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T. PERNYESZI, K. HONFI, B. BOROS, K. TÁLOS, F. KILÁR, C. MAJDIK
It should be noticed that for the utilization of this model, the
experimental value of qeq is not necessary to be pre-estimated. By plotting
t/q against t for the initial concentrations (12.5, 25.0, 50.0 mg/L), straight
lines were obtained as shown in Figure 3b. The second-order rate constants
k2,ad and qeq values are presented in table 1 were determined from the
slopes and intercepts of the plots. The results show that the second-order
rate constants k2,ad increased with an increase in initial phenol concentration.
The biosorption of 2,4-dichlorophenol from aqueous solution on non-living
pellets of Phanerochaete chrysosporium grown by Kirk et al [20] was also
studied by Wu and Yu [12,13]. On the basis of their experiments they also
found that the biosorption process to biomass followed pseudo secondorder
kinetics. The pseudo-second-order kinetic constants decreased with an
increase in initial concentration for 2,4-dichlorophenol biosorption [13].
The correlation cefficients for the second-order kinetic model were
close to 1.0, and the theoretical values of qeq also agreed well with the
experimental data. On the other hand, the correlation coefficients for the
pseudo-first-order kinetics were lower than those for the pseudo-secondorder
one. Using pseudo-first-order model the theoretical qeq values did not
give reasonable values. This can be explained that the sorption of phenol
on mycelial pellets follow the second-order kinetics. The second-order
kinetic parameters can be used to determine the equilibrium sorption capacity,
percent of the removal of phenol, rate constants and initial sorption rate for
a bioreactor design.
log(qeq - q)
-0.5
-1
-1.5
-2
-2.5
-3
-3.5
0
0 10 20 30 40 50 60 70
a
t (min)
12.5 mg/L
25.0 mg/L
t/q (min g/mg)
2500
2000
1500
1000
500
0
b
0 50 100 150 200
t (min)
12.5 mg/L
25.0 mg/L
50.0 mg/L
Figure 3. (a) Linearized pseudo-first-order kinetic model for phenol by mycelial pellets
of Phanerochaete chrysosporium at different initial concentrations, initial concentrations:
12.5 and 25.0 mg/L, temperature: 22.5 ° C, biomass concentration: 5 g/L.
(b) Linearized pseudo-second-order kinetic model for phenol by mycelialpellets of
Phanerochaete chrysosporium at different initial concentrations, initial concentrations:
12.5, 25.0, 50.0 mg/L, temperature: 22.5 °C, biomass concentration: 5 g/L.