Uranium sorption on bentonite modified by octadecyltrimethylammonium bromide.
The sorption of U(VI) on octadecyltrimethyl-bentonite was investigated at the pH values of the aqueous phase ranging from 3 to 10 and the concentrations of U(VI): 0.1-1 mmol/dm(3). The concentrations of alkylammonium cation in bentonite were increased from 21% to 150% of CEC (cation exchange capacity). It was determined that the sorption of U(VI) on modified bentonite, i.e. the distribution constant -K(d) decreases with the percent of mineral modification until it attains a minimum at 76% of CEC and then increases again. The effective sorption of U(VI) was found to be in the pH range: 6-10 for the modified bentonite and was explained as the consequence of U(VI) anionic hydroxy complexes sorption. Both FT-IR and XRD spectra of the modified bentonite were analyzed and provided arguments for the existence of surfactant cations in the form of monolayer and bilayer in the interlamellar space of bentonite. In turn the luminescence spectra of bentonite suspensions, i.e. their character at different values of pH, proved the existence of hydroxide-like planar polymeric U(VI) species in the bentonite phase at pH 9.
Majdan
Marek
M
Maria Curie Skłodowska University, Faculty of Chemistry, 20-031 Lublin, Poland. Electronic address: marek@hermes.umcs.lublin.pl.
Pikus
Stanisław
S
Maria Curie Skłodowska University, Faculty of Chemistry, 20-031 Lublin, Poland.
Gajowiak
Agnieszka
A
Maria Curie Skłodowska University, Faculty of Chemistry, 20-031 Lublin, Poland.
Sternik
Dariusz
D
Maria Curie Skłodowska University, Faculty of Chemistry, 20-031 Lublin, Poland.
Zięba
Emil
E
Catholic University of Lublin, SEM Laboratory, 20-718 Lublin, Poland.
D000327:Adsorption; D000473:Alkanes / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D049449:Luminescence; D008855:Microscopy, Electron, Scanning; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013501:Surface-Active Agents / Q000737:chemistry; D013818:Thermogravimetry; D014501:Uranium / Q000737:chemistry*; D014961:X-Ray Diffraction
D000473:Alkanes; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; C518260:octadecyltrimethylammonium bromide; D001546:Bentonite; D014501:Uranium