Adsorption of Suwannee River fulvic acid on aluminum oxyhydroxide surfaces: An in situ ATR-FTIR study

The adsorption of Suwannee River fulvic acid (SRFA) on boehmite, gammaw-AIO(OH), has been examined by both macroscopic adsorption and in situ ATR-FTIR spectroscopic techniques. At a SRFA concentration approaching surface saturation (Gamma = 5.3 mumol m(-2)), adsorption is at a maximum at low pH and decreases as pH is increased. The ATR-FTIR spectral features of adsorbed SRFA are very similar to those measured approximately 1-2 pH units higher in solution, indicating that (i) the SRFA appears to be predominantly adsorbed at the boehmite/water interface in an outer-sphere complexation mode and (ii) the positively charged boehmite/water interface stabilizes SRFA molecules against protonation at low pH.