Comparative study on metal biosorption by two macroalgae in saline waters: single and ternary systems

abstract

The biosorption capability of two marine macroalgae (green Ulva lactuca and brown Fucus vesiculosus) was evaluated in the removal of toxic metals (Hg, Cd and Pb) from saline waters, under realistic conditions. Results showed that, independently of the contamination scenario tested, both macroalgae have a remarkable capacity to biosorb Hg and Pb. In single-contaminant systems, by using only c.a. 500 mg of non-pre-treated algae biomass (size < 200 mu m) per litter, it was possible to achieve removal efficiencies between 96 and 99 % for Hg and up to 86 % for Pb. Despite the higher removal of Hg, equilibrium was reached more quickly for Pb (after 8 h). In multi-contaminant systems, macroalgae exhibited a similar selectivity toward the target metals: Hg > Pb > > Cd, although Pb removal by U. lactuca was more inhibited than that achieved by F. vesiculosus. Under the experimental conditions used, none of the macroalgae was effective to remove Cd (maximum removal of 20 %). In all cases, the kinetics of biosorption was mathematically described with success. Globally, it became clear that the studied macroalgae may be part of simple, efficient, and cost-effective water treatment technologies. Nevertheless, Fucus vesiculosus has greater potential, since it always presented higher initial sorption rates and higher removal efficiencies.

keywords

ULVA-LACTUCA BIOMASS; FUCUS-VESICULOSUS; AQUEOUS-SOLUTION; MERCURY; ALGAE; REMOVAL; BIOACCUMULATION; COPPER; IONS; BIOSORBENTS

subject category

Environmental Sciences & Ecology

authors

Figueira, P; Henriques, B; Teixeira, A; Lopes, CB; Reis, AT; Monteiro, RJR; Duarte, AC; Pardal, MA; Pereira, E

our authors

acknowledgements

We would like to thank University of Aveiro, FCT/MEC for the financial support to CESAM, CICECO, and CIIMAR (UID/AMB/50017/2013, UID/CTM/50011/2013, UID/Multi/04423/2013) through national funds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement. We also would like to thank the National Funds through the Portuguese Foundation for Science and Technology (FCT) through a FCT project (PTDC/MAR-BIO/3533/2012), postdoctoral grants to B. Henriques and C. B. Lopes (SFRH/BPD/112576/2015, SFRH/BPD/99453/2014), and a doctoral grant to R.J. Monteiro (SFRH/BD/108535/2015).

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