Synthesis and Characterization of Mesoporous Carbon Hybrids for Environmental Applications M.A.Karakassides Department of Materials Science & Engineering University of Ioannina, Greece Olomouc March 2011
Environmental Remediation Why mesoporous carbon? Why hybrids? activated carbon mesoporous carbon High surface area (up to 1700 m 2 g -1 ) Uniform pore size Large pore volumes High Periodicity R. Ryoo, S. Hoon and S. Jun, J. Phys. Chem. B, 103 (1999) 7743 hybrids Various properties possible depending on precursors and processing Nanomaterial properties Magnetic properties Catalytic properties hybrids ( mesoporous carbon + magnetic nanoparticles )
OUTLINE Introduction to mesoporous carbons Synthesis of hybrids, type-a (/magnetic nanoparticles) Synthesis of hybrids type-b (/ZVi nanoparticles) Study of synthesis stages and characterization of hybrids Example of use of hybrids (sorption of hexavalent chromium) Conclusions
Pore geometry Pore dimensions Introduction to mesoporous carbons classification M41S zeolite microporous d<2 nm mesoporous d=2-50 nm foams macroporous d>50 nm MATERIALS 1D 3D CNTs 2D SBA-15 Graphite sheets LDH
CMK: Mesoporous carbon materials with ordered crystalline structure SBA-15 Mesoporous Carbon/silicon Mesoporous carbon MCM-48 R. Ryoo, S. Hoon and S. Jun, J. Phys. Chem. B, 103 (1999) 7743
P. Selvam, S. K. Bhatia and C. S. Sonwane, Ind. Eng. Chem. Res., 40 (2001) 3237
SBA-15 Synthesis of C 2 H 5 C 2 H 5 O O Si O C 2 H 5 O C 2 H 5 TEOS 38 o C 95 o C 500 o C 22 hours 24 hours 6 hours SBA-15 Template P123/HCl/H 2 O SBA-15 100 o C 160 o C 877 o C/N 2 6 hours 6 hours 6 hours Sugar/H 2 O/H 2 SO 4 1,25 / 5 / 0,14κ.β. Sugar /H 2 O/H 2 SO 4 0,8 / 5 / 0,07κ.β.
Hybrids based on type-a with nanoparticles Fe x O y -----@Fe x O y type-b with nanoparticles Fe 0 -----@ZVI
Preparation of carbon hybrids ( /Fe x O y ) H 2 O OCH 2 (CH)O OCH 2 (CH 3 )O OH 2 + HO Fe OCH 2 (CH 3 )O Fe OCH 2 (CH 2 )O Fe OH NO 3 - H 2 O OCH 2 (CH 3 )O OCH 2 (CH 3 )O OH 2 HOOC HOOC HOOC COOH COOH COOH Fe(NO 3 ) 3 9H 2 O 1:4 Vapor CH 3 COOH pyrolysis 400 ο C/Ar Fe x O y -O -O@Fe -O@ac -O@m4 vapor CH 3 COOH pyrolysis 400 ο C/Ar Fe x O y @Fe @ac @mx
(110) (200) Intensity (100) (110) (200) (100) Characterization of SBA-15 SBA-15 110 200 d 100 = 9.0 nm P6mm pore 10 1,5 2,0 2,5 3,0 3,5 4,0 d 100 = 10.5 nm 1 2 3 4 5 2θ( ο ) SBA-15 a o =2d 100 / 3 a o = 12.1 nm a o = 10.4 nm
Absorbance Characterization of @Fe x O y Hybrids FT-IR Spectroscopy -O@m4 1700 1580 1230 -COO - 1595 1382 1716 1445 Fe-O 567 O-C=O H 2 O OCH 2 (CH)O OCH 2 (CH 3 )O OH 2 HO Fe OCH 2 (CH 3 )O Fe OCH 2 (CH 2 )O Fe OH H 2 O OCH 2 (CH 3 )O OCH 2 (CH 3 )O OH 2 -O@m4 + NO 3 - NO 3 -COO - Fe + 661 613 -COOH, -COO - 823 670 -O@ac C=C 1580 1350 1165 C-H 661 -O@Fe -O 2000 1800 1600 1400 1200 1000 800 600 Wavenumbers (cm -1 )
Characterization of @Fe x O y Hybrids Raman spectra I D /I G =0.8-0.95 FWHF~110cm -1 @m10 -O@m4 @m2 @m1
