The reduction of l-cystine hydrochloride at lead using static and rotating disc electrodes
Ralph, T.R., Hitchman, M.L., Millington, J.P. and Walsh, F.C., Walsh, F.C. (ed.) (2005) The reduction of l-cystine hydrochloride at lead using static and rotating disc electrodes. Journal of Electroanalytical Chemistry, 583, (2), 260-272. (doi:10.1016/j.jelechem.2005.06.009).
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Description/Abstract
The reduction of the disulphide, l-cystine hydrochloride to the l-cysteine hydrochloride thiol, in 0.1 mol dm−3 HCl at 298 K, has been studied at pre-treated, circular, 0.50 cm2 lead disc electrodes using steady state linear sweep voltammetry, non-steady state voltammetry and controlled potential coulometry. The diffusion coefficient for l-cystine hydrochloride was approximately 4.8 × 10−10 m2 s−1 from the three techniques. Reduction of the disulphide was irreversible and hydrogen evolution occurred as a competitive reaction at approximately −1.35 V vs. SCE. Analysis of the mixed control kinetics, using a Koutecky–Levich approach, allowed the relative roles of charge transfer and mass transport to be resolved. Anomalously high Tafel slopes, of typically −183 mV, were observed due to disulphide adsorption. The charge transfer kinetics are consistent with the first electron gain being rate determining while reaction orders are +1 with respect to both the disulphide and proton concentrations. The mechanism of l-cystine hydrochloride reduction has been critically discussed.
| Item Type: | Article |
|---|---|
| ISSNs: | 0022-0728 (print) |
| Related URLs: | |
| Keywords: | amino acid electrosynthesis, charge transfer control, controlled potential coulometry, koutecky–levich equation, l-cystine hydrochloride, l-cysteine hydrochloride, lead electrodes, mass transport control, rotating disc electrode, voltammetry |
| Subjects: | T Technology > TK Electrical engineering. Electronics Nuclear engineering Q Science > QD Chemistry Q Science > QC Physics |
| Divisions: | University Structure - Pre August 2011 > School of Engineering Sciences |
| Item ID: | 23752 |
| Date Deposited: | 21 Mar 2006 |
| Last Modified: | 01 Jun 2011 11:11 |
| Contributors: | Ralph, T.R. (Author) Hitchman, M.L. (Author) Millington, J.P. (Author) Walsh, F.C. (Author) Walsh, F.C. (Editor) |
| Date: | 2005 |
| Status: | Published |
| Contact Email Address: | f.c.walsh@soton.ac.uk |
| URI: | http://eprints.soton.ac.uk/id/eprint/23752 |
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