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استخلاص ايونات العناصر الرصاص والكادميوم والزك والرينيوم بتقنية الغشاء السائل باستخدام المركبات الحلقية العيانية == Extraction of Lead, Cadmium, Zinc and Rhenium ions by Liquid Membrane Technique Using Macrocyclic Compounds
Author name:
يسرى عمران موسى
Supervisor name:
مؤيد كاصد جلهوم | جميل موسى ضباب
General topic:
Chemistry
Specific topic:
Chemistry
Degree:
Doctorate
University:
Mustansiriyah University - College Of Science
Language:
English
University location:
Baghdad
First pages:
25T1886 - p.pdf
Abstract:
Liquid - Liquid extraction of metal salts (MA) by Crown compounds(L) to less - polar diluents such as Chloroform,1,2 - dichloroethane and Carbon tetrachloride have previously been studied by considering an ion - pair formation between a complex metal ion ML+ and a pairing ion A - in water (W) and a distribution of the formed ion pairs MLA in the diluents. Liquid membrane transport is a new separation process as a modification of solvent extraction the simultaneous extraction and stripping operation is very attractive ,because the solute of interest can move from a high concentration solution to a low concentration solution with a suitable crown ether derivatives which have been widely used as suitable neutral carriers for the selective and efficient transportation of cations through liquid membranes.Liquid membranes have shown a great potential in this way especially in cases where metal concentration are relatively low and other techniques cannot be applied efficiently. Cation and anion transport by neutral macrocycles in liquid membranes is often diffusion limited extraction constants, permeability, flux coefficients and an aqueous phase macrocycle - cation and anion - cation interaction constants and membrane geometry are the parameters in the diffusion limited transport equation.The transport kinetic was analyzed by means of a kinetic model involving two consecutive irreversible first - order reactions. The rate constants of extraction stripping reactions and the transport rate fluxes of Pb2+, Cd2+, Zn2+ and ReO4 - through the bulk liquid membrane were determined for all experimental conditions studied.The present thesis reports the first application in Iraq ,by using macro cyclic compounds (crown ethers) as carrier in Liquid Membrane techniques as well as the matching size model of crown ethers with various ionic radius of metal ions, from evaluation of dibenzo 18 - Crown - 6, dicyclohexyl 18 - crown - 6 Kryptofix 2.2.2 and diaza 18 - crowwn - 6 as carrier molecule and study theXVIItransport behavior of Pb2+, Cd2+, Zn2+ and ReO4 - across (1,2 - dichloroethane, chloroform and carbon tetrachloride) as Bulk Liquid Membrane.In the present work transport experiments were performed across Bulk Liquid Membranes(BLMs) using U - Shape Setup from source phase which consist of 10 - 3M of metal ions dissolved in 10 mL of double distilled deionized water at pH=5.2 - 5.5 for Pb2+, Cd2+, Zn2+ metal cations and at pH= 6.2 - 6.5 for ReO4 - metal anion to receiving phase consist of 10ml of double distilled deionized water at pH= 3.2 - 3.7 across organic phase consisting 0.001M of dibenzo18 - crown - 6, dicyclohexyl 18 - crown - 6, Krypto fix2.2.2 and 1,10 - diaza 18 - crown - 6 were dissolve in 1,2 - dichloroethane, chloroform and carbon tetrachloride.The effects of operating conditions such as stirring speed, type of carrier, type of solvent, temperature and pH were studied. The results of permeability and flux coefficients show that the transport rate of metal ions can be enhanced by increasing stirring speed but not higher than l00 rpm using dicyclohexyl 18 - crwon - 6 as carrier due to the presence of donating group (cyclohexyl group) , It is well known that transition metal ions form stable complexes with ligands having N or S donors, which are hard bases ,but the affinities of crown ethers to soft transition metal ions are rather weak because crown ethers have hard O donors. In addition ,because of the large solvation energy of transition metal ions, crown ethers rarely form complexes with transition metal ions.1,2 - dichloro ethane is the best solvent due to its moderate polarity constant and the favorable temperature of the reaction is 30C 1 according to Arrhenius equation. There is no trend observed in the PH effect because the type of carriers is a neutral extract ant molecule which is less interaction than basic and acidic extractants with concentration of hydronium ion in solution. Also, the selectivity and efficiency of transport rate of metal ions matching with the values of its hydration
