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T-
COPY AD-A221 135AD
NEHOAANDUH REPOAT ARCCB.MN.gOO I O
DETERMINATION OF SOD'UM CYAN/,DE IN COPPER
AND CADMIUM CYANIDE PLATING SOLUTIOA'S
BY PRECIPITATION.FORMATION TITRATION
SAMUEL SOPOK
,IARCH '990
US TRilY ARIilIiIETT RESEARCII,
DETEIOPiIEIIT AIIII EII EI II EERI 1I C C EIITERCLOSE COMBAS ABUAUENTS CENTEB
BENÉT TABOBáIOBIE§wt[EnvLIET, N.Y. 12189-{060
APPROVED tOR PUBLIC RELEASE; DISIRIBUIIOX UNIIMITED
DTIC
§,ff0
I 05 o" 04lf
II
OISCIAIMER
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stcñeponr oocutlENTATloN rlGE
ARCCB-¡a-900I0 ;=ñ; REFoRT ¡ PERloo covEtÉoa. flf LE (rd Su¡tlt¡')
DETERMINAÍION OF SODIIJM CYA¡{IDE TN COPPER
AND CADMIIJ}'! CYA}¡IDE PIATING SOLUTIONS BY
PRECIP ITATION-FORMATION TTTRATION¡ErG ,ffiñé.nEPonr truraen
A!,lCt,lS No. 6126. 23. 1BL0.OAP'PRON No. I¡.O2ZRAENI'LSC
iññEIx¿rttox xa¡E
U.S. A¡rnY A3DEC
Benet laloratories, SMCAR-CCB-TL
wateti\rliet, NY 12189-405 12. REPORf OATE
March l99Offi^Ho^oonEssU.S. Arff,Y ARDEC
Close Conbat Armaments Center
UNCLA.SSIFIED
Approved for public release' olst'ribution unlÍtrriEed'
20' tl dttl'?at laa
@oc¡nGD")
Che¡nical AnalYsisSodiLún CYanideCopper Cyanide
Plating SolutionsCad¡nium CYanide PlatinqPreciPitat ion-Formation
SolutionsTitration
ffirrtrDlocliú'at.I;l:T.ff; il"r..*" lacks an acceptable analvtical merhod ro adequarelv
detennine and monitor sodium cva'¿aá-li coPper ád cadmirm-::::t:i*:tl:::::ffiH i:"J:";;:i"n"ni""';;;:- ii'r'i",'"r::: -1"^:':il:':,T:'l:ui:presented providing "."ápi"¡r"
.rr"ry=i" .r,a *"it"ring of this salt in these
plating nrocess.-.s.' *: épti¡n* o'.r"iir,i--t*g""-of sáalu¡n cyanide are 58 g'l1
maxi.mum in copper .r.r,iuá'n,;;i"; ="i:il;":I?- 1:-n1:-'.?:tTH :1"::T.,*§]}lH ;1.;::;':";íil;:.'^il."l"lii.1ns preclsiel: 1:" in rhe ranse of
. ÍCONTID ON RE:VERSE)
DOtoL
t ,at rl rm Éor?¡o¡ o, t tloY aS 13 o.l¡o|.Etc
¡¡c¡?ror or'l'rat¡ rlcgfD- D-.
ABSTIACT (COT.D)
'0.5 to 4.O g/L, prowiding adequate monitoringsolutions sr4{pr:ted by six years of testing.
of these metal finishine
[,NCI.ASSIFIED¡aCUtttV CLA3¡tFtCAftOX OF fXt3 ,AOClrñrñ D... ¿a..?.¿)
TAELE OF COIITEI{TS
Eese
ACKNOI{LEDGEMENTS i i
I¡¿TROOUCTION.... 1
EXPERIHENTAL PROCEDURE ... 1
RESULTS ANO OISCUSSION . 2
REF EREI{cES Á
TABLES
:, EXPERIHENTAL TITRATION CATA FOR THE SODIUM CYANIDE STANDARDSOLUTION
:I. IXPERII'IENTAL fITRATION OAÍA FOR SOOIUM CYANIDE IN COPPERCYANIDE SAMPLE SOLUTIONS
III. EXPERII,IENTAL fITRATION DATA FOR SO0IUtl CYANIDE IN CAOMIUMCYA}.IIDE SATPLE SOLUTIONS
:V. PRECISION 0F A 2-ml CLASS-A PIPET
v. PRECISION OF 5O-g/1 SOotUr{ CyANtO€
VL PRECISION OF 11-9/1 SILVER NITRATE
VII. PRECISION OF A sO-m.I CLASS-A EURET
STANOARO SOLUTION
TITRANT SOLUTION
NTIS GFA&IDTI,C IÁBU¡annou¡¡ced
i Justtflr¡aLl
6
6
7
un
I
,-- frvalr ;Ed/oiDlst I Speotet
in,t I Iidi-_t_
ACTilOXLEDGE!,IET{TS
Specia) thariks are given to E'l]en Fogarty and Rose Neifeld of Benet
;aboratories for their rssDective word processing and technical editing work on
th'is nanuscriot.
