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A study was carried out of the uptake of Cu2+, Ni2+, Co2+ and Ca2+ cations by hydrous titanium oxides prepared at different pH values using titanous chloride as the starting material and hydrogen peroxide as the oxidizing agent. Characterization of the oxides was carried out by nitrogen adsorption and infrared studies. The oxides were found to be amphoteric in nature and exhibited an isoelectric point of 6.6. An attempt was made to elucidate the mechanism of cation uptake which does not entail a simple ion-exchange mechanism.

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The surface characteristics of mixed zirconium and titanium oxides prepared from different starting materials are investigated. One mode of preparation entailed the use of zirconium sulfate and titanium oxysulfate as starting materials and ammonium hydroxide as precipitating agent. The produced oxides were washed to different extents to obtain samples with different sulfate content. A second preparative mode used zirconium oxychloride and titanous chloride as starting materials also with ammonium hydroxide as precipitating agent. The oxidation of the titanous to the titanic form for these oxides was carried out by means of oxygen gas. Resulting samples were heat treated at 400°C and 600°C, and textural characteristics determined from the adsorption of N 2 at 77 K, complemented by infrared and thermal studies.The samples precipitated from the oxychloride and chloride salts of zirconium and titanium, as well as those precipitated from the sulfate and oxysulfate salts and washed free of the sulfate ions displayed quite similar textural characteristics. The unheated samples and those heat-treated at 400°C were mesoporous, with some microporosity, and relatively large surface areas in the order of 200-300 m 2 /g. Heat treatment to 600°C led to a relative decrease in surface area, in the order of 100 m 2 /g, and to the disappearance of microporosity.The mixed zirconium and titanium oxides with a sulfate content of ≈17% displayed significantly lower surface areas, smaller than 10 m 2 /g, with a prevalence of micro and mesoporosity. Infrared and thermal studies indicated the presence of differently bounded sulfato groups, which seem to have a blocking effect on the pores, resulting in the observed smaller surface areas.

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