Synthesis, complexation and ion-exchange reactivity of polymethacrylohydroxamic acid

ELSEVIER

Reactive & Functional Polymers 31 (1996) 225-235

REACTIVE & FUNCTIONAL POLYMERS

Synthesis, complexation and ion-exchange reactivity of polymethacrylohydroxamic acid Y.K. Agrawal

*, K.V. Rao

Chemistry Department, School of Sciences, Gujarat University, Ahmedabad, 380 009, India

Received 4 January 1996; accepted 10 June 1996

Abstract Five new polymethactylohydroxamic acids have been reported for complexation with divalent metal ions and their plausible separations. The metal ligand stability constants (log p2) of divalent metal ions were determined in 70% dioxanwater media at 35 f O.l”C. The order of stability constant is discussed. Their physico-chemical properties have been determined. These acids are used as resins and parameters like rate of sorption, sodium ion uptake, total ion-exchange capacities, effect of pH on distribution coefficient, break through capacities etc. were determined. The chromatographic separations for binary, ternary, quatemary and quinary systems of metal ions (Cu, Zn, Ni, Co, Fe and Pb) have been described. The method is used for the determination of metal ions in synthetic and environmental samples. Keywords:

Polymethacrylohydroxamic

acid; Divalent metal ions; Separation

1. Introduction Advances in modern instrumentation have resulted in the development of several new simple, rapid, selective and sensitive techniques for the determination of ppm to sub-ppm quantities of the constituents. A number of methods for determining metals in the environmental and biological samples have been prescribed. However, because of the cost, sensitivity and the nature of the sample, the choice have to be narrowed down depending upon the existing facilities. Hence the organic reagents play an important role for the determination of metal ions. Hydroxamic acids because of their stability and strong complexing ability have been an imporCorresponding author.

??

tant tool in inorganic analysis [l-4]. The separation and atomic absorption spectrophotometric determination of few metals with polyacrylohydroxamic acids have been described earlier [5]. However, many analogous compounds can be synthesised by introducing various substituent groups, with the hope of developing reagents with superior analytical properties. It has been observed that the change in substitution in the hydroxamate moiety, alters the selectivity and sensitivity of the reagent towards the metal ions. The empirical approach, although sometimes inescapable, is generally wasteful and in particular with their metal complexes. The stability constants, distribution coefficient etc. which could be leading to a better understanding of causes of selectivity and sensitivity of relevant analytical reactions.

1381-5148/96/$15.00 Copyright 0 1996 Elsevier Science B.V. All rights reserved. PII Sl381-5148(96)00060-O

226

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& Functional Polymers 31 (1996) 225-235

With this in view the physico-chemical properties stability constants, distribution ratio, metal ion capacity etc. of the five new polymethacrylohydroxamic acids have been determined. The chromatographic separation and determinations of copper@), zinc@), nickel@), cobalt(II), iron(I1) and lead@) from their mixtures have been studied. 2. Experimental The details of materials needed and experimental technique have been described earlier [5]. 2.1. Metal ion solutions A 0.01-M solution of copper, zinc, nickel, cobalt, iron( and lead@) were prepared by dissolving requisite amount of sulphate or chlorides in 250 ml double-distilled water. Their concentrations were determined spectrophotometritally [6] and by AAS. 2.2. Methacryloylchloride Transferred 0.295 mol of methacrylic acid and 0.149 mol of phosphorous trichloride into a 50-ml pear-shaped flask, fitted with a reflux condenser. The contents were gently warmed to boiling, then the flask was kept at 60-70°C for 15 min and finally at room temperature for two hours. The mixture was separated into two layers, the lower layer was discarded. The upper layer was removed and after the addition of 0.5 g of cuprous chloride, was distilled under vacuum at room temperature bp 95-96°C [7]. Yield is 70%. 2.3. Poly(methacryloylchloride) In a lOO-ml B-24 round-bottom flask, fitted with B-24 condenser, were added 10 ml of methacryloylchloride, 27 ml of benzene and cyclohexane (1: 9 v/v) mixture and 0.3 g of azobisiso-butyronitrile. The contents were kept at 70“ for 12 hr. The solvent was decanted from the solid polymer and more completely removed under reduced pressure. The solid polymer thus obtained was dried over phosphorous pentoxide.

