The Study On Degradation Of Ionic Liquids And Their Quantiative Structure-Property Relationship

Ionic liquids are receiving considerable attention because of their beneficial physico-chemical properties properties, such as extremely low vapor pressure. And they have broad applicability, especially in chemical reactions and separation processes. It was indicated that ILs are toxic to aquatic organisms and are difficult to biodegradable and may become persistent pollutants.In this paper, imidazolium-based ionic liquids were selected as test chemicals. Then examin the usefulness of Fenton process, Fe/C micro electrolysis process and electrolysis treatment for the degradation of ILs in water. The single factor test and orthogonal experiment show that the factors arranged in important order and the optimum reaction conditions. (1) The factors that choosed for Fenton process are:the hydrogen peroxide dosage, pH, the ratio of H2O2 and Fe2+ and the reaction time. The important order is as the follows:the ratio of H2O2 and Fe2+, pH, the reaction time. And the results also show such optimum values of parameters as 10 the ratio of H2O2 and Fe2+,3 of initial pH and 1.5h of reaction time. (2) The factors that choosed for Fe/C micro electrolysis process are:the iron concentration, the ratio of Fe and C, pH, the reaction time and the initial concentration of ILs. The important order is as the follows:the ratio of Fe and C, pH, the reaction time. And the results also show such optimum values of parameters as 0.5 the ratio of Fe and C,2.5 of initial pH and 1.5h of reaction time. (3) The factors that choosed for electrolysis treatment are:the voltage, pH and the reaction time. The important order is as the follows:the voltage, pH, the reaction time. And the results also show such optimum values of parameters as 50V of the voltage,10 of initial pH and 1.5h of reaction time. The results also show that the decomposing reaction of Fenton process accords with the zero order kinetics and the first order kinetics; the decomposing reaction of of Fe/C micro electrolysis process accords with the first order kinetics, the second order kinetics and the third order kinetics; the decomposing reaction of electrolysis treatment accords with the zero order kinetics.The structure of ILs also affects the removal efficiency. The influent of anions of ILs in three methods is as follow:PF6> BF4>DMP>C1. And the cations effect on the Fenton process is as follow: the longer of their R1 chains, the removal efficiency is lower. On the contrary, the effcect of cations on Fe/C micro electrolysis process and electrolysis treatment is as follow:the longer of their R1 chains, the removal efficiency is higher. Moreover, the model of quantitative structure-property relationship which can reflect the relations betweent 1gK caused by degradation of ILs and twelve kinds of moleeular structure parameters. And it can be predicted the degradation rate constant through this QSPR model.