استخراج پيوسته فلزات سنگين با استفاده از روش غشاء مايع امولسيوني

چكيده انگليسي :

85 Continuous Extraction of Heavy Metals Using Emulsion Liquid Membrane Technique Mohammad Ebrahim Soltani Me soltany@gmail com January 19 2013 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Keyghobad Shams k shams@cc iut ac ir Abstract Emulsion liquid membranes ELMs are means by which one can integrate extraction and stripping Integration of separation steps and high flux are the two major advantages of separation of chemical species using ELM technique In practice the combination of the extraction and stripping processes removes the equilibrium limitations and as a result the solute concentrations in the feed phase can be reduced to very low levels Therefore highly dilute feed solutions amenable for enrichment separation by ELM separation technique However ELM separation technique still suffers from two substantial problems a membrane breakage and b emulsion swelling These two drawbacks need to be addressed whenever this technique is utilized Emulsion liquid membranes have been successfully used in separation and enrichment processes because of high mass transfer flux of and no equilibrium limitation The high flux mass transfer in ELMs is attributed to high surface area of contact and enhanced mass transfer induced by chemical reaction One of the most important applications of this process is the extraction of heavy and precious metals In this study attempt has been made to experimentally investigate continuous extraction of heavy metals using emulsion liquid membrane from synthesized model media Comparison of the results obtained in both batch and continuous processes using ELMs has been the main objective of this research To perform extraction experiments using ELM technique in continuous mode a column like Oldshue Rushton extraction column was designed constructed and utilized Briefly the home made column was composed of eleven separate cells that could easily be assembled thus the total height of the column could be adjusted as needed by changing the number of cells Because of the large number of variables affecting this process the optimal values of variables were first determined results acquired using the batch process Then these values were used in the continuous experiments In this study the extraction of Chromium and Zirconium ions from the model media were investigated Span80 as the surfactant D2EHPA as the carrier light and heavy paraffin as the membrane HCl as the internal phase and model media solutions of Cr III and Zr IV ions in water as the external phase feed were used in performing the experiments Model compound media for both ions were prepared using chloride salts of the pertinent elements Optimal operating condition for extraction of chromium ions were obtained from literature and were used in the continuous ELM separation column The operating variables in the continuous ELM process for separation of Cr III ions include feed flow rate and its ratio to emulsion Results show that the Cr III extraction under optimal conditions were 99 in the continuous process compared to 95 in the batch process This indicates a 4 enhancement of the efficiency in continuous operation In addition the extraction from the feed external phase increases as the viscosity composition of heavy paraffin in the liquid membrane of the membrane phase increases however the emulsion swelling first decreases and then increases as viscosity concentration of heavy paraffin goes up In extraction of Zr ions from the external phase the influence of the variables such as agitation speed carrier concentration surfactant concentration the ratio of membrane to internal phase O W and extraction time were investigated and the optimal operating values of these process variables were determined The results show that the optimal values of the aforementioned variables were 400 rpm 1 V V 1 V V 2 and 6 minutes respectively Application of the ELM technique in batch and c

سلطاني، محمد ابراهيم

استخراج پيوسته فلزات سنگين با استفاده از روش غشاء مايع امولسيوني

كروم , زيركونيوم