11
^l
IT{TROOUCTIOtr
The chemical Iiteratune Iacks an acceptab'le analytical method to deternine
and monitor sodium cyanide in copper and cadmium cyan'ide plat'ing solutions in
the plating processes. Lack of optim'ization of these plating solutions causes
serious problems for the me'ral finishing industry sueh as poor quality products
and wasted resources.
The only common chemica'l analysis method to determine sod'ium cyanide in
these solutions is a co] or comparison test kit such as the one Drovided by l¡lerck
Corporation (ref 1), however, th'i s method provides poor precis.ions.
The specific method described in this report provides acceptab'le analysis
and mon'i toring of this salt in the meta.l f inish'i ng processes. The method con-
sists or a precipitatioil-tormation ritration (refs 2,3). Re'lative precisions of
this method are in the raige of 2 to 3 peneent.
EXPERIIIEnIAL PROCEOURE
Strict analytical chemistry methods and procedures are foi'lowed throughout
thls exoerimental orocedure sect.ion. An excellent source of reference for these
rethods and orocedures is by Fritz and Schenk (ref 3).
Two analytical reagent grade standard solutions are required. The first rs
a 50 + 0.S-gt '1 sodium cyanide solution (l g/1 sodium hydroxide for stabil ira-
tion), and the second is a 1? 1 0.1-gll si lver nitrate t,i trant so.l ution. These
:,{o solut'ions are prepared and standardized as described'in References 2 and 3.
Two orher analytical reagents are required. The first is potassium iodide
indicator powder and the second is concentrated ammoni,¡m hydrox.ide solution.
The procedure to prepare standard and sample solutions is the same for the
copper anc, cadmium cyanide solutions. This titration analysis requ.ires that a
mi'l 'l i'l iters (ml ) of sanpie or standard solution i.s pipetted into a 400-mi
S
beaker. Then the beaker is fil]ed to about the 100-ml mark with deionized v{ater
and a stirring bar is added. Also added to this beaker is 0.1 gram of potassium
iodtde'indicator anc! 5 nl of concentrated ammoniun hydroxide solution.
The solution is titrated using the si'lver nitrate titrant to a fa'int ye11ow
turoid pernanent endpo'int, recording the amount of titrant dispensed in millili-
ters at the endgoint.
All standard and samole solutions are analyzed in triplicate. Sod'ium
cyan'ide concentrations in the samo'les are calcul ated by normal chemical
stoiciliometry.
RESULTS ANO OISCUSSIOI{
Exoerimenta'l standard titration data are presented in Table I for these
solutions. Experimenta'l sample titration data are presented in Table II for
copper cyanide sample so] ut'i ons one and two and in Table III for cadmium cyanide
sample solutions three and four. The titration can be summarized using the
fo!lowing equations. The f irst tvro involve the cyanide-si'l ver ion relationsh'io
ano the th'i rd involves the iod'ioe-si lver ion endpoint indicator re'l ationship:
Ag* * 2CN- <--> (Ag(CN)e)-
(Ag(CN)2)- + Ag+ <--> 2A9CN
Ag+ * I- <--> AgI
(1)
\¿)
(3)
Sriver cyan'icle vúil'l not precipitate in these solutions due to the presence of
ammonium ions allowing on'ly the silver iodide to precipitate at the endpoint.
The calcu'lat'ion for determining the concentration of sodium cyanide in the
original sample so'l utions is
g/'l NaCN = (50)(All(B) (¿)
1
where
A=n'l of
= m] of
titrant for samole
titrant for standard
is the combined result of many constants
B
iwhere the constant va'l ue
( refs 2,3 ) .
n Eq. (4 )
Using Eq. (4), -he respective sodium cyan'ide values for ccpper cyanide
samo'le solutions one and two in Table II are 35.1 and 49.9 g/1. Lirewise, rrs¡no
ihe same equation, the resoect'ive sodium cyanide vaiues for cadmium cyanidc
samo]e solutions three and foulin fable III are 84.9 and 140.1 gz1.
