10.1016/j.powtec.2013.11.008
Synthesis, characterization of mesoporous silica powders and application to antibiotic remotion from aqueous solution. Effect of supported Fe-oxide on the SiO2 adsorption properties
Cetyltrimethylammonium p-toluene sulfonate or tosylate (CTAT, MW = 455.7 gmol- 1), Pluronic F68 and tetraethyl orthosilicate (TEOS, 99%) were purchased from Aldrich. Iron(III) nitrate nonahydrate, potassium hydroxide, potassium chloride, potassium nitrate, nitric acid, hydrochloric acid, sodium acetate, acetic acid, sodium carbonate, sodium hydrogen carbonate, disodium phosphate anhydrous, and monosodium phosphate anhydrous were obtained from Anedra. 
All chemicals were of analytical grade and used as received. Doubly distilled water was used for the preparation of solutions. 
Mesoporous silica was prepared using a procedure similar to that described in an earlier work [12]. Briefly, 11.6 mL of TEOS were mixed with 2 mL of water and stirred in an autoclave flask for 10 min at 500 rpm. At the same time, 38 mL of CTAT-Pluronic F68 mixed solution were prepared with a 0.75:0.25 M ratio by adding the desired amount of surfactants to water. This mixture was stirred in a conical flask at 35 degC to form a transparent template solution and then it was left at room temperature. To obtain the mesoporous material, 20 mL of a 1.43 M HCl solution were added drop by drop to the TEOS solution under stirring and 2 min later the surfactant solution was incorporated. The resulting gel, whose composition was 1 TEOS:0.53 HCl:0.011 CTAT:0.0037 F68, was stirred for 5 min and then left for 48 h in an autoclave at 100 degC. After this, the gel was filtered and washed with distilled water and dried at room temperature. Finally, it was calcined in an air flux by increasing the temperature from room temperature to 540 degC with a heating rate of 2degCmin- 1, and holding for 7 h at 540 degC.
Fe-SiO2 was synthesized by a simple batch equilibrium adsorption method. In a beaker, 2 g of calcined SiO2 were mixed with 40 mL of a 0.13 M Fe(NO3)3 solution and stirred for 1 h at 600 rpm. Then, the solid was filtered and washed with water and dried at room temperature. Finally, it was calcined in an air flux for 2 h at 540 degC. The iron content on the silica support was 10.3 mgg- 1 (1.03 wt.%), which was measured by UV-VIS spectroscopy using the thiocyanate colorimetric method [23] after extracting the Fe(III) ions from the solid with concentrated HNO3[24].
Cetyltrimethylammonium p-toluene sulfonate or tosylate (CTAT
MW
455.7 gmol- 1
gmol- 1
Pluronic F68 and tetraethyl orthosilicate (TEOS
99%
%
TEOS
mixed
11.6 mL
mL
11.6 mL of TEOS were mixed with 2 mL of water
stirred
10 min
min
11.6 mL of TEOS were mixed with 2 mL of water
stirred
500 rpm
rpm
water
2 mL
mL
CTAT-Pluronic F68 mixed solution
M ratio
0.75:0.25
CTAT-Pluronic F68 mixed solution
prepared
38 mL
mL
mixture
stirred
35 degC
degC
1.43 M HCl solution
added
20 mL
mL
HCl solution
1.43 M
M
TEOS solution
surfactant solution was incorporated
2 min
min
resulting gel
TEOS
1
resulting gel
HCl
0.53
resulting gel
CTAT
0.011
resulting gel
F68
0.0037
resulting gel
stirred
5 min
min
autoclave
48 h
h
autoclave
100 degC
degC
it
increasing the temperature from room temperature
540 degC
degC
increasing the temperature from room temperature to 540 degC
heating rate
2degCmin- 1
degCmin- 1
temperature
holding
7 h
h
temperature
holding for 7 h
540 degC
degC
calcined SiO2
mixed
2 g
g
Fe(NO3)3
mixed
40 mL
mL
Fe(NO3)3
mixed
0.13 M
M
2 g of calcined SiO2 were mixed with 40 mL of a 0.13 M Fe(NO3)3 solution
stirred
1 h
h
2 g of calcined SiO2 were mixed with 40 mL of a 0.13 M Fe(NO3)3 solution
stirred
600 rpm
rpm
it
calcined
2 h
h
it
calcined
540 degC
degC
iron content
1.03 wt.%
wt.%
silica support
iron content
10.3 mgg- 1
mgg- 1