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Precipitation of nickel salicylaldoximate from homogeneous solution
Talanta. 1967, Vol. 14, pp. 299 KJ 304.
Pergamon Press Ltd.
Printed in Northern Mlmd
PRECIPITATION OF NICKEL SALICYLALDOXIMATE FROM HOMOGENEOUS SOLUTION B. S. KRISHNA RAO and 0. E. HILEMAN, JR. Department of Chemistry, McMaster University, Hamilton, Ontario, Cauada (Received 27 .TIue 1966. Accepted 19 August 1966) Summary-me reaction between hydroxylamine and salicylaldehyde in the presence of nickel ions has been made the basis of the precipitationofnickelsalicylaldoximatefrom homogeneoussolution. Conditions for quantitative precipitation of uicke1 when present alone or with such metal ions as FelL+,C?+, Al’+, Zns+, Mu- and Cd’+ are described. The recommeuded procedure is shown to be useful iu the analysis of a steel sample.
advantages of precipitation from homogeneous solution (PFHS) over the conventional precipitation techniques have been recognized and demonstrated with great success in recent years. Methods have been suggested for the preparation, in sit@, of such reagents as dimethyl~yo~me,l 8-hydroxyq~no~ne,2 cupferron,8 8hydroxyquinaldine~ and othersp thus modifying the well-established gravimetric procedures for the analysis of several metals. The compact crystalline precipitates formed by PFHS are generally purer and easier to handle analytically. Salicylaldoxime was tirst reported by Ephrain9 as a reagent for the detection and de~~na~on of copper and nickel. Since then the use of this reagent has been extended to the detection or determination of iron, zinc, bismuth, copper, cadmium, and lead.7*s However, only copper has received much attention, and procedures have been worked out for its determination either by direct weighing of the copper salicylaldoximate9 or by extraction of the chelate into n-amyl acetate and measurement of the absorbance of the solution.1° An indirect method, reported by Flagg and Furmann,* is based on the d~omposition of the chelate by excess of iron(II1) in hydroc~o~c acid and titration of the resultant iron(I1). Only one study on the determination of nickel with salicylaldoxime has been reported. g Vogel” has suggested that a few metals such as silver, lead and mercury do not interfere in the determination of nickel, but that there is marked interference by iron, cobalt and copper. Pietrzak and Gordon12 have shown that copper salicylaldoximate can be precipitated from homogeneous solution, and that the chelate thus obtained is easy to filter off. Surprisingly, however, the determination of copper by this method was found to be less satisfactory than the conventional procedure. The present study was undertaken to examine the precipitation of nickel salicylaldoximate by PFHS and to use the procedure for the determination of nickel in a steel sample. THE
EXPERIMENTAL Regents Metal ion solutions. Solutions of appropriate amounts of metal salts were made in distilled water, filtered and diluted. The nickel solution was standardized by precipitation of nickel dimethylglyoximate by the procedure of Sale& and Gordon.’ 299
B. S. KRISHNA RAO and 0. E. HUMAN, JR.
300
Salicylakfehdye. About 4-O g of the reagent were stirred into 1 1. of distilled water. Complete dissolution was ensured by stirring for about 6 hr. The solution was stable for at least 48 hr. All other chemicals were reagent grade. The pH measurements were made with a Radiometer pH meter, and a filtered ammonia solution (1 + 2) was used for pH adjustments. Procedure Place an aliouot of solution, containine 2-75 me of nickel. in a 400-ml beaker. add ammonium chloride (l-2 g).and an I-fold excess of a Kydroxyl&ine hydrochloride solution. Adjust the pH to W-6.8 with the ammonia solution. Add a few ml of the salicylaldehyde solution and wait until a turbid&v annears. Then add enough sa~~vl~dehvde solution to make the total aldehvde concentration 3-15 timesi’he stoichiometric req&eme& Let
The results obtained by use of these procedures are shown in Figs. 1 and 2, and Tables I-IV. For comparison, a few determinations were carried out by Riley’s
IOOL
s
s
z = 0 x li
YY-
98-
97-
96
-
i
I 55
I
60
I
6-5
I
I
75
70
I
6.0
I a5
I
90
PH FIG. 1.-Effect
of pH on precipitation of nickel salicylaldoximate. A-standing time 12 hr. O-standing time 4-6 hr;
Precipitation of nickel salicylaldoximate from homogeneous solution
I
I 4
I
I
I
Reagent
I
I
16
12
8
20
X.-CO~~PAFUS~N
METHODS
OF
m
OF PRECIPRATUW
Nickel taken, mg
~~.--&RCTZ
32
of nickel ~Iicyl~do~te.
