Hydrated phosphorus oxyacids alone and adsorbed on nanosilica

V M Gun'ko; L P Morozova; A A Turova; A V Turov; V E Gaishun; V M Bogatyrev; V V Turov

doi:10.1016/j.jcis.2011.11.018

Hydrated phosphorus oxyacids alone and adsorbed on nanosilica

J Colloid Interface Sci. 2012 Feb 15;368(1):263-72. doi: 10.1016/j.jcis.2011.11.018. Epub 2011 Nov 16.

Authors

V M Gun'ko¹, L P Morozova, A A Turova, A V Turov, V E Gaishun, V M Bogatyrev, V V Turov

Affiliation

¹ Chuiko Institute of Surface Chemistry, General Naumov Street 17, 03164 Kyiv, Ukraine. vlad_gunko@ukr.net

PMID: 22138264
DOI: 10.1016/j.jcis.2011.11.018

Abstract

Low-temperature (1)Н NMR spectroscopy was used to study states of water bound to phosphoric and phosphonic acids (phosporus oxyacids, POA) alone or adsorbed onto nanosilica OX-50 (specific surface area S(BET)=52 m(2)/g) or A-300 (S(BET)=297 m(2)/g). Concentrated solutions or weakly hydrated solid POA or dried silica/POA powders placed in CCl(4) medium are characterized by different temperature dependences of the chemical shift of the proton resonance (δ(H)) because of partial dissociation of PO-H bonds strongly affected by water amounts and temperature. NMR cryoporometry results show that both small water clusters and nanodomains are present at the interfaces of hydrated solid POA and silica/POA powders. Quantum chemical calculations of the (1)H NMR spectra demonstrate the influence of POA/water cluster structure and dissociation of the PO-H bonds on the δ(H) values.