Indian Journal of Chemical Technology Vol. lO, July 2003, pp. 367-369

Articles

Chromatographic behaviour of metal ions on egg shell layers

Aditya K Misra

Department of Chemistry, NMSN Dass PO College, Budaun 243 601 , India

Received 26 September 2001; revised received 28 February 2003; accepted 3 April 2003

; : . 'lii� thin layer' chi&':llatogra�hy.'Of metal ion, has ' been' perform� in tweive solvent ' system' s on egg.sli�Il)Il.Y�rs. r'Je sfii��op:of Me�>an�,�'froin.T���, ,!?2+, Fe2\ Fe3+, UQ22+, �aS+ a�d}�b5+; Tl+, from Hg:+ �d ��2�; ,H�2�,!i,OW}:lg:. �av.e ,�elt.llchieyed oil. egg"Shell lay\!� , m dIStilled ,water, 0. 1 M calCIUm �trat� aJ)d 0) ¥ potaSSIUm thl�y�ate, resptX:tlvely. TIre .separation oi'i'egg sli¢lt:layers follow the ion exchange 'precipitation mechanism as evidenced by thtr'X-I'aY �alysis re-sur�:iirid::the solilbilitj -d�t8 of vanous,carbOriates.. ' ,. : ' ,

; ," " " . " , ' . ' ',, ' . ' " S; "

The synthetic inorganic ion exchangers and organic ion exchangers have been extensively used for the separation of metal ion in last three decades l.7. Mo­hammed et al. have used silica gel layers impregnated with metal salts8,IO for the difficult separations of in­organic ions. The complexing agents have also been used for the separation of toxic metals of forensic im­portancei l . 1 2 • Phenolic acids impregnated layers have also been utilised for the same purpose 13 . A reviewl4

and papers published recentlys.7.1 2 provide the infor­mation about the thin layer chromatographic analysis of metal ions during 1950 to 2000.

The egg shell layers have good separation potential for the separation of metal chlorosulphates IS , amines and phenol 16 and synthetic dyes 1 7• The separation of metal ions on egg shell layers is difficult due to the restriction that egg shell layers are unstable in acid medium and the solvents of acidic nature cannot be used in mobile phase.

This report is an attempt to use the egg shell layers as stationary phase in TLC for the separation of metal ions of importance in the field of environmental pol­lution and radio-active waste analysis. The separa­tions of Tl+ from Pb2+ and Hg2+ ; W6+ and M06+ from V02+, U022

+, Ti4+, Fe2+, Fe3+, Tas+ and Nbs+; and Hg2+

from Hg+ are of specific interest.

Experimental Procedure

Apparatus A Stahl apparatus with universal applicator

E-mail: akmisraI234@hotmail.com; Fax: 0581 -550091

(Toshniwal, India Inc.) was used to make thin layers of various thickness. X-ray studies were made on a Philips X-ray unit with a Philips camera.

Reagents

Chemicals and solvents used were of analytical grade (Romali, BOH, E. Merck, etc). The egg shells were collected from a natural source.

Test solutions and detection reagents

The test solution were generally 0. 1 M metal ni­trate or chloride and the ion were detected by the method described earlier6. Nitrate of Th4+, Ce4+, Be3+, Cd2+, C02+, Pb2+, Cu2+, Hg22

+, zr02+, Ag+ and Tt, hl 'd f H 2+ C 3+ A13+ F 3+ M 2+ P 4+ 5 2+ C on es 0 g , r , , e , n , t , n

and 5n4+, sulphates of Ne+, Zn2+, V02+, Fe2+, oxides of Nbs+ and Tas+, uranyl acetate, sodium molybdate, sodium tungstate and titanium oxalate were used.

Preparation of chicken egg shell powder

Broken pieces of egg shell were first washed with boiling water then distilled water and then soaked in 1 0% NaOH solution for 20-30 h to remove the protein content. The clean egg shell pieces were than washed several times with distilled water to ensure complete removal of NaOH, dried at 1 00°C, ground and sieved to furnish 250- 1 50 mesh powder. The resulting egg shell powder was used to prepare slurry for coating on to the TLC plates without addition of binder.

