Hydrous oxide gels

Oil and hydrocarbon leaks that return with the condensate coat heat-exchange surfaces and cause FW system fouling and deposit binding. These materials must be removed or they will reenter the boiler to produce nonwettable boiler surfaces, and create serious problems. Oil in condensate should be removed by the use of an inline pre-coat filter. The pre-coating should be either aluminum hydroxide ox ferric hydroxide becaue both these hydrous oxide gels have an affinity for oil. 

Fig. 30. Spectra of three high area, amorphous, hydrous oxides of titanium compared with that of the crystalhne anhydrous oxide, rutile. One is a straight titania gel, two are coprecipitated with different elements to form mixed metal hydrous oxide gels.

Adsorption of alkaline earth, transition, and heavy metal cations by hydrous oxide gels of iron and aluminum. Soil Sci. Soc. Am. J. 40 796-799... 

Venkatesan, K.A., Sasidharan, N.S., and Wattal, P.K., Sorption of radioactive strontium on a shica-titania mixed hydrous oxide gel, J. Radioanal. Nucl. Chem., 220, 55, 1997. 

Coprecipitated NiO-AljOi samples are typical of a wide variety of dual hydrous oxide gels. They are precursors to reduced Ni/AIjO) catalysts used in hydrogenation and methanation. Although these catalysts are produced by other routes, the intimate interactions fostered by coprecipitation are believed to impart improvements in activity and stability to the nickel crystallites/ although mechanical strength is lower. It may also be possible that irreducible compounds of NiO and AljOj, facilitated by coprecipitation, play some role in forming stable promoters. 

R. M. McKenzie, The adsorption of lead and other heavy metals on oxides of manganese and iron, Aust. J. Soil Res. 18 61 (1980). H. Kerndorf and M. Schnitzer, Sorption of metals on humic acid, Geochim. Cosmochim. Acta 44 1701 (1980). D. G. Kinniburgh, M. L. Jackson, and J. K. Syers, Adsorption of alkaline earth, transition, and heavy metal cations by hydrous oxide gels of iron and aluminium, Soil Sci. Soc. Am. J. 40 796 (1976). H. Farrah and W. F. Pickering, Influence of clay-solute interactions on aqueous heavy metal ion levels, Water, Air and Soil Pollution 8 189 (1977). 

Ramsay and Avery have continued to apply SANS in their studies of porous oxides in their present paper they utilise H O/t O mixtures to investigate mechanisms of pore fiiiing and conclude that significant differences are apparent between the state of adsorbed water in mesoporous silicas and microporous ceria. In another paper, Ramsay and his co-workers report the findings of extensive SANS and adsorption studies of a range of hydrous oxide gels in a polymer matrix. 

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