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Biosorption of monovalent and divalent ions on baker's yeast
Padma Vasudevan1, V Padmavathy, S C Dhingra
1Centre for Rural Development and Technology, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi. padmav@rdat.iitd.ernet.in
Abstract:
Biosorption of monovalent ions Na+ and K+, by deactivated protonated yeast (Saccharomyces cerevisiae) at controlled pH, was compared with biosorption of divalent ions Ca2+ and Mg2+ to help to understand the underlying bindingmechanisms. The adsorption for monovalent ions was accompanied by H+ release. Divalent ions were sorbed by proton displacement, and also an additional mode not accompanied by release of H+. The sorption uptake of both monovalent and divalent metal ions increased with pH in the range 3-7 peaking at 6.75. Equilibrium sorption isotherms at pH = 6.75 showed that the totalmaximum biosorptive capacity for metal ions decreased in the following order: Ca > Mg > Na > or = K.