Photodesorption of fulvic acid from iron oxide surfaces into aqueous solutions

Photodesorption of thin films of fulvic acid adsorbed on planar iron oxide surfaces was monitored by ellipsometry. Description was first observed at 5 46 nm, and additional fractions of the adsorbed acid left the surfaces at 4 05 and 365 nm Similar kinetics for photodesorption was observed from metall ic iron films and from porous iron oxide prepared electrochemically by depo sition on porous silicon substrates. Soluble photoproducts leaving the surf ace H ere monitored by UV absorbance spectroscopy at 200 nm Gaseous product s were not detected by mass spectrometry but the results seemed to indicate that net all of the photoproducts entered the liquid phase. Of the metal f ilms tested which adsorbed fulvic acid from aqueous solution (Fe. Cr, Ni, A l, and Pt), it was only iron which exhibited a photodesorption effect. (C) 2001 Elsevier Science B.V. All rights reserved.