2.4. Polymethacrylohydroxamic acid In a 250-ml three-necked flask equipped with mechanical stirrer, were placed 12.09 g (0.12 mol) of freshly prepared and crystallized N-phenylhydroxylamine in 50 ml of diethyl ether, and aqueous suspension of 12.6 g (0.15 mol) sodium bicarbonate in 10 ml of water and 10 g of poly(methacryloylchloride). The contents were stirred for 2 hr and 30 min at room temperature. After completion of the reaction 150 ml of distilled water was added, the contents were stirred for 10 min. Almost the entire amount of polyhydroxamic acid was precipitated as a white solid. It was filtered, washed with water and dried. Acids were recrystallized from a mixture of dioxan and water or acetone and water and dried over phosphorous pentoxide under vacuum. 2.5. Procedure of the determination of ionization constants The titration procedure for determining pK,

has been essentially the same as recommended by Agrawal [8,9]. Generally the known amount of the acid in 70% dioxan-water mixture was titrated with 0.1 M tetrabutyl ammonium hydroxide at 35°C. In the thermostated (35 f 0. l°C) titration vessel, carrying a combined electrode and microburette, 0.5 g of polyhydroxamic acid in 50 ml of 70% (v/v) dioxan-water mixture were taken. Nitrogen gas, presaturated with thermostated solvent of 70% (v/v) dioxan-water, was passed through the solution and titration carried out after 15 min adding 0.2 ml aliquots of 0.1 M tetrabutyl ammonium hydroxide (prepared in 70% (v/v) dioxan-water) and noting the highest pH meter reading that did not drift. 2.6. HPLC A ChromSep Cis (250 x 4.6; L x id) was used at ambient temperature. The detector wavelength was set at 260 nm and the sensitivity at 4 mV full-scale deflection. The chart speed was

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& Functional Polymers 31 (1996) 225-235

1 cm rnin-‘. The mobile phase was a methanolammonium acetate (0.1%) (80 : 20) mixture used at a flow rate of 1 ml min-‘. Stock solution of polyhydroxamic acids were prepared by dissolving 50 mg of the compound in 100 ml of acetone. The standard solutions for calibration were prepared as needed [lo]. A 20.0~~1 aliquot of the sample solution was injected.

221

min-’ and eluted with the appropriate eluant at the optimum flow rate. The concentration of the metal ions were determined in the effluent by AAS or EDTA titrations [6]. 3. Results and discussion The synthesis and properties of polymetbacrylohydroxamic acids are given in Table 1. The physical properties viz. solid %, moisture density, swelling, volume capacity, concentration of ionogenic groups exchange capacity etc. have been summarised in Table 2. The moisture content is found 3.4 f 0.4% less than the polyacrylohydroxamic acids [5]. The dry and wet densities

2.7. Separation of metal ions The appropriate amount of the metal ions are mixed thoroughly and pH was adjusted with 25 ml of buffer solution. The mixture was passed through the column at the flow rate of 1 ml

Table 1 Infrared, pKa, HPLC and thermal analysis of N-arylpolymethacrylohydroxamic acids Compound no.

Polymethacrylohydroxamic acid

IR frequency (cm-‘)

HPLC

VOH

w=o

W-N

W-O

RT (min)

Purity (%)

I

N-Phenyl-

3600

1600

1390

935

1.150

99.38

II

N-p-Tolyl-

3350

1605

1390

910

1.092

99.00

III

N-m-Tolyl-

3340

1690

1390

930

1.138

99.93

IV

N-p-Cl-phenyl-

3340

1600

1395

930

1.197

99.98

V

N-m-Cl-phenyl-

3320

1600

1390

925

1.132

99.16

PK~

DTA (“C)

7” (“C)

wt. loss (%)

10.00 5.40 10.65 5.60 9.90 5.50 10.42 5.60 9.80 5.55

120 480 120 560 420 580 410 570 400 570

400 550 390 560 420 580 410 570 400 570

15 55 20 60 18 59 20 62 30 65

RT = retention time (min). Table 2 Physical properties of substituted polymethacrylohydroxamic acids Properties

(i) (ii) (iii) (iv)

(v) (vi) (vii) (viii) (ix) (x) (xi)

