The kinetics, equilibriums, and thermodynamics of metal ion Pb2+, Ag2+, Cu2+, Zn2+, Co2+, Sr2+, and Cs+ biosorption by the
waste yeast cells of Saccharomyces cerevisiae from a local brewery were investigated. The results showed that the biosorption of these
metal ions on the biomass was a very rapid process, following the pseudo-second-order equation gave the better fitting results in
describing the kinetic data than the pseudo-first-order equation. The equilibrium data could be fitted well with the Langmuir model. The
maximum sorption capacity obtained from the Langmuir model followed PbAgCuZnCoSrCs based on mmol g−1. The
biosorption process by the yeast was favorable for these metal ions removal according to the constant separation factor 0RL1 from
the Langmuir model. The dried yeast cells showed high affinity for Pb2+ uptake as soft ion and low affinity for Cs+ as hard ion biosorption.
The calculated values of the thermodynamic constants demonstrated that the biosorption process of Ag+, Cu2+, Zn2+, or Co2+ was
spontaneous and the entropy increased. pH increased during the metal biosorption by the yeast cells. Pb2+, Ag2+, Cu2+, Zn2+, or Co2+
exhibited a certain degree of covalent binding with the waste yeast cells. Cs+, as a typical hard ion, showed ionic binding with the
biomass.