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Electrochemical investigation of Pb<sup>2+</sup> binding and transport through a polymerized crystalline colloidal array hydrogel containing benzo-18-crown-6

Geary, CD and Zudans, I and Goponenko, AV and Asher, SA and Weber, SG (2005) Electrochemical investigation of Pb<sup>2+</sup> binding and transport through a polymerized crystalline colloidal array hydrogel containing benzo-18-crown-6. Analytical Chemistry, 77 (1). 185 - 192. ISSN 0003-2700

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Abstract

The transport of Pb2+ through a sensory gel, a polymerized crystalline colloidal array hydrogel with immobilized benzo-18-crown-6, is important for understanding and optimizing the sensor. Square wave voltammetry at a Hg/ Au electrode reveals many parameters. The partition coefficient for Pb2+ into a control gel (no crown ether), Kp, is 1.00 ± 0.018 (errors reported are SEM). The porosity, ε, of the gel is 0.90 ± 0.01. Log Kc for complexation in the gel is 2.75 ± 0.014. Log Kc in aqueous solution for Pb2+ with the ligand 4-acryloylamidobenzo-18-crown-6 is 3.01 ± 0.010 with dissociation rate kd = (8.34 ± 0.45) × 102 s-1 and association rate kf = (8.79 ± 0.025) × 107 M-1 s-1. The partition coefficient of the ligand 4-acryloylamidobenzo-18-crown-6 into the control gel, K p,L is 2.07 ± 0.15. The diffusion coefficient of Pb 2+ in the control gel is 6.72 × 10-6 ± 0.12 cm2/s. For the sensor gel, but not control gel, diffusion coefficients are location dependent. The range of diffusion coefficients for Pb2+ in the probed locations was found to be (6.11-12.60) × 10-7 cm2/s for 0.91 mM Pb2+ and (2.84-9.39) × 10-7 cm2/s for 0.35 mM Pb2+. Lead binding in the sensor gel is slightly less avid than in solution. This is attributed, in part, to the demonstrated affinity of the ligand 4-acryloylamidobenzo-18-crown-6 to the gel. Diffusion coefficients determined for the sensor gel were found to be location dependent. This is attributed to heterogeneities in the crown concentration in the gel. Analysis of diffusion coefficients and rate constants show that diffusion and not chemical relaxation will limit the time response of the material.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Geary, CD
Zudans, I
Goponenko, AV
Asher, SAasher@pitt.eduASHER
Weber, SG
Date: 1 January 2005
Date Type: Publication
Journal or Publication Title: Analytical Chemistry
Volume: 77
Number: 1
Page Range: 185 - 192
DOI or Unique Handle: 10.1021/ac048616k
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 0003-2700
MeSH Headings: Colloids; Crown Ethers--chemistry; Diffusion; Electrochemistry--methods; Hydrogels; Lead--analysis; Lead--chemistry; Polymers
PubMed ID: 15623295
Date Deposited: 08 Feb 2013 21:20
Last Modified: 02 Feb 2019 16:55
URI: http://d-scholarship.pitt.edu/id/eprint/17188

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