This study evaluated the biosorption of Cd 2+ , Cr 3+ , Pb 2+ and Cu 2+ at pHs 3, 4, 5 and 6 for Saccharomyces cerevisiae both alive and biologically inactivated by different heating procedures (oven, autoclave or spray dry technique originated from alcohol industry). The material inactivated by autoclave (IA, at 120°C, 30 min) had the best performance for metals uptake: 1.88 ± 0.07 (Cu 2+ ), 2.22 ± 0.02 (Cr 3+ ) and 1.57 ± 0.08 g kg -1 (Pb 2+ ). For Cd 2+ ; while the material inactivated by spray dry (RY) presented the higher sorption capacity, 2.30 ± 0.08 g kg -1 . The sorption studies showed that the biosorbent materials presented different sorption capacities and an ideal sorption pH. The sorption sites were investigated by potentiometric titration and FT-IR and showed that different heating processes used to inactivate biological samples produce materials with different characteristics and with a diverse sorption capacity due to modification of the available sorption sites. This suggests that inactivation by heating can be an alternative to improve the performance of biosorbents. The main sorption sites for each material were phenolic for live yeast (LY) and carboxylic for yeast inactivated by heating in an autoclave (IA).
Sorção de metais por levedura viva e resíduo de levedura modificado por processos de aquecimento RESUMOSaccharomyces cerevisiae viva e biologicamente inativada por diferentes processos de aquecimento (forno, autoclave ou spray dry) foram empregadas para biossorção de Cd 2+ , Cr 3+ , Pb 2+ e Cu 2+ em pHs 3, 4, 5 e 6. O material inativado por autoclave (IA, a 120°C, 30 min) teve o melhor desempenho para a sorção de metais: 1,88 ± 0,07 (Cu 2+ ), 2,22 ± 0,02 (Cr 3+ ) e 1,57 ± 0,08 g kg -1 (Pb 2+ ). Para Cd 2 + o material inativado por spray dry (RY) apresentou a maior capacidade de sorção, 2,30 ± 0,08 g kg -1 . Os estudos de sorção mostraram que os materiais
