Location and migration of cations in Cu(2+)-adsorbed montmorillonite.
Locations of Cu2+ ion in Cu(2+)-adsorbed montmorillonite have been studied by electron paramagnetic resonance (EPR), supplemented by X-ray diffraction (XRD) and differential thermal analysis (DTA). In the EPR spectra of Cu(2+)-adsorbed montmorillonite, three signals, corresponding to Cu2+ ion, have been simultaneously recorded. Some Cu2+ ions seemed to replace the original interlayer metal cations and some entered into the hexagonal cavities. A small fraction of Cu2+ ions penetrated into the octahedral vacancies. There were two ways for the adsorption of Cu2+ ion by montmorillonite--exchangeable and specific. On heating, the hydrated Cu2+ ion in the interlayer loses the coordinating water and then enters into the hexagonal cavities. When the heating temperature further increased, dehydroxylation occurs, which facilitates Cu2+ ion in the hexagonal cavities to penetrate into the octahedral vacancies.
He
H P
HP
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Canton 510640, People's Republic of China. hehp@gig.ac.cn
Guo
J G
JG
Xie
X D
XD
Peng
J L
JL
D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D002412:Cations; D003300:Copper / Q000032:analysis* / Q000737:chemistry; D004055:Differential Thermal Analysis; D004578:Electron Spin Resonance Spectroscopy; D013696:Temperature; D014961:X-Ray Diffraction
D002412:Cations; D001546:Bentonite; D003300:Copper