UNSPECIFIED (1994) ROTATING-DISC ELECTRODE VOLTAMMETRY AS A PROBE OF ADSORPTION RATES ON SOLID PARTICLES IN LIQUIDS - APPLICATION TO ZN-II ADSORPTION AT THE HYDROXYAPATITE AQUEOUS INTERFACE. JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, 90 (20). pp. 3109-3115. ISSN 0956-5000

Full text not available from this repository.

Abstract

A simple new approach for the measurement of the extent and kinetics of adsorption at the interface between a solid particle and a liquid is proposed. The technique employs a rotating-disc electrode to suspend the particles fully in the liquid under study, while the temporal dependence of the transport-limited current for the electrolysis of the solution component of the adsorbate serves as a concentration probe. The technique is used to study Zn-II adsorption on hydroxyapatite (HAP) from aqueous solution (containing 0.1 mol dm(-3) KCl as a supporting electrolyte). In the absence of dissolved Ca2+, adsorption is effectively irreversible with Zn-II adsorbed on HAP at a coverage of 7.5 x 10(-10) mol cm(-2). Adsorption appears to involve at least two rate processes: ca. 70% of adsorption sites (fraction theta(1)) are filled in an initial rapid process which is complete on the timescale (ca. 5 s) of mixing the adsorbate solution with the suspension of hydroxyapatite particles. The remaining sites (fraction theta(2)) are filled in an irreversible, surface-controlled process governed by the following kinetic rate law: d theta(2)/dt = {k'[Zn2+(aq)](1 - theta(1) - theta(2))}/N, where N is the surface density of (total) adsorption sites (7.5 x 10(-10) mol cm(-2)), [Zn2+(aq)] is the bulk solution concentration, t is time and the adsorption rate constant, k', has a value of 2.6 (+0.6, -0.3) x 10(-5) cm s(-1).

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry Q Science > QC Physics
Journal or Publication Title:	JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS
Publisher:	ROYAL SOC CHEMISTRY
ISSN:	0956-5000
Date:	21 October 1994
Volume:	90
Number:	20
Number of Pages:	7
Page Range:	pp. 3109-3115
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/20244

Data sourced from Thomson Reuters' Web of Knowledge

Request changes to a record

Actions (login required)

View Item