Hydrous oxides of titanium: cation exchange properties and kinetics of exchange
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The ion exchange properties of hydrous titania gels of different particle sizes, precipitated from titanous chloride through the agency of ammonium carbonate and hydroxide have been studied. Such studies were carried out under acidic and alkaline conditions with respect to Cu2+, Ni2+, Co2+ and Cr3+ ions.
In the case of gels precipitated by ammonium carbonate, oxygen gas was used as the oxidizing agent whereas with ammonium hydroxide as precipitant, oxidation was performed with hydrogen peroxide.
Ion exchange capacities were determined by visible spectrophotometry. Increasing the pH of preparation lead to an increase in exchange capacities of the hydroxide precipitated gels that are characterized to be mesoporous. Such an increase is not observed in the case of carbonate precipitated microporous gels. It is shown that in the latter case the NH 4 + ions generated by the initial interaction of (NH4)2CO3 with the acidic titanous chloride lead to the formation of titania exchangers that are predominantly in the ammonium form. The textural characteristics of the exchanger resulting from different conditions of preparation is a significant contributing parameter to the resulting data.
Ageing of the microporous titania samples markedly reduces the exchanger capacity of the smaller Ni2+ ions but increases that of the bulkier Cr3+ as a result of the presence of some wide pores that appear upon agglomeration. The presence of Cr3+ ions in the hydroxo form in solution seems to inhibit its exchange with the appropriate surface species.
Studies on the kinetics of exchange with respect to the Ni2+ ions seem to indicate that a particle diffusion mechanism is partly or completely responsible for the rate of exchange.
KeywordsAmmonium Hydroxide Exchange Property Titania Sample Ammonium Carbonate Hydrous Titania
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- 4.A. M. Andrianov, V. P. Koryukova, V. E. Roladyan, L. K. Sakhno, L. V. Smirnova and E. V. Shabanov, Zh. Prikl. Khim. 51 (1978) 1892.Google Scholar
- 9.T. D. Semenouskaya, M. Deak and K. V. Chamutov, Zh. Fiz. Khim. 49 (1975) 462.Google Scholar
- 12.H. P. Boehm, Adv. Catal. 16 (1966) 179.Google Scholar
- 15.K. Nakamoto, in “Infrared and Raman Spectra of Inorganic and Coordination Compounds” (John Wiley, New York, 1978) pp. 288.Google Scholar
- 18.M. Elsaidi, MSc, Thesis, American University in Cairo, Egypt (1989).Google Scholar
- 19.C. F. Boes Jr and R. E. Meswar, (eds) “The Hydrolysis of Cations” (John Wiley, New York, 1976) pp. 218.Google Scholar
- 21.J. E. Huheey, “Inorganic Chemistry Principals of Structure and Reactivity” (Harper and Row, New York, 1983).Google Scholar
- 22.V. V. Strelko, S. A. Khainakov, A. P. Kuasheuko, V. N. Belyakov and A. I. Bortun, Zh. Prikl. Khim (Leningrad) 61 (1988) 2124.Google Scholar
- 24.N. N. Greenwood and A. Earnshaw, “Chemistry of the Elements” (Pergamon Press, Oxford, 1984).Google Scholar
- 28.S. T. Gregg and K. S. W. Sing, “Adsorption, Surface Area and Porosity” (Academic, London, 1967) pp. 201.Google Scholar