Transportation cobalt (II) ion across multicomponent liquid membranes

 

Гаджиева Севиндж Рафиг кызы,

доктор химических наук, профессор, зав. кафедрой экологической химии,

Кулиева Егана Гияс кызы,

аспирантка кафедры экологической химии, зав. лабораторией общей и неорганической  химии,

Абдуллаева Элгуль Алиага кызы,

НИИ Геотехнологических проблем нефти, газа и химии.

Бакинский государственный университет.

 

It has been prepared multicomponent liquid membrane on the base of 6-methyl-dibenzo-18-Crown –6 (CW) for transportation of cobalt (II) in precence of  ion and  kations.

Liquid membrane experiments were performed with systematically varried liquid membrane compositions including 6-methyl-dibenzo-18-Crown-6 ether as carrier (I) and various ratios of ethylene chloride and a C₃₃ carbon a liphatic oil. The partitioning of macrocyclic ether samples toward the mambrane phase increased markedly with ethylene chloride addition to the aliphatic oil.

Theese experimental datas focus attention upon the important practical problems of non-infinite partitioning of carrier between the mambrane phase and the contiguous aqueous phase.

 

Introduction

 

The preparation of stable membranes depends upon a delicate balanc between the rheological properties of the oil and the stabilizing surfactant selected for formulation [1-4] suitable oil phases, which may dissolve adequate concentration.

It has been develople multicomponent liquid membrane on the base of Crown ether (CW) for transportation of cobalt (II) in precence of  ion of macroheterocycle, may undergo excessive partitioning of the carrier and carrier complexes toward the aqueous phase thereby markedly reducing the residual concentration of carrier in the relativly low volume “membrane” phase.

It is better to transfer heavy metal to anion complex form II and transport it using macrocyclic compound I.

(II)

It has been shown that in precence of  or  cations crown ether is formin carrier complexes III with  ion which is transported across multicomponent liquid membranes.

(III)

The results reported here are confined to liquid membrane experiments which define the effects of several compositional variables on the detailed properties characterizing the transport of anion coplex of cobalt (II) across multicomponent liquid menbranes.

 

Experimental methods

 

Reagent grade NH₄SCN, ethylene chloride were used as received. Other chemicals were obtained from the Merk Company. 6-methyl-dibenzo-18-Crown-6 ether (CW) was obtained From laboratory “Chemical Reagens and sensors” of State oil academy (Baku, Azebaijan).

Deionized water was obtained by passing tap water throgh water Purifier.

A 0,02 M Stock solution of  was prepared by mixing equimolar quantities of  and CoCl₂ in aqueous solutions.

The solvent oil was Kindly provided bythe research institut of additives (National Academy of Sciences, Baku, Azerbaijan). The oil is specially taylored for preparation of stable liquid membrane separation systems. It is characterized as a 33 carbon atom aliphatic oil containing approximately 9% by weight aromatics.

The density at 20°C is 0,8705.

 

Analytical methods

 

Cobalt concentration was determined by atomie absorption spectroscopy with a Perkin Elmer 603 spectrophotometer.

[Co(SCN)₄]^2- was determined by ultraviolet spectroscopy. The extinction coefficients determined by direct calibration in water containing [Co(SCN)₄]^2- solutions was 1,82´10⁴cm^-1m^-1 at 352 nm.

The extinction coefficient in ethylene chloride was determined to be 1,79´10⁴cm^-1m^-1 by determining the absorbance at 366 nm of macroheterocycle-containing ethylne chloride extracts from aqueous [Co(SCN)₄]^2- solutions. The concentration in ethylene chloride phase was determined by difference between the initial and final aqueous phase concentrations attending the extraction.

 

Results and discussion

 

The transport of [CoSCN]^2- ion from (NH₄)₂[Co(SCN)₄] solutions across 6-methyl-dibenzo-18-Crown-6 containing liquid membranes was studed as function of ethylene chloride and 6-methyl-dibenzo-18-Crown-6 concentrations in the oil. The [Co(SCN)₄]^2- counterion was selected since it has been reported that the transport of the [Co(SCN)₄]^2- -containing complex was very high [1].

Within a very conprehensive set of data describing the ffect of anion type on the transport of various kobalt coplexes across Crown ether containing liquid membranes an eighth order ov magnitude variation in transport rate has been reported by Lamb et al×[2] for the carrier-faciliated transport of metal ion through bulk liquid membranes containg dibenzo-18-Crown-6 ether.

The transport kinetics of [Co(SCN)₄]^2- anion are presented in the plots of figure 1, which describe the effect of Crown etheraddition to the oil phase of liquid membrane containing 12% percent (weight) ethylene chloride in the 33 carbon atom aliphatic oil.

In the absence of Crown compound, virtually no [Co(SCN)₄]^2- ion is transported. Bisides, in absence of  and  ions also no [Co(SCN)₄]^2- ion is transported. These results clearly demonstrates and explains the role of a Carrier (Crown ether I) and  and  ions in facilitating the transfer of anion complex of cobalt II across oil membranes. The other plots which describe the effect of Crown ether addition to the oil phase reveal that although a maximum of 5% of the amonia initially present upstream has been transported across the membrane, the ion transport is clearly unstable state, characterized

 

[Co(SCN)₄]^2- ´10^-3m (downsstrlam datas).

hours

Figure. The effect ox 6-methyl-dibenzo-18-Crown-6 concentratration in the liquid membrane on the kinetics describin the membrane transport of (NH₄)₂[Co(SCN)₄]

 

[C₂H₄Cl₂]= 12 wt%

o [cw]= 10 wt%

D [cw]=12 wt %

 [cw]= 2 wt%

g [cw] = 0.

 

by a continhously decreasing rate of transport even though the concentration transport should only drop by a maximum presence of 10 percent Crown ether I should be linear with a slope 5 times lager than the slope of the corresponding plot characterizing transport in the presence of 2weight percent Crown ether I.

This expectation is based upon the assumption that Crown ether I is mobile and rapidly complexed. With amonia –or potassium tetra rodanidekobalt at the feed ing membrane aqueous solution interference.

It is further implicitly assumed that partitioning of the Crown ether species between the oil and aqueous phase is essentially instantaneous and invariant with time or Crown concentration.

 

References

 

1.                   Hadjieva S.R., Kulieva E.Q., Abdullaeva E.A. Influence of nature macrocyclic ring on velocity of translation picrats alkali metals through liguid diaphragm [Ecology: problems of nature and society. International conference helding in memory centenary jubilee by member of the Academy Hasan Aliev] Baku, 2007, p. 505-506.

2.                   Hadjieva S.R., Kulieva E.Q., Abdullaeva E.A. Ion-translation method ail refiningfrom heavy metals. // Journal of chemical Problems № 2, 2007 p.288-291.

3.                   George R. Painter and Berton C.Pressman. Dinamic aspects of ionophore mediated membrane transport. Host Guest complex chemistry II// Akademie.-Verlag. Berlin 1982, p.83-108.

4.                   Morf W.E. Cation selectivity of neutral macrocyclic and nonmacrocyclic complexing agents in membrane in: Progr. macro macrocyclic chem., vol.1, John Wiley and sons, New York, 1979, p.1.

 

Поступила в редакцию 13.01.2010 г.