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An ultraviolet spectrophotometric method for the determination of small amounts of vanadium in ores and steel
I\SI\I.YTIC,Z CIIIMICA ACT-h
224
VOL. 21 (1959)
A sI,cctroI,liotortlctric l~rwccliirc lias lxxn tlcvc~1opccl for tlic tlctcrmination of small of \~illl;diUJll in ores and steels. ‘I’lw Inutliotl dcIwncls upoil tlw absorption of tllc ortllo~~itt~~ttli~t~ion at 27~ onyxin a I ;V socli\~ln I~ychxsidc solution. A study IKLS hen n~x.lc of tlic: iolis tliat niigiit intcrfcr, ant1 iI rnctliocl clcscribcd for tllc removal of tllc intcrfcritlg iolis \vitll aI1 .ic>*l-caXcllilngc t-win. ‘l’liis lllctll~~cl avoids il nunilwr of qmxtirms clcscrihxl prcvioiislyl sucli as t’clwxtccl c.straction witll ilI1 Orgilnic SOI\‘cllt, cV~lpoKltiol1, flision witli suclillm CiLr1~0ni1tC illltl filtration. amounts
A 2.oooo g sample of ~uiinioniurn vanaclatc was ciissolvctl iii water mcl trmsfc:rrctl to a I-1 \*oliimctric flask and clilutcrl to tlic ITli~rli. IO ml of tllc stock solution wcrc: pipttd into LL loo-ml volumetric flasl i allcl clilutccl to tllc Illilrk witli I LV NilOl-I. 5, 4, ;3 aid 2. ml, rcspcctivclp, of this solutim wc:rc: pipcttccl into SCI)iLr;ltC roe-ml voliirnctric flrLsl
‘l’ranskr ;i I.0000 g saniplc of tlic arc! to a Idatiniw crucil~lc and rnis wit11 5 g of anliytlrous sodium CZilI+l>Ol~~~t~. SlXCiltl ot’cr t Iic mixture anotlw- 0.5 6’ of sodium cm-bonxtc. L;usc tlic niisturc mxl dlow to cool to room tcniIxx;~turo. ‘l’rmsfcr tlic crucildc :11lC.l cO~ItC%tS to a. 400-1111 pyres Ixxl;ur and iltltl il ZcW ml of water. I-IC!iLt to boiling in orclcr to loosim tlic! rcsicluc in tlic crucible ant1 crlisll any large particks witli ;L fli~ttL!ll~tl stirring rod. Rc’fncwc tlic criiciblc, \ViLSll witli \Viltcr mid add tlic wasllin~s to tllC! h!ilkcr. Add 3-5 Jill Of WilgcBtlt @ilClc lllctllyl i~lcOll01 to rcclucc tllc III~~~I~i~~lELtC!, boil for 5 niin nncl filter liot tlirou@i a filter paper (Wlintniun no. 42) into a small ~~lcllrllcJ~crfli~sli. Wasll tlic rcsicluc wit11 Iiot water illld xclcl tllc \ViKllill@i to tlic filtrate AllWV t0 COOI, iKiclify to pII 2 with I-ICI, transfer to a Ioo-ml flask i\IlCl clilutc to tlw mark. Pipct 20 nil of tlic solution into an ion-c:.schan~c column containing nnibcrlitc IRA-400. Acljust tlw rate of flow of tlw sample through the colu~nn to upprosinlntcly 30 drops per min and collect tlw cluatc in a x00-d volunictric flask. Rinse tlw colunin f~efcvolcc!s
p.
2aG
VOL.
