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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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.
|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
|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)
|Contact Email Address:||firstname.lastname@example.org|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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