Biosorption of lead ions on dried waste beer yeast and the analysis by FTIR

The biosorption of lead ions on dried waste beer yeast was investigated with respect to the adsorption conditions and the biosorption mechanism was analyzed with the instruments of AAS, SEM/EDS and FTIR. The results show that the metal uptake value obtained was 47.6 mg·g-1 and the adsorptive efficiency was above 90%. Under our experiment conditions, the biosorption of Pb2+ on dried waste beer yeast is a fast process. The biosroption quantity of Pb2+ on beer yeast cells was 47.6 mg·g-1 and the adsorption efficiency obtained was 91.6% in fisrt 30 min, then the metal uptake value obtained was 48.8 mg·g-1 and the adsorptive efficiency was above 94% at 90 min. The cells cracking and breaking off were seen after the biosorption of lead ions on beer yeast through SEM analysis, and the cytoplasts from yeast cell should be responsible for the last period biosorption of lead ions. EDS analysis also proved that lead ions were absorbed on the yeast cells. FTIR analysis showed that the infrared spectrograms are different at different pH and biosorption time, especially hydroxyl groups, carboxylate groups and amide groups have obviously changed. Amylase and amide of protein were considered as main components to participate the chemical absorption of lead ions on yeast cells. Consequently, dried waste beer yeast is an inexpensive, readily available adsorbent for metals and especially has a high adsorption capacity for lead ions.