Fate and Effect of Hydroxyl Functionalized Imidazolium Ionic Liquids on Biological Systems

1-(2-hydroxyethyl)-3-methyl imidazolium chloride [IM12OHCl], 1-(3-
hydroxypropyl)-3-methyl imidazolium chloride [IM13OHCl] and 1-(6-hydroxyhexyl)-
3-methyl imidazolium chloride [IM16OHCl] have been synthesized in the laboratory by
reacting 1-methylimidazole with 2-chloroethanol, 3-chloropropanol, and 6-
chlorohexanol, while 1-(2-hydroxyethyl)-3-ethyl imidazolium chloride [IM22OHCl]
has been synthesized by reacting 1-ethylimidazole with 2-chloroethanol. The toxicity of
these ionic liquids are determined according to OECD Guideline 203. Six aquarium
filled with 5 L of lake water are prepared. The water temperature is kept at 23 ±1 °C
and aerated to restore the concentration of dissolved oxygen to at least 60% of its air
saturation value. 10 fish are placed in each aquarium and the aquariums are kept under
normal laboratory illumination with a daily photoperiod of 12 h. A limit test is
performed at the concentration of 100 mg L-1 of each synthesized ionic liquid and left
for 96 hours. After 96 hours, 2 fish died in the aquarium containing 1-(2-hydroxyethyl)-
3-ethyl imidazolium chloride, while no fish died in the other aquariums. The full
toxicity test according to OECD Guideline 203 is performed using 1-(2-hydroxyethyl)-
3-ethyl imidazolium chloride at five concentrations from 20.0 to 100.0 mg/L and result
shows that no fish died. It is concluded that all the four ionic liquids tested are non-toxic
to freshwater fish