TY - JOUR
T1 - Facet-Dependent Competitive Adsorption Mechanisms of Chromate and Oxalic Acid on γ-FeO(OH) Nanocrystals
AU - Li, Xiaofei
AU - Guo, Chuling
AU - Pillai, Suresh C.
AU - Jin, Xiaohu
AU - Yao, Qian
AU - Bao, Yanping
AU - Jiang, Xueding
AU - Lu, Guining
AU - Wang, Hailong
AU - Dang, Zhi
N1 - Publisher Copyright:
© 2023 American Chemical Society
PY - 2023/10/17
Y1 - 2023/10/17
N2 - Facet-dependent toxic metal adsorption of iron oxides widely occurred in natural environments. It is known that organic acids can alter the adsorption behaviors of trace elements by cooperative or competitive effects. However, the coadsorption mechanisms of the specific facets are still not fully understood. In the current investigation, Cr(VI) adsorption onto the lepidocrocite (γ-FeO(OH))-exposed facets in the presence of oxalic acid (OA) was studied using macroexperiments, in situ attenuated total reflectance Fourier transform infrared spectroscopy, X-ray adsorption fine structure, and density functional theory calculations. Rod-like lepidocrocite (R-LEP) with a high ratio of {001}/{010} facet showed excellent Cr(VI) adsorption capacity than that of plate-like lepidocrocite (P-LEP, the dominant facet is {010}) in the absence/presence of OA. Interestingly, OA reacted with R-LEP would be easier to diminish Cr(VI) adsorption than with P-LEP. The competitive adsorption occurred on the {001} facet due to the formation of inner-sphere OA configurations (monodentate mononuclear and bidentate mononuclear structures) and a bidentate binuclear Cr(VI) complex. However, OA coordinated with {010} facets via the outer-sphere complexes, while Cr(VI) could form a protonated monodentate binuclear configuration. These observations suggest that the competitive adsorption processes between OA and Cr(VI) exhibit facet dependence. Furthermore, lepidocrocite-exposed facets determine the interfacial interactions and geochemical behaviors of Cr(VI) in polluted environments.
AB - Facet-dependent toxic metal adsorption of iron oxides widely occurred in natural environments. It is known that organic acids can alter the adsorption behaviors of trace elements by cooperative or competitive effects. However, the coadsorption mechanisms of the specific facets are still not fully understood. In the current investigation, Cr(VI) adsorption onto the lepidocrocite (γ-FeO(OH))-exposed facets in the presence of oxalic acid (OA) was studied using macroexperiments, in situ attenuated total reflectance Fourier transform infrared spectroscopy, X-ray adsorption fine structure, and density functional theory calculations. Rod-like lepidocrocite (R-LEP) with a high ratio of {001}/{010} facet showed excellent Cr(VI) adsorption capacity than that of plate-like lepidocrocite (P-LEP, the dominant facet is {010}) in the absence/presence of OA. Interestingly, OA reacted with R-LEP would be easier to diminish Cr(VI) adsorption than with P-LEP. The competitive adsorption occurred on the {001} facet due to the formation of inner-sphere OA configurations (monodentate mononuclear and bidentate mononuclear structures) and a bidentate binuclear Cr(VI) complex. However, OA coordinated with {010} facets via the outer-sphere complexes, while Cr(VI) could form a protonated monodentate binuclear configuration. These observations suggest that the competitive adsorption processes between OA and Cr(VI) exhibit facet dependence. Furthermore, lepidocrocite-exposed facets determine the interfacial interactions and geochemical behaviors of Cr(VI) in polluted environments.
UR - http://www.scopus.com/inward/record.url?scp=85174751229&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.3c01739
DO - 10.1021/acs.langmuir.3c01739
M3 - Article
C2 - 37791534
AN - SCOPUS:85174751229
SN - 0743-7463
VL - 39
SP - 14539
EP - 14549
JO - Langmuir : the ACS journal of surfaces and colloids
JF - Langmuir : the ACS journal of surfaces and colloids
IS - 41
ER -