This paper deals with the degradation of diclofenac by electrochemical oxidation in NaClO4 medium at neutral pH using a FM01-LC reactor equipped with a boron doped diamond electrode (BDD). Microelectrolysis studies were carried out to find the current density domain where hydroxyl radical (•OH) formation is favored, 10 ≤ j ≤ 20 mA cm−2. Electrolysis experiments at mean linear flow velocities of 14.6 ≤ u ≤ 58.4 cm s−1 were performed. The experimental set-up achieved 100% diclofenac mineralization with 78% current efficiency and energy consumption of 2.54 kWh m−3 at j = 15 mA cm−2 and u=29.2 cm s−1.

Este trabajo muestra la degradación de diclofenaco por oxidación electroquímica en medio de NaClO4 y pH neutro empleando el reactor el FM01-LC equipado con un ánodo de diamante dopado con boro (BDD). Se llevaron a cabo estudios de microelectrólisis para determinar el dominio de densidad de corriente donde se favorece la formación de radicales hidroxilo (•OH), 10 ≤ j ≤ 20 mA cm−2. Se realizaron electrolisis a velocidades promedio de flujo comprendidas entre 14.6 ≤ u ≤ 58.4 cm s−1. La degradación completa de diclofenaco (100%) se logró a 15 mA cm−2 and u=29.2 cm s−1, con una eficiencia de corriente de 78% y un consumo de energía de 2.54 kWh m−3.

The electrochemical oxidation of Alphazurine A (αzA) has been studied in Na2SO4 media at Ti/IrO2, Pb/PbO2 and boron-doped diamond (Si/BDD) electrodes by bulk electrolysis experiments under galvanostatic control at j = 30 and 60 mA cm-2. The obtained results have clearly shown that the electrode material plays an important role for the electrochemical incineration of azA, where Pb/PbO2 and Si/ BDD lead complete mineralization of dye, while Ti/IrO2 disfavoured such process. The complete mineralization of ±zA on Pb/PbO2 and Si/BDD is due to the production of hydroxyl radicals on these materials surfaces. Current efficiencies obtained at Ti/IrO2, Pb/PbO2 and Si/ BDD gave values of 3, 24 and 42%, for each electrode material, at 30 mA cm-2, respectively. These values were higher than those obtained at 60 mA cm-2. Energy consumption values from the electrolyses performed at 30 mA cm-2 were 254, 124 and 51 kWh m-3, for Ti/IrO2, Pb/PbO2 and Si/BDD, respectively. UV spectrometric measurements showed faster αzA elimination at the Si/BDD electrode than those obtained on Ti/IrO2 and Pb/PbO2.

Se estudió la oxidación electroquímica del colorante Alfazurina A (αzA) en medio acuoso de Na2SO4 con electrodos de Ti/IrO2, Pb/PbO2 y diamante dopado con boro (Si/BDD), a través de experimentos de electrólisis, en modo galvanostático a j = 30 y 60 mA cm-2 . Los resultados obtenidos en este trabajo mostraron que el material del electrodo desempeña un papel importante para la incineración electroquímica del colorante azA, indicando que los electrodos de Pb/PbO2 y Si/BDD permiten la completa degradación del colorante, mientras que el electrodo de Ti/IrO2 desfavorece tal proceso. La completa degradación del colorante αzA en los electrodos de Pb/PbO2 y Si/BDD fue debida a la formación de radicales hidroxilo en la superficie de estos materiales. Los valores de las eficiencias de corriente fueron de 3, 24 y 42%, para Ti/IrO2, Pb/PbO2 y Si/BDD, respectivamente, a j = 30 mA cm-2. . Estos valores fueron mayores que los obtenidos a 60 mA cm-2. Por otro lado, el consumo de energía a j = 30 mA cm-2 presentó valores de 254, 124 and 51 kWh m-3 para los electrodos de Ti/IrO2, Pb/PbO2 y Si/BDD, respectivamente. La cinética de eliminación de color empleando el electrodo de Si/BDD fue mayor que la obtenida con los electrodos de Ti/IrO2 y Pb/PbO2.

This paper shows the applicability of the carbon paste electrode-mineral (CPE-mineral) to study the dissolution mechanisms of minerals in powder form and in flotation concentrates. A potentiodynamic strategy to find the dissolution mechanism of galena (PbS) is presented. In this way, minerals less studied such as orpiment (As2S3) and realgar (As2S2) are investigated. The electrochemical activity of a more complicated mineral such as sphalerite (ZnS), containing 12.3 and 0.43% of iron in solid solution, is discussed. The mechanism of a complex zinc concentrate (containing 63.4% ZnS, 20.1% FeS2, 5% CuFeS2, 0.33% PbS, 0.45% Cu12Sb4S13 and 0.4% FeAsS) is described. Finally, an electrochemical method for the detection of the different leachable and refractory silver phases (contained in two mineral concentrates) is presented. This paper reviews the power of the use of CPE-mineral coupled to electrochemical techniques in hydrometallurgy.