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The leaf sheath fibres of the Mediterranean seagrass Posidonia oceanica (L.) were used as a renewable and low cost biological adsorbent for the removal of textile metal complex dye from aqueous solutions. Batch experiments were carried out for sorption kinetics and isotherms. Experimental operating variables studied were pH, contact time at different initial dye concentrations, and biomass dosage. Maximum color removal was observed at pH 2. Adsorption capacity was enhanced by increasing both initial dye concentration and biomass quantity up to 20 g/L. The sorption kinetic data were found to follow the pseudo-second-order equations, thereby predicting a chimisorption process. Besides, the equilibrium data were modelled using Langmuir, Freundlich, Temkin, and Redlich-Peterson equations. Based on several error calculation methods, equilibrium data were well represented by both Redlich-Peterson and Langmuir isotherm models, suggesting a monolayer coverage of dye molecules onto the marine biomass surface and adsorption active sites of quite similar affinities toward the tested textile pollutant. Key words: adsorption, Posidonia oceanica, metal complex dye, kinetics, isotherms, modelling. Les xgagropiles du vegetal marin Posidonia oceanica (L.) ont ete utilisees comme un adsorbant biologique renouvelable et bon marche pour l'elimination de colorant textile metallifere a partir de solutions aqueuses. Les experiences en batch ont ete effectuees aussi bien pour les cinetiques que pour les isothermes d'adsorption. Les variables experimentales etudiees etaient le pH, le temps de contact a differentes concentrations initiales et la quantite de fibres. La capacite d'adsorption s'est averee maximale a un pH de 2. De plus, elle semble etre optimisee par une augmentation de la concentration initiale de colorant et la quantite d'adsorbant jusqu'a 20 g/L. La modelisation des donnees experimentales relatives aux cinetiques a montre que le modele de pseudo-second ordre decrit d'une facon satisfaisante l'adsorption sur fibres brutes, suggerant ainsi une << chimiosorption >>. De plus, les donnees a l'equilibre ont ete modelisees en utilisant les equations de Langmuir, Freundlich, Temkin et Redlich-Peterson. L'analyse statistique des constantes relatives a chaque modele par plusieurs methodes de calcul de l'erreur a montre que les modeles de Langmuir et de Redlich-Peterson semblent etre les plus appropries pour decrire le present phenomene d'adsorption avec une probable adsorption en monocouche sur des sites actifs d'affinites similaires. Mots-cles : adsorption, Posidonia oceanica, colorant metallifere, cinetiques, isothermes, modelisation., Introduction Plusieurs types d'industries utilisent les colorants synthetiques pour teindre leurs produits y compris l'industrie textile. Annuellement, plus de 7 x [10.sup.5] tonnes de ces colorants sont produites a l'echelle [...]

Abstract: The partitioning behaviour of dye-labeled dextrans of high molecular weight in aqueous suspensions of native cellulose nanocrystals was studied. Cellulose concentrations lie in the isotropic-nematic coexistence region. Blue dextrans [...]

The diffusional and orientational behavior of single terrylene diimide derivative (TDI) dyes molecules diffusing in cetyltrimethylammoniumbromide (CTAB)-templated pores of hexagonal mesoporous films are analyzed. The results have shown that the diffusion of TDI in the mesoporous film is more complicated due to the presence of adsorption sites in which the TDI molecules is occasionally trapped.

A study was conducted on the reaction of a dye cation recombining with an electron in Ti[O.sub.2] in the presence of L[i.sup.+], C[a.sup.2.sup.+], and TB[A.sup.+] cations by using laser-induced transient absorption measurements. The results suggested that the rate of charge recombinations is proportional to the concentration of initially deposited active cations.

A combined NMR and UV-vis spectroscopic investigation of the binding of DiSC2(5) to a short DNA duplex is described. The UV-vis allows for the rapid screening of many different DNA sequences for DiSC(sub 2)(5) dimerization based on well-defined spectral shifts.

The effects of metallic silver colloids on the fluorescence spectral properties of indocyanine green (ICG), a dye used for in vivo medical testing are examined. The results suggest the use of metal colloid-enhanced ICG for applications to retinal angiography and vascular imaging and as a contrast agent for optical tomography.

Research has been conducted on the blue ultramarine pigments. The results of the quantitative study of these pigments carried out in determining the S (sub)3 (super)- chromophore concentration are discussed.

Research has been conducted on the dye-modified beta-cyclodextrins. The heterodimerization behavior of these cyclodextrins has been investigated in an aqueous solution via absorption and induced circular dichroism spectroscopy and the results indicate that heterodimerization can be used in the supramolecular heteropolymer preparation.

The optical and analytical characteristics of a series of neutral [H.sup.+]-selective chromoionophores in PVC membranes are described. Such indicators have been synthesized so that they can operate in bulk optode membranes as the chemically active region of integrated waveguide absorbance optodes (IWAOs), [lambda.sub.max] near 780 nm. Their spectral characteristics, acid-base properties, chemical stability, and solubility in the membrane phase are given and discussed. The response characteristics are first tested in a conventional absorbance/transmittance flow cell. They offer a wide range of p[K.sub.a]'s in PVC membranes, good sensitivity as a result of their high molar absortivities, excellent solubility in the plasticizer, and quick response times. They present good chemical stability in common laboratory conditions when stored in the dark, and the absence of leaching guarantees a long lifetime. Membranes have been finally applied as the sensing region of an integrated waveguide optode, demonstrating the extraordinary sensitivity improvement while preserving the remaining analytical features. Calibration curve slopes are multiplied by 3-28, and response times lower than 2 min are obtained.