Preparation of TLC plates

The sorbent was mixed with demineralized water in 1 :3 ratio (w/w) with constant shaking to furnish a ho-

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mogenous slurry. The slurry was applied to 3.0x 1 5 cm glass plate as 0.25 m m layer by means of TLC applicator. The plates were dried at room temperature and then activated at 1 05±2°C by heating in an elec­trically controlled oven for 1 h. The activated plates were stored in a closed chamber at room temperature until used.

Solvent systems

The following mobile phases have been used for investigation:

(i) Distilled water (S I ), (ii) Lime water (S2), (iii) 0. 1 M Calcium chloride (S3), (iv) 0. 1 M Sodium chloride (S4), (v) 0. 1 M Potassium thiocyanate (S5), (vi) 0. 1 M Potassium iodide (S6), (vii) 0 . 1 M Potas­sium sulphate (S7), (viii) 0. 1 M Calcium nitrate (S8), (ix) H2S water (S9), (x) Formaldehyde (S 10), (xi) Acetone (S l l ) and (xii) Ethanol (S I2)

Results and Discussion

As a result of these studies the following separa­tions were achieved on egg shell layers M06+ and W6+ from Th4+, Ce4+, Be+, Pb2+, Cu2+, Hg/+, zr02+, Ag+, Cr3+, Fe3+, Mn2+, Sn2+, Sn4+, Zn2+, V02+, Fe2+, Pt4+, VO/+ and Ti4+ in distilled water, Pt4+, M06+ and W6+ from Th4+, Ce4+, Bi3+, Cd2+, Pb2+, Cu2+, zr02+, Ag+, Cr3+, Fe3+, Sn2+, Sn4+, V02+, Fe2+ and Ti4+ in lime water, 0. 1 M calcium chloride, 0. 1 M sodium chloride and formaldehyde; Hg2+ and Pt4+ from Th4+, Bi3+, Cd2+, Pb2+, Hg/+, zrO/+, Ag+, Cr3+, Fe3+, Mn2+, Sn2+, S 4+ Z 2+ VO 2+ Nb5+ T 5+ VO 2+ d T·4+ . n , n , 2 , , a , 2 an 1 III ace-tone and ethanol; Hg2+, Pt4+, M06+ and W6+ from Th4+, Ce4+ Pb2+ Cu2+ zrO 2+ Ag+ Cr3+ Fe3+ M 2+ Sn2+ , , , 2 , , , , n , , Sn4+, V02+, Fe2+, Ti4+ in 0. 1 M potassium sulphocya­nate, and 0. 1 M potassium iodide; Au3+, Mo6+, W6+ and Pt4+ from Th4+, Ce4+, B i3+, Cd2+, Pb2+, Cu2+, Z 02+ A + H 2+ C 3+ F 3+ d T·4+ . . r , g , g , r , e , an 1 III potasSIUm sulphate; Tt, W6+, Mo6+, VO/+ and Pt4+ from Th4+, Ce4+ Bi3+ Cu2+ Pb2+ Zr02+ Hg2+ Cr3+ Fe3+ Mn2+ , , , , , , , , , Sn2+, Sn4+, V02+, Fe2+ and Ti4+ in calcium nitrate. Some other interesting separations have been given in Table 1 . Metal ions do not move in kerosene oil on egg shell layers, hence the egg shell layer can be used for purifying the petroleum products. The TLC be­haviour of metal ions was independent of drying tem­perature (25-400°C) of the plates, but layers, show cracking above 200°C. Different thickness of the egg shell layers were studied for the TLC behaviour of metal ions, as the thickness of the layer increases the spot area of the metal ions decreases. The pair of ions

368

Indian J. Chern. Techno!., July 2003

for which the value of y i s greater than 1 can be sepa­rated where y = a/(b+0. 1 9) and a and b are the Rf val­ues of the faster and slower moving metal ions re­spectively. The above studies indicated that 0. 1 M calcium nitrate solution is best solvent system.