Crosslink (%) Solid (%) Moisture (%) True density (g cmm3) (a) Dry (b) Wet Apparent density Swelling Vol. capacity (m mol cm-‘) Concentration of ionogenic groups (m mol cm-‘) Void volume Sodium hydrogen capacity (m mol cm-‘) Cation-exchange capacity (m eq g-l)

Polymethacrylohydroxamic acid I

II

III

IV

V

5 83.0 0.31

5 81.0 1.4

5 76.0 1.1

5 74.0 1.7

5 73.0 0.97

1.4 1.3 0.28 1.8 5.8 1.53 0.83 4.0 5.9

1.1 1.0 0.30 0.8 5.1 1.42 0.80 3.80 9.0

1.1 1.0 0.22 2.5 6.0 1.55 0.78 3.75 6.6

1.5 1.4 0.21 1.4 6.3 1.60 0.75 3.68 3.6

1.5 1.4 0.20 1.0 6.4 1.62 0.75 3.67 5.6

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228 3600

r

3600 r

3200 2800

2000 I ,600

c

1200

c I 800

800

7I.I 400

2.0

4.0

1

I

6.0

4.0

PH

b),

,

6.0

6.0

PH

Fig. 1. Variation of Kd with pH for N-phenyl-substituted polymethacrylohydroxamic acid (compounds I-V). (a) Cu(I1). (b) Zn(II).

3200

-

3200

-

2600

-

2800

-

f

2400

-

2400

-

E

2000

-

2000

-

2 >

1600

-

1600

-

v Y

1200

-

1200

-

I

800400

-

(a)l 8.0

PH

2.0

4.0

6.0

6.0

PH

Fig. 2. Variation of Kd with pH for N-phenyl-substituted polymethacrylohydroxamic acid (compounds I-V). (a) Ni(I1). (b) Pb(I1).

are around 1.3 f 0.2 and 1.2 & 0.2 g cme3, respectively. The p-tolyl- and m-tolyl-substituted polymethacrylohydroxamic acids (compounds II and III) have lower densities compared to the other hydroxamic acids. The compound III (Nm-tolylpolymethacrylohydroxamic acid) has the maximum swelling tendency. The sodium ion uptake of the polymethacrylohydroxamic acids has been studied. The tip is around 10 f 5 for compound IV The compounds I and II have tip of 10 min and 11 min, respectively, while the compounds III-V have tip of 12, 14 and 15 min, respectively. The effect of pH on the distribution coefficient, &, of the polymethacrylohydroxamic acids for Cu(II), Zn(II), Ni(II), Co(I1)

and Fe@) is shown in Figs. l-3. The copper has the maximum & values with all the substituted acids, while Zinc(I1) and Nickel(I1) have nearly the same & values. Iron is having the lowest Kd values. These maximum values are in the range of 3520-3600 and show that all the metal ions have greater affinity to form the chelates with polymethacrylohydroxamic acids. The order of & values is: Cu(I1) > Zn(I1) > Ni(I1) > Co(I1) > Pb(I1) - Fe(I1). The pH for maximum sorption of the metal ions viz. copper, zinc, nickel, cobalt, iron and lead with the resins (compounds III-V) and corresponding capacities are given in Tables 3 and 4. The time (t) for the maximum sorption of the metal ions is in

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& Functional Polymers 31 (1996) 225-235

COBALT (II)

,

,

4.0

6.0

2400

-

1600

-

1200

-

800

-

400

(4

229

L

8.0

2.0

4.0

PH

6.0

6.0

PH

Fig. 3. Variation of Kd with pH for N-phenylpolymethacrylohydroxamic

acid (compounds I-V). (a) Co(I1). (b) Fe(H).

Table 3 Metal sorption properties of polymethacrylohydroxamic acids Polymethacrylohydroxamic acid, compound no.

