Toxicity And Biodegradability Of Ionic Liquid[bmim]PF₆ And [bmim]CF₃CO₂

Ionic liquids,low melting point salts composed entirely of ions,exhibit liquid at room temperature.It has stable properties,strong conductivity,no flammability and low vapor pressure,which is called"green solvent"after water and supercritical carbon dioxide.With the wide application and continuous development of ionic liquids,some researchers have shown that ionic liquids are not toxic to some cells and organisms,but highly toxic to other microbes and elements in the environment.Ionic liquids may be nontoxic to some cells and organisms,but they will be highly toxic to other biological elements in the environment.Therefore,the current study suggests that the indirect changes in the environment by these chemical pollutants have greatly exceeded their direct and immediate toxicity to a single organism.In order to achieve accurate evaluation of the toxicity of ionic liquids,we should consider the effects of these ionic liquids on various habitats in water and soil ecosystems.In this paper,two different fluorinated anions[bmim]PF₆ and[bmim]CF₃CO₂,were selected as objects and monotyledonous wheat and dicotyledonous radish were selected as experimental indicative organisms.The plants were treated with hydroponics under ILs treatment.The concentration of hydroponic culture was 0,10,50,100,200,400,and700mg/kg,respectively.The infected solution was loaded into the culture box according to the concentration of exposure,and two plants were cultured for 12 days in water culture.Some indexes of two kinds of crops,such as growth index?root length,stem length,dry weight?,physiological indexes?chlorophyll,MDA?,proline,enzyme activity,superoxide dismutase?SOD?,peroxidase?POD?,catalase?CAT?were determined.The effects of ionic liquids on the growth and physiological indexes of two plants were analyzed.At the same time,the degradation of two ionic liquids was preliminarily explored by activated sludge acclimatization.The results of the study are as follows:?1?the effect of ionic liquid on the growth index:?1?with the increase of ionic liquid concentration,for two plants,the two ionic liquids can inhibit the growth of wheat and radish seedlings,which will lead to the decrease of stem length and root length.?2?the ionic liquid[bmim]PF₆ had a single inhibitory effect on both wheat and radish seedlings,and[bmim]CF₃CO₂ had a single inhibitory effect on wheat seedlings,but it showed low growth inhibition to radish seedlings.?3?the inhibition effects of two ionic liquids on roots were greater than those on stems.?4?Radish seedlings had higher resistance to ionic liquid than wheat seedlings,that is,the toxicity to monocotyledonous plants was greater than that of dicotyledonous plants.?5?According to the growth of root length,stem length and dry weight of two plants,the toxicity of the two ILs is[bmim]PF₆>[bmim]CF₃CO₂.?2?the effects of different concentrations of ionic liquids on physiological indexes of radish and wheat seedling:when the concentration of two ionic liquids increased from10mg/kg to 700mg/kg,the content of chlorophyll a and b decreased,while the content of proline and MDA increased;Under the ionic liquid treatment of 6 concentration gradients?10 mg/kg,50 mg/kg,100 mg/kg,200 mg/kg,400 mg/kg,700 mg/kg?,the activity of antioxidant enzyme SOD and POD in the two plant seedlings increased first and then decreased with the increase of concentration,indicating that the low concentration ionic liquid treatment could activate the oxidase activity,while the high concentration ionic liquid treatment had a inhibitory effect on the oxidase activity.And CAT showed an upward trend.?3?the effects of ionic liquids with different anions on physiological indexes of radish and wheat seedlings:the chlorophyll content of two plant seedlings treated by inorganic fluorine anion[bmim]PF₆ was less than that of organic fluorine anion[bmim]CF₃CO₂;the content of proline and MDA increased more;at the same time,The activities of SOD,POD and CAT of of inorganic fluorine anion[bmim]PF₆ were significantly higher than those of[bmim]CF₃CO₂,indicating that[bmim]PF₆ is more toxic than[bmim]CF₃CO₂.?4?The biodegradability of[bmim]PF₆ and[bmim]CF₃CO₂ in 28 days was investigated by activated sludge acclimation.The degradation rate was 90%and 92%after 10 days in the domestication period,and the maximum concentration of[bmim]CF₃CO₂ was 90mg/L and[bmim]PF₆ was 110mg/L.The toxicity of inorganic fluorinated anions is greater than that of organic fluorinated anions,but the degradation is opposite.The greater the toxicity,the easier it is to degrade.It is proved that the toxicity of ionic liquids has a certain effect on the degradability,and the acclimation activated sludge method is conducive to the degradation of ILs.