Research has been conducted on the on the novel class of organic dyes. Results indicate that these dyes undergo reversible one-electron oxidation and one-electron reduction and exhibit absorption maxima in the long-wavelength region.

Research has been conducted on the beta-cyclodextrin oligomers with single or multiligated metal centers. The cooperative binding ability of these oligomers has been investigated via the inclusion behavior of the bis(beta-cyclodextrin)s linked with such dye guests as methyl orange and acridine red by the 2,2'-bipyridine-4,4'-dicarboxy tethers and their copper(II) complexes and the results are presented.

Research has been conducted on the ruthenium(II) bipyridyl complexes with the phosphonic acid functional groups. The synthesis, photophysical properties, surface attachment and photochemical properties of these complexes have been investigated and the results are reported.

Research has been conducted on the [Cr(L) (sub)2 (NCS) (sub)2]X complexes. The preparation of these complexes for the study of the diisothiocyanotobis-(2,2'-bipyridine-4,4'-dicarboxylic acid)ruthenium(III) redox-inactive surrogates is described.

Research has been conducted on the calix[4]arene-tethered mono- and bis(beta-cyclodextrin). The molecular recognition behavior of these compounds with the fluorescence dyes in the aqueous buffer solution has been investigated and the results are reported.

Research has been conducted on the platinum-based sensitizers. The synthesis of these sensitizers with different ground-state oxidation potentials has been carried out and anchored to the nanocrystalline titanium dioxide electrodes for the light-to-electricity conversion.

The ionization of crystal violet luconitriles occurs from S(sub)1 or from T(sub)1 depending on the solvent used with no influence of solvents on the homolysis of the C-CN bond. The di-pi-methane rearrangement transient gives rise to norcaradiene intermediate, which undergoes oxidation producing carbene under 350-nanometer light.

Synthetic organic colorants, the majority of which are recalcitrant in nature, are used universally in many different manufacturing processes. The dyes are released into the environment in industrial effluents and are highly visible even at low concentrations (20 g/L) to inhibitory (IC(sub 50) 0.2 mg/L). Batch biodegradability assays indicated that the dyes were not readily utilized by the anaerobic microorganisms as a sole substrate. Decolorization of the dye tartrazine was investigated in a laboratory-scale anaerobic baffled reactor at a concentration of 250 mg/L. Reduction in COD of 50-60% and color reduction of about 95% was achieved. Initially the tartrazine was not readily decolorized; however, decolorization improved with acclimation of the biomass. An industrial wastewater from a food dye manufacturer was fed to a second laboratory-scale anaerobic baffled reactor at a concentration of 5% (volume-to-volume ratio) and then increased to 10% (volume-to-volume ratio). Anaerobic degradation of the wastewater was efficient. Methanogenic activity was high; the organic content of the influent was reduced by about 70%, and color was reduced by almost 90%

LC/NMR and LC/MS (the latter technique in the MS(super n) mode) were used to characterize the organic constituents of industrial wastewater with emphasis on polar, nonvolatile compounds. In the effluent of a textile company, various compounds such as anthraquinone-type dyes and their byproducts, a fluorescent brightener, a byproduct from polyester production, and auxiliaries such as anionic and nonionic surfactants and their degradation products were identified. It is shown that the combined use of both hyphenated techniques provides complementary structural information. If applied under comparable chromatographic conditions, they are well-suited for the nontarget analysis.

Second harmonic generation (SHG) and angle-resolved absorbance with photoacoustic detection were combined to evaluate both the mean orientation angle and the width of the angular distribution for two surface-bound molecular systems. Assuming a Gaussian distribution function, a physisorbed stilbene dye on fused silica exhibited a narrow distribution centered at 73 degrees with a root-meansquare (rms) width of less than approximately 8 degrees. In contrast, a covalently bound azo dye resulted in a broad orientation distribution (rms width of approximately 30 degrees) centered at 60 degrees. It was also demonstrated that the combination of nonlinear (SHG) and linear (absorbance) spectroscopic techniques provides valuable insight into molecular orientation that a combination of two linear techniques (such as fluorescence and absorbance) is unable to provide.

Laser-induced fluorescence spectroscopy is used to profile solvent fractionation in an electrospray plume containing Nile Red, a solvatochromic dye (i.e., a dye for which spectral features are sensitive to solvent polarity). The results confirm gradual enrichment of the less volatile component in spray droplets as a result of solvent evaporation. Changes in solvent composition are evident in both axial and lateral profiles. The influences of capillary voltage, nebulizing gas, an electrolyte modifier, and flow rate on the extent of solvent fractionation are assessed. The results suggest that, in addition to volatility of the solvents, major factors affecting solvent fractionation include initial droplet size, droplet velocity, and the cooling effect of the nebulizing gas. Isolating contributions from these factors will require complementary data from other experiments.

A study concerning development of new 'BODIPY' dyes that fluoresce at long wavelengths is presented. Involvement of Suzuki couplings of arylboronic acids in the title compounds preparation is discussed.