COLUMN CHROMATOGRAPHY SMK Negeri 13 Bandung

R+OH- + X- === R+X- + OH- n R-H+ + Mn+ === (R)n-Mn+ + n H+

Objective  After this session the students are expected to be able to conduct the analysis of chemical substance using the ion exchanger resin.

ION EXCHANGER RESIN Definition: ion exchange from the same charge ions between the solution and the insoluble solid Definition: ion exchange from the same charge ions between the solution and the insoluble solid

Condition  The solid substance to exchange should have the same ion with the ion in solution  Molecular structure of solid has an opened structure and permeable (easy to be penetrated) so the solute is easy come and out. Exchanging process will be past and efficient

ION EXCHANGER RESIN  The solid substance is stationary phase and the solution is mobile phase.  Solid ion exchanger is made of polymer polystirene cross-linked with divinyl benzee. Polymer with cross- linking called resin. It has free phenyl group easy to react with ionic functional group (addition)  Resin used in analysis to separate inorganic ions (cation and anion)

Ptroperties of Ion Exchanger Resin 1.Insoluble in water but has an ability to absorbp water molecule in it structure. 2.Has a high molecular relative mass (High Mr). 3.Resistant to chemical substance (Acid, base, organic solvent) 4.When an ionic solution flow in to resin, it will release an ion and at the same time it will capture an ion of the solution. 5.Ion exchange carry out on the same type ion (cation with cation, anion with anion).

4 types of ion exchanger resin 1.Strong acid cation exchanger. The exchanger functional group is sulfonic acid. 2.Weak acid cation exchanger. The exchanger functional group is carboxilic acid. 3.Strong base anion exchanger. The exchanger functional group is quarterner ammonium ion. 4.Weak base anion exchanger. The exchanger functional group is anion group.

(Cation Exchanger Resin) AA column filled by acid / R-H to exchange cations in solution with H + ion in the resin. RR z – H + C +  R z – C + H + CC + could be : Na +, K +, Ca 2+, Mg 2+, etc.

Cation Exchanger Resin  In weak acid exchanging type, H is carboxilic acid that only partly ionized. The reaction is: nR z – CO 2 H + + M n+  (R z – CO 2 ) n M + nH +  In strong acid exchanging type, H is sulfonic acid group. It is strong acid like sulfuric acid. The reaction is. nR z – SO 3- + M n+  (R z – SO 3 ) n M + nH + (Cation Exchanger Resin)

(Anion Exchanger Resin) AA column filled by base / R- OH to exchange anions in solution with OH - ion in the resin. RR Z – OH + A -  R Z – A + OH - AA - could be : Cl -, SO 4 2-, NO 3 -, etc.

 In strong base anion exchanger, the reaction is :  n R z NR 3 + OH - + A n-  (R z NR 3 )­nA + n OH -

Ion Exchanger Selectivity  There are 2 factors influence the selectivity :  The exchanged ions properties  The ion exchanger properties.

Exchanged ions properties: AAt room temperature and low concentration, ion with higher charge will tightly held by resin. Ex : Al 3+ > Ca 2+ > Na + IIn the same condition for the same charge ion : ++1 ion Lower the size of ion, stronger the resin hold the ion. Ex : Li + < H + < Na + < NH 4+ < K + ++2 ion Resin absorption determinated by the ion size and dissosiation of salt. Ex : Cd 2+ < Ba 2+ < Mn 2+ < Mg 2+ = Zn 2+ < Cu 2+ < Co 2+

In strong base ion exchanger -1 anionhas the equivalent absorption selectivity with the +1 cation. ( Lower the size of ion, stronger the resin hold the ion) Ex : F - < HCO 3- < Cl - < HSO 3- < OH - < Br - < NO 3- < I - In dilute solution -X anion (X>1) absorbed stronger than the -1 anion.

WWhen the charge of cations to be exchanged is not same. Ion activity with the higher charge is higher when the concentration of higher charge ion is lower. Example : M +2 in solution and M +1 in resin will effectively exchanged at low concentration M +1 in solution and M +2 in resin will effectively exchanged at high concentration.

Ion exchanger properties QQQQuantitatively, afinity of ion exchanger resin to the exchanged ions terms as distribution coefficient (D):

Complexing agent CComplexing agent is anions like Cl -, Br - and I - which have ligand nature. The complexion is influenced by pH value. MMany metals could be separated in anion exchanger column after transformed to anion by complexing agent. MMetal separation in anion exchanger column carry out by addition of high concentration acid to transform metal ion to be complex anion. Example Concentrated HCL forms complex anion with most metal except alkali and earth alkali metal. Al(III), Ni(II), dan Cr(III) form complex anion with Cl -. Almost all complex anion of metal absorbed by quarternar ammonium resin.

Resin Regeneration AAmount of cation and anion to be exchanged by resin depends on the resin capacity. WWhen resin absorb amount of ion more than its capacity, resin is exhausted. It should be regenerated. RRegeneration of anion exchanger resin : Acid : HCl, H 2 SO 4. Reaction : Rz – C + H +  Rz – H + C + RRegeneration of cation exchanger resin : Base : NaOH. Reaction : Rz – A + OH -  Rz – OH + A -

Resin Column a. a.