CONVENTIONAL NICKEL
PFHS
AND
SALICYLALDOXIMATE
Error in amount found, mg PFHS Conventional
2.12
TABLE
I
26
(X-fold1
FIG. Z.-Effect of excess of reagent on pr~pi~tion
TABLE
I
24
-0% -0.06 -0.07
-0~01 -0.02 -0.01
10*62
-t@O5 +0.06 40.08 +O-08
-0.01 fO+lO -0.01 -0.03
21.24
f0.08 +@08 -to*10
-0.01 -0.02 *0+lO
OF SoME
DIVBRSE
301
IONS ON
THE PRECD’lTATION
OF NICK3L
SALIC~~~~
Foreign ion
Amount taken, ZZorin amount of nickel found, mg
Tartrate (NH,)
Mn
2000
50
-0*02 -0,Ol +O*Oi
-o*oz -0.03 fOG0
zn
Al
Co
100
100
20
-O*Ol fOQ0 +0*02
-0.02 +0*01 -0.01
t-3.0
Cr 50 _tO*Ol -0.02 -0.02
CU 50
10
+5-o
1.0
The amount of nickel taken was 10.62 mg, and 2.0 g of ammonium tartrate were added.
302
B. S. KRISHNA ICI0 and 0. E. HILRMAN, JR. TABLEIIL-THE
EPFECTOFIRONONTHEPRECIPITAnONOFNICKELSALICY~~TE
reagent added, x-fold
Tartaric acid added, g
Error in weight of nickel found, W
Iron found in precipitate,* mg
15 20
3.0 2.5
20 20 20 24 25 25 25
3.0 3.5 4.0 3.0 2.5 3.5 6.0
-0.12 to.01 +0.06t -0.06 -0.06 -0.09 -0.05 to.10 -0.06 -0.20
0.08 0.05 0.01 000 o+N3 0.06 0.10 0.02 0.00
Excessof
om
* Determined calorimetrically by the thiocyanate method. t A reaction time of 18 hr was allowed. For all other determinations the period was 15 hr. The amount of nickel taken was 9.92 mg, and about 100 mg of iron(II1) were added. A 200to 300-fold excess of hydroxylamine hydrochloride was used. TABLE IV.-DEIXRMINATION
OF NICKEL IN A STEEL SAMPLE
Aliquot taken, ml
Nickel found, %
25.0
11.06 11.05 11.08
0.00 O*OO 0.02
50.0
11.06 11.12 11.18 11.19 11.12 10+0* 11.89t
0.00 004 0.06 0.06 0.02 0.08 0.65
* Conventional t Conventional
procedure, procedure,
Iron in precipitate, W
NBS Certificate value for nickel present, % 11.14
time of standing, 6 hr. time of standing, 16 hr.
method.s He suggested that an excess of reagent should be added and the solution stirred to coagulate the precipitate. In the present work a two-fold excess of the reagent was added to the metal solution at pH 64-6-5. The solution was stirred and then allowed to stand for 3 hr before filtration. The results are presented in Table I. The behaviour of iron in this system deserves special mention. Citric acid, EDTA and tartaric acid were tried as masking reagents. Tartaric acid was found to be suitable, but citric acid and EDTA prevented the precipitation of nickel salicylaldoximate. However, with the procedure outlined above, the amounts of tartaric acid and hydroxylamine hydrochloride must be kept within certain limits to give quantitative precipitation of nickel. Amounts of tartaric acid below a minimum value gave positive errors and impure precipitates. Large amounts of tartaric acid gave pure precipitates but low recoveries of nickel. Large excesses of hydroxylamine hydrochloride were required for quantitative recovery. Some of the results of these experiments are collected in Table III.