I II III IV V

Zinc

Copper

Nickel

pHa

Capacity (m mol g-‘)

Timeb (mm)

pHa

Capacity (m mol g-‘)

Time b (min)

pHa

Capacity (m mol g-‘)

Time b (min)

4.0 4.0 4.0 4.0 4.0

1.51 1.36 1.20 1.06 1.12

2.3 2.4 2.6 2.8 2.8

4.5 4.5 4.5 4.5 4.5

1.44 1.30 1.14 0.97 1.04

2.5 2.5 2.5 3.0 3.0

4.0 4.0 4.0 4.0 4.0

1.22 1.20 1.oo 0.90 0.94

2.5 2.5 2.1 2.1 2.8

Time b (min)

pHa

Capacity (m mol g-l)

Time b (min)

3.0 3.0 3.0 3.0 3.0

3.5 3.5 3.5 3.5 3.5

0.97 1.03 0.88 0.78 0.82

2.0 2.2 2.5 2.5 2.5

BpH for maximum sorption. b Approximate time for maximum sorption min-’ . Table 4 Metal sorption properties of polymethacrylohydroxamic acids Polymethacrylohydroxamic acid, compound no.

I II III IV V

Iron

Cobalt

Lead

pHa

Capacity (m mol g-‘)

Time b (min)

pHa

Capacity (m mol g-‘)

5.0 5.0 5.2 5.2 5.2

1.Ol 1.05 0.90 0.85 0.88

2.5 2.4 2.5 2.5 2.5

4.5 4.5 4.5 4.5 4.5

1.26 1.22 1.10 0.96 0.98

a pH for maximum sorption. b Approximate time for maximum sorption

min-

’

the range of 2.0 to 3.0 min. The complete change takes place within 20-24 hr for all the resins. The time required (tip) for the sorption to reach 50% of its maximum value, which is the measure of the uptake of various metal ions, are given in Table 5. The tip values, less than 4 min, show that the sorption of the metal is very rapid.

3.1. Metal ligand stability constants It has been pointed out be several workers [ 1l171 that an approximately linear relationship exists between the logarithm of the stability constants of a series of metal complexes derived from one metal ion with a set of closely related ligands.

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& Functional Polymers 31 (1996) 225-235

Table 5 Polymethacrylohydroxamic acids: time (1112) for 50% of maximum sorption min-’ of metal Compound no. I II III IV V

17.0,

tip (min-‘) Copper

Zinc

Nickel

Cobalt

Iron

Lead

1.8 2.0 2.0 2.0 2.0

2.0 2.3 2.5 2.5 2.5

2.2 2.5 2.7 2.8 2.8

2.2 2.5 2.5 2.7 2.8

2.5 2.5 2.5 2.5 2.5

3.0 3.0 3.0 3.0 3.0

Hence it is expected that more basic ligand should form more stable complexes. A linear relationship between metal complexes of polymethacrylohydroxamic acids and their pKa values is obtained. The overall stability constants (log 82) of divalent metal ions are plotted against the pKa values of corresponding polymethacrylohydroxamic acids, exhibiting a straight line (Table 6, Fig. 4). It can be seen from the data given in Table 6 that the stability constants of Cu*+ are considerably large compared to the other metals. Under the influence of the ligand field Cu*+ (3d9) will receive stabilization [ 181 due to tetrahedral distortion of octahedral symmetry according to the Jahn-Teller effect. The relatively low value of Ni(I1) may be explained by steric hinderance preventing the formation of square-planar structure. Thus, in the present study, the order of stability is as follows: Cu(I1) > Zn(I1) > Ni(I1) > Co(I1) > Fe(I1). A similar order is found in case of N-arylhydroxamic acids and other ligands [ 19-2 11. The stability constants of the divalent metal ions with polymethacrylohydroxamic acids are

Table 6 Metal-ligand stability constants of polymethacrylohydroxamic acids with copper( zinc(H), nickel(II), cobalt(I1) and iron(I1) in 70% dioxan-water media at 35 f O.l”C Compound no.

pKa

I II III IV V

10.00 10.65 9.90 10.42 9.80

log 82 Cu(I1)

Zn(I1)

Ni(I1)

Co(I1)

Fe(I1)

15.18 16.29 15.30 15.85 14.65

13.20 14.18 12.75 13.95 12.50

12.80 14.00 12.52 13.52 12.30

11.70 12.95 11.43 12.50 11.20

10.20 11.73 10.25 11.10 10.15

m"

E?

phct Fig. 4. Variation of stability constants logp2 with pK, of polymethacrylohydroxamic acids (compounds I-V).