The X-ray analysis of egg shell powder shows similar pattern as that of aragonite and calcite. Egg shell powder treated with distilled water, cobalt ni­trate and nickel sulphate solutions separately, filtered, washed and dried at 100°C, on analysis shows no change in chemical structure, while on treatment with zinc sulphate, cadmium nitrate and copper sulphate solutions shows the presence of 2CaS04.H20, ZnC03, aragonite and calcite; CdC03 and aragonite; CU4(CaS04h.(OHk3H20, aragonite and 2CaS04.H20 phases respectively. Because calcium carbonate is a major component of egg shell layers as evidenced by its constitutionl 8, the studies were compared with the metal carbonates. The reported formula of the metal carbonates with their solubility product19 and Rf val­ues on egg shell layers have been given in Table 2.

Table I-Separation achieved on egg shell thin layers

S. No. Solvent Metal ion Separated from system

1 . S I Mo6+ Ti4+, V02+, Fe2+, Fe3+, UO/+, Ta5+ and Nb5+,

2. SI vI'+ Ti4+, V02+, Fe2+, Fe3+, U022+, Ta5+ and Nb5+

3. S5 Hg2+ Pb2+, TI+, Ag+, Zn2+ and Cd2+

4. S8 TI+ Hg2+ and Pb2+ 5. S9 Hg2+ TI+ and Hg/+

Table 2-Metal carbonates with their solubility productsl9 and

Metal carbonates

CaC03 CdC03 Hg2C03 PbC03 Ag2C03 MnC03 ZnC03 CuC03 NiC03 ThC03

Rf values on egg shell layers

Solubility product

8.0x 1 0-21 . 1

5.2x 10-1 1 . 1

9.0x l O-16. 1

1 .5x 1 0-12.8

8.2x lO-11 . 1

!WX IO-IO· 1

2.0x lO-9.7

2.5x lO-9.6

1 .4x lO-6·8

5.7x lO-8.o

Rfvalue

0.32

0.00

0.00

0.00

0.00

0.00

0.09

0.00

0.42

0.45

Misra: Chromatographic behaviour of metal ions on egg shell layers

It is evident from the solubility products data and X-ray analysis results that when a metal ion Mn+ in solution is brought in contact with solid calcium car­bonate Mn+ - Ca2+ exchange takes place followed by the precipitation of carbonate corresponding to the lower solubility product e.g. when calcium carbonate is treated with zinc sulphate or copper sulphate solu­tion, zinc or copper carbonate is precipitated along­with the calcium sulphate, similarly in the case of cadmium nitrate solution cadmium carbonate is pre­cipitated and water soluble calcium nitrate remains in solution. The carbonate of zinc, copper and cadmium have lower solubility product than calcium carbonate and the Rf values 9f zinc, cadmium and copper are zero. Hence, the process of separation of metal ions is governed by the ion exchange precipitation mecha­nism. On the basis of the above facts the metal ions which stayed at the point of application are exchanged and precipitated in the form of water insoluble car­bonates e.g. CdC03, PbC03, MnC03, Ag2C03, Hg2C03• Tl and Ni form soluble carbonates and basic carbonates of type MiOH)y'(C03h. where M=Ta5+, Hg2+, C02+, etc., show tailing due to exchange and precipitation. The metal ions forming the negatively charged species (MoO/-, wot, PtcIl, HgIt, Hg(SCN)t, etc) were not exchanged and precipitated in the form of carbonates, resulting in high Rf values. The solubility of thallium carbonate in water is greater than that of calcium carbonate, so it tails in water. Solubility product of calcium carbonate is fur­ther decreased by common ion effect in calcium ni­trate solution and TI+ gives compact spot of high Rf value and uol+ also behaves in the same way.

Acknowledgement

The author is thankful to State Council of Science and Technology, UP (UPCST), India for financial

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support and Prof. B .K. Puri, Department of Chemis­try, Indian Institute of Technology, New Delhi, India for necessary help for carrying out the studies.

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