British Library Electronic Table of Contents (United Kingdom)

This study examined kinetics and mass transfer in the biosorption of heavy metals onto Caulerpa lentillifera. The sorption capacity of Cu^2^+, Pb^2^+ and Cd^2^+ from aqueous solution increased with initial metal concentration and decreased with biosorbent dose. Kinetic data were well described using the pseudo-second-order model. Results showed that both external mass transfer and intraparticle diffusion were rate limiting steps in the biosorption process. Activation energy of biosorption kinetics fell in the range of 3-13kJ/mol. The biosorption of Cu^2^+, Cd^2^+ and Pb^2^+ on the biomass correlated well with the Langmuir isotherm (R^2>0.99) with maximum sorption capacities at 293K of 0.169, 0.085 and 0.177mol/kg for Cu^2^+, Cd^2^+ and Pb^2^+ ions, respectively. Thermodynamic studies demon...

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The aim of this article was to investigate the interactions of metal cations in aqueous solutions with the biomass of the freshwater macroalga Vaucheria sp. This problem is important when elaborating new applications of biosorption, e.g. the production of mineral feed additives for livestock from the biomass of algae enriched with microelement ions. Potentiometric titration was applied as a quick and cheap screening test to search for new efficient biosorbents. It revealed a variety of functional groups capable of cation exchange on the macroalgal surface, including carboxyl, phosphate, hydroxyl or amino groups. Fourier transform infrared spectroscopy on natural and chromium-loaded Vaucheria sp. confirmed that carboxyl groups played a dominant role in the biosorption. The study also showed that Ca(II), Na(I), K(I), and Mg(II) ions were released from the biomass after biosorption of Cu(II), Mn(II), Zn(II), and Co(II) ions, indicating that ion exchange was a key ...

British Library Electronic Table of Contents (United Kingdom)

We studied the mechanism of Ascophyllum nodosum (a brown macroalga) induced resistance in Arabidopsis thaliana against Pseudomonas syringae pv. tomato DC3000. Root treatment of A. thaliana Col-0 plants with extracts of A. nodosum [aqueous (ANE), chloroform (C-ANE) and ethylacetate fractions, (E-ANE)] reduced the development of disease symptoms on the leaves. These extracts also induced resistance in salicylic acid deficient NahG and ics1 plants. However, the extracts did not elicit an effect on jar1 (jasmonic acid resistance 1) mutant. A. nodosum extract induced resistance to Pst DC3000 correlated with increased expression of jasmonic acid related gene transcripts PDF1.2 while PR1 and ICS1 expression were less affected. Additionally, pretreatment of Arabidopsis plants with ANE, protected t...

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Germination inhibition of the marine macrophyte Phyllospora comosa was utilized as a sub-lethal end-point to assess and compare the effects of four oil dispersants and dispersed diesel fuel and crude oil combinations. Inhibition of germination by the water-soluble fraction of diesel fuel increased following the addition of each of the dispersants; the nominal 48-h EC{sub 50} concentration of diesel fuel declined from 6800 to approximately 400 {mu}l 1{sup -1} nominal for each dispersed combination. This contrasted with crude oil, where the addition of two dispersants resulted in an enhanced germination rate and an increase in nominal EC{sub 50} concentrations from 130 {mu}l 1{sup -1} for the undispersed crude to 4000 and 2500 {mu}l 1{sup -1}. The results indicate that, while germination inhibition of P. comosa may be enhanced by the chemical dispersal of oil response varies with type of both oil and oil dispersant. (author)