Precipitation of nickel salicylaldoximate from homogeneous solution
303
Analysis of a steel sample for nickel About 1-Og of the steel (NBS No. 121b) was dissolved in the usual way and diluted to 500.0 ml. Aliquots (25 or 50 ml) were transferred into 400-ml beakers. Tartaric acid (3.0-3.5 g), hydroxylamine hydrochloride (2.5 or 5.0 g, according to the aliquot) and ammonium chloride (2-O g) were added to each and the pH was adjusted (6+6.5) with dilute ammonia solution. Enough aqueous solution of salicylaldehyde to give a 20- to 25-fold excess was then added. The mixture was set aside for 14-16 hr before filtration. Some results obtained by this procedure are shown in Table IV. DISCUSSION
This study has shown the expected superiority in the quality of the precipitates obtained by the PFHS method and has established a set of experimental conditions under which the recovery of nickel is quantitative. The procedure suggested, however, failed to achieve a successful separation of nickel from copper. (Copper salicylaldoximate is known to be precipitated in varying amounts from solutions over a wide range of PH.) Cobalt also seriously interferes, but this was not investigated in detail. The precipitation of zinc and cadmium was found to begin at pH 6.5. When nickel was precipitated at pH 6.0-6.3 there was no co-precipitation of these elements. In the presence of tartaric acid zinc did not co-precipitate even at pH 7.0. Hence the use of tartaric acid was recommended. However, when cadmium was present, tartaric acid could not be used because the cadmium tartrate complex is sparingly soluble. In the procedure of Salesin and Gordon for the determination of nickel, the generating reaction was found to be extremely slow (24 hr standing time required) in the presence of iron. In the present case it was found that large excesses of iron and tartaric acid also retarded the precipitation of nickel. However, it was shown that a proper combination of the amounts of tartaric acid and hydroxylamine hydrochloride did produce a successful separation of nickel from large amounts of iron, within a reasonable reaction time. Acknowledgemen&-The authors acknowledge the partial assistance of the National Research Council of Canada in supporting this investigation. Zusanuneufassung-Die Reaktion zwischen Hydroxylamin und Salicylaldehyd in Gegenwart von Nickelionen wurde zur FWmg von Nickelsalicylaldoximat aus homogener Lasung verwendet. Die Arbeitsbedingungen xur quantitativen F&hung von Nickel allein oder neben Metallionen wie Fe*+, Cu’+, Al*+, ZtP+, Mn*+ und Cd*+ werden beschrieben. Die empfohlene Vorschrift erweist sich bei der Analyse einer Stahlprobe ah niitzlich. R&run&-La reaction entre l’hydroxylamine et el salicylaldehyde en presence d’ions nickel a Cte prise comme base pour la precipitation du salicylaldoximate de nickel il partir dune solution homog&ne. On d&it les conditions de precipitation quantitative du nickel seul ou en presence d’ions tels que Fe’+, Cr*+, Al*+, ZIP+, Mn*+ et Cd*+. On montre que la technique recommand6e est utile pour l’analyse d’tm 6chantillon d’acier.
304
1. 2. 3. 4. 3. 6. 7. 8. 9. 10. 11. 12. 13.
B. S. KRISHNARAO and 0. E. HUMAN, JR. REFERENCES E. D. Salesin and L. Gordon, Tuhta, 1960,5,81. K. Takivama and L. Gordon. ibid.. 1960,5,231. A. Hes and N. Dave, ibid., i960,%, 119. _ E. J. Billo, B. E. Robertson and R. P. Graham, ibid., 1963,10,757. F. H. Firs&@ in C. N. Reilley and F. W. McL&erty, Advances in Analytical Chemistry Instrumentation, Vol. 4. p. 1. Interscience, New York, 1964. F. Ephraim, Ber., 1930,63,1928. J. F. Flagg and N. H. Furmann, Znd. Erg. Chem. Anal. Ed., 1940,12,663. I&m, ibid., 1940,12,738. H. L. Riley, J. Chem. Sot., 1933, 895. S. H. Simonsen and H. M. Burnett, Anal. Chem., 1955,27,1336. A. Vogel, Text-Book of Quantitative Analysis, 3rd. Ed., p. 526 Longmans, London, 1962. R. F. Pietrzak and L. Gordon, Tulanta, 1962,8,327. D.A. Skoog, M-G. Lai and A. Furst, AnaL Chem., 1958,30,365.
