Toxicity of imidazolium- and pyridinium-based ionic liquids and the co-metabolic degradation of N-ethylpyridinium tetrafluoroborate.
We examined the effects of the ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF₆], N-ethylpyridinium tetrafluoroborate [EtPy][BF₄], and N-ethylpyridinium trifluoroacetate [EtPy][CF₃COO] on Pseudomonas fluorescens, a ubiquitous soil bacterium. In the presence of 0.5- and 1% of [BMIM][PF₆] or [EtPy][CF₃COO] the growth of bacteria was inhibited, whereas exposing them to 1% [EtPy][BF₄] increased the lag period wherein bacteria adapt to growth conditions before continuing to grow. However, at higher concentrations (5% and 10%), no growth was observed. The inhibitory effects were evident by a decrease in the optical density of the culture, a decline in the consumption of the carbon source, citric acid, and a change in the size of the bacterium. At concentrations below 1%, [EtPy][BF₄] was metabolized by P. fluorescens in the presence of citric acid. Oxidation of the side alkyl-chain of [EtPy][BF₄] caused the accumulation of N-hydroxylethylpyridinium and pyridinium as major degradation products.
Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07104, USA.
C
C
Zhang
S V
SV
Malhotra
A J
AJ
Francis
D001673:Biodegradation, Environmental; D019343:Citric Acid / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000378:metabolism / Q000633:toxicity*; D052578:Ionic Liquids / Q000378:metabolism / Q000633:toxicity*; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D011726:Pyridinium Compounds / Q000378:metabolism / Q000633:toxicity*; D012989:Soil Pollutants / Q000378:metabolism / Q000633:toxicity
C412621:1-butyl-3-methylimidazolium hexafluorophosphate; D007093:Imidazoles; D052578:Ionic Liquids; D011726:Pyridinium Compounds; D012989:Soil Pollutants; C011815:ethylpyridinium; D019343:Citric Acid