Toxicity of imidazolium salt with anion bromide to a phytoplankton Selenastrum capricornutum: effect of alkyl-chain length.
Room-temperature ionic liquids are regarded as environmentally benign alternatives to volatile organic solvents. However, the product designs for this promising group of compounds should take account, not only the technological needs, but also the eco-toxicological hazards. Therefore, this study aimed to evaluate the toxicity of some important ionic liquids on the growth of the freshwater alga, Selenastrum capricornutum. The ionic liquids examined in this study included 1-propyl-3-methylimidazolium [PMIM], 1-butyl-3-methylimidazolium [BMIM], 1-hexyl-3-methylimidazolium [HMIM] and 1-octyl-3-methylimidazolium [OMIM] with a bromide anion. The susceptibility of alga to ionic liquids was strongly dependent on the alkyl-chain length. According to our results, a longer alkyl-chain resulted in stronger inhibition of algal growth. In general, the toxicity could be summarized as decreasing in the following order: [OMIM]>[HMIM]>[BMIM]>or=[PMIM]. Among the ionic liquids examined, [OMIM] [Br] was found to be most toxic to S. capricornutum, with EC(50) values ranging from 26.3 microM to 54.9 microM after an incubating time of 96 h. Although [BMIM] [Br] and [PMIM] [Br] was relatively less toxic than [OMIM] and [HMIM], their toxicity increased as increasing the incubation time from 48 h to 96 h. This fact indicates that these kinds of ionic liquids may become more toxic after being released and contacted to freshwater ecosystem.
Cho
Chul-Woong
CW
Department of Bioprocess Engineering, Chonbuk National University, Chonbuk 561-756, Republic of Korea.
Pham
Thi Phuong Thuy
TP
Jeon
You-Chul
YC
Vijayaraghavan
K
K
Choe
Woo-Seok
WS
Yun
Yeoung-Sang
YS
D000460:Chlorophyta / Q000187:drug effects* / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D006842:Hydrocarbons, Brominated / Q000737:chemistry / Q000633:toxicity*; D007093:Imidazoles / Q000737:chemistry / Q000633:toxicity*; D052578:Ionic Liquids / Q000737:chemistry / Q000633:toxicity*; D013329:Structure-Activity Relationship; D013997:Time Factors; D018675:Toxicity Tests
D006842:Hydrocarbons, Brominated; D007093:Imidazoles; D052578:Ionic Liquids