Pergamon Press Ltd.
Printed in Northern Mlmd
PRECIPITATION OF NICKEL SALICYLALDOXIMATE FROM HOMOGENEOUS SOLUTION B. S. KRISHNA RAO and 0. E. HILEMAN, JR. Department of Chemistry, McMaster University, Hamilton, Ontario, Cauada (Received 27 .TIue 1966. Accepted 19 August 1966) Summary-me reaction between hydroxylamine and salicylaldehyde in the presence of nickel ions has been made the basis of the precipitationofnickelsalicylaldoximatefrom homogeneoussolution. Conditions for quantitative precipitation of uicke1 when present alone or with such metal ions as FelL+,C?+, Al’+, Zns+, Mu- and Cd’+ are described. The recommeuded procedure is shown to be useful iu the analysis of a steel sample.
advantages of precipitation from homogeneous solution (PFHS) over the conventional precipitation techniques have been recognized and demonstrated with great success in recent years. Methods have been suggested for the preparation, in sit@, of such reagents as dimethyl~yo~me,l 8-hydroxyq~no~ne,2 cupferron,8 8hydroxyquinaldine~ and othersp thus modifying the well-established gravimetric procedures for the analysis of several metals. The compact crystalline precipitates formed by PFHS are generally purer and easier to handle analytically. Salicylaldoxime was tirst reported by Ephrain9 as a reagent for the detection and de~~na~on of copper and nickel. Since then the use of this reagent has been extended to the detection or determination of iron, zinc, bismuth, copper, cadmium, and lead.7*s However, only copper has received much attention, and procedures have been worked out for its determination either by direct weighing of the copper salicylaldoximate9 or by extraction of the chelate into n-amyl acetate and measurement of the absorbance of the solution.1° An indirect method, reported by Flagg and Furmann,* is based on the d~omposition of the chelate by excess of iron(II1) in hydroc~o~c acid and titration of the resultant iron(I1). Only one study on the determination of nickel with salicylaldoxime has been reported. g Vogel” has suggested that a few metals such as silver, lead and mercury do not interfere in the determination of nickel, but that there is marked interference by iron, cobalt and copper. Pietrzak and Gordon12 have shown that copper salicylaldoximate can be precipitated from homogeneous solution, and that the chelate thus obtained is easy to filter off. Surprisingly, however, the determination of copper by this method was found to be less satisfactory than the conventional procedure. The present study was undertaken to examine the precipitation of nickel salicylaldoximate by PFHS and to use the procedure for the determination of nickel in a steel sample. THE
EXPERIMENTAL Regents Metal ion solutions. Solutions of appropriate amounts of metal salts were made in distilled water, filtered and diluted. The nickel solution was standardized by precipitation of nickel dimethylglyoximate by the procedure of Sale& and Gordon.’ 299
B. S. KRISHNA RAO and 0. E. HUMAN, JR.
300
Salicylakfehdye. About 4-O g of the reagent were stirred into 1 1. of distilled water. Complete dissolution was ensured by stirring for about 6 hr. The solution was stable for at least 48 hr. All other chemicals were reagent grade. The pH measurements were made with a Radiometer pH meter, and a filtered ammonia solution (1 + 2) was used for pH adjustments. Procedure Place an aliouot of solution, containine 2-75 me of nickel. in a 400-ml beaker. add ammonium chloride (l-2 g).and an I-fold excess of a Kydroxyl&ine hydrochloride solution. Adjust the pH to W-6.8 with the ammonia solution. Add a few ml of the salicylaldehyde solution and wait until a turbid&v annears. Then add enough sa~~vl~dehvde solution to make the total aldehvde concentration 3-15 timesi’he stoichiometric req&eme& Let
The results obtained by use of these procedures are shown in Figs. 1 and 2, and Tables I-IV. For comparison, a few determinations were carried out by Riley’s
IOOL
s
s
z = 0 x li
YY-
98-
97-
96
-
i
I 55
I
60
I
6-5
I
I
75
70
I
6.0
I a5
I
90
PH FIG. 1.-Effect
of pH on precipitation of nickel salicylaldoximate. A-standing time 12 hr. O-standing time 4-6 hr;
Precipitation of nickel salicylaldoximate from homogeneous solution
I
I 4
I
I
I
Reagent
I
I
16
12
8
20
X.-CO~~PAFUS~N
METHODS
OF
m
OF PRECIPRATUW
Nickel taken, mg
~~.--&RCTZ
32
of nickel ~Iicyl~do~te.
