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 60-800 degrees C. Chemically bound water volatilizes around 200 degrees C and the matrix undergoes extensive oxidative decomposition at 450 degrees C, the weight loss reaching 75% at 800 degrees C. The sorption capacity of the matrix for nickel(II) ion increases on heat treatment from 60 to 200 degrees C (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.