Fractionation of Suwannee River fulvic acid and aldrich humic acid on alpha-Al2O3: spectroscopic evidence.
Sorptive fractionation of Suwannee River Fulvic Acid (SRFA) and Purified Aldrich Humic Acid (PAHA) on alpha-Al2O3 at pH 6 was probed in the supernatant using different spectroscopic techniques. Comparison of dissolved organic carbon (DOC) analysis with UV/vis spectrophotometric measurements at 254 nm, including specific UV absorbance (SUVA) calculation, revealed a decrease in chromophoric compounds for the nonsorbed extracts after a 24 h contact time. This fractionation, only observable below a certain ratio between initial number of sites of humic substances and of alpha-Al2O3, seems to indicate a higher fractionation for PAHA. C(1s) near-edge X-ray absorption fine structure spectroscopy (NEXAFS) confirmed this trend and points to a decrease in phenolic moieties in the supernatant and to an eventual increase in phenolic moieties on the surface. Time-resolved luminescence spectroscopy (TRLS) of Eu(III) as luminescent probe showed a decrease in the ratio between the (5)D0-->(7)F2 and (5)D0-->(7)F1 transitions for the fractionated organic matter (OM) that is thought to be associated with a lower energy transfer from the OM to Eu(III) due to the loss of polar aromatics. These modifications in the supernatant are a hint for the modification of sorbed humic extracts on the surface.
Claret
Francis
F
Commissariat à l'Energie Atomique, CE Saclay, DEN/DANS/DPC/SECR/Laboratoire de Speciation des Radionucléides et des Molécules, Bâtiment 391-P.C. 33, F-91191 Gif-sur-Yvette CEDEX, France.
Schäfer
Thorsten
T
Brevet
Julien
J
Reiller
Pascal E
PE
D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D001578:Benzopyrans / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry; D005591:Chemical Fractionation; D006812:Humic Substances; D009930:Organic Chemicals / Q000737:chemistry; D045483:Rivers / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors
D001578:Benzopyrans; D006812:Humic Substances; D009930:Organic Chemicals; D002244:Carbon; D000537:Aluminum Oxide; C005023:fulvic acid