Jv. Macpherson et al., IMAGING LOCAL MASS-TRANSFER RATES WITHIN AN IMPINGING JET AND STUDIESOF FAST HETEROGENEOUS ELECTRON-TRANSFER KINETICS USING THE MICROJET ELECTRODE, Journal of the Chemical Society. Faraday transactions, 91(5), 1995, pp. 899-904
Citations number
55
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
The microjet electrode (MJE) is a recently introduced hydrodynamic ele
ctrode in which a jet of solution impinges on a disc ultramicroelectro
de (UME) under conditions of well defined, variable and high mass-tran
sfer rates. It is shown that these properties make MJE voltammetry a p
owerful technique for characterising rapid electron-transfer kinetics
under steady-state conditions. The MJE approach is illustrated through
studies of the hexacyanoferrate(II/III) couple in aqueous strontium n
itrate solutions (0.2 mol dm(-3)). The standard rate constant is found
to be 0.76 +/- 0.11 cm s(-1) and the transfer coefficient is in the r
ange 0.35-0.55. Complementary mass-transfer imaging experiments, in wh
ich the transport-limited current at the UME is monitored as a functio
n of the nozzle position, as a jet of solution is scanned over the ele
ctrode surface in a raster pattern, are shown to provide useful inform
ation on the positioning requirements of the MJE and a unique insight
into the nature of mass transfer from an impinging jet. The spatial va
riation of local mass transfer deduced from these experiments is found
to be in qualitative agreement with the theoretical predictions for t
he fluid velocity profile of the impinging jet under laminar flow cond
itions.