plotted against atomic numbers. Beyond iron the stability constant increases with increase in atomic number, reaching maximum for copper, and decrease is observed with zinc. The order is as follows: Fe(I1) < Co(I1) < Ni(II), Cu(I1) > Zn(II).. It has been shown by Born [22] that if the ions are assumed to be spherical, the energy of solution (i.e. of solvation) of gaseous ion should be expressed by the relation E = D (D is the dielectric constant of the solvent) and since log 82 is directly related to energy, it would be expected that the ratio of the square of the charge (e) to the radius (r) or charge/radius ratio should be directly proportional to the stability of metal chelates with the same ligand. The plot of stability constants (logb2) of Fe(II), Co@), Ni(II), Zn(I1) and Cu(I1) chelates of polymethacrylohydroxamic acids against 1/r is linear.

e*/r

3.2. Metal ion capacity A glass column (20 cm x 1 cm), was placed with the resin and was conditioned with appropri-

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& Funcrional Polymers 31 (1996) 225-235

ate buffer for 2 hr. The metal ion solutions were passed through the column at the flow rate of 0.5 ml min-’ after adjusting the pH. The effluent fractions were collected in IO-ml portions and were analysed for the concentration of the metal ion. The pH for maximum sorption of the metal ions, copper( zinc(II), nickel(II), cobalt(II), iron(I1) and lead(I1) with the polymethacrylohydroxamic acids (compounds I-V) and corresponding metal ion capacities are given in Tables 3 and 4. These data given in Tables 3 and 4 reveal that the polymethacrylohydroxamic acids show high affinity to form the chelates with divalent metal ions, pH 3.0-5.0. The Kd value varies from zero to a maximum of 3520 for copper, zinc, nickel, iron and lead for compounds I-V The complete exchange takes place within 24 hr. Copper(I1) has the maximum Kd value while lead(I1) has the minimum. The metal ions have the order of Kd values as: Cu(I1) > Zn(II) > Ni(I1) > Co(I1) > Fe(I1) - Pb(I1). The same order is observed in case of log ,&. It is evident that polymethacrylohydroxamic acids can be used for the selective separation of metal ions. 3.3. Kinetics of sorption The time required for the sorption to reach the 50% of its maximum value, which is a measure of uptake of various metal ions, is given in Table 5. The values are less than 5 min showing that the sorption of the metal ions is rapid. The favourable sorption kinetics make the resin useful for chromatographic separation of Cu(II), Zn(II), Ni(II), Co(II), Fe(I1) and Pb(I1) from their mixtures. 3.4. Breakthrough studies The breakthrough capacities are more significant for chromatographic applications of the resins, compared to the batch capacities. The breakthrough curves of a representative Nphenylpolymethacrylohydroxamic acids (compound I) for copper( zinc@), nickel(II),

231

80

60

i Effluent _-._

Volumr,

Pb _..-

---Fe

Ni

400

ml -C”

____-_Zn

Fig. 5. Breakthrough curves for Cu(II), Ni(II), Pb(I1) with N-phenylpolymethacrylohydroxamic pound I).

Zn(II), acid

Fe(II), (com-

cobalt(II), iron( lead(I1) at the pH of maximum sorption with the flow rate of 0.5 ml min-’ are given in Fig. 5. All the curves are steep at the breakthrough point. The metals Cu(II), Zn(II), Ni(II), Co(II), Fe(I1) and Pb(I1) reach their breakthrough point at different time indicating the possibility of separating these metals from their mixtures. 3.5. Effect of eluants The various eluants have been used for the elution of copper( zinc(II), nickel(II), cobalt(II), iron( lead(I1) from the polymethacrylohydroxamic acids (compounds I-V) loaded resins in columns. These studies were restricted to acids viz. HCl, HNOs, H$Od, CH3COOH and tartrate only, since it was observed that the electrolytes swell to a larger extent. The studies show that copper can be easily eluted quantitatively with HCl, HNOs, H2S04; however, the elution with CHsCOOH is only 2.5-10.5% (compounds I-V). Similarly, zinc and cobalt can also be eluted with HCl, HNOs and H2S04. Nickel is eluted with tartrate; however, all attempts have been failed to elute nickel with HCl, HNOs and H2S04. Lead