CONVENTIONAL NICKEL
PFHS
AND
SALICYLALDOXIMATE
Error in amount found, mg PFHS Conventional
2.12
TABLE
I
26
(X-fold1
FIG. Z.-Effect of excess of reagent on pr~pi~tion
TABLE
I
24
-0% -0.06 -0.07
-0~01 -0.02 -0.01
10*62
-t@O5 +0.06 40.08 +O-08
-0.01 fO+lO -0.01 -0.03
21.24
f0.08 +@08 -to*10
-0.01 -0.02 *0+lO
OF SoME
DIVBRSE
301
IONS ON
THE PRECD’lTATION
OF NICK3L
SALIC~~~~
Foreign ion
Amount taken, ZZorin amount of nickel found, mg
Tartrate (NH,)
Mn
2000
50
-0*02 -0,Ol +O*Oi
-o*oz -0.03 fOG0
zn
Al
Co
100
100
20
-O*Ol fOQ0 +0*02
-0.02 +0*01 -0.01
t-3.0
Cr 50 _tO*Ol -0.02 -0.02
CU 50
10
+5-o
1.0
The amount of nickel taken was 10.62 mg, and 2.0 g of ammonium tartrate were added.
302
B. S. KRISHNA ICI0 and 0. E. HILRMAN, JR. TABLEIIL-THE
EPFECTOFIRONONTHEPRECIPITAnONOFNICKELSALICY~~TE
reagent added, x-fold
Tartaric acid added, g
Error in weight of nickel found, W
Iron found in precipitate,* mg
15 20
3.0 2.5
20 20 20 24 25 25 25
3.0 3.5 4.0 3.0 2.5 3.5 6.0
-0.12 to.01 +0.06t -0.06 -0.06 -0.09 -0.05 to.10 -0.06 -0.20
0.08 0.05 0.01 000 o+N3 0.06 0.10 0.02 0.00
Excessof
om
* Determined calorimetrically by the thiocyanate method. t A reaction time of 18 hr was allowed. For all other determinations the period was 15 hr. The amount of nickel taken was 9.92 mg, and about 100 mg of iron(II1) were added. A 200to 300-fold excess of hydroxylamine hydrochloride was used. TABLE IV.-DEIXRMINATION
OF NICKEL IN A STEEL SAMPLE
Aliquot taken, ml
Nickel found, %
25.0
11.06 11.05 11.08
0.00 O*OO 0.02
50.0
11.06 11.12 11.18 11.19 11.12 10+0* 11.89t
0.00 004 0.06 0.06 0.02 0.08 0.65
* Conventional t Conventional
procedure, procedure,
Iron in precipitate, W
NBS Certificate value for nickel present, % 11.14
time of standing, 6 hr. time of standing, 16 hr.
method.s He suggested that an excess of reagent should be added and the solution stirred to coagulate the precipitate. In the present work a two-fold excess of the reagent was added to the metal solution at pH 64-6-5. The solution was stirred and then allowed to stand for 3 hr before filtration. The results are presented in Table I. The behaviour of iron in this system deserves special mention. Citric acid, EDTA and tartaric acid were tried as masking reagents. Tartaric acid was found to be suitable, but citric acid and EDTA prevented the precipitation of nickel salicylaldoximate. However, with the procedure outlined above, the amounts of tartaric acid and hydroxylamine hydrochloride must be kept within certain limits to give quantitative precipitation of nickel. Amounts of tartaric acid below a minimum value gave positive errors and impure precipitates. Large amounts of tartaric acid gave pure precipitates but low recoveries of nickel. Large excesses of hydroxylamine hydrochloride were required for quantitative recovery. Some of the results of these experiments are collected in Table III.
