Surface complexation of catechol to metal oxides: an ATR-FTIR, adsorption, and dissolution study.
The interaction of catechol with chromium(III) oxide (Cr(2)O(3)), manganese dioxide (MnO(2)), iron(III) oxide (Fe(2)O(3)), and titanium dioxide (TiO(2)) was evaluated as a function of pH conditions (pH 3-10) and ionic strength using a combined approach of bulk adsorption, attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and dissolution analysis. Adsorption of catechol showed a strong pH-dependent behavior with the metal oxides, remaining constant under acidic-neutral pH (3-7) and increasing under more basic conditions. In situ ATR-FTIR measurements indicate that catechol binds predominately as an outer-sphere complex on MnO(2) and as an inner-sphere complex on Fe(2)O(3), TiO(2), and Cr(2)O(3) substrates. Catechol complexation on Fe(2)O(3), TiO(2), and Cr(2)O(3) promotes dissolution at pH >5, whereas MnO(2) dissolution occurs under acidic and basic conditions (pH 3-10).
Gulley-Stahl
Heather
H
Department of Chemistry, Northern Kentucky University, Highland Heights, Kentucky 41099, USA.
Hogan
Patrick A
PA
Schmidt
Whitney L
WL
Wall
Stephen J
SJ
Buhrlage
Andrew
A
Bullen
Heather A
HA
D000327:Adsorption; D002396:Catechols / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000737:chemistry*; D010087:Oxides / Q000032:analysis*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared
D002396:Catechols; D008670:Metals; D010087:Oxides; C034221:catechol