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Rui A.r. Boaventura - One of the best experts on this subject based on the ideXlab platform.
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ion exchange prediction model for multi metal systems obtained from single metal systems using the macroalga Pelvetia canaliculata phaeophyceae as a natural cation exchanger
Chemical Engineering Journal, 2015Co-Authors: Fabiola V Hackbarth, Rui A.r. Boaventura, Vitor J P Vilar, Antonio Augusto Ulson De Souza, Francielle Girardi, J C Santos, Selene Guelli M A U De SouzaAbstract:The aim of this study was to investigate the cation exchange capacity of the macroalga Pelvetia canaliculata (Linnaeus) Decaisne & Thuret in a multi-metal system containing Cd2+, Pb2+, Cu2+ and Zn2+. The Na-loaded alga was established as a cation exchanger, in which cadmium, lead, copper, zinc and hydrogen ions present in the liquid phase exchange with sodium ions bound to the functional groups on the algal surface, mainly weakly acidic carboxylic groups and strongly acidic sulfonic groups. A mass action law for the senary system (Na+/H+/Cd2+/Pb2+/Cu2+/Zn2+) was able to predict the equilibrium data using the selectivity coefficients determined for the single-metal systems. Multi-metal equilibrium results, in agreement with the selectivity coefficients, showed a higher preference (affinity) of the biomass toward lead ions followed by copper, cadmium and zinc ions. A mass transfer model, considering equilibrium given by the mass action law, and a linear driving force model for intraparticle diffusion, was able to fit well the batch kinetic experimental data for all chemical species in the liquid and solid phase. The results indicate that the biomass of P. canaliculata is an efficient natural cation exchanger for multi-metal systems.
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insights into trivalent chromium biosorption onto protonated brown algae Pelvetia canaliculata distribution of chromium ionic species on the binding sites
Chemical Engineering Journal, 2012Co-Authors: Vitor J P Vilar, Cidália M.s. Botelho, João C. Santos, Amit Bhatnagar, Jose Alexandre Borges Valle, Selene Guelli M A U De Souza, Antonio Augusto Ulson De Souza, Rui A.r. BoaventuraAbstract:In the present study, biosorption of trivalent chromium by protonated brown algae, Pelvetia canaliculata, was studied in batch system. FTIR analyses provided information about the possible binding ...
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Valorisation of marine Pelvetia canaliculata Ochrophyta for separation and recovery of nickel from water: equilibrium and kinetics modeling on Na-loaded algae
Chemical Engineering Journal, 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, João C. Santos, Vitor J P Vilar, Rui A.r. BoaventuraAbstract:In the present study, biosorption of Ni2+ by Na-loaded (raw algae treated with NaCl), algae Pelvetia canaliculata Ochrophyta, was studied in a batch system. Kinetics and equilibrium experiments were conducted at different pH values (2.0, 3.0 and 4.0). The metal uptake capacity decreased by decreasing the solution pH, suggesting that competition exists between hydrogen ions, present in high concentrations at low pH values, and metal ions. An ion-exchange model, considering two different binding sites, sulfonic and carboxylic groups, was developed to describe equilibrium data. A mass transfer model, considering intraparticle resistance was also developed to describe kinetics in a batch system. The release of sodium ions during the uptake of nickel ions revealed that the biosorption mechanism involved ion-exchange between sodium and nickel ions with a stoichiometrical ratio of 2:1. Nickel showed higher affinity to the sulfonic groups than for carboxylic ones of algae biomass. Kinetic results show that hydrogen ions diffuse faster as compared to nickel and sodium ions. The maximum uptake capacity of Na-loaded algae, P. canaliculata, for Ni2+ was found to be ca. 100 mg/g at pH 4.0.
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optimization of nickel biosorption by chemically modified brown macroalgae Pelvetia canaliculata
Chemical Engineering Journal, 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, Vitor J P Vilar, Catarina Ferreira, Rui A.r. BoaventuraAbstract:In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potenti ...
