Influence of the supporting electrolyte on the removal of ionic liquids by electrolysis with diamond anodes

[Display omitted] •ILs based on imidazolium can be completely removed by electrolysis with diamond.•Dmim+ electropolymerization is observed during the electrolysis with diamond anodes.•Sulfate leads to a more efficient oxidation and prevents polymerization.•Nitrites, nitrates and ammonium are formed...

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Bibliographic Details
Published in:Catalysis today 2018-09, Vol.313, p.203-210
Main Authors: Mena, Ismael F., Cotillas, Salvador, Díaz, Elena, Sáez, Cristina, Mohedano, Ángel F., Rodrigo, Manuel A.
Format: Article
Language:English
Subjects:
Diamond
Electrolysis
Hydroxyl radical
Ionic liquid
Peroxodisulfate
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Summary:[Display omitted] •ILs based on imidazolium can be completely removed by electrolysis with diamond.•Dmim+ electropolymerization is observed during the electrolysis with diamond anodes.•Sulfate leads to a more efficient oxidation and prevents polymerization.•Nitrites, nitrates and ammonium are formed from the nitrogen of the imidazolium groups.•The chloride counter ion is transformed into perchlorates and chloramines. In this work, it is studied the electrolysis with diamond anodes of three different ionic liquids (ILs): 1-butyl-3-methylimidazolium chloride (BmimCl), 1-hexyl-3-methylimidazolium chloride (HmimCl) and 1-decyl-3-methylimidazolium chloride (DmimCl), which differ only in the length of the aliphatic carbon chain attached to the imidazolium group. In addition, the effect of the presence of sulfate in the electrolyte is also evaluated. Results confirmed that this type of ILs can be completely transformed into carbon dioxide, nitrates, ammonium (the imidazolium cation) and perchlorate and chloramines (the chloride anion) during the electrolysis of the synthetic waste containing sulfate. The electrolysis of wastes without sulfate anions leads to a much less efficient process, with the same final products in the case of the BminCl and HminCl ILs and with the formation of a polymer as the main final product in the case of the DmimCl. These results are of a paramount significance from a mechanistic point of view since, because of the high conductivity of the ILs, there is not a necessity of salt addition and they inform about the pure removal of these compounds by electrolysis with BDD, pointing out the important influence of peroxodisulfate on the electrolyses with diamond of organic wastes.
ISSN:0920-5861
1873-4308
DOI:10.1016/j.cattod.2017.10.025