The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
BIOSORPTIONOFTHOMUMUSINGJANIARUBENS-SACCHAROMYCES
CEREVISIAE - SILICA GEL COMPOSITE BIOSORBENT
S. AYTAS1. C. GO K 1, D. A. TURKOZÜ2
‘Ege University, Institute o f Nuclear Sciences, 35100 Bornova, Izmir, Turkey
2 Yuzuncu Yil University, Faculty o f Engineering and Architecture, 65080, Van, Turkey
B iosorption o f toxic heavy m etal contam inants from aqueous w aste is a safe an d cost- effective process for treatm ent o f high volum es o f low -concentration polluted solutions w hich could be com bined w ith m etal recovery. B iom ass o f brow n m arine m acroalgae is a renew able biological resource, w hich is available in large quantities and can form a good base for the developm ent o f biosorbent m aterial. B row n algae contain h igh concentrations o f alginic acid and sulfated polysaccharides. It has been postulated th at th e function o f these polysaccharides, w hich are absent in terrestrial plants, is to enable m arine algae to selectively absorb m etallic ions in a saline m edium through ion exchange.
B iosorption o f m etals involves several m echanism s that differ qualitatively an d quantitatively, according to the species used, the origin o f the biom ass, and its processing procedure. T here are several chem ical groups in biom ass that can attract an d sequester the m etals: acetam ido, am ino, am ido, sulfhydryl, sulfate, and carboxyl. M etal sequestration during biosorption follow s com plex m echanism s th at include m ainly ionic interactions and form ation o f com plexes betw een m etal cations and ligands contained in the structure o f the cell w all biopolym ers, as w ell as precipitation on the cell w all m atrix. T he binding characteristics o f m etallic cations during biosorption can partially be explained by Pearson’s concept o f hard and soft acid and base theory and by Irv in g - W illiam s series.
In this study, the adsorption o f thorium from aqueous solutions on jania rubens - saccharomyces cerevisiae - silica gel com posite biosorbent w as investigated. T he effect o f pH , initial concentration o f thorium , the co ntact tim e, tem perature and volum e/m ass ratio on adsorption w ere exam ined by
The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
batch technique. The m orphological analysis o f the com posite biosorbent w as perform ed b y the scanning electron m icroscopy (SEM ) and functional groups in the biosorbent w ere determ ined by FT-IR spectroscopy.
T he sorption results have been subjected to different sorption isotherm s, nam ely Freundlich, L angm uir and D ubinin-R adushkevich. B iosorption equilibrium better fit L angm uir equation than Freundlich equation, besides d o n ’t fit D ubinin-R adushkevich m odel. T he therm odynam ic param eters such as variation o f enthalpy AH, variation o f entropy AS and variation o f G ibbs free energy AG w ere calculated from the slope and intercept o f lnK d vs. 1/T plots. T he results o f this study show ed that natural and cheap Jania Rubens - Saccharomyces Cerevisiae - Silica gel com posite biosorbent can be successfully u sed for thorium rem oval from diluted aqueous solutions.