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Optimization of nickel biosorption by chemically modified brown macroalgae (Pelvetia canaliculata)
'Elsevier BV', 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, Vitor J P Vilar, Catarina Ferreira, Rui A.r. BoaventuraAbstract:In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potentiometric titration revealed that the carboxyl groups were more abundant (3.9 mmol/g) as compared to hydroxyl groups (2.0 mmol/g) on the biosorbent surface. Fourier transform infrared (FUR) analysis of algae was done to identify the role of different functional groups present on algae surface during nickel biosorption. The protonated algae showed least sorption of nickel suggesting that after acid treatment, some of the binding sites were destroyed. Among the various forms of prepared algae. Na-algae prepared directly from raw algae (without protonation) showed highest uptake of nickel. The release of sodium ions during the uptake of nickel ions has shown that the current biosorption mechanism involves ion-exchange being a stoichiometrical ratio of 2:1 between sodium and nickel ions
Susan H. Brawley - One of the best experts on this subject based on the ideXlab platform.
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evolution of the fucaceae phaeophyceae inferred from nrdna its
Journal of Phycology, 1999Co-Authors: Ester A Serrao, Lawrence A Alice, Susan H. BrawleyAbstract:Sequences of the internal transcribed spacer region (ITS-1, 5.8S, and ITS-2) of nuclear ribosomal DNA were obtained from 16 species representing all six genera of Fucaceae (Ascophyllum, Fucus, Hesperophycus, Pelvetia, Pelvetiopsis, and Xiphophora) plus one outgroup (Hormosira). Parsimony analysis indicated that the family Fucaceae is monophyletic and that the northern hemisphere taxa are highly divergent from the only southern hemisphere genus, Xiphophora. The genus Pelvetia is not monophyletic because the European P. canaliculata is more closely related to Fucus, Hesperophycus, and Pelvetiopsis than to other Pelvetia species. We establish Silvetia, gen. nov. and transfer the 3 Pacific species of Pelvetia to the new genus. Fucus is monophyletic and not ancestral in the Fucaceae. The ITS sequences identified two strongly supported lineages within Fucus, one with F. serratus sister to the clade containing F. gardneri, F. distichus, and F. evanescens and a second including F. vesiculosus, F. spiralis, F. ceranoides, and F. virsoides. The ITS was not useful for resolving relationships within each of these clusters and between populations of F. vesiculosus. Within-individual variation in ITS sequences is high in Fucus, a derived genus, compared to Ascophyllum, a more ancestral genus. Mapping of the two characters that form the basis of Powell’s model for speciation in the Fucaceae showed that 1) number of eggs per oogonium has not followed a gradual reduction and that 2) monoecy/dioecy has changed several times during evolution of this family.
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a model for signal transduction during gamete release in the fucoid alga Pelvetia compressa
Plant Physiology, 1998Co-Authors: Gareth A Pearson, Susan H. BrawleyAbstract:Fucoid algae release gametes into seawater following an inductive light period (potentiation), and gamete expulsion from potentiated receptacles of Pelvetia compressa began about 2 min after a light-to-dark transition. Agitation of the medium reversed potentiation, with an exponential time course completed in about 3 h. Light regulated two signaling pathways during potentiation and gamete expulsion: a photosynthetic pathway and a photosynthesis-independent pathway in which red light was active but blue light was not. Uptake of K+ appears to have an important role in potentiation, because a 50% inhibition of potentiation occurred in the presence of the tetraethylammonium ion, a K+-channel blocker. A central role of anion channels in the maintenance of potentiation is suggested by the premature release of gametes in the light when receptacles were incubated with inhibitors of slow-type anion channels. An inhibitor of tyrosine kinases, tyrphostin A63, also inhibited potentiation. A model for gamete release from P. compressa is presented that proposes that illumination results in the accumulation of ions (e.g. K+) throughout the cells of the receptacle during potentiation, which then move into the extracellular matrix during gamete expulsion to generate osmomechanical force, resulting in gamete release.
