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Degradation of imidazolium‐based ionic liquids in aqueous solution by Fenton oxidation
Author(s) -
Domínguez Carmen M.,
Munoz Macarena,
Quintanilla Asunción,
de Pedro Zahara M.,
Ventura Sonia P.M.,
Coutinho João A.P.,
Casas Jose A.,
Rodriguez Juan J.
Publication year - 2014
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.4366
Subject(s) - ecotoxicity , ionic liquid , aqueous solution , chemistry , stoichiometry , degradation (telecommunications) , hydrogen peroxide , catalysis , alkyl , solubility , inorganic chemistry , effluent , precipitation , organic chemistry , environmental engineering , telecommunications , physics , toxicity , meteorology , computer science , engineering
BACKGROUND The breakdown of imidazolium ionic liquids ( ILs ) by Fenton oxidation has been demonstrated, but using unaffordable doses of hydrogen peroxide ( H 2 O 2 ). The literature studies so far do not report on the evolution of total organic carbon ( TOC ) and ecotoxicity. Therefore, the potential application of the process for the degradation of ILs still remains an open question. This work investigates the feasibility of the Fenton process for the treatment of aqueous effluents containing imidazolium‐based ILs of different structures, represented by the length of the alkyl chain and the nature of the anion. Special attention is paid to the evolution of the ecotoxicity and the consumption of H 2 O 2 as a critical issue for the economy of the process. The experiments were performed at 70 °C . RESULTS With the stoichiometric H 2 O 2 dose, the complete conversion of the starting imidazolium‐based ILs was achieved in less than 5 min, at 70°C , with 60% of TOC reduction after 4 h, except in the [C 4 mim][ CH 3 CO 2 ] case, where iron precipitation was observed, thus inhibiting its catalytic action. Low ecotoxicity effluents were obtained at the stoichiometric H 2 O 2 dose, even in the cases of the highly ecotoxic ILs of long alkyl chain with chloride anion. CONCLUSION Fenton oxidation is shown to be a promising solution for the degradation of imidazolium‐based ILs in water, allowing deep detoxification with the stoichiometric H 2 O 2 dose. © 2014 Society of Chemical Industry