tannins and pyrene

The interactions between pectins of different degrees of esterification (DE) and highly galloylated persimmon tannins with average degrees of polymerisation (DP26 and DP5) were investigated by UV-Vis spectrophotometry, dynamic light scattering, transmission electron microscopy, isothermal titration calorimetry and pyrene fluorescence methods Pectins displayed strong effects on the self-aggregation of persimmon tannins and improved the homogeneity of condensed tannin aggregates. The interaction between tannins and pectins may result from hydrogen bonding and hydrophobic interactions; by contrast, electrostatic interactions, which involve charged molecules in general, played no dominant role. In addition, the presence of gallate moieties in the high-polymerisation proanthocyanidin could enhance affinity with highly methylated pectins. Stronger association was observed with the high-polymerisation tannins (DP26) with high-methoxyl pectin (DE74) (Ka=(8.50±3.0)×10

Topics: Diospyros; Esters; Fluorescent Dyes; Fruit; Gallic Acid; Hydrogen Bonding; Hydrophobic and Hydrophilic Interactions; Kinetics; Methylation; Pectins; Proanthocyanidins; Pyrenes; Spectrometry, Fluorescence; Tannins; Thermodynamics

The ubiquity of dissolved organic matter (DOM) in an aqueous environment may have influence on the carbonaceous material's impact on the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) to benthonic organisms in contaminated sediment. In the present study, 1 multiwalled carbon nanotube (MWNT); 2 types of DOM (fulvic acid and tannic acid), and 2 PAHs (pyrene and chrysene) were selected to study the influence of MWNT with preloaded and coexisting DOM on the bioaccumulation of PAHs to Chironomus plumosus larvae in sediment. Moreover, the freely dissolved concentrations of PAHs were measured to explore the influence mechanisms. The results showed that despite the presence or absence of preloaded or coexisting DOM, the presence of 1% MWNT in sediments suppressed the biota-sediment accumulation factor (BSAF) and elevated the water-based bioaccumulation factor (BAF) of PAHs. However, the BSAF and BAF values generally decreased with the increase of 2 forms of both DOM; this was caused by the combined impact of DOM and MWNT on the freely dissolved concentrations of PAHs and the ingestion behavior of benthic organisms.

Topics: Animals; Benzopyrans; Chironomidae; Chrysenes; Geologic Sediments; Larva; Nanotubes, Carbon; Pyrenes; Tannins; Water Pollutants, Chemical