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& Functional Polymers 31 (1996) 225-235

umn utilization. The effluent history obtained for polymethacrylohydroxamic acids (compounds IV) in column operation for copper( zinc(II), nickel(n), cobalt@), iron(I1) and lead@) show that all the curves are of nonequilibrium nature. The values calculated for breakthrough capacity, column capacity and degree of column utilization are given in Tables 7 and 8. The degree of column utilization for copper is 0.50-0.55 for compounds I-V and the column capacity is 1.05-1.20. The column utilization, column capacity and breakthrough capacity follow the order Compounds II > III > I > IV > V. Similarly the data given in Tables 7 and 8 reveal that the degree of column utilization, the column capacity and breakthrough capacity follow almost the same order as: Compounds II > III > I > IV > V for all the metals studied here. The copper ion has the highest value of column utilization, column capacity and breakthrough capacity compared to zinc, nickel, cobalt and iron with all the polymethacrylohydroxamic acids. The order can be written as: Cu(II) > Zn(II) > Ni(I1) > Co@) > Fe@).

could not be eluted with H2S04. Iron is only eluted with 4 M HCl and the results are quantitative. It has also been observed that the elution with CHsCOOH is poor and hence can not be used for the separation of the metal ions. The metal ions can be separated from their mixtures by the proper adjustment of pH and judicious choice of the various concentrations of the eluants. Thus lead can be separated from copper, zinc, nickel and cobalt using H2SO4, as eluant of appropriate concentration to elute all the metals except lead, which is eluted with 0.5 M HNOs. Iron can be separated from copper, cobalt and zinc as later cations can be easily eluted with appropriate lower concentration of acids (HCl, HNOs and HzS04) at which iron remains loaded on the resins. The maximum elution (99.9%) of iron was obtained with 4 M HCl for compounds I-V Similarly the separation of other metal ions can be done. 3.6. Efluent history study In the present investigation, the resin column height was kept five cm and the maximum flow rate of 5 ml min-’ is maintained. The increase in the column height offered resistance to flow. The flow rate is the important parameter, which determines the degree of column utilization. The flow rate may increase the degree of column utilization, but it may suffer from the disadvantages that less volume of effluent will treat the column, which obviously leads to under utilization of column. The flow rate may lead to equilibrium history curves, thereby increasing the degree of col-

Table 8 Column capacity for polymethacrylohydroxamic acids Cation

Copper Zinc Nickel Cobalt Iron Lead

Polymethacrylohydroxamic acids, capacity (m mol g-‘) I

II

III

IV

V

1.10 0.95 0.90 0.85

1.20 1.00 0.95 0.90

1.12 0.92 0.95 0.90

1.08 0.90 0.89 0.80

1.05 0.90 0.85 0.81

0.82

0.90

0.92

0.75

0.75

0.78

0.89

0.85

0.70

0.72

Table 7 Breakthrough capacity for polymethacrylohydroxamic acids Cation

Copper Zinc Nickel Cobalt Iron Lead

Polymethacrylohydroxamic acids (m mol 8-l) I

II

III

IV

V

0.58

0.61

0.62

0.50

0.49

0.55 0.50 0.48 0.45 0.48

0.58 0.55 0.52 0.50 0.52

0.57 0.55 0.54 0.52 0.52

0.53 0.48 0.45 0.45 0.45

0.52 0.47 0.43 0.45 0.45

E K. Agrawal, K. V Rae/ Reactive & Functional Polymers 31 (1996) 225-235

(4

(c)

Cu + Ni + Pb , pH 4.0, Eluant 0.5 M H$O,

i

Ni+Pb Eluant OSM

ww Ernuent

Column

I

4 zn

1

CU

&SO,

I

Column

1

, ptl 4.0,

Zn + Ni + Pb Eluant 0.5M

EUlWflt

Emua

233

I Ni+Pb Eluant 0.5 M HNOS

cm) HNOQ Ernuent

I (

Column

1

Column

I

&

d Ni Eluant 1 M Tatite 1M

1 Ni Eluant 1 M Taltrpto

& Ni (AAS)

k Ni (AAS)

(b)

(4

Co+NI+Pb.pH 4.0. Eluant 0.5 M H$04 Ernlmnt

I I

I

& Ni+Pb Eluant 0.5M

VW Ernuent &

4.0. HN03

Ernud

Column

1 CO

Fa+Pb+Ni,pH Eluant 0.5M

I

Column

& HNQ Column I NI Elute 1 M Tartrate @AS)

Ni (AAS)

1 Fe+NI Eluant 4M HCI

z.8

I Ernuent 4

I

Cdumn

1 NI Elute 1 M _

Ni (MS)

Fig. 6. Separation scheme for ternary mixture of metals. (a) Separation of copper, nickel and lead. (b) Separation of cobalt, nickel and lead. (c) Separation of zinc, nickel and lead. (d) Separation of iron, lead and nickel.

