A combined study by XRD, FTIR, TG and HRTEM on the structure of delaminated Fe-intercalated/pillared clay.
Fe-PILC samples were synthesized by the reaction between Na(+)- and/or Ca(2+)-montmorillonite (Mt) and base-hydrolyzed solutions of Fe(III) nitrate. Different from the known usual microporous pillared structure, a meso-microporous delaminated structure containing intercalated or pillared fragments was found in the respective resulting Fe-intercalated or -pillared clays. XRD patterns of Na(+)-Mt-based Fe-intercalated/pillared clays show one large d-spacing above 6.4 nm corresponding to the mesoporous delaminated part, whereas another d-spacing of ca. 1.5 nm was indicative of the microporous pillared part. Fe-intercalated/pillared clays based on Ca(2+)-Mt lead to similar results, but with a d-spacing less than 6 nm and a second low intense d-spacing less than 1.5 nm. In the delaminated Fe-intercalated clays, NO(-)(3) anions were retained even after thorough washing process. They play as counterions to neutralize the positive-charged iron aggregates in the delaminated structure, and can be exchanged by heteropolyanions as [PW(12)O(40)](3-). The delaminated Fe-pillared clays show good thermal stability at 500 degrees C and exhibit at this temperature dramatically higher specific surface area and porosity than the starting montmorillonites. However, calcination at a higher temperature leads to the formation of nanocrystalline hematite. Air-drying after ethanol extraction (EAD) method has an advantage over air-drying (AD) method in preserving the delaminated structure.
Yuan
Peng
P
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China. yuanpeng@gig.ac.cn
Annabi-Bergaya
Faïza
F
Tao
Qi
Q
Fan
Mingde
M
Liu
Zongwen
Z
Zhu
Jianxi
J
He
Hongping
H
Chen
Tianhu
T
D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry; D000077215:Clay; D005290:Ferric Compounds; D007501:Iron / Q000737:chemistry*; D015394:Molecular Structure; D053758:Nanoparticles; D016062:Porosity; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
D000538:Aluminum Silicates; D005290:Ferric Compounds; D001546:Bentonite; C000499:ferric oxide; D007501:Iron; D000077215:Clay