Tags

Type your tag names separated by a space and hit enter

Metal Adsorption Controls Stability of Layered Manganese Oxides.
Environ Sci Technol. 2019 07 02; 53(13):7453-7462.ES

Abstract

Hexagonal birnessite, a typical layered Mn oxide (LMO), can adsorb and oxidize Mn(II) and thereby transform to Mn(III)-rich hexagonal birnessite, triclinic birnessite, or tunneled Mn oxides (TMOs), remarkably changing the environmental behavior of Mn oxides. We have determined the effects of coexisting cations on the transformation by incubating Mn(II)-bearing δ-MnO2 at pH 8 under anoxic conditions for 25 d (dissolved Mn < 11 μM). In the Li+, Na+, and K+ chloride solutions, the Mn(II)-bearing δ-MnO2 first transforms to Mn(III)-rich δ-MnO2 or triclinic birnessite (T-bir) due to the Mn(II)-Mn(IV) comproportionation, most of which eventually transform to a 4 × 4 TMO. In contrast, Mn(III)-rich δ-MnO2 and T-bir form and persist in the Mg2+ and Ca2+ chloride solutions. However, in the presence of surface adsorbed Cu(II), Mn(II)-bearing δ-MnO2 turns into Mn(III)-rich δ-MnO2 without forming T-bir or TMOs. The stabilizing power of the cations on the δ-MnO2 structure positively correlates with their binding strength to δ-MnO2 (Li+, Na+, and K+ < Mg2+ and Ca2+ < Cu(II)). Since metal adsorption decreases the surface energy of minerals, our finding suggests that the surface energy largely controls the thermodynamic stability of LMOs. Our study indicates that the adsorption of divalent metal cations, particularly transition metals, can be an important cause of the high abundance of LMOs, rather than the more stable TMO phases, in the environment.

Authors+Show Affiliations

Department of Ecosystem Science and Management , University of Wyoming , Laramie , Wyoming 82071 , United States.Department of Mineral Sciences , Smithsonian Institution , Washington , District of Columbia 20013 , United States.Department of Ecosystem Science and Management , University of Wyoming , Laramie , Wyoming 82071 , United States.X-ray Science Division, Advanced Photon Source , Argonne National Laboratory , Lemont , Illinois 60439 , United States.Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , United States.Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , United States.Department of Ecosystem Science and Management , University of Wyoming , Laramie , Wyoming 82071 , United States.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

31150220

Citation

Yang, Peng, et al. "Metal Adsorption Controls Stability of Layered Manganese Oxides." Environmental Science & Technology, vol. 53, no. 13, 2019, pp. 7453-7462.
Yang P, Post JE, Wang Q, et al. Metal Adsorption Controls Stability of Layered Manganese Oxides. Environ Sci Technol. 2019;53(13):7453-7462.
Yang, P., Post, J. E., Wang, Q., Xu, W., Geiss, R., McCurdy, P. R., & Zhu, M. (2019). Metal Adsorption Controls Stability of Layered Manganese Oxides. Environmental Science & Technology, 53(13), 7453-7462. https://doi.org/10.1021/acs.est.9b01242
Yang P, et al. Metal Adsorption Controls Stability of Layered Manganese Oxides. Environ Sci Technol. 2019 07 2;53(13):7453-7462. PubMed PMID: 31150220.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Metal Adsorption Controls Stability of Layered Manganese Oxides. AU - Yang,Peng, AU - Post,Jeffrey E, AU - Wang,Qian, AU - Xu,Wenqian, AU - Geiss,Roy, AU - McCurdy,Patrick R, AU - Zhu,Mengqiang, Y1 - 2019/05/31/ PY - 2019/6/1/pubmed PY - 2019/9/19/medline PY - 2019/6/1/entrez SP - 7453 EP - 7462 JF - Environmental science & technology JO - Environ. Sci. Technol. VL - 53 IS - 13 N2 - Hexagonal birnessite, a typical layered Mn oxide (LMO), can adsorb and oxidize Mn(II) and thereby transform to Mn(III)-rich hexagonal birnessite, triclinic birnessite, or tunneled Mn oxides (TMOs), remarkably changing the environmental behavior of Mn oxides. We have determined the effects of coexisting cations on the transformation by incubating Mn(II)-bearing δ-MnO2 at pH 8 under anoxic conditions for 25 d (dissolved Mn < 11 μM). In the Li+, Na+, and K+ chloride solutions, the Mn(II)-bearing δ-MnO2 first transforms to Mn(III)-rich δ-MnO2 or triclinic birnessite (T-bir) due to the Mn(II)-Mn(IV) comproportionation, most of which eventually transform to a 4 × 4 TMO. In contrast, Mn(III)-rich δ-MnO2 and T-bir form and persist in the Mg2+ and Ca2+ chloride solutions. However, in the presence of surface adsorbed Cu(II), Mn(II)-bearing δ-MnO2 turns into Mn(III)-rich δ-MnO2 without forming T-bir or TMOs. The stabilizing power of the cations on the δ-MnO2 structure positively correlates with their binding strength to δ-MnO2 (Li+, Na+, and K+ < Mg2+ and Ca2+ < Cu(II)). Since metal adsorption decreases the surface energy of minerals, our finding suggests that the surface energy largely controls the thermodynamic stability of LMOs. Our study indicates that the adsorption of divalent metal cations, particularly transition metals, can be an important cause of the high abundance of LMOs, rather than the more stable TMO phases, in the environment. SN - 1520-5851 UR - https://www.unboundmedicine.com/medline/citation/31150220/Metal_Adsorption_Controls_Stability_of_Layered_Manganese_Oxides_ L2 - https://dx.doi.org/10.1021/acs.est.9b01242 DB - PRIME DP - Unbound Medicine ER -