Lead@) has lower value than iron( except the breakthrough capacity which is higher than iron with all the polymethacrylohydroxamic acids (compounds I-V). 3.7. Chromatographic

nickel; and cobalt, zinc, lead, iron and nickel) have been shown in the flow charts, Figs. 6-8. 3.8. Determination of divalent metals in standard and environmental samples

separation of metal ions

The studies on pH of sorption, batch capaci-

ties, breakthrough curves, column utilization capacity, degree of column utilization, eluant history curves, etc. reveal that the separation of copper@), zinc@), nickel@), cobalt@), iron and lead@) can be obtained. The separation of binary mixtures (cobalt and lead; zinc and lead; cobalt and iron; and zinc and iron), ternary mixtures (copper, nickel and lead; cobalt, nickel and lead; zinc, nickel and lead; and iron, lead and nickel), quaternary mixtures (copper, iron, lead and nickel; cobalt, lead, iron and nickel; and zinc, lead, iron and nickel) and quinary mixtures (cobalt, copper, lead, iron and

The present chromatographic method is applied for the separation and determination of copper, zinc, lead, nickel, iron and cobalt, in synthetic NBS standard samples and environmental samples (Nandesari industrial area of Baroda). Generally the known quantity (0.5 g) of alloy samples were digested with cont. HCl and cont. HNOs (20 : 1) and diluted to 100 ml with distilled water. An appropriate aliquot was transferred and its desired pH was adjusted with the appropriate buffer solution and passed through the column. The metal ions were eluted as described in the above flow chart (Figs. 6-8). When both copper and zinc are present together then both are eluted with 0.5 N HzS04 and separated by liquid-liquid

ZK. Agrawal, K.V Rae/Reactive & Functional Polymers 31 (1996) 225-235

234

Cu+Fe+PbNi.pH 40. Eluant 0.5M HZSO,

(4

I Ernuent

Column

I

1

J Fe + Pb + Ni Eluant 0.5M HNO3

Ernuent

Column

I

4

4

Fe + Ni Eluant 4 M HCI Column ERluent

I

i

i

Ni

Fe

Eluant 1 M Tartrate

VW

k Ni (AAS)

(W

Co+Pb+Fa+Ni.pH

40.

(d

Zn+Pb+Fa+Ni,pH 4.0. Eluant 0.5 M H2S04

Elliant 0.5 M HISO,

I I

Etnuent

I

Column J

k VW

1 Pb+Fe+Ni Eluant 0.5 M HNO,

1

Pb+Fe+Ni Eluant 0.5N HNOQ

CO

Column

Ernuent

&

I Efiluent

1

J

Column

Emh

&,

Column

I

J Fe+Ni Eluant 4M HCI

1

$ Fe + Ni Eluant 4M HCI

7As)

I

I Ernuant

Emuent

COhVl

1

L Fe+NI Eluant IM Tarbate

1

A

J

:-S,

Ni Eluant 1 M Tarbate

Cdumn

:;s,

4

J

Ni (AAS)

Ni (MS)

Fig. 7. Separation scheme for quaternary system of metals. (a) Separation of copper, iron, lead and nickel. (b) Separation of cobalt, lead, iron and nickel. (c) Separation of zinc, lead, iron and nickel. Table 9 Determination of metals in NBS standard and environmental samples NBS certified samples

37b brass 63b phosphor bronze 52b bronze, cast Iron-nickel alloy Nandesari b (Baroda) effluent samples

Metals a Zn (%)

cu (%)

Pb (%)

Ni (%)

Fe (%)

co (%)

Certif. value

Present method

Certif. value

Present method

Certif. value

Present method

Certif. value

Present method

Certif. value

Present method

76.33

76.95

27.09

27.00

0.90

0.84

0.45

0.42

0.21

0.25

77.94

77.54

0.71

0.76

9.36

9.30

0.33

0.36

0.47

0.45

88.25

88.10

2.96

3.01

0.011

0.02

0.72

0.69

0.32

0.35

9.00

9.21 0.58

90.00

89.50 6.00

1.50

a The values are the average of seven determinations. b Values are in ppm and confirmed by AAS.

