Study On CCl₄Solubilities In Ionic Liquids And Its Catalytic Degradation In Aqueous Solution

As one kind of common organic solvent and important industrial material, carbontetrachloride (CCl4) is widely used in cleaning, paint, pharmaceutics, leather and otherindustrial fields. Due to stable chemical property and high biotoxicity, CCl4releasedinto natural environment through various ways, such as evaporation and leakage, canexist steadily for a long time and exert much demages on ecological environment.Moreover, CCl4with the features of higher volatility and lipid solubility could beabsorbed by the life body through skin and mucosa, resulting in irreversible biohazardto liver and other organs, and causing the seriously adverse effects on human health.Therefore, in recent decades the production and application of CCl4have beenrestricted in most countries. In order to reduce the hazards of CCl4on the livingenvironment of human beings, the degradation, conversion and replacement for theexisting CCl4should be an advisable and efficient path.This work mainly involves the following contents:1. Research on Dissolving Behaviour and Dissolving Thermodynamic of CCl4inIonic Liquids. In the temperature range of298.15~318.15K, the solubilities of CCl4in four ionic liquids:1-butyl-3-methyl imidazolium Bis (trifluoromethyl sulfonyl)imide ([Bmim][NTF2]),1-butyl-3-methyl imidazolium Dicyanamide([bmim][N(CN)2]),1-butyl-3-methyl imidazolium Hexafluorophosphate ([Bmim][PF6])and1-butyl-3-methyl imidazolium tetrafluoroborate ([Bmim][BF4]) were determinedat seven different temperatures. An empirical formula was proposed to accuratelycorrelate the solubilities with temperature for the first time. Based on thethermodynamic principle and method, the dissolution thermodynamic functionvariations, such as standard dissolution Gibbs free energy ΔGθs, standard dissolutionenthalpy ΔHθsand standard dissolution entropy ΔSθshave been exactly calculated, and the dirving force of ionic liquid dissolving CCl4have been calculated. Meanwhile，theeffects of temperature on the dissolving capacity of ionic liquids have also beeninvestigated. According to the polarity characterstics of the ionic liquids thedifferences of their dissolving capacity for CCl4have been theoretically analyzed.2. Ultrasonic-assisted Catalytic Degradation of CCl4by Zero-valent Iron Reduction.In allusion to four main influencing factors, e.g. reaction temperature, zero-valent irondosage, pH value and ultrasonic power, the orthogonal design method was employed toarrange the experiments, and the reduction degradation processes of CCl4under thecorresponding conditions have been carried out. Through the range analysis for theexperimental results, the primary and secondary relationship for the related factors andtheir optimization configuration have been judged and proposed. According to theas-obtained optimum conditions, the impact of such independent factors as reactiontemperature, zero-valent iron dosage, pH value and ultrasonic power on degradationresults of CCl4has been further investigated, and the related degradation mechanismhas been briefly discussed. In terms of chemical reaction kinetics, the rate constants ofCCl4degradation reaction under different reaction conditions were calculated and thereaction mechanism was briefly explained.3. Study on Advanced Oxidation Degradation of Aqueous CCl4by UltrasonicAssisted Fenton Process. According to Fenton advanced oxidation process and bymeans of ultrasound radiation, the oxidation degradation experiments of aqueous CCl4under different conditions such as ultrasonic power, reaction temperature, pH value,H2O2concentration and Fe2+concentration have been carried out. The interaction andchanging law for these parameters have been scientifically ayalysized, and the optimalconfiguration among these parameters has also been determined by means oforthogonal design. At the optimum conditions, the effect of reaction temperature, pHvalue and H2O2/Fe2+molar ratio on oxidation degradation of CCl4solution werefurther studied. Meanwhile, on consideration of the degradation experimental data, thefitting curve between lnc0/c and reaction time has made the degradation reaction rateconstant calculated. In line with the Arrhenius equation, the variation rule of reactionrate constant with the temperature has been definitely explained.4. Synthesis, Characterization and Photocatalytic Performance Evaluation ofγ-Bi2MoO6.Photocatalyst γ-Bi2MoO6was synthesized by hydrothermal treatment withthe assistance of surfactants, and the resulting products were characterized by x-raypowder diffraction. The photocatalytic activity of as-prepared γ-Bi2MoO6powders were evaluated by employing degradation of CCl4in solution as probe reaction.Through orthogonal experiment design, the detailed investigation of CCl4degradationprocess in solution under such conditions as visible light power, pH value, γ-Bi2MoO6dosage and exposure time has provided us the optimal configuration for these mainfactors. According to the optimum conditions, the influences of the single reactionfactor, e.g. reaction temperature, pH value and γ-Bi2MoO6dosage on CCl4degradationhave been independently carried out. In addition, as for special conditions of theultraviolet, visible light and no light, a comparative study has been made to analyzephotocatalytic degradation rule for CCl4in solution. Based on the principle of chemicalreaction kinetics, the change of reaction rate constant with different temperatures wasalso theoretically discussed.