What is it about?
In this present work, the effect of different anions such as Cl-, NO3-, SO4 - -, CH3COO-, SCN- and ClO3- on separation of cadmium and zinc by supported liquid membrane using TOPS-99 as mobile carrier was studied. Celgard 2400, a micro-porous poly- propylene film was used as the solid support for the liquid membrane. It was observed that, in the presence NaCl, NaNO3, Na2SO4, CH3COONa, NaSCN and NaClO3 salt solutions in feed, decreases the zinc flux JZn from 9 x 10-6 where as cadmium flux Jcd remain constant at 0.125x 10-6. In presence of NaCl, NaNO3 anions the highest flux for JZn 8 .4 x 10-6,5.066 x 10-6 obtained at 500 mol/m3 solution respectively , where as in presence of CH3COONa,SCN , NaClO3 anions the highest flux for JZn 6.587 x 10-6 , 6 x 10-6 and 3 x 10-6 at 100 mol/m3 of solution in feed Solution respectively. But in presence of Na2SO4 anions the highest flux for JZn 4.307 x 10-6 obtained at 50 mol/m3 of added salt solution in feed solution .At pH 2.25 the co-permeation of cadmium with zinc was negligible, so highest separation factor was obtained at this pH. The maximum separation factors were obtained in the absence of anions i.e. 41.842 but in presence of NaCl, NaNO3, Na2SO¬4, CH3COONa, NaClO3 and SCN salt solution the highest separation factors are 39.047 , 23.556 , 20.021, 27.89 13.940 and 30.619, respectively.
Why is it important?
Effect of different anions such as Cl-, NO3- ,ClO3- , SCN- and CH3COO- in feed solution, on separation of cadmium and zinc were studied by supported liquid membrane technique using TOPS-99 as mobile carrier. Following conclusions may be drawn from the above studies. (a) In presence of 10 mol/m3 of added mono valent strong electrolyte anions such as Cl-, NO3- ,ClO3- , SCN- and CH3COO- in feed solution, the zinc flux (JZn) decreases from 9 x 10-6 to 4 x 10-6, 4 x10-6 , 2 x 10-6 ,5.6363 x 10-6 and 1.667 x 10-6 mol/m2.s. respectively. In presence of di-valent strong electrolyte anion i.e. SO4 – - the zinc flux decreased from 9 x 10-6 to 4 x 10-6 mol/m2.s., which provides better evidence of existence of long range columbic force of interaction in that limit. (c) As the concentration of added electrolyte increases from 10mols/m3 to100 mols/m3 the flux JZn increases to 6.587 x 10-6,6 x 10-6, and 3 x 10-6 mol/m2.s highest separation factors obtained in presence of these salts are 30.619, 27.89 and 13.940 for SCN- CH3COO- and ,ClO3- respectively. (d) Similarly concentration of added electrolyte increases from 10mols/m3 to500 mols/m3 the flux JZn increases to 8.4 x 10-6 and 5.066 x 10-6 ,which gives the highest separation factor 39.047 and 23.556 in presence of NaCl and Na NO3 respectively. (e) In presence of divalent anion SO4 - - the highest separation factor 13.6201 , the flux JZn obtained at 50 mol/m3 . (f) The flux values which obtained at 1000 mol/m3 for all anionic system is follows order SO4- - > ClO3- > NO3-> CH3COO->SCN->Cl- ,which follows the neuleophilicity order of anions or legands towards formation of the transition activated metal-anion complex [Zn(anion)4]2- at the feed solution-membrane interface which is the cause of decreases flux values. (g) The fluxes for cadmium JCd remains constant in entire system studied.
The following have contributed to this page: Dr Basudev Swain