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Sublethal stress in the intertidal zone: tidal emersion inhibits photosynthesis and retards development in embryos of the brown alga Pelvetia fastigiata
Oecologia, 1993Co-Authors: Ian R. Davison, Ladd E. Johnson, Susan H. BrawleyAbstract:The effect of tidal emersion on survivorship, photosynthesis and embryonic development was studied in 8 h old zygotes and 7 d old embryos of the intertidal brown alga Pelvetia fastigiata (J. Ag.) DeToni. Zygotes and embryos were outplanted for single low tides in the intertidal zone on the central coast of California (U.S.A.) during June, 1990. Both zygotes and embryos exhibited close to 100% survival when outplanted beneath the canopy of adult P. fastigiata . Embryos (7 d old) also exhibited high survival when outplanted in a red algal turf, the microhabitat where most successful recruitment occurs. However, zygotes (8 h old) experienced high mortality (65–90%) when outplanted in the turf microhabitat. Embryos and zygotes that survived emersion experienced sub-lethal stress that temporarily impaired light-saturated photosynthesis when plants were reimmersed in seawater. The effects of sub-lethal stress were more pronounced in 8 h old zygotes than 7 d embryos, and more severe in the turf microhabitat than beneath the adult Pelvetia canopy. Zygotes outplanted in the red algal turf did not re-establish net photosynthesis until at least 6 h after re-immersion. Photosynthesis was less inhibited in 8 h old zygotes outplanted beneath the adult Pelvetia canopy, and recovered to control (non-emersed) levels within 3 h of re-immersion. Embryos (7 d old) were able to achieve positive net photosynthesis immediately on re-immersion after emersion in the turf or canopy microhabitats. Emersion also retarded the rate of embryonic development in 8 h old zygotes, delaying the formation of primary rhizoids, which help to attach the plant to the substrate. For example, at 19 h post-fertilization, 75% of control (non-emersed) zygotes had developed rhizoids, compared to 3% and 30% for zygotes outplanted in the turf and canopy microhabitats. The different emersion responses of 8 h old zygotes and 7 d old embryos appeared to be related to their ability to tolerate cellular dehydration. Overall, our data suggest that the effects of sub-lethal stresses may have been underestimated in studies of intertidal ecology.
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the fast block against polyspermy in fucoid algae is an electrical block
Developmental Biology, 1991Co-Authors: Susan H. BrawleyAbstract:Abstract Fertilization potentials in Pelvetia fastigiata, Fucus vesiculosus , and Fucus ceranoides were studied to examine whether eggs of fucoid algae have an electrical block against polyspermy. The resting potential of eggs of all species was about −60 mV, depolarizing, respectively, to −24 ± 5 mV (SD, n = 9) for 7.5 ± 2.1 ( n = 8) min, −26 ± 5 ( n = 9) mV for 6.4 ± 2.3 ( n = 9) min, and −24 ± 6 ( n = 5) mV for 6.7 ± 1.9 ( n = 4) min. The depolarization was slower, and the fertilization potential was about 10 mV more negative in eggs of both F. vesiculosus and Pelvetia fertilized in 45-m M Na + ASW; many of these eggs were polyspermic. Steady current was passed through unfertilized eggs of F. vesiculosus prior to insemination to test the potential dependence of fertilization. Eggs ( n = 10) bound sperm at all potentials tested (−45 to −23 mV), but fertilization was prevented if eggs were held at potentials more positive than −45 to −37 mV. Eggs underwent a second depolarization if artificially hyperpolarized to potentials more negative than −50 mV immediately after the rise of a normal fertilization potential. Thus, fucoid eggs have an electrical fast block against polyspermy. Only in F. ceranoides does the formation of the cell wall after fertilization appear to be fast enough (i.e., 3–6 min postfertilization versus at 10–15 min in F. vesiculosus and P. fastigiata ) to replace the fertilization potential as a polyspermy block. Nonfertilizing fucoid sperm swim away from the egg surface by 1–3 min after rise of the fertilization potential. This suggests that there is another “intermediate block” against polyspermy.
Vitor J P Vilar - One of the best experts on this subject based on the ideXlab platform.
