| The ionic liquids refers to a salt substance which is composed entirely of ions and which is liquid in the vicinity of room temperature or room temperature,and is also referred to as room temperature ionic liquids or room temperature molten salt.The ions that make up the ionic liquid are generally organic cations and inorganic or organic anions.Since the different types of ionic liquids can be designed and synthesized according to the actual needs,the ionic liquids is called "adjustable liquids".Due to the particularity of the ionic liquids structure,the ionic liquids has the special properties of difference with the general substance,such as low melting point,good solubility,stable chemical properties,easy to burn and strong conductivity,ionic liquids are considered to be a "green solvent".Ionic liquids gradually replace the traditional organic solvents,organic synthesis,separation and extraction,material development and electrochemistry and other fields,have shown a very broad application prospects.With the industrial applications of ionic liquids more and more widely,there will inevitably be the risk of loss to the natural environment.Although ionic liquids are considered environmentally friendly,there is a certain risk to ecosystems due to the good water solubility and poor degradation of ionic liquids.In this study,three typical imidazolium nitrate ionic liquids?[C4mim]NO3,[C6mim]NO3,[C8mim]NO3?with different carbon chain lengths were selected,and brown soil was used as the tested soil,Using electrode method,ammonium acetate exchange method,fumigation extraction-K2Cr2O7 capacity analysis,fumigation extraction-ninhydrin colorimetric method.The changes of soil pH,conductivity,cation exchange capacity,microbial biomass carbon and microbial biomass nitrogen were studied at 10,20,30 and 40 days after exposure to ionic liquids.The main findings are as follows:?1?The results showed that the pH value of the soil decreased with the increase of the concentration of the ionic liquid,and the dose-effect relationship existed with the increase of the ionic liquid concentration.High concentration?100mg/kg?treatment group decreased significantly,low concentration?10mg/kg,1mg/kg?treatment was not significant.The soil is related to the self-regulation of acid-base.?2?The ionic conductivity of the ionized liquid showed an increasing trend,and there was a dose-effect relationship with the concentration of the ionic liquid.?100mg/kg?treatment group was significantly higher than that of the control group.The effect of ionic liquid on the conductivity of soil was not correlated with the ionic liquid structure during the whole experimental period.?3?There was no significant difference in the amount of cation exchange between the experimental ionic liquids [C4mim]NO3,[C6mim]NO3 and [C8mim]NO3 treated groups compared with the control group,and the effect was not significant during the whole experimental period.?4?[C4mim]NO3 dampen but not significantly in the soil biomass carbon previous experiments,high concentrations?10mg/kg,100mg/kg?produced significant inhibition,low concentrations?1mg/kg?treatment group in the experiment in the late In the 30 days of the experiment,the recovery was inhibited and the recovery was lost at the end of the experiment.[C6mim]NO3 and [C8mim]NO3 treatment groups showed significant inhibitory effect and showed dose-effect relationship.?5?The soil biomass nitrogen of [C4mim]NO3 and [C6mim]NO3 treated groups showed a tendency of inhibition-recovery-inhibition during the experimental period.?10mg/kg?and high concentration?100mg/kg?showed a decrease in the inhibitory effect in the treatment group [C8mim]NO3 treatment group at 30 days.The inhibitory effect of ionic liquid on biomass nitrogen is [C8mim]NO3>[C6mim]NO3>[C4mim]NO3,which is enhanced with the increase of carbon chain length. |
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