Thermal and spectroscopic studies on sorption of nickel(II) ion on protonated baker's yeast

Protonated form (Hy) of yeast was subjected to thermal analysis (TGA and DTG) in the temperature range 60800 degreesC. Chemically bound water volatilizes around 200 degreesC and the matrix undergoes extensive oxidative decomposition at 450 degreesC, the weight loss reaching 75% at 800 degreesC. The sorption capacity of the matrix for nickel(II) ion increases on heat treatment from 60 to 200 degreesC (from 16.9 to 25.0 mg/g), but was reduced on heating to higher temperatures at an initial nickel (II) ion concentration of 1200 mg/g. The FTIR spectra of Hy and nickel(II) ion saturated yeast, indicated that biosorption occurs on the sugar and nucleic acid regions, possibly involving -COOH and -NH groups. (C) 2003 Elsevier Ltd. All rights reserved.