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ion exchange prediction model for multi metal systems obtained from single metal systems using the macroalga Pelvetia canaliculata phaeophyceae as a natural cation exchanger
Chemical Engineering Journal, 2015Co-Authors: Fabiola V Hackbarth, Rui A.r. Boaventura, Vitor J P Vilar, Antonio Augusto Ulson De Souza, Francielle Girardi, J C Santos, Selene Guelli M A U De SouzaAbstract:The aim of this study was to investigate the cation exchange capacity of the macroalga Pelvetia canaliculata (Linnaeus) Decaisne & Thuret in a multi-metal system containing Cd2+, Pb2+, Cu2+ and Zn2+. The Na-loaded alga was established as a cation exchanger, in which cadmium, lead, copper, zinc and hydrogen ions present in the liquid phase exchange with sodium ions bound to the functional groups on the algal surface, mainly weakly acidic carboxylic groups and strongly acidic sulfonic groups. A mass action law for the senary system (Na+/H+/Cd2+/Pb2+/Cu2+/Zn2+) was able to predict the equilibrium data using the selectivity coefficients determined for the single-metal systems. Multi-metal equilibrium results, in agreement with the selectivity coefficients, showed a higher preference (affinity) of the biomass toward lead ions followed by copper, cadmium and zinc ions. A mass transfer model, considering equilibrium given by the mass action law, and a linear driving force model for intraparticle diffusion, was able to fit well the batch kinetic experimental data for all chemical species in the liquid and solid phase. The results indicate that the biomass of P. canaliculata is an efficient natural cation exchanger for multi-metal systems.
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insights into trivalent chromium biosorption onto protonated brown algae Pelvetia canaliculata distribution of chromium ionic species on the binding sites
Chemical Engineering Journal, 2012Co-Authors: Vitor J P Vilar, Cidália M.s. Botelho, João C. Santos, Amit Bhatnagar, Jose Alexandre Borges Valle, Selene Guelli M A U De Souza, Antonio Augusto Ulson De Souza, Rui A.r. BoaventuraAbstract:In the present study, biosorption of trivalent chromium by protonated brown algae, Pelvetia canaliculata, was studied in batch system. FTIR analyses provided information about the possible binding ...
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Valorisation of marine Pelvetia canaliculata Ochrophyta for separation and recovery of nickel from water: equilibrium and kinetics modeling on Na-loaded algae
Chemical Engineering Journal, 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, João C. Santos, Vitor J P Vilar, Rui A.r. BoaventuraAbstract:In the present study, biosorption of Ni2+ by Na-loaded (raw algae treated with NaCl), algae Pelvetia canaliculata Ochrophyta, was studied in a batch system. Kinetics and equilibrium experiments were conducted at different pH values (2.0, 3.0 and 4.0). The metal uptake capacity decreased by decreasing the solution pH, suggesting that competition exists between hydrogen ions, present in high concentrations at low pH values, and metal ions. An ion-exchange model, considering two different binding sites, sulfonic and carboxylic groups, was developed to describe equilibrium data. A mass transfer model, considering intraparticle resistance was also developed to describe kinetics in a batch system. The release of sodium ions during the uptake of nickel ions revealed that the biosorption mechanism involved ion-exchange between sodium and nickel ions with a stoichiometrical ratio of 2:1. Nickel showed higher affinity to the sulfonic groups than for carboxylic ones of algae biomass. Kinetic results show that hydrogen ions diffuse faster as compared to nickel and sodium ions. The maximum uptake capacity of Na-loaded algae, P. canaliculata, for Ni2+ was found to be ca. 100 mg/g at pH 4.0.
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optimization of nickel biosorption by chemically modified brown macroalgae Pelvetia canaliculata
Chemical Engineering Journal, 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, Vitor J P Vilar, Catarina Ferreira, Rui A.r. BoaventuraAbstract:In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potenti ...
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Optimization of nickel biosorption by chemically modified brown macroalgae (Pelvetia canaliculata)
'Elsevier BV', 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, Vitor J P Vilar, Catarina Ferreira, Rui A.r. BoaventuraAbstract:In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potentiometric titration revealed that the carboxyl groups were more abundant (3.9 mmol/g) as compared to hydroxyl groups (2.0 mmol/g) on the biosorbent surface. Fourier transform infrared (FUR) analysis of algae was done to identify the role of different functional groups present on algae surface during nickel biosorption. The protonated algae showed least sorption of nickel suggesting that after acid treatment, some of the binding sites were destroyed. Among the various forms of prepared algae. Na-algae prepared directly from raw algae (without protonation) showed highest uptake of nickel. The release of sodium ions during the uptake of nickel ions has shown that the current biosorption mechanism involves ion-exchange being a stoichiometrical ratio of 2:1 between sodium and nickel ions
Amit Bhatnagar - One of the best experts on this subject based on the ideXlab platform.