Precipitation of nickel salicylaldoximate from homogeneous solution
303
Analysis of a steel sample for nickel About 1-Og of the steel (NBS No. 121b) was dissolved in the usual way and diluted to 500.0 ml. Aliquots (25 or 50 ml) were transferred into 400-ml beakers. Tartaric acid (3.0-3.5 g), hydroxylamine hydrochloride (2.5 or 5.0 g, according to the aliquot) and ammonium chloride (2-O g) were added to each and the pH was adjusted (6+6.5) with dilute ammonia solution. Enough aqueous solution of salicylaldehyde to give a 20- to 25-fold excess was then added. The mixture was set aside for 14-16 hr before filtration. Some results obtained by this procedure are shown in Table IV. DISCUSSION
This study has shown the expected superiority in the quality of the precipitates obtained by the PFHS method and has established a set of experimental conditions under which the recovery of nickel is quantitative. The procedure suggested, however, failed to achieve a successful separation of nickel from copper. (Copper salicylaldoximate is known to be precipitated in varying amounts from solutions over a wide range of PH.) Cobalt also seriously interferes, but this was not investigated in detail. The precipitation of zinc and cadmium was found to begin at pH 6.5. When nickel was precipitated at pH 6.0-6.3 there was no co-precipitation of these elements. In the presence of tartaric acid zinc did not co-precipitate even at pH 7.0. Hence the use of tartaric acid was recommended. However, when cadmium was present, tartaric acid could not be used because the cadmium tartrate complex is sparingly soluble. In the procedure of Salesin and Gordon for the determination of nickel, the generating reaction was found to be extremely slow (24 hr standing time required) in the presence of iron. In the present case it was found that large excesses of iron and tartaric acid also retarded the precipitation of nickel. However, it was shown that a proper combination of the amounts of tartaric acid and hydroxylamine hydrochloride did produce a successful separation of nickel from large amounts of iron, within a reasonable reaction time. Acknowledgemen&-The authors acknowledge the partial assistance of the National Research Council of Canada in supporting this investigation. Zusanuneufassung-Die Reaktion zwischen Hydroxylamin und Salicylaldehyd in Gegenwart von Nickelionen wurde zur FWmg von Nickelsalicylaldoximat aus homogener Lasung verwendet. Die Arbeitsbedingungen xur quantitativen F&hung von Nickel allein oder neben Metallionen wie Fe*+, Cu’+, Al*+, ZtP+, Mn*+ und Cd*+ werden beschrieben. Die empfohlene Vorschrift erweist sich bei der Analyse einer Stahlprobe ah niitzlich. R&run&-La reaction entre l’hydroxylamine et el salicylaldehyde en presence d’ions nickel a Cte prise comme base pour la precipitation du salicylaldoximate de nickel il partir dune solution homog&ne. On d&it les conditions de precipitation quantitative du nickel seul ou en presence d’ions tels que Fe’+, Cr*+, Al*+, ZIP+, Mn*+ et Cd*+. On montre que la technique recommand6e est utile pour l’analyse d’tm 6chantillon d’acier.
304
1. 2. 3. 4. 3. 6. 7. 8. 9. 10. 11. 12. 13.
B. S. KRISHNARAO and 0. E. HUMAN, JR. REFERENCES E. D. Salesin and L. Gordon, Tuhta, 1960,5,81. K. Takivama and L. Gordon. ibid.. 1960,5,231. A. Hes and N. Dave, ibid., i960,%, 119. _ E. J. Billo, B. E. Robertson and R. P. Graham, ibid., 1963,10,757. F. H. Firs&@ in C. N. Reilley and F. W. McL&erty, Advances in Analytical Chemistry Instrumentation, Vol. 4. p. 1. Interscience, New York, 1964. F. Ephraim, Ber., 1930,63,1928. J. F. Flagg and N. H. Furmann, Znd. Erg. Chem. Anal. Ed., 1940,12,663. I&m, ibid., 1940,12,738. H. L. Riley, J. Chem. Sot., 1933, 895. S. H. Simonsen and H. M. Burnett, Anal. Chem., 1955,27,1336. A. Vogel, Text-Book of Quantitative Analysis, 3rd. Ed., p. 526 Longmans, London, 1962. R. F. Pietrzak and L. Gordon, Tulanta, 1962,8,327. D.A. Skoog, M-G. Lai and A. Furst, AnaL Chem., 1958,30,365.