21 (1959)
SPECTROPHOTOMETRY
OF
1’
225
with several portions of water. Adcl enough NaOl-3 solution to the flask in order to make the contents I Jf after diluting to the mark. Obtain the ultraviolet absorbance at 270 m/c on a spcctrophotometcr (Cnry Model II) using x-cm cells and I 1V NnOH as refcrencc. Rcacl the concentration of vanadium from a standard working curve. Detevntination
of vnmditrns
in steel
Weigh a x.oooo g sample of the steel sha\Ggs into ;L small he;lkcr and acld IO ml of 6 N I-ICI. I’lacc: t!w beaker on a steam bath and al!ow it to hcilt until the sample Evaporntc the solution to a few ml, being careful not to is dissol\-ccl complctcly. cvaporatc to dryness, and add 2 or ?, drops of nitric acid. FTcat for a few min and transfer to ;L Ioo-ml volumetric flask containing 40 ml of hot 2.5 1V NaOl-I. The iron will prccipitntc illld the vanadium remain in solution as sodium vanxlntc. .4ftcr dilute to tlic mark with wntcr. allowing the solution to cool to room temperature, IXtcr the solution or allow it to stand for in few min during which tinic the prccipitiltc will scttlc out. Rcmo\*c a x0 or zo-ml aliquot clcpcntling on tile concentration of vanadium. Acidify to ~II 2 or less anti continue as given unclcr the clctcrmination of vanadium in ores.
A study of the interfering clcmcnts found in arcs and steel indicated thut chromium was the grcatcst offcnclcr. Chromate ions have a strong absorption at 275 m/dand cause ihlcrcrrccs
p. 226
I<. J. WARMIN,
220
J. 1’. IIAZEL,
w.
VOL.
AI. ?dCSAI3I3
21 (rgsg)
serious intcrfcrcncc. Scpration of chromate was accomplishccl by use’ of an ionacid solutions vanadium is present in tlic forln of czschangc resin. In conccntratccl while the cl~romium is in the form of dichromatc. ‘I’lic vanadium (VCq?-’ and (VO)+:J can 1~ aclsorbcd as a cation on a cation-cxcllang,lc resin or the chromium can lx aclsorlxd as an anion on an anion-cxcliangc resin. ‘I‘llc latter was founcl to be most ‘I’l~c vanadi~lni W;LS difficult to clute from tlic cation resin siltisf:lctfWy for two r(:xsons. and tllc cliromutc rcactccl wit11 tlkc cutioli resin and causccl erroneous results. l’lic proccclurc W;L~tried first Lvith stxntlarcl solutions in the following manner. A stnnclard was passwl tlirough VZlll~lcliltL! solution W:LS xljuStcC1 to pII I . 20 ml of tlic: solution 11<.4-400 in t 1ic: cliloridc form. an pinion-cscliangc column consisting of Amlxrlitc: ‘I’liis was fr,llowctl by 50 ml of clilutc: I-ICI of tlic same pll. ‘1’1~ solution ant1 washings Wc!rc: colh!ctccl ill ;L roe-~111 volilmctric flask :lIId mxdc :llkilliIIc with SocliuIn llyrlro_sitlc. ‘I’IIC IlltrilVi0lC’t through
tlw
SJMXtrllJll
cvluInn.
\ViLS 0bt;iinctl
‘I’llcy
wcrc:
i&:llticill
alltl
comptrcxl
intlicatilig
to tllat nolic
Of ;L St~lltlard
of tlic
ion
not
li;icl lwcn
lxiSScc1
aclsorbcd
‘1’1~ proccdlirc was rcpcatccl risilig IL solution consisting of wit11 tlic rcsiii. sliowcd alxcncc of vxnaclatc and cliromatc ions. ‘II ic resulting spcxtruni of cliromatc and full rccovcry of tlic vanidiiun. or
rc:uAxtl
a misturc
‘l’lic ores usccl in tlic tlctcrmi17;ltions ZlS (.h!
110.
of viiliadiiun
were
of
tlic
same
$$Ilerill
t>y)c
I,
'I'lli? lnctlit~l proposotl is suitalh for a cllliclcroutiiic tlctc1’1ili11;~Lio1~ ~~Ism;rll al1~oiilitSof Villli~tlill~ll in CXrti~ill 0I’cS ;Ltltl StCcl. ‘L’llc intcrfcrclicc of cllmJniuJ31 in tllc fillill clctcrmin;rtion r~f \*;rti:ltlilini ilsiriK tllc ultraviolet spectra was clirrlilliltcil I)y tlic 1i.w of ill1 ion-cxcllan~:c resin. I~cl~ro(llicc;rl)ilit~ r~f rcslllts was fotind Lx> Ix acccl~tal~lt: for ;L cc>lorinictric nicll~orl.
