3614
R.N. Coimbra et al.
adsorbed onto PS800-150 at the equilibrium, q e (mgg calculated by the following mass balance relationship:
1 ) was
Table 3
Main properties of the STP secondary effluent used
in this work.
V W
q e ¼ð C 0 C e Þ 2 Þ For comparison purposes in terms of capacity, equilibrium experiments were also carried out following the same proce- dure but using ultrapure water as aqueous matrix. ð
Parameter pH
7.6±0.1
Conductivity ( l Scm 1 )
612±3 22±1 21±2 47±3 17±2
TSS (mgL 1 ) BOD 5 (mgL COD (mgL 1 ) NTK (mgL 1 ) N-NH 4 (mgL
1 )
2.5. Modeling of adsorption results
1 ) 1 ) 1 )
13.1±0.4 1.7±0.2 0.5±0.1 1.8±0.1
N-NO 3 (mgL N-NO 2 (mgL
The experimental kinetic results were fitted with the pseudo first-order (Lagergren, 1898) and the pseudo second-order (Ho and McKay, 1999) equations. Both the pseudo-first order (Eq. (3)) and the pseudo-second order (Eq. (4)) are empirical rate equations based on the overall sorption rate: q t ¼ q e ð 1 e k 1 t Þ ð 3 Þ q t ¼ q 2 e k 2 t 1 þ q e k 2 t ð 4 Þ where k 1 (min 1 ) and k 2 (mgg 1 min) are the pseudo-first and the pseudo-second order rate constants, respectively.
Total P-PO 4 (mgL 1 )
Note: Each ± stands for standard deviation of three analytical replications.
as inferred from kinetic results. Then, from each flask, three aliquots were taken, filtered and chromatographically analyzed to determine the equilibrium concentration ( C e ,mgL 1 ) of the target pharmaceutical. The amount of each pharmaceutical
0 1 2 3 4 5 6 7 8 9 10
(b)
25
(a)
20
15
10
Experimental data pseudo-first order kinetic equation pseudo-second order kinetic equation
Experimental data pseudo-first order kinetic equation pseudo-second order kinetic equation
5
0
0
200
400
600
800
1000
1200
0
200
400
600
800
1000 1200
t (min)
t (min)
(c)
(d)
16
16
14
14
12
12
10
10
8
8
6
6
4
4
Experimental data pseudo-first order kinetic equation pseudo-second order kinetic equation
Experimental data pseudo-first kinetic equation pseudo-second kinetic equation
2
2
0
0
0
200
400
600
800
1000 1200
0
200
400
600
800
1000
1200
t (min)
t (min)
Figure 1 Kinetic results on the removal of (a) diclofenac, (b) salicylic acid, (c) ibuprofen, and (d) acetaminophen from a secondary effluent of a STP by adsorption onto PS800-150. Experimental results throughout time are shown together with the corresponding fittings to the pseudo-first and to the pseudo-second order kinetic equations. Note: error bars stand for standard deviation of three experimental replications.
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