استخراج اورانيوم، هافنيوم ، زيركونيوم و كادميوم از پسماند صنعتي ﴿ضايعات جامد و پساب﴾ با استفاده از دي اكسيد كربن فوق بحراني

چكيده انگليسي :

Extraction of Uranium Hafnium Zirconium and Cadmium from Industrial Waste Solid and Liquid Matrix Using Supercritical Carbon Dioxide Kamran Ansari Kamran @yahoo com June Department of Chemical Engineering Isfahan University of Technology Isfahan Iran Degree Ph D language Farsi S M Ghoreshi ghoreshi@cc iut ac ir Abstract Extraction of toxic heavy metals such as uranium hafnium zirconium and cadmium from synthesis waste water waste and solid matrix was studied Supercritical fluid SCF extraction of toxic heavy metals has been the subject of many studies The high diffusivity low viscosity high solubility and no surface tension are the specifications which make supercritical fluid extraction the most attractive and suitable technology over the conventional extraction methods Several fluids such as carbon dioxide ethane ethylene propane propylene chlorotrifluoro methane trifluoromethane Fluoroform can be used as supercritical fluid The choice of the SCF solvent is similar to the traditional extraction solvents Principle considerations for choosing the SCF are good solvation property inert to the product easy separation from the solute inexpensive low critical point CP conditions because of economic reasons Among different extraction parameters C MPa being inexpensive nontoxic nonflammable readily available and methods the supercritical fluid extraction using carbon dioxide was chosen With respect to these specifications carbon dioxide is the most commonly used solvent as SCF due primarily to its low critical recycling capability Supercritical fluid inherits the best specifications of liquid and gas phases for example the diffusivity of gases and solubility of liquids So supercritical fluid extraction is expected to have higher efficiency with respect to liquid solvents which are all toxic and carcinogenic Carbon dioxide is a nonpolar gas The solubility of polar toxic heavy metals in supercritical carbon dioxide is low In order to increase the solubility of polar species in SC CO the polarity of supercritical fluid must be increased via utilization of co solvents such as methanol ethanol and propanol Without chelating agent metal ions cannot be removed by supercritical fluid Maybe they can be extracted but the efficiency is so low Metal ions can be extracted by supercritical carbon dioxide treated by proper chelating agent Among the chelating agents organophosphorus reagents such as cyanex are suitable chelating agents for a group of metal ions including uranium in different media So cyanex was chosen as the proper agent in this study Two synthetic waste sample were prepared and the effects of some parameters such as temperature pressure static and dynamic time amount of modifier amount of chelating agent variety of modifier variety of chelating agent and flow rate of supercritical fluid were investigated in this study The liquid sample was consists of uranium hafnium and zirconium and the solid waste is consists of cadmium in addition to the three other species in liquid sample In order to decrease the numbers of examinations use the design of experiment Finally the effects of parameter interaction between parameters on the extraction efficiency of species were evaluated and the optimum operating condition was obtained Among the different experimental design methods RSM was chosen in this study to determine the effects of temperature pressure static and dynamic time on the extraction efficiency of each species on liquid sample and the effects of temperature pressure dynamic time variety of modifier and chelating agent on the extraction efficiency of each species PDF created with pdfFactory trial version www pdffactory com

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استخراج اورانيوم، هافنيوم ، زيركونيوم و كادميوم از پسماند صنعتي ﴿ضايعات جامد و پساب﴾ با استفاده از دي اكسيد كربن فوق بحراني

استخراج فوق بحراني , فلزات سمي سنگين , طراحي آزمايش , روش سطح پاسخ