ISSN:
1662-0356
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Allgemeine Naturwissenschaft
,
Technik allgemein
Notizen:
Hydroxyapatite (HA) microspheres of diameter 〈70 μm have been synthesized by solgelprocessing. The starting sols were prepared by ultrasonic mixing of concentrated solutions ofcalcium acetate (1.7M) with 85% H3PO4, followed by emulsification in dehydrated 2-ethyl-1-hexanol. Drops of emulsion were solidified by extraction of water with this solvent. The finalthermal treatment was a 2 h soaking in air at 900ºC. Properties such as hydraulic resistance andsedimentation rate, which are important for application in ion-exchangers, were superior for ourprepared microspheres in comparison with irregularly shaped commercial HA. Adsorption of thefollowing metals was investigated: U, Zn, Fe, Cu, Ni, Co, Cd, Pb, Mn, Al, Cr, As, Sb, Bi andMo. Retention was ≈100% for of all the metals studied when pH 〉 3–4. On average, ≈1/20 molesof metal reacted with 1 mole of HA. Adsorbed metals could be desorbed with efficiencies of60–90%. In addition, nuclear-waste-saturated beds of HA could be transformed to insolubleceramics by thermal treatment. The cost of producing HA microspheres was estimated to becomparable to current prices of irregularly shaped commercial hydroxyapatite powders. Forradioactive contaminants such as U, for which resorption need not be considered, porousmonoliths were produced by use of industrial reagents. The retention capacity was determined tobe 30 mg of U per 1 mg of monolith
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.45.2198.pdf
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