Evaluation of Dry Protonated Calcium Alginate Beads for Biosorption Applications and Studies of Lead Uptake |
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Authors: | Ricardo Lagoa J R Rodrigues |
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Institution: | (1) School of Technology and Management, Polytechnic Institute of Leiria, Morro do Lena, Alto do Vieiro, 2411-901 Leiria, Portugal |
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Abstract: | Alginate polysaccharide is a promising biosorbent for metal uptake. Dry protonated calcium alginate beads for biosorption
applications were prepared, briefly characterized and tested for lead uptake. Several advantages of this biosorbent are reported
and discussed in comparison with other alginate-based sorbents. The alginate beads contained 4.7 mmol/g of COOH groups, which
suffered hydrolysis near pH 4. The Weber and Morris model, applied to kinetic results of lead uptake, showed that intraparticle
diffusion was the rate-controlling step in lead sorption by dry alginate beads. Equilibrium experiments were performed and
the data were fitted with different isotherm models. The Langmuir equation was the most adequate to model lead sorption. The
maximum uptake capacity (q
max) was estimated as 339 mg/g and the Langmuir constant (b) as 0.84 l/mg. These values were compared with that of other sorbents found in the literature, indicating that dry protonated
calcium alginate beads are among the best biosorbents for the treatment and recovery of heavy metals from aqueous streams. |
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Keywords: | Biosorption Alginate Lead Heavy metal Water treatment Metal recovery Polysaccharide |
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