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Adsorption of phosphate by halloysite (7 Å) nanotubes (HNTs) / Nia Gray-Wannell, Peter Holliman, H. Christopher Greenwell, Evelyne Delbos, Stephen Hillier

Clay Minerals, Volume: 55, Issue: 2, Pages: 184 - 193

Swansea University Author: Peter Holliman

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DOI (Published version): 10.1180/clm.2020.24

Abstract

The adsorption and retention of phosphates in soil systems is of wide environmental importance, and understanding the surface chemistry of halloysite (a common soil clay mineral) is also of prime importance in many emerging technological applications of halloysite nanotubes (HNTs). The adsorption of...

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Published in: Clay Minerals
ISSN: 0009-8558 1471-8030
Published: Mineralogical Society 2020
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa55534
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Abstract: The adsorption and retention of phosphates in soil systems is of wide environmental importance, and understanding the surface chemistry of halloysite (a common soil clay mineral) is also of prime importance in many emerging technological applications of halloysite nanotubes (HNTs). The adsorption of phosphate anions on tubular halloysite (7 Å) has been studied to gain a greater understanding of the mechanism and kinetics of adsorption on the surface of HNTs. Two well-characterized tubular halloysites with differing morphologies have been studied: one polygonal prismatic and one cylindrical, where the cylindrical form has a greater surface area and shorter tube length. Greater phosphate adsorption of up to 42 μmol g–1 is observed on the cylindrical halloysite when compared to the polygonal prismatic sample, where adsorption reached a maximum of just 15 μmol g–1 compared to a value for platy kaolinite (KGa-2) of 8 μmol g–1. Phosphate adsorption shows strong pH dependence, and the differences in phosphate sorption between the prismatic and cylindrical morphologies suggest that phosphate absorption does not occur at the same pH-dependent alumina edge sites and that the lumen may have a greater influence on uptake for the cylindrical form.
Keywords: adsorption, anion-exchange capacity, halloysite nanotube, HNT, phosphate
College: College of Engineering
Issue: 2
Start Page: 184
End Page: 193