Electrochemical oxidation of succinic acid in aqueous solutions using boron doped diamond anodes

Abstract

In this work, the electrochemical oxidation of succinic acid on boron-doped diamond (BDD) anodes was investigated. Voltammetric study had shown that no peaks appeared in the region of electrolyte stability which indicates that succinic acid oxidation can take place at a potential close to the potential region of electrolyte oxidation. Galvanostatic electrolyses achieved total chemical oxygen demand (COD) removals and high mineralization yields under different operating conditions (initial COD, current density and nature of supporting electrolyte). Oxalic, glycolic and formic acids were the main intermediates detected during anodic oxidation of succinic acid on BDD electrode and carbon dioxide as the final product. The mean oxidation state of carbon reached the value of 4 at the end of electrolysis which is indicative of mineralization of almost all organics present in aqueous solution. The exponential profile of COD versus specific electrical charge has shown that mass transfer is the limiting factor for the kinetics of electrochemical process. A simple mechanism was proposed for the mineralization of succinic acid. First, hydroxyl radicals attack of succinic acid leading to formation of glycolic, glyoxylic, fumaric and maleic acids. Then, theses acids undergo rapid and non-selective oxidation by hydroxyl radicals to be transformed into oxalic and formic acids which leads to further oxidation steps to mineralize these acids into carbon dioxide and water.

Remediation of wastewaters containing tetrahydrofuran. Study of the electrochemical mineralization on BDD electrodes

“…Furthermore, BDD anodes have a high overpotential for the oxygen evolution reaction (1.3 V) compared with the platinum anode (0.3 V).The ability of BDD to mineralize a wide range of recalcitrant organic compounds and actual wastewaters were reviewed by Panizza and Cerisola [27] and Anglada et al [26]. Relevant to the present work the degradation of carboxylic acids [30,31], landfill leachates [32,33], industrial saline wastewaters [34,35], emerging contaminants [36,37] and reverse osmosis concentrates [38] are highlighted.…”

“…Mehrvar et al [24] also found that during the TiO 2 photocatalytic degradation of aqueous THF the main intermediates were 2-hydroxytetrahydrofuran, -butyrolactone, succinic acid and formic acid. On the other hand, Bensalah et al [30] studied the electrochemical oxidation of succinic acid on BDD and they found that glycolic, glyoxylic, fumaric and maleic acids were formed. Nevertheless, they proposed that these acids were oxidized through a rapid and non-selective way into oxalic and formic acids.…”

Large-Area Cylindrical Diamond Electrodes

“…The presence of non-diamond carbon impurity at the surface can be detected from the background voltammogram in a strong acid media, especially with the effect on the width of the potential domain, where the electrode is ideally polarizable. [54][55][56][57][58][59][60][61][62][63] The background for Nb/BDD ( Fig. 9) electrodes is featureless, low and ideally polarizable in the respective potential ranges from −380 to 1056 mV and from −420 to 1360 mV in 2.0 mol L −1 H 2 SO 4 .…”

“…The voltammograms also indicate that no significant level of non-diamond carbon impurities is present. The voltammograms show that the diamond has enough quality to be applied in electrodegradation and also does not have the different characteristics of voltammograms obtained on plates or wafers [54][55][56][57][58][59][60][61][62][63] …”

“…[23][24][25][26][27] In particular, the use of anodes coated with boron-doped diamond films for electrochemical application is a new technology with great potential for wastewater treatment in large scale. Conventionally electrochemical cells usually use plate-shaped electrodes, [23][24][25][26][27] which present difficulty to: (i) seal and make hydraulic connections; (ii) make electrical contact with quality and impermeable; and (iii) make assembly of parts. 28 Cylindrical-shape (rod and tube substrates) diamond coatings are promising for solving this problems with same advantages, including make sealing and hydraulic connections suitable without the need to use resins or adhesives; easy handling; assembly connections and enabling large-scale in series and/or parallel; make electrical contact with quality and impermeable and minimize the physical space.…”