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insights into trivalent chromium biosorption onto protonated brown algae Pelvetia canaliculata distribution of chromium ionic species on the binding sites
Chemical Engineering Journal, 2012Co-Authors: Vitor J P Vilar, Cidália M.s. Botelho, João C. Santos, Amit Bhatnagar, Jose Alexandre Borges Valle, Selene Guelli M A U De Souza, Antonio Augusto Ulson De Souza, Rui A.r. BoaventuraAbstract:In the present study, biosorption of trivalent chromium by protonated brown algae, Pelvetia canaliculata, was studied in batch system. FTIR analyses provided information about the possible binding ...
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Valorisation of marine Pelvetia canaliculata Ochrophyta for separation and recovery of nickel from water: equilibrium and kinetics modeling on Na-loaded algae
Chemical Engineering Journal, 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, João C. Santos, Vitor J P Vilar, Rui A.r. BoaventuraAbstract:In the present study, biosorption of Ni2+ by Na-loaded (raw algae treated with NaCl), algae Pelvetia canaliculata Ochrophyta, was studied in a batch system. Kinetics and equilibrium experiments were conducted at different pH values (2.0, 3.0 and 4.0). The metal uptake capacity decreased by decreasing the solution pH, suggesting that competition exists between hydrogen ions, present in high concentrations at low pH values, and metal ions. An ion-exchange model, considering two different binding sites, sulfonic and carboxylic groups, was developed to describe equilibrium data. A mass transfer model, considering intraparticle resistance was also developed to describe kinetics in a batch system. The release of sodium ions during the uptake of nickel ions revealed that the biosorption mechanism involved ion-exchange between sodium and nickel ions with a stoichiometrical ratio of 2:1. Nickel showed higher affinity to the sulfonic groups than for carboxylic ones of algae biomass. Kinetic results show that hydrogen ions diffuse faster as compared to nickel and sodium ions. The maximum uptake capacity of Na-loaded algae, P. canaliculata, for Ni2+ was found to be ca. 100 mg/g at pH 4.0.
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optimization of nickel biosorption by chemically modified brown macroalgae Pelvetia canaliculata
Chemical Engineering Journal, 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, Vitor J P Vilar, Catarina Ferreira, Rui A.r. BoaventuraAbstract:In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potenti ...
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Optimization of nickel biosorption by chemically modified brown macroalgae (Pelvetia canaliculata)
'Elsevier BV', 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, Vitor J P Vilar, Catarina Ferreira, Rui A.r. BoaventuraAbstract:In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potentiometric titration revealed that the carboxyl groups were more abundant (3.9 mmol/g) as compared to hydroxyl groups (2.0 mmol/g) on the biosorbent surface. Fourier transform infrared (FUR) analysis of algae was done to identify the role of different functional groups present on algae surface during nickel biosorption. The protonated algae showed least sorption of nickel suggesting that after acid treatment, some of the binding sites were destroyed. Among the various forms of prepared algae. Na-algae prepared directly from raw algae (without protonation) showed highest uptake of nickel. The release of sodium ions during the uptake of nickel ions has shown that the current biosorption mechanism involves ion-exchange being a stoichiometrical ratio of 2:1 between sodium and nickel ions
Cidália M.s. Botelho - One of the best experts on this subject based on the ideXlab platform.
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insights into trivalent chromium biosorption onto protonated brown algae Pelvetia canaliculata distribution of chromium ionic species on the binding sites
Chemical Engineering Journal, 2012Co-Authors: Vitor J P Vilar, Cidália M.s. Botelho, João C. Santos, Amit Bhatnagar, Jose Alexandre Borges Valle, Selene Guelli M A U De Souza, Antonio Augusto Ulson De Souza, Rui A.r. BoaventuraAbstract:In the present study, biosorption of trivalent chromium by protonated brown algae, Pelvetia canaliculata, was studied in batch system. FTIR analyses provided information about the possible binding ...
