Adsorption Isotherm
In order to determine the sorption capacity of NR5 biosorbent it is
required to generate an equilibrium data set which can further be
subjected to Langmuir and Freundlich adsorption isotherm equation.
Biosorption potential of NR5 was evaluated at concentration of 100
mgL-1 of As (V), and found that concentration of
arsenic (V) on NR5 cell surface increased with time progression, and
reached at a saturation point. This possibly because of high
availability of arsenic in medium and thus result in enhanced arsenic
biosorption capacity. Further when all surface is entirely covered with
As (V) adsorption potential reached to limit, and can be defined as
maximum biosorption capacity. The results suggested that both Langmuir
and Freundlich isotherm fitted, although Langmuir was comparatively more
demonstrative than Freundlich (Figure 2a) with a higher correlation
coefficient value (R2). Freundlich exhibits some
degree of linearity but Langmuir model was perfectly fit (Figure 2b).
Thus, results advocated of monolayer adsorption possibly due to topology
of bacterial (NR5) cell and binding sites. In addition to this when
adsorption behavior was evaluated using Elovich, Pseudo-first order
reaction couldn’t explain adsorption precisely due to its low
correlation coefficient value, although on the other hand second-order
kinetic model pronounced adsorption fittingly with correlation
coefficient R2 > 0.992. Thus, pseudo
second order kinetic model was best fitted in arsenic removal