3.1. Biosorption kineticsBiosorptio

3.1. Biosorption kinetics
Biosorption is considered as the rapid process (Chu
et al., 1997) with the equilibrium reached after few minutes.
The experiments presented included biosorption of
heavy metal ions on the cells suspended in deionized
water, thus showing no metabolic activities (no cellular
growth nor other metabolic activity, such as production/
consumption of O2/CO2 were detected (Chojnacka,
2003)). It was found that under these conditions no bioaccumulation
into cellular interior occurred, since metal
ions were bound only to cellular surface (Chojnacka,
2003). The kinetic experiments of heavy metal ions removal
from solutions (Fig. 1) showed that biosorption
is the equilibrium process, in which the equilibrium is
reached after ca. 10min. The ions are bound with the
biomass stably: the concentration of metal ions remained
unchanged for 100h. The experimental results
are shown only for one morphological form of cells
(A). It was found that kinetics pattern for all the forms
are similar, independently on the biomass growth conditions
(Chojnacka, 2003).
The process of biosorption proceeded according to
equilibrium first order kinetics pattern. Reaction rate
constants (kad and kde) were determined by non-linear
regression (Mathematica v. 3.0) (Table 1). The values
of kad were in the range 14–33h
1 and kde: 3–
8.7meqhkg
1 for different metal cations. The experimental
points were described with the model equation
(Fig. 1) according to Langmuir model for chemiso