Intensity Intensity (110) (200) (110) (200) (100) (100) Characterization of @Fe x O y Hybrids X-ray Diffraction (XRD) @m1 -O -O@m4 1.0 1.5 2.0 2.5 3.0 2θ( ο ) @m2 @m10 1.0 1.5 2.0 2.5 3.0 2θ( ο )
Intensity Characterization of @Fe x O y Hybrids X-ray Diffraction (XRD) Fe 3 O 4 (311) Scherrer: D 0,9* Cu B*cos Β (220) @m10 (400) Average size Fe x O y 20nm -O@m4 @m2 13nm 8nm @m1 γ-fe 2 O 3 28 32 36 40 44 2θ (degrees)
endo %TG Characterization of @Fe x O y Hybrids Thermal Analysis 100 DTA exo 356 400 90 80 70 60 50 iron oxide content (Fe 2 O 3 ) of hybrids 27.3 wt% 40 -O@m4 30 20 -O@m4 11.5 wt% 100 200 300 400 500 600 700 800 Temperature( o C) 10 0 12,6% 100 200 300 400 500 600 700 800 Temperature( o C)
Vads (cm 3 /g) V liq (cm 3 /g) dv/dr Characterization of @Fe x O y Hybrids SURFACE AREA MEASUREMENTS Isotherms V-t plots 2.0 1200 r~1.7nm 1000 1.6 800 1.2 1.5 1.8 2.1 2.4 2.7 3.0 r(nm) -O 1.2 2 -O 600 @m1 0.8 @m1 400 @m4 0.4 -O@m4 200 1 0.0 0.2 0.4 0.6 0.8 1.0 p/p 0 0.0 0.0 0.4 0.8 1.2 1.6 2.0 t/nm
Characterization of @Fe x O y Hybrids Mössbauer spectroscopy @m1 Μössbauer parameters resulting from least square fits of the spectra γ-fe 2 O 3
Characterization of @Fe x O y Hybrids Magnetic measurements @m1 T (K) M max+ (7 T) (emu/g) H C (Oe) M R (emu/g) @m1 5 2.1205 500 0,5811 300K
Characterization of @Fe x O y Hybrids Transmission Electron Microscopy (ΤΕΜ) -O@m4
Characterization of @Fe x O y Hybrids Transmission Electron Microscopy (ΤΕΜ) @m1 @m1 a o =9 nm d=3 nm
Synthesis of /Fe 0 Hybrids FeCl 3 6H 2 O NaBH 4 1:2 @ZVI
Intensity Characterization of /Fe 0 Hybrids @ZVI-12:1 44,9 o @ZVI-4:1 35,5 o <2,7nm ~2,7nm Scherrer: D 0,9* Cu B *cos Β ZVI Fe 0 25 30 35 40 45 50 55 60 2θ( ο ) ~11,2nm
Vads (cm 3 /g) Vads (cm 3 /g) Characterization of /Fe 0 Hybrids 1000 800 800 S BET (m 2 /g) 1284 708 700 600 S BET (m 2 /g) 993 696 600 500 @ZVI-4 400 @ZVI-12 400 300 200 V pore (cm 3 /g) 0,65 0,39 200 100 V pore (cm 3 /g) 0,54 0,41 0 0.0 0.2 0.4 0.6 0.8 1.0 p/p 0 0 0.0 0.2 0.4 0.6 0.8 1.0 p/p 0
Absorbance Absorbance Environmental remediation ( aqueous solution Cr 6+ ) Cr 6+ + 1,5-diphenylcarbohydrazide 1,00 542nm 0,90 0,75 1 mg/l 0,75 A=0,85186*C-0,00836 0,50 0,8 mg/l 0,6 mg/l 0,60 0,45 0,25 0,4 mg/l 0,2 mg/l 0,00 400 450 500 550 600 650 700 Wavelength (nm) 0,30 0,15 0,00 0,0 0,2 0,4 0,6 0,8 1,0 1,2 Συγκέντρωση Cr(VI) mg/l
Absorbance Absorbance Absorbance Absorbance Environmental remediation ( aqueous solution Cr 6+ ) @ZVI - Hybrid Cr 6+ =6ppm 0,6 0,5 0,4 0,3 542 0h 0,5h 1h 2h 6h 9h 0.6 0.5 0.4 0.3 0,4686 0,3774 @ZVI-12 542 0h 0.5h 1h 2h 3h 6h 9h 24h Cr 6+ =6ppm =180ppm 0,2 0.2 @ZVI=180ppm 0,1 ph=5,5 0,0 400 450 500 550 600 650 700 Wavelength (nm) 0,6 0,5 0,4 0,3 0,4702 542 0h 0,5h 1h 2h 3h 6h 9h 24h 0.1 0.0 400 450 500 550 600 650 700 0.6 0.5 0.4 0.3 Wavelength (nm) ph=5,5 @ZVI-12 0h 542 0.5h 1h 2h 3h 6h 9h 24h 0,2 0,1 0,0375 ph=3 0,0 400 450 500 550 600 650 700 Wavelength (nm) 0.2 0.1 ph=3 0.0 400 450 500 550 600 650 700 Wavelength (nm)
