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Removal of inorganic mercury from aqueous solutions by biomass of the marine macroalga Cystoseira baccata

Removal of inorganic mercury from aqueous solutions by biomass of the marine macroalga Cystoseira baccata
Removal of inorganic mercury from aqueous solutions by biomass of the marine macroalga Cystoseira baccata
The ability of Cystoseira baccata algal biomass to remove Hg(II) from aqueous solutions is investigated. The mercury biosorption process is studied through batch experiments at 25 degrees C with regard to the influence of contact time, initial mercury concentration, solution pH, salinity and presence of several divalent cations. The acid-base properties of the alga are also studied, since they are related to the affinity for heavy metals. The studies of the pH effect on the metal uptake evidence a sharp increasing sorption up to a pH value around 7.0, which can be ascribed to changes both in the inorganic Hg(II) speciation and in the dissociation state of the acid algal sites. The sorption isotherms at constant pH show uptake values as high as 178 mg g-1 (at pH 4.5) and 329 mg g-1 (at pH 6.0). The studies of the salinity influence on the Hg(II) sorption capacity of the alga exhibit two opposite effects depending on the electrolyte added; an increase in concentration of nitrate salts (NaNO3, KNO3) Slightly enhances the metal uptake, on the contrary, the addition of NaCl salt leads to a drop in the sorption. The addition of different divalent cations to the mercury solution, namely Ca2+, Mg2+, Zn2+, Cd2+, Pb2+ and Cu2+, reveals that their effect on the uptake process is negligible. Finally, the equilibrium sorption results are compared with predictions obtained from the application of a simple competitive chemical model, which involves a discrete proton binding constant and three additional constants for the binding of the main neutral inorganic Hg(II) complexes, HgCl2, HgOHCl and Hg(OH)2, to the algal surface sites.
Cystoseira baccata, mercury, adsorption, marine macroalga
0043-1354
3199-3210
Herrero, R.
ee7f0139-d8ac-4084-a73e-5eaa91b2e29a
Lodeiro, P.
2a3db327-ecb7-4c32-bc61-13e01aed7182
Rey-Castro, C.
1c26884f-0c33-40c4-b97b-111e7ec26fd7
Vilarino, T.
db8d5aa1-82b5-4879-afe5-12fa09398cd7
Sastre de Vicente, M.E.
2bd016ef-20cf-4fb4-9282-1ca22142bcb4
Herrero, R.
ee7f0139-d8ac-4084-a73e-5eaa91b2e29a
Lodeiro, P.
2a3db327-ecb7-4c32-bc61-13e01aed7182
Rey-Castro, C.
1c26884f-0c33-40c4-b97b-111e7ec26fd7
Vilarino, T.
db8d5aa1-82b5-4879-afe5-12fa09398cd7
Sastre de Vicente, M.E.
2bd016ef-20cf-4fb4-9282-1ca22142bcb4

Herrero, R., Lodeiro, P., Rey-Castro, C., Vilarino, T. and Sastre de Vicente, M.E. (2005) Removal of inorganic mercury from aqueous solutions by biomass of the marine macroalga Cystoseira baccata. Water Research, 39 (14), 3199-3210. (doi:10.1016/j.watres.2005.05.041).

Record type: Article

Abstract

The ability of Cystoseira baccata algal biomass to remove Hg(II) from aqueous solutions is investigated. The mercury biosorption process is studied through batch experiments at 25 degrees C with regard to the influence of contact time, initial mercury concentration, solution pH, salinity and presence of several divalent cations. The acid-base properties of the alga are also studied, since they are related to the affinity for heavy metals. The studies of the pH effect on the metal uptake evidence a sharp increasing sorption up to a pH value around 7.0, which can be ascribed to changes both in the inorganic Hg(II) speciation and in the dissociation state of the acid algal sites. The sorption isotherms at constant pH show uptake values as high as 178 mg g-1 (at pH 4.5) and 329 mg g-1 (at pH 6.0). The studies of the salinity influence on the Hg(II) sorption capacity of the alga exhibit two opposite effects depending on the electrolyte added; an increase in concentration of nitrate salts (NaNO3, KNO3) Slightly enhances the metal uptake, on the contrary, the addition of NaCl salt leads to a drop in the sorption. The addition of different divalent cations to the mercury solution, namely Ca2+, Mg2+, Zn2+, Cd2+, Pb2+ and Cu2+, reveals that their effect on the uptake process is negligible. Finally, the equilibrium sorption results are compared with predictions obtained from the application of a simple competitive chemical model, which involves a discrete proton binding constant and three additional constants for the binding of the main neutral inorganic Hg(II) complexes, HgCl2, HgOHCl and Hg(OH)2, to the algal surface sites.

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More information

Published date: September 2005
Keywords: Cystoseira baccata, mercury, adsorption, marine macroalga
Organisations: Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 355101
URI: http://eprints.soton.ac.uk/id/eprint/355101
ISSN: 0043-1354
PURE UUID: c27c0cea-327e-4cf1-93c2-d1a1cb2f82be

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Date deposited: 30 Jul 2013 14:10
Last modified: 14 Mar 2024 14:28

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Contributors

Author: R. Herrero
Author: P. Lodeiro
Author: C. Rey-Castro
Author: T. Vilarino
Author: M.E. Sastre de Vicente

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