest levels in the year. Particularly, the mole fraction of ubiquinone-10 in total quinones in the sediment, indicating the presence of alpha subclass of Proteobacteria, increased by 9.3%. These facts suggest that the bacterial growth was enhanced markedly by the biological activities of worms in the sediment, and the bacteria played an important role in the decomposition of the organic matter in the sediment.