r (mg*l -1 *h -1 ) Evaluation of hybrids 1,0 (ph=5,5) [Cr 6+ ] t / [Cr 6+ ] 0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 @ZVI-12:1 (ph=5,5) (ph=3) 0,1 @ZVI-12:1 (ph=3) 0,0 0 2 4 6 8 10 12 14 16 18 20 22 24 time (hours) 18 16 14 12 10 8 6 @ZVI-12:1 14,4 ph=3 1/[Cr(VI)] t @ZVI - Hybrid 5 4 3 2 1 0 @ZVI-12:1 1 [ Cr( VI )] 0 2 4 6 8 10 12 14 16 18 20 22 24 26 time (hours) t second order 1 k2t [ Cr( VI )] Second order equation K 2 (L mg -1 h -1 ) R 2 t 1/2 (h) 0,066 0,989 2,7 @ZVI-12:1 0,417 0,986 0,4 0 4 2 0 2,1 6 5 4 3 2 1 0 [Cr(VI)] (mg*l-1 ) r k 2 2 ([ Cr( VI )] t )
r (mg*l -1 *h -1 ) Evaluation of hybrids 1,0 0,8 (ph=5,5) @Fe x O y - Hybrid 5 [Cr 6+ ] t / [Cr 6+ ] 0 0,6 0,4 0,2 0,0 16 14 12 0 2 4 6 8 10 12 14 16 18 20 22 24 time (hours) 14,5 @m2 (ph=5,5) (ph=3) @m2 (ph=3) @m2 ph=3 1/[Cr(VI)] t 4 3 2 1 0 @m2 1 [ Cr( VI )] t 1 k2t [ Cr( VI )] 0 2 4 6 8 10 12 14 16 18 20 22 24 time (hours) second order 0 10 8 6 4 2 0 2,7 6 5 4 3 2 1 0 [Cr(VI)] (mg*l-1 ) r k Second order reaction k 2 (L mg -1 h -1 ) R 2 t 1/2 (h) @m2 0,434 0,983 0,4 0,082 0,989 2,1 2 2 ([ Cr( VI )] t )
Conclusions Hybrids for environmental applications were prepared: a) via interaction of acetic acid vapors with iron cations dispersed on the surface of a mesoporous carbon. (@Fe x O y ) b) using a carbon as a matrix for wet impregnation of FeCl 3, followed by reduction of iron species by means of NaBH 4 and drying of the sample in vacuum. (@Fe 0 ) The XRD, FT-IR, TEM, DTA/TG and surface area measurements revealed the well defined carbon mesoporous structure and the successfully preparation of hybrids. Magnetic experiments suggested the ultrafine character of the iron oxide nanoparticles which exhibit a superparamagnetic behaviour. Mössbauer measurements showed: a) γ-fe 2 O 3 as the major magnetic iron oxide phase in @Fe x O y hybrids b) the well known iron core-shell structure for the ZVI nanoparticles in @Fe 0 c) almost zero recoil-free nanoparticles at temperatures above 77K in hybrids. @Fe 0 and @Fe x O y hybrids showed very rapid uptake kinetics in the removal of aqueous Cr 6+ ions and total remediation of aqueous solution of Cr 6+ at conditions- ph: 3, concentration: 6ppm, treatment time: 24hours. Both type of hybrids showed significant improvement of sorption and/or reduction capability of Cr 6+ ions/g of specific sorbent in comparison with pristine or unsupported ZVI nanoparticles.
Acknowledgements Dr. M.Baikousi Dr. D.Dimos Mrs. E.Petala, M.Sc. Department of Materials Science &Engineering University of Ioannina Greece Assist. Prof. A.Bourlinos Assist. Prof. A.Douvalis Professor T.Bakas Department of Physics University of Ioannina Greece Professor R.Zboril Dr. Jiří Tuček Dr.Klára Šafářová Dr. Jan Filip
Thank you