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Valorisation of marine Pelvetia canaliculata Ochrophyta for separation and recovery of nickel from water: equilibrium and kinetics modeling on Na-loaded algae
Chemical Engineering Journal, 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, João C. Santos, Vitor J P Vilar, Rui A.r. BoaventuraAbstract:In the present study, biosorption of Ni2+ by Na-loaded (raw algae treated with NaCl), algae Pelvetia canaliculata Ochrophyta, was studied in a batch system. Kinetics and equilibrium experiments were conducted at different pH values (2.0, 3.0 and 4.0). The metal uptake capacity decreased by decreasing the solution pH, suggesting that competition exists between hydrogen ions, present in high concentrations at low pH values, and metal ions. An ion-exchange model, considering two different binding sites, sulfonic and carboxylic groups, was developed to describe equilibrium data. A mass transfer model, considering intraparticle resistance was also developed to describe kinetics in a batch system. The release of sodium ions during the uptake of nickel ions revealed that the biosorption mechanism involved ion-exchange between sodium and nickel ions with a stoichiometrical ratio of 2:1. Nickel showed higher affinity to the sulfonic groups than for carboxylic ones of algae biomass. Kinetic results show that hydrogen ions diffuse faster as compared to nickel and sodium ions. The maximum uptake capacity of Na-loaded algae, P. canaliculata, for Ni2+ was found to be ca. 100 mg/g at pH 4.0.
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optimization of nickel biosorption by chemically modified brown macroalgae Pelvetia canaliculata
Chemical Engineering Journal, 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, Vitor J P Vilar, Catarina Ferreira, Rui A.r. BoaventuraAbstract:In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potenti ...
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Optimization of nickel biosorption by chemically modified brown macroalgae (Pelvetia canaliculata)
'Elsevier BV', 2012Co-Authors: Amit Bhatnagar, Cidália M.s. Botelho, Vitor J P Vilar, Catarina Ferreira, Rui A.r. BoaventuraAbstract:In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potentiometric titration revealed that the carboxyl groups were more abundant (3.9 mmol/g) as compared to hydroxyl groups (2.0 mmol/g) on the biosorbent surface. Fourier transform infrared (FUR) analysis of algae was done to identify the role of different functional groups present on algae surface during nickel biosorption. The protonated algae showed least sorption of nickel suggesting that after acid treatment, some of the binding sites were destroyed. Among the various forms of prepared algae. Na-algae prepared directly from raw algae (without protonation) showed highest uptake of nickel. The release of sodium ions during the uptake of nickel ions has shown that the current biosorption mechanism involves ion-exchange being a stoichiometrical ratio of 2:1 between sodium and nickel ions
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application of the nernst planck approach to lead ion exchange in ca loaded Pelvetia canaliculata
Water Research, 2010Co-Authors: Joana F De Sa S Costa, Cidália M.s. Botelho, Vitor J P Vilar, Eduardo Borges A Da Silva, Rui A.r. BoaventuraAbstract:Ca-loaded Pelvetia canaliculata biomass was used to remove Pb(2+) in aqueous solution from batch and continuous systems. The physicochemical characterization of algae Pelvetia particles by potentiometric titration and FTIR analysis has shown a gel structure with two major binding groups - carboxylic (2.8 mmol g(-1)) and hydroxyl (0.8 mmol g(-1)), with an affinity constant distribution for hydrogen ions well described by a Quasi-Gaussian distribution. Equilibrium adsorption (pH 3 and 5) and desorption (eluents: HNO(3) and CaCl(2)) experiments were performed, showing that the biosorption mechanism was attributed to ion exchange among calcium, lead and hydrogen ions with stoichiometry 1:1 (Ca:Pb) and 1:2 (Ca:H and Pb:H). The uptake capacity of lead ions decreased with pH, suggesting that there is a competition between H(+) and Pb(2+) for the same binding sites. A mass action law for the ternary mixture was able to predict the equilibrium data, with the selectivity constants alpha(Ca)(H)=9+/-1 and alpha(Ca)(Pb)=44+/-5, revealing a higher affinity of the biomass towards lead ions. Adsorption (initial solution pH 4.5 and 2.5) and desorption (0.3M HNO(3)) kinetics were performed in batch and continuous systems. A mass transfer model using the Nernst-Planck approximation for the ionic flux of each counter-ion was used for the prediction of the ions profiles in batch systems and packed bed columns. The intraparticle effective diffusion constants were determined as 3.73x10(-7)cm(2)s(-1) for H(+), 7.56x10(-8)cm(2)s(-1) for Pb(2+) and 6.37x10(-8)cm(2)s(-1) for Ca(2+).