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CHEMICAL AND PHYSICAL CHARACTERIZATION OF THREE GRANULOMETRIC FRACTIONS FROM THREE OXIDIC LITHOLOGICAL MATERIALS

Abstract:

Present paper focus on the characterization of oxidic lithological materials of variable charges from Mérida city, Venezuela in order to use them for preparing calcined adsorbents substrate for ionic adsorption. XRD shows common mineralogical composition, quartz as main component, albite and amorphous phases in Lagunillas and Guáimaros materials. TDA show presence of amorphous silica minerals and elemental allophanes. ICPMS analysis show diverse metallic composition especially those metals that form amphoteric oxides (Fe 3–7%, Al 7–12%, Ti 0, 4–0, 6%, Mn 0,007–0, 03%). Significant quantities of zirconium confer refractory properties to materials. ZCP lies around pH 8 for Lagunillas and Guáimaros materials and 4 for Vallecito material. First one is characteristic of amphoteric oxides; second one is associated to kaolinite. SS of crude material agree with that of amphoteric oxides and are greater in fine fractions but calcination process reduce up to 70% superficial area affecting the adsorption capacities. IR spectra show characteristic kaolinite and smectite bands that disappear with thermal treatment. Nevertheless, adsorption capacities depend also on surface charge density. After alkaline treatment of adsorbing substrates (deprotonation reaction of oxides) adsorption increase up to 51% because of a greater density of negative charges on the oxide surface. Metallic richness as well as albite and zirconium presence confers thermal and mechanic resistance to these materials and make them suitable for preparation of calcined substrates and use them in cationic and anionic adsorption from aqueous media.