Figure 1: Min contact time, at 30 ºC; B. Evaluation of qe (mmol erythromycin/g sorbent) at different sorbent concentrations
|
Experimental factors |
|||
Coded levels |
Time |
Temperature |
Neutral microstructured materials (g/L) |
Erythromycin (mM) |
- |
6.5 |
25 |
0.3 |
0.8 |
-1 |
20.0 |
35 |
2.0 |
1.5 |
0 |
40.0 |
50 |
4.5 |
2.5 |
1 |
60.0 |
65 |
7.0 |
3.5 |
|
73.5 |
75 |
8.7 |
4.2 |
Table 1: Coded and decoded levels of experimental factors studied in erythromycin recovery from growth media
Sorbent |
k1 (min-1) |
qmax (mmol/g) |
||||||
30 ºC |
40 ºC |
50 ºC |
60 ºC |
30 ºC |
40 ºC |
50 ºC |
60 ºC |
|
XAD-16N™ |
0.015 |
0.025 |
0.030 |
0.020 |
0.24 |
0.25 |
0.40 |
0.40 |
XAD-18™ |
0.025 |
0.035 |
0.032 |
0.029 |
0.25 |
0.35 |
0.47 |
1.34 |
XAD-1600N™ |
0.015 |
0.022 |
0.030 |
0.030 |
0.32 |
0.32 |
0.50 |
0.45 |
Table 2: Estimated parameters (k1 and qmax) for the model fitted to the uptake of erythromycin against time at different temperatures
Sorbent |
Freundlich Model |
Langmuir Model |
|||
kf |
n |
qmax (mmol/g) |
kL |
RL |
|
XAD-16NTM |
0.14 |
0.17 |
0.15 |
0.05 |
0.04 |
XAD-18TM |
0.19 |
0.80 |
0.64 |
2.32 |
0.77 |
XAD-1600NTM |
0.20 |
0.57 |
0.35 |
0.70 |
0.46 |
Table 3: Estimated parameters of the isotherms models of Freundlich and Langmuir
Sorbent |
ΔHads (kJ/mol) |
ΔGads (kJ/mol) |
ΔSads (J/mol.K) |
XAD-16NTM |
3.68 |
52.47 |
16.10 |
XAD-18TM |
2.56 |
1.10 |
4.80 |
XAD-1600NTM |
2.72 |
3.60 |
2.90 |
Table 4: Thermodynamics parameters, sorption enthalpy (ΔHads), sorption free energy (ΔGads), and sorption entropy (ΔSads) on erythromycin sorption on different sorbents
Variables |
Residual [Erythromycin] (mM) |
|||||
XAD-16N |
XAD-18 |
XAD-1600N |
||||
|
(p) |
(p) |
|
(p) |
||
Time (Linear term) |
-0.4002 |
(0.0408*) |
-0.3625 |
(0.1627) |
-0.7010 |
(0.0126) |
Time (Quadratic term) |
0.6777 |
(0.0045**) |
0.5051 |
(0.0343*) |
0.4904 |
(0.0123*) |
Temperature (Linear term) |
-0.4208 |
(0.0333*) |
-0.4592 |
(0.1018) |
-0.3867 |
(0.0594) |
Temperature (Quadratic term) |
0.5628 |
(0.0124*) |
0.3902 |
(0.0646) |
0.2461 |
(0.0726) |
[Sorbent] (Linear term) |
-0.6053 |
(0.0057**) |
-0.6321 |
(0.0155*) |
-0.8264 |
(0.0022**) |
[Sorbent] (Quadratic term) |
0.5053 |
(0.0208*) |
0.1458 |
(0.3636) |
0.3035 |
(0.0439*) |
[Erythromycin] (Linear term) |
1.6046 |
(0.0000***) |
1.1360 |
(0.0103**) |
1.0635 |
(0.0039*) |
[Erythromycin] (Quadratic term) |
0.4334 |
(0.0400*) |
0.1027 |
(0.5063) |
-0.0126 |
(0.8978) |
Time x Temperature |
-0.3461 |
(0.5564) |
-1.1099 |
(0.0229*) |
-0.7556 |
(0.0214*) |
Time x [Sorbent] |
0.0610 |
(0.8681) |
0.1524 |
(0.4249) |
-0.0915 |
(0.4657) |
Time x [Erythromycin] |
-0.2307 |
(0.6897) |
-0.2865 |
(0.3464) |
-0.3969 |
(0.1024) |
Temperature x [Sorbent] |
-0.0813 |
(0.8252) |
0.3963 |
(0.0963) |
0.3354 |
(0.0552) |
Temperature x [Erythromycin] |
0.0643 |
(0.9102) |
0.0541 |
(0.8468) |
-0.2436 |
(0.2484) |
[Sorbent] x [Erythromycin] |
-0.0813 |
(0.8252) |
-0.1118 |
(0.5477) |
-0.2947 |
(0.0747) |
* p < 0.05, ** p < 0.01, *** p < 0.001
Table 5: Effects and respective significance levels (p) of time, temperature, [neutral polymeric sorbent], and [Erythromycin] on erythromycin sorption, evaluated as residual erythromycin in solution (not adsorbed) (mM)Sorbent |
Model Equations |
R2 |
R2adj |
XAD-16NTM |
[Erythromycin]Residual = 7.0106 – 0.0778Time – 0.00085 Time2 – 0.1391Temperature + 0.0013Temperature2 – 0.4849[XAD-16N] + 0.0404[XAD-16N]2 – 0.28124 [Erythromycin] + 0.2167[Erythromycin]2 |
0.939 |
0.885 |
XAD-18TM |
[Erythromycin]Residual = 0.00063Time2 – 0.00185 Time x Temperature + 0.00447Temperature x [XAD-18] |
0.989 |
0.941 |
XAD-1600NTM |
[Erythromycin]Residual = 0.0006Time2 – 0.4235[XAD-1600N] + 0.0243 [XAD-1600N]2 – 1.6316[Erythromycin] - 0.0013Time x Temperature + 0.00447Temperature x [XAD-1600N] |
0.995 |
0.969 |
Table 6: Second-order model equations for the response surfaces fitted to the experimental data points, as a function of Time, Temperature, [Sorbent] and [Erythromycin], respectively, and coefficient of determination, R2, and R2adj. The dependent variable was the residual [Erythromycin] (not adsorbed)
Tables at a glance
Figures at a glance