IJnc: nV2Llicxli: cchrindtriquc cst prqxdc laour Ic tlcxap: clu VilllilCli~llll. rapitlc tic cut i'ldnicllt tlails ilcs niincmis ct tics irCicl%. l..c clironic ~61lc; :ulsorplicm slur ilnc rdsinc tl'bcl~uiigc Cl’ioiis.
1%
win1
Still11
wcrtlcii.
cinc
colorirnctriscllc
~JcSC!~lriC!h!ll.
~tl3Y~lll,
tl:lS
Scliiic:ll-ljtrstinlillu~lh' van die
h!Stillllllllll~
stiirt,
ltlcirwll
k;rnn
nii
Xlcnjicii t cincJ33
IZllc pcrnint liti tlos;~gc il l>cllt Ctrc: stip;lrC l,ar
Vcrn;Ltlitlln JC~J3c11;3llstnllscl3~r
in 15rzcn
untl
cntfcrJ3t
224
VOL. 21 (1959)
A sI,cctroI,liotortlctric l~rwccliirc lias lxxn tlcvc~1opccl for tlic tlctcrmination of small of \~illl;diUJll in ores and steels. ‘I’lw Inutliotl dcIwncls upoil tlw absorption of tllc ortllo~~itt~~ttli~t~ion at 27~ onyxin a I ;V socli\~ln I~ychxsidc solution. A study IKLS hen n~x.lc of tlic: iolis tliat niigiit intcrfcr, ant1 iI rnctliocl clcscribcd for tllc removal of tllc intcrfcritlg iolis \vitll aI1 .ic>*l-caXcllilngc t-win. ‘l’liis lllctll~~cl avoids il nunilwr of qmxtirms clcscrihxl prcvioiislyl sucli as t’clwxtccl c.straction witll ilI1 Orgilnic SOI\‘cllt, cV~lpoKltiol1, flision witli suclillm CiLr1~0ni1tC illltl filtration. amounts
A 2.oooo g sample of ~uiinioniurn vanaclatc was ciissolvctl iii water mcl trmsfc:rrctl to a I-1 \*oliimctric flask and clilutcrl to tlic ITli~rli. IO ml of tllc stock solution wcrc: pipttd into LL loo-ml volumetric flasl i allcl clilutccl to tllc Illilrk witli I LV NilOl-I. 5, 4, ;3 aid 2. ml, rcspcctivclp, of this solutim wc:rc: pipcttccl into SCI)iLr;ltC roe-ml voliirnctric flrLsl
‘l’ranskr ;i I.0000 g saniplc of tlic arc! to a Idatiniw crucil~lc and rnis wit11 5 g of anliytlrous sodium CZilI+l>Ol~~~t~. SlXCiltl ot’cr t Iic mixture anotlw- 0.5 6’ of sodium cm-bonxtc. L;usc tlic niisturc mxl dlow to cool to room tcniIxx;~turo. ‘l’rmsfcr tlic crucildc :11lC.l cO~ItC%tS to a. 400-1111 pyres Ixxl;ur and iltltl il ZcW ml of water. I-IC!iLt to boiling in orclcr to loosim tlic! rcsicluc in tlic crucible ant1 crlisll any large particks witli ;L fli~ttL!ll~tl stirring rod. Rc’fncwc tlic criiciblc, \ViLSll witli \Viltcr mid add tlic wasllin~s to tllC! h!ilkcr. Add 3-5 Jill Of WilgcBtlt @ilClc lllctllyl i~lcOll01 to rcclucc tllc III~~~I~i~~lELtC!, boil for 5 niin nncl filter liot tlirou@i a filter paper (Wlintniun no. 42) into a small ~~lcllrllcJ~crfli~sli. Wasll tlic rcsicluc wit11 Iiot water illld xclcl tllc \ViKllill@i to tlic filtrate AllWV t0 COOI, iKiclify to pII 2 with I-ICI, transