Manganese oxide coatings

The waste organic acids dissolved carbonate minerals, alumino-silicate minerals, and iron/manganese-oxide coatings on the primary minerals in the injection zone. 

Stahl R.S., James B.R. Zinc sorption by manganese-oxide-coated sand as a function of pH. Soil Sci Soc Am J 1991 55 1291-1294. 

In Limnodrilus sp., an oligochaete worm, copper bioavailability from surhcial freshwater sediments is associated with the amount of copper present in the manganese oxide fraction of the sediment. The redox potential and pH in the gut of Limnodrilus allows the dissolution of the manganese oxide coating, making copper and other metals available for uptake (Diks and Allen 1983). 

Adsorption may influence precipitation by means other than the processes mentioned above. Davies (Chapter 23) discusses the role of the surface as a catalyst for oxidation of adsorbed Mnz+. Redox reactions may contribute substantially to the formation of manganese oxide coatings on mineral surfaces in soils and sediments. 

Tani, Y., Miyata, N., Iwahori, K. et al. (2003). Biogeochemistry of manganese oxide coatings on pebble surfaces in the Kikukawa river system, Shizuoka, lapan. Applied Geochemistry, 18, 1541-54. 

Figure 8. Micro-XRF image of Pu sorbed onto manganese oxide coatings on smectite grains in Yucca Mountain tuff reacted with a Pu(V)-containing aqueous solution. Image was collected on the insertion device beam line 13- - at GSECARS (Advanced Photon Source), (after Duff et al. 1999a,b)...

Mehlich (155) observed that ferrous sulfate solutions were able to solubilize freshly precipitated manganese oxide. The addition of copper sulfate increased the Eh value of unlimed Dunbar fine sandy loam from about +460 mv. to about +530 mv., whereas, when lime was added, copper sulfate increased the Eh from +310 to +380 mv. (253). These data also show a decrease of 0.1 pH unit upon the addition of copper sulfate for both the limed and unlimed samples. Dhar and Kishore (60) observed that several metal cations increased the oxidation rate of Mn(OH)2. Also, Futral and Ingols (80) found that 0.5 p.p.m. copper sulfate speeds up the oxidation of manganese during water treatment and metallic copper parts often have manganese oxide coatings. In the case of iron, Stumm and Lee (226) have found a marked catalytic eflFect of copper ions on the ferrous to ferric oxidation rate. 

Rhodes, C,P, J,W, Long, M,S, Doescher, B,M, Dening, and D,R, Rolison, Charge insertion into hybrid nanoarchitectures mesoporous manganese oxide coated with ultrathin polylphenylene oxide). Journal of Non-Crystalline Solids, 2004, 350 pp, 73-79 Kuznetsov, A,M, and J, Ulstrup, ElectrochemicaActa, 2000, 45 p, 2339 Fawcett, W,R, J, Lipkowski and P,N, Ross, Editors, Electrocatalysis 1998, Wiley New York, p, 323... 

Wu, M. Q., L. P. Zhang, J. H. Gao et al. 2008. Effects of thickness and electrolytes on the capacitive characteristics of anodically deposited hydrous manganese oxide coatings. Journal of Electroanalytical Chemistry 613 125-130. 

Figure 4 AFM picture of manganese oxide coating on Si-water.

Figure 6.15. SEM micrograph of sample (a) zeolites (b) manganese oxide coated zeolites (Zou et al, 2006).

In a study by Han et al (2007), manganese oxide coated zeohtes (MOCZ) were synthesized and the adsorption properties for U(VI) by MOCZ were investigated. Their study clearly established that MOCZ is an effective adsorbent for U(VI) removal from aqueous solutions. They reported that the U(VI) binding capacity by MOCZ was strongly dependent on the initial pH, initial U(VI) concentration and temperature. It was noted that an increase in the temperature resulted... 

Han, R., Zou, W, Wang, Y. Zhu, L. (2007) Removal of uranium(VI) from aqueous solutions by manganese oxide coated zeolite discussion of adsorption isotherms and pH effect Journal of Environmental Radioactivity, 93, 127-143. 

Zou, W, Han, R., Chen, Z., Jinghua, Z., Shi, J. (2006) Kinetic study of adsorption of Cu(ll) and Pb(II) from aqueous solutions using manganese oxide coated zeolite in batch mode. Colloids and Surfaces A Physicochemical and Engineering Aspects, 279, 238-246. 

FIGURE 10.2 (A) Schematic representing the synthesis of manganese oxide-coated TiN nanotubes. (B)... 

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