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Esclapez M.D.,Instituto Universitario Of Electroquimica | Saez V.,Instituto Universitario Of Electroquimica | Milan-Yanez D.,Instituto Universitario Of Electroquimica | Tudela I.,Instituto Universitario Of Electroquimica | And 3 more authors.
Ultrasonics Sonochemistry | Year: 2010

The sonoelectrochemical treatment of aqueous solutions of trichloroacetic acid (TCAA) has been scaled-up from the voltammetric analysis to pre-pilot stage. The degradation in absence of ultrasound field has yield to a poor performance which has been improved in presence of ultrasound. The sonovoltametry study has provided the range of potentials and/or current densities to be used with the lowest current efficiency penalty. Sonoelectrolyses at batch scale (carried out with a horn-transducer 24 kHz positioned at about 3 cm from the surface of the electrode) achieved little improvement in the degradation. However, when a specifically designed sonoelectrochemical reactor (not optimized) was used during the scale-up, the presence of ultrasound field provided better results (fractional conversion 97%, degradation efficiency 26%, selectivity 0.92 and current efficiency 8%) at lower ultrasonic intensities and volumetric flow. © 2009 Elsevier B.V. All rights reserved.

Abyaneh M.Y.,Coventry University | Saez V.,Instituto Universitario Of Electroquimica | Gonzalez-Garcia J.,Instituto Universitario Of Electroquimica | Mason T.J.,Coventry University
Electrochimica Acta | Year: 2010

The kinetics of the early stages of the electrocrystallization of lead dioxide onto a vitreous carbon electrode is studied via the analysis of the early rising portion of the current-time transients (CTT's). The CTT's are recorded when the rate of charge-transfer across the electrode/electrolyte interface is the sole controlling mechanism for crystal growth. Induction times for the nucleation of the 3D growth centres are determined as a function of the applied potential. A possible controlling mechanism for the onset of the nucleation of the 3D growth centres is thus considered to be the need for the formation of at least a monolayer of deposit and/or adsorbed layers. It has been shown that CTT's that are recorded during the charge-transfer controlled growth processes allows the possibility of observing the formation of two distinct phases of a deposit, a phenomenon that would not be observed if CTT's are recorded when diffusion is the controlling mechanism for growth. The electrocrystallization of lead dioxide is shown to proceed, at least initially, via the formation of two distinct phases of PbO2. © 2009 Elsevier Ltd. All rights reserved.

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