حذف الكتروشيميايي هريك از يونهاي كادميم، نيكل و نقره از محلولهاي آبي رقيق با استفاده از الكترود بستر جهنده

چكيده انگليسي :

Electrochemical Removal of Cadmium Nickel and Silver Ions from Dilute Aqueous Solutions by Application of a Spouted Bed Electrode Elaheh Baghban e baghban@ce iut ac ir Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree PhD Language FarsiSupervisor s Name and Email address Professor Arjomand Mehrabani Zeinabad arjomand@cc iut ac irAbstractThe electrochemical removal of metal ions from dilute aqueous solutions was investigated in this study byuse of a spouted bed electrode To design and construct the cell the effective hydrodynamic characteristics ofthe cell including inlet nozzle diameter and central duct height weight and position were optimized byresponse surface methodology The performance of the relevant cell was investigated for cadmium ionremoval from 1 L of a solution with the initial concentration of 180 ppm cadmium ion in 0 5 M sodiumsulfate with the initial pH of 4 4 by applying the electrical current density of 9 5 A m 2 The effects ofoperational parameters consisting cadmium ion initial concentration electrolyte concentration appliedelectrical current density and catholyte initial pH were also investigated by monitoring of cadmium ionconcentration instantaneous current efficiency and the pHs of the catholyte and anolyte solutions with time It was observed that the effect of catholyte initial pH and electrolyte concentration on the process isnegligible Applied electrical current must be optimized according to initial concentration of cadmium ion A theoretical model was developed for the electrochemical removal of metal ion over the three dimensionalelectrode surfaces which was validated by the experimental data The most unique characteristic of thismodel is consideration of the simultaneous effects of mass transfer charge transfer and electrochemicalreaction on the process It was then generalized and validated for multi stage electrolysis for the first time The effect of enlargement of the cathode surface area on improvement of cadmium ion removal process inthe spouted bed cell was studied Enlargement of cathode surface area from 1000 to 1500 cm 2 resulted in adecrease of nearly 30 in both of the process time and the specific energy consumption The multi stageelectrolysis process was also investigated to increase the cadmium ion final removal efficiency and todecrease the specific energy consumption Application of a three stage electrolysis process for a solutioncontaining 270 ppm of cadmium ion resulted in the removal of 99 9 cadmium ion in 135 minutes with thespecific energy consumption of 2 29 kWh kg 23 less than the value of a single stage process For asolution with 180 ppm of cadmium ion 99 9 of cadmium ion was removed with the specific energyconsumption of 2 82 i e 30 less than that of a single stage process Finally the electrochemical removal of nickel and silver ions in the spouted bed reactor were investigated tostudy the validation of the developed model for these metal ions The adjusted theoretical model was alsoconfirmed for electrochemical removal of nickel and silver ions It was necessary to increase the appliedelectrical current density from 5 8 to 14 4 A m2 by increasing nickel ion initial concentration from 56 to 179ppm Upon application of the process for silver ion recovery from a solution containing 150 ppm silver ion itwas observed that 99 9 of silver ion was recovered in 65 minutes with the specific energy consumption of1 79 kWh kg and the average current efficiency of 26 4 by applying the electrical current density of 9 5A m2 In order to decrease the specific energy consumption in this process the oxygen evolution reaction inthe anodic compartment was replaced by the anodic reaction of copper dissolution for the first time Thisresulted in a decrease of nearly 26 in the cell voltage and specific energy consumption of the process It was observed that the efficient electrochemical removal of metal ions from dilute aqueous solutions isachieved using t

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حذف الكتروشيميايي هريك از يونهاي كادميم، نيكل و نقره از محلولهاي آبي رقيق با استفاده از الكترود بستر جهنده

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