Toxicity and inhibition assessment of ionic liquids by activated sludge.
Ecotoxicol Environ Saf
; 187: 109836, 2020 Jan 15.
Article
em En
| MEDLINE
| ID: mdl-31675504
Toxicity of 13 ionic liquids (ILs) corresponding to different families were studied by inhibition respiration assays (15â¯min) using activated sludge. Toxicity increased as increasing the number of carbons in the alkyl-chain of imidazolium-based ILs, with EC50 values from 4.19 to 0.17 for 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) and 1-octyl-3-methylimidazolium chloride ([Omim][Cl]), respectively. An increase in toxicity was observed for aromatic-based ILs (pyridinium- and imidazolium-based ILs) due to the hydrophobic character of the head groups in comparison with linear structures as phosphonium and ammonium cations. Among to the anions studied fixing [Emim]+ as cation, [HSO4]- and [NTf2]- presented low EC50 values (0.34â¯mM and 1.69â¯mM, respectively) while [Cl]- and [EtSO4]- were considered harmless anions due to the hydrophilic character of chloride and the organic nature of [EtSO4]-. ILs toxicity/inhibition was determined by adding a biodegradable compound and measuring the sludge response after being in contact with the ILs for at least 15â¯h. The exposure of sewage sludge to ILs for more than 15â¯min used in short inhibition assays caused more toxic effect on microorganisms, even for [Choline][NTf2], previously defined as practically harmless (EC50â¯=â¯2.79â¯mM). Biodegradability assays confirmed the biodegradable nature of choline cation, related with TOC conversion of 40%, only due to cation consumption. No oxygen consumption or even lysis of microbial cells was observed for Tetrabutylammonium bis(trifluoromethylsulfonyl)imide and for 1-Ethyl-3-methylimidazolium hydrogensulphate due to the presence of anions previously defined as hazardous ([NTf2]- and [HSO4]-), maintaining their recalcitrant character to sewage systems.
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Base de dados:
MEDLINE
Assunto principal:
Esgotos
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Líquidos Iônicos
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Imidazóis
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article