Sorption of phosphate onto mesoporous γ-alumina studied with in-situ ATR-FTIR spectroscopy
Open Access
- 3 April 2012
- journal article
- Published by Springer Science and Business Media LLC in Chemistry Central Journal
- Vol. 6 (1), 26
- https://doi.org/10.1186/1752-153x-6-26
Abstract
Due to the extensive use of phosphates in industry, agriculture and households, the phosphate - γ-alumina interactions are important for understanding its detrimental contribution to eutrophication in lakes and rivers. In situ Fourier transform infrared (FTIR) spectroscopy can provide more detailed information on the adsorbate-adsorbent interaction and the formation of hydrogen bonds. In situ ATR-FTIR spectroscopy was used to identify phosphate complexes adsorbed within the three-dimensional network of mesoporous γ-alumina at pH 4.1 and 9.0. The integrated intensity between 850 cm-1 and 1250 cm-1 was used as a relative measure of the amount of adsorbed phosphate. The integrated intensity proved to be about 3 times higher at pH 4.1 as compared with the corresponding intensity at pH 9.0. The adsorption of phosphate at the two pH conditions could be well described by the Langmuir adsorption isotherm at low concentrations and the empirical Freundlich adsorption isotherm for the whole concentration range, viz. 5 - 2000 μM. From the band shape of infrared spectra at pH 4.1 and pH 9.0, it was proposed that the symmetry of the inner-sphere surface complex formed between phosphate and γ-alumina was C1 at the lower pH value, whilst the higher value (9.0) implied a surface complex with C2v or C1 symmetry. The difference in adsorbed amount of phosphate at the two pH values was ascribed to the reduced fraction of ≡ AlOH2+ surface sites and the increased fraction of ≡ AlO- sites upon increasing pH from 4 to 9.Keywords
This publication has 34 references indexed in Scilit:
- Surface acid–base properties and hydration/dehydration mechanisms of aluminum (hydr)oxidesJournal of Colloid and Interface Science, 2007
- Phosphate Reaction Dynamics in Soils and Soil Components: A Multiscale ApproachAdvances in Agronomy, 2007
- Charging Behavior of the Gibbsite Basal (001) Surface in NaCl Solution Investigated by AFM Colloidal Probe TechniqueLangmuir, 2006
- In-Situ Infrared Spectroscopic Studies of Adsorption Processes on Boehmite Particle Films: Exchange of Surface Hydroxyl Groups Observed upon Chelation by AcetylacetoneLangmuir, 2004
- Evaluation of phosphorus bioavailability in sediments of three contrasting lakes in China and the UKChemosphere, 2001
- Dehydroxylation of Aluminum (Oxo)Hydroxides Using Infrared Emission Spectroscopy. Part II: BoehmiteApplied Spectroscopy, 1999
- Vibrational Spectroscopy and Dehydroxylation of Aluminum (Oxo)Hydroxides: GibbsiteApplied Spectroscopy, 1999
- The Role of Phosphorus in the Eutrophication of Receiving Waters: A ReviewJournal of Environmental Quality, 1998
- Reactivity at the mineral-water interface: dissolution and inhibitionColloids and Surfaces A: Physicochemical and Engineering Aspects, 1997
- Significance of phosphorus in lakes and coastal water sediments and benthosWater Research, 1973