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1353919 
Journal Article 
An investigation of arsenate and arsenite bonding structures on goethite by FTIR 
Sun, XH; Doner, HE 
1996 
1 
Soil Science
ISSN: 0038-075X
EISSN: 1538-9243 
161 
12 
865-872 
WOS:A1996WB17300006 
The bonding structures of arsenite (As(III)) and arsenate
(As(V)) on goethite (alpha-FeOOH) were studied by Transmission-Fourier Transform Infrared (T-
FTIR) and Attenuated Total Reflectance-FTIR (ATR-FTIR) spectroscopy, ATR-FTIR spectra of
deuterated goethite showed three bands of OD stretch, corresponding to singly, doubly, and triply
coordinated OH hydroxyls on the goethite surface, Both FTIR modes provided similar structural
information for arsenic adsorption, Most arsenate and arsenite oxyanions replaced two singly
coordinated surface OH groups (A-type) to form binuclear bridging complexes Fe-O-AsO(OH)-O-Fe and
Fe-O-As(OH)-O-Fe, However, their effects on doubly (C-type) and triply (B-type) coordinated
surface OH groups are different, As(III) mainly reacted with C-type OH groups, whereas As(V)
reacted with B-type OH groups. These reactions may be attributed to hydrogen-bonding and/or
chemical bonding, Finally, we applied a sequential extraction method to evaluate the fractions
with different bonding strengths, Relatively strong chemical extraction was necessary to remove
75 to 80% of adsorbed arsenite or arsenate from goethite. The strong retention of As(III) and As
(V) is most likely caused by the formation of binuclear complexes with goethite.