| In recent years, as a technical means to improve the chemical processes and the environment processes, ultrasound has attracted widespread attention in improving adsorption and extraction process. This article based on the adsorption of azo dye Orange G on granular activated carbon, and the extraction of the polychlorinated biphenyls by ionic liquid in the headspace liquid phase microextraction, the influence of the factors including ultrasonic power, ultrasonic frequency and organic concentration impact on the adsorption, volatilization and absorption process has been studied. The main research content includes the following two aspects:1. Ultrasound improve the adsorption of azo dye orange G on granular activated carbon In this paper, the research object was the solution of orange G, compare the role of mechanical stirring, single-frequency ultrasound and dual-frequency ultrasound impact the adsorption rate and adsorption capacity of orange G on granular activated carbon. By the factors include the ultrasonic frequency, ultrasonic power and the initial concentration of the orange G solution, the effect of ultrasound enhance the adsorption of Orange G on granular activated carbon were explored. The adsorption isotherm and adsorption kinetics curves of orange G on activated carbon ware described under the conditions of different ultrasound system. Finally, the effects of ultrasound change the parameters of adsorption isotherm and adsorption kinetic has been studied.The experimental results were as follows. Under the experimental power, the degradation of Orange G under ultrasound was not obvious.When the ultrasonic power is300W, the decreases of ultrasonic frequency could promote the adsorption of Orange G on activated carbon, the removal rate obtain from40kHz ultrasound action for8hours was56.2%, and from28kHz ultrasound action was up to60.4%.When the initial concentration of orange G is27mg/L, within the experimental range of the ultrasonic power, the removal rate appear the phenomenon of after the first increase and then decrease with the increase of power. After the ultrasound action for8hours, in the ultrasound systems with the power of100W,200W,300W and400W, the corresponding removal rate were32.9%,34.7%,40.2%,39.2%. Ultrasound can alter the adsorption isotherm curve of Orange G on activated carbon. Compared with the Freundlich model, Langmuir isotherm adsorption model is more suitable for the adsorption of orange G on activated carbon. Through the adsorption kinetics curve, it can be seen the adsorption capacity of the activated carbon in different ultrasound systems were different. The value obtain from the orthogonal dual-frequency ultrasound(28kHz+40kHz) was lower than28kHz single-frequency ultrasound, but higher than40kHz single-frequency ultrasound. There are two possible reasons, one is the heating effect of ultrasound can reduce saturated adsorption amount, the other is the mechanical effect which increasing the specific surface area of activated carbon and produced by the ultrasound. It can be seen that the system with a low frequency about28kHz of ultrasound radiation and it also fixed at the bottom of device can create more mechanical action on the granular activated carbon and the surrounding solution. This make the specific surface area of activated carbon increased to a maximum, and the adsorption capacity also increased. Finally, three kinetic models, namely pseudo first-order, pseudo second-order and intraparticular diffusion were used to test the experimental data. And the results show that pseudo-second order kinetics model is more suitable for fitting the adsorption kinetics process of orange G on the activated carbon under the ultrasound.2. Ultrasound improve the extraction of Polychlorinated Biphenyls by ionic liquids in the headspace liquid phase microextraction technology.Ultrasound device was used to instead of stirring device, take ionic liquid [C4MIM][PF6] as the extractant, the headspace liquid phase microextraction technology was adopted to study the enhancement effect by ultrasound in extraction process of ionic liquid for polychlorinated biphenyls (PCBs). PCBs were analyzed and determined by gas chromatography-mass spectrometry instrument. The effect of measurement results in the different experimental conditions has been discussed in this article. A new analysis method of ultrasound improved ionic liquid-headspace liquid phase microextraction-gas chromatography-mass spectrometry was established based on the best experimental conditions. The main research content includes the following:The experimental conditions of USE-IL-HDLM-GC-MS method have been optimized. The results show that by improving the liner tube size, the optimal volume for ionic liquid is1μL. Under280℃maintained one minute, the desorption can be achieved completely. The absorption effect of PCBs on ionic liquid with ultrasound increased with the extension of time, and after28minutes can achieve extraction equilibrium. The absorption effect enhanced with the rise of the sample solution temperature, the optimum temperature is25℃. The absorption effect also will increase first and then reduced with the rising salt concentration, the optimal salt concentration is15g/L. The new USE-IL-HDLM-GC-MS method has been successfully applied to the samples of actual sea water in rapid determination and analysis of the five kinds of PCBs, the correlation coefficient was0.9994to0.9999. |
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