0.39

4.8

Certif. value

Present method

0.60

0.62 0.33

IX. Agrawal, K.V Rae/Reactive

& Functional Polymers 31 (1996) 225-235 pH

Co + Zn + Pb + Fe + Ni

(4

Pass through the column

I I CO

I

Column

I

Emuant

I Cu+Pb+fe+Ni Eluani 0.5M H2S0,

(MS)

I CU

I I

Efh?nt

I

Emuent

Column I Pb+Fe+Ni Eluant 0.W

Effluent

I

I

I I

I Fe+Nl Eluant 4M HCI

I

Column

Effluent

I

I

I

Ni Eluant 1 M Tarbat,

I (MS) Fig. 8. Separation scheme for quinary zinc, lead, iron and nickel.

system of metals. (a) Separation

extraction and determined by AAS [6]. The effluent samples of industrial area of Nandesari Baroda were filtered through Whatman filter paper and analysed as per flow chart (Figs. 6-8). The results are shown in Table 9.

Acknowledgements The authors are grateful to C.S.I.R., Delhi, for the financial assistance.

New

References [I] A.K. [2] [3] [4] [5] [6]

Column

I

Fe+Ni Eluant 4M I-ICI Effluent

HNO,

I

Column

I

I

I

I Pb+Fe+Ni Eluant 05M HN03

WS)

Column I Zn+Pb+Fe+NI Eluant 0.5M &SO,

W)

Column

I

(

A

I Effluent

3 0

M

Co+Cu+Pb+Ni+ Fe + pti3.0. Pass through the column Effluent

235

Majumdar, N-Benzoylphenylhydroxylamine and its Analogues. Pergamon, London, 197 1. Y.K. Agrawal, Rev. Anal. Chem., 5 (1980) 3. F. Vernon and H. Eccles, Anal. Chim. Acta, 83 (1976) 187. I.P. Alimarin, F.P. Sudakov and B.G. Golovkin, Russ. Chem. Rev., 3 1 (1962) 466. Y.K. Agrawal and K.V. Rao, React. Poly., 25 (1995) 79. G.H. Jeffery, J. Bassett, J. Mendham and R.C. Denney, Vogel’s Textbook of Quantitative Chemical Analysis, 5th ed. ELBS, Longman, 1994.

I

Column

I Ni Eluant Tartrate

1M

(MS)

of cobalt, copper, lead, iron and nickel. (b) Separation

of cobalt,

[71 C.E. Rehberg, B.D. Marion and C.H. Fisher, J. Am. Sot., Chem. 67 (1945) 208. @I Y.K. Agrawal, Russ. Chem. Rev., 48 (1979) 948. [91 Y.K. Agrawal, Thermochim. Acta, 18 (1977) 250. [lOI C. Gertz, HPLC Tips and Tricks. Alden Press, Oxford, 1990. 1111 H. Irving and H. Rossotti, Acat. Chem. Stand., 10 (1956) 72. [I21 E. Nieborer and W.A.E. McBryde, Cand. J. Chem., 51 (1973) 2511. [I31 M. Irving and M.S. Rossotti, J. Chem. Sot., (1954) 2904. [I41 W.D. Johnston and H. Freiser, J. Am. Chem. Sot., 74 (1952) 5239. [I51 L.G. Van Uitert, W.C. Fernelius and B.E. Douglas, J. Am. Chem. Sot., 75 (1975) 2376. [I61 H.F. Steger and A. Corsini, J. Inorg. Nucl. Chem., 35 (1973) 1637. 1171 E. Barsson, 2. Phys. Chem., Al69 (1934) 215. 1181 K.S. Menon and Y.K. Agrawal, Trans. Metal Chem., 8 (1983) 292. 1191 Y.K. Agrawal and S.G. Tandon, J. Inorg. Nucl. Chem., 34 (1972) 1291; 36 (1974) 869. PO1 Y.K. Agrawal, Montash Chem., 108 (1977) 7 13. Pll W.D. Johnston and H. Freiser, Anal. Chem. Acta, 11, 301 (1954). [22] M. Born, Z. Physik, 1 (1920) 45.