!t is useful to evaluate the variations in prec'ision for the materials and
rerhods ,lsed. Taoles IV through VII present the data for the 2-m'! c lass-A
oioets, 50-g; ! sod-¡um cyanide stanctard solution, 17-g/1 silver nitrate titrañt
sojution, and the 50-ml class-A burets, respective'ly.
The data obtained by this riethocl are sufficient to aclequately monitor the
sodiun cyanide'i n the meta'l finishing processes, thus prov'iding efficient use of
resources. fhe opt'imum operating ranges of sodium cyan'ide are 58 q,l max:rnr¡m :n
the coooer cyanide platrng solr¡tions and 149 gr'1 maximum in the caomium.:yan.:r)
oirting onl*.¡iions. Íhe nesu'l t'ing precisions are in the range of 0.5 rc t.0 § :.
orovioing adequate monitoring of these metal finishing solutions suoporteo bv
srx years of testing.
,a
t.
2.
REFEREIICES
"EM Quant Chlorine and Cyanide fests," El¡t Science Civision of Herck
Corooration, Cherry H'i l l, NJ, 1980.
0. Peters, J. Hayes. and G. HieftJe, themiqal separatio-!_q_a!q.Measure-rne¡ts:
Theorv and Prqglice of Analytical Chemistrv, W. B. Saunders Company
3.
ohl laclelphia, PA, |9?4.
i. Fritz and G. Schenk,
A1 lyn and Bacon. Inc.,
q@cal Chen.istrv, Fif th Ectitron.
Boston, l,tA, 198? .
_^
TAELE I. EXPERI}TENTAL TITRATIOÍI DATA FOR THESOOIUI{ CYATIIOE STA}TOARO SOLUTIOil
Rep I icates
1
2
3
¡((avgl
Titrant Used (ml)
10. 2s
10. 20
10.20
t0.22 r_t
TABLE II. EXPERII{EilTAL TITRATIOII DATA FOR
CYAilIOE It{ COPPER CYA}¡IOE SAI'{PLESOOIUil
SOLUfIONS
i Sample OneI - i '-¡nt Jsed (ml I
-----t---l
Sample TwoIitrant Used (ml I
, :<
?. i5
7 .20
?.1?
10. 20
10. 20
10. 20
10.20
?eO; rCareS
:
?
3
x(avg)
TAELE III.
----fI
I
I
iI
EXPERII{ENTAL TITRATIOT{ DAÍA FOR SOOIU}ICYAi|IDE I¡l CAOl,lIUl,l CYAiIIDE SAI'IPLE S0LUTIOI{S
--T--Samg le 'hree I Samole For¡r
' _ :::_:':11.'''' __L__""1: :'"0 '*''i?.35
1?.35
1?.35
1?.35
28. 60
28,65
28. 65
28. 63
ÍAELE IV. PRECISIOT¡ OF A 2-MI CLASS.A PIPET
I Rep l icatei
:
2
3
J
5
6
x(avg)
Sn
1
2
3
I
5
6
X(avg)
Sn
*Sodi ur¡ cyanide concentrat.ionsgiven in References 2 and 3.
49. 9?
49. 99
¿9.99
50.01
50.00
50.02
50.00
a,o2
are :alculated.by methods
2-ml Pipetvolume (ml)*
2 .00
2.01
i .99
1 .99
1 .99
2 .01
2 .00
0.01
rvoiumes are ca lcu'! ated f rom the *eignt-vo.l ume re,l ation_shio -f a croetted deionlzed ¡¡ater so'l ution corrected fortemoerature.
fAELE V. PRECISIO}I OF A 5O.g/.I soolu¡t CYA}IIOE STAN0ARO soLUTIoI{
I
Reo l i cate Sodium Cyanide (OZt¡*
TABLE /I. PRECISIOT{ C2 A 77.9/ I SILVER I{ITRATE T¡TRANT SOLUTIOT{
Repl icate Si'lver N'i trat
I
2
2
4
5
6
(avg)
Sn
1?.1
1? .0
t7 .2
16.8
16. 9
16.8
17.0
o.2
X
__J*Srlver nrtrate conceñtrations are ca¡culated by methodsEiven in References 2 and 3.
TABLE VII. PRECISION OF A sO.mI CLASS.A BURET
Rep I : cate Volume 1¡1 ¡*
'I
2
3
4
5
6
x(avg)
Sn
24.9A
2¿ .98
25.02
25.05
24.98
25. 05
25.00
0.0¿
*Volumes are calculated from the Height-volume relation-ship of a contained deionized ,rater solution correctedÉor temperature at a point one-half ful'l --25 rnt.
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