1 Introduction
2 Experimental
2.1 Chemicals
2.2 Photocatalysts preparation
2.3 Photocatalysts characterization
2.4 Photocatalytic studies
PPCPs | λmax (nm) | Molecular weight (g mol−1) | pKa | log Kow |
---|---|---|---|---|
Diclofenac | 4.51 | 0.7 | ||
2-(2-(2,6-dichlorophenylamino) phenyl) acetic acid CAS No. 15307-86-5 | 276 | 318.13 | Non steroidal anti-inflammatory and analgesics drug; | |
estrone | 10.4 | 3.13 | ||
3-hydroxy-13-methyl-6,7,8,9,11,12,13,14,15,16-decahydrocyclopenta [a]phenanthren-17-one | 222 | 270.37 | Steroidal female sexual hormone (estrogene) similar to estradiol | |
chloramphenicol | 9.61 | 1.14 | ||
2,2-dichloro-N-[1,3-dihydroxy-1-(4-nitrophenyl)propan-2-yl]acetamide | 275 | 323.132 | Bactericidal antibiotic | |
metoprolol | 9.5 | 2.055 | ||
(RS)-1-(isopropylamino)-3-[4-(2-methoxyethyl)phenoxy]propan-2-ol | 222 | 267.36 | β-blocker |
3 Results and discussion
3.1 Characterizations of the samples
3.1.1 BET
Catalyst | BET surface (m2 g−1) | The pore volume (cm3 g−1) | Mean pore diameter (Ǻ) | The presence of rutile | Crystallinity (nm)*
|
---|---|---|---|---|---|
T1 | 12.08 | 0.024620 | 81.53 | −/+ | 19 |
T2 | 11.50 | 0.025734 | 89.50 | + | 59 |
T3 | 61.03 | 0.150906 | 98.90 | + | 20 |
T4 | 55.33 | 0.134603 | 97.30 | – | 21 |
3.1.2 SEM
3.1.3 XRD
3.2 Photocatalytic test
3.2.1 DFC photoremoval
3.2.2 CPL photooxidation
3.2.3 E1 photoremoval
3.2.4 Mt photoremoval
3.3 Kinetics of photooxidation
Catalyst | Kinetic parameter | Compound | ||||
---|---|---|---|---|---|---|
DCF | E1 | CFL | Mt | |||
T1 |
k
1
| (×10−2) (min−1) | 1.3476 | 0.4518 | 1.2007 | 0.5758 |
k
w
| (×10−2) (min−1 g−1) | 0.308 | 0.103 | 0.276 | 0.131 | |
k
s
| (×10−4) (min−1 m−2) | 2.547 | 0.854 | 2.283 | 1.088 | |
t
1/2
| (min) | 51.43 | 153.41 | 57.38 | 120.37 | |
R
2
| – | 0.93 | 0.99 | 0.99 | 0.95 | |
r
0
| (×10−6) (mol·dm−2 min−1) | 1.324 | 1.869 | 0.836 | 1.077 | |
T2 |
k
1
| (×10−2) (min−1) | 0.8591 | 0.2353 | 0.8497 | 0.4771 |
k
w
| (×10−2) (min−1 g−1) | 0.196 | 0.054 | 0.194 | 0.109 | |
k
s
| (×10−4) (min−1 m−2) | 0.321 | 0.088 | 0.318 | 0.947 | |
t
1/2
| (min) | 80.68 | 294.56 | 81.57 | 145.27 | |
R
2
| – | 0.95 | 0.99 | 0.95 | 0.92 | |
r
0
| (*10−6) (mol dm−2 min−1) | 1.350 | 1.215 | 0.435 | 0.892 | |
T3 |
k
1
| (*10−2) (min−1) | 0.6982 | 0.5442 | 0.8840 | 0.3300 |
k
w
| (*10−2) (min−1 g−1) | 0,159 | 0,124 | 0,202 | 0,075 | |
k
s
| (*10−4) (min−1 m−2) | 0.261 | 0.204 | 1.755 | 0.028 | |
t
1/2
| (min) | 99,27 | 127,36 | 78,41 | 210,03 | |
R
2
| – | 0.90 | 0.90 | 0.95 | 0.92 | |
r
0
| (*10−6) (mol dm−2 min−1) | 1,097 | 1.368 | 1.006 | 0.617 | |
T4 |
k
1
| (*10−2) (min−1) | 0.8782 | 0.7456 | 0.5162 | 0.6134 |
k
w
| (*10−2) (min−1 g−1) | 0.201 | 0.170 | 0.118 | 0.141 | |
k
s
| (*10−4) (min−1 m−2) | 0.362 | 0.308 | 0.213 | 0.058 | |
t
1/2
| (min) | 78.92 | 92.96 | 134.27 | 112.99 | |
R
2
| – | 0.97 | 0.95 | 0.92 | 0.94 | |
r
0
| (*10−6) (mol dm−2 min−1) | 1.8025 | 0.7987 | 1.3789 | 1.1471 |
4 Conclusions
-
The time dependence of treatment of studied pollutants revealed that the best changes in the water condition were observed during first hour of treatment and further prolongation of treatment time till 4 h. did not result in the total removal of pollutants because produced by- and end-products of photooxidation were stable and resistant to further oxidation what may suggest that, the photocatalytic treatment using described photocatalysts and rector configuration can not totally solve the environmental hazards arising from PPCPs;
-
The presence of rutile and large TiO2 crystals in TiO2 slightly diminished the photocatalytic efficiency of DFC removal;
-
The mineralization of DFC over T3 was as fast as the DFC photoremoval;
-
The photooxidation of CPL proceeded faster over smaller crystals of TiO2 and the photocatalysts with enhanced surface area were more effective than their low surface area counterparts;
-
The similar general tendency for low and high surface area photocatalysts can be observed during E1 removal;
-
The presence of rutile and the highest surface area favored the Mt photooxidation. The photocatalysts with lowest SBET value revealed the lowest activity in Mt photocatalytic oxidation.
-
The photooxidation of all studied pollutants followed the pseudo-first order kinetics.