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Calcium-phosphorus interactions at a nano-structured silicate surface


Southam, DC and Lewis, TW and McFarlane, AJ and Borrmann, T and Johnston, JT, Calcium-phosphorus interactions at a nano-structured silicate surface, Journal of Colloid and Interface Science, 319, (2) pp. 489-497. ISSN 0021-9797 (2008) [Refereed Article]

DOI: doi:10.1016/j.jcis.2007.12.012


Nano-structured calcium silicate (NCS), a highly porous material synthesized by controlled precipitation from geothermal fluids or sodium silicate solution, was developed as filler for use in paper manufacture. NCS has been shown to chemisorb orthophosphate from an aqueous solution probably obeying a Freundlich isotherm with high selectivity compared to other common environmental anions. Microanalysis of the products of chemisorption indicated there was significant change from the porous and nano-structured morphology of pristine NCS to fibrous and crystalline morphologies and non-porous detritus. X-ray diffraction analysis of the crystalline products showed it to be brushite, CaHPO4ṡ2H2O, while the largely X-ray amorphous component was a mixture of calcium phosphates. A two-step mechanism was proposed for the chemisorption of phosphate from an aqueous solution by NCS. The first step, which was highly dependent on pH, was thought to be desorption of hydroxide ions from the NCS surface. This was kinetically favoured at lower initial pH, where the predominant form of phosphate present was H2PO- 4, and led to decreased phosphorus uptake with increasing pH. The second step was thought to be a continuing chemisorption process after stabilization of the pH-value. The formation of brushite as the primary chemisorption product was found to be consistent with the proposed mechanism. © 2007 Elsevier Inc. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Macromolecular and materials chemistry
Research Field:Physical properties of materials
Objective Division:Environmental Management
Objective Group:Fresh, ground and surface water systems and management
Objective Field:Measurement and assessment of freshwater quality (incl. physical and chemical conditions of water)
UTAS Author:Southam, DC (Mr Daniel Southam)
UTAS Author:Lewis, TW (Associate Professor Trevor Lewis)
ID Code:55831
Year Published:2008
Web of Science® Times Cited:15
Deposited By:Chemistry
Deposited On:2009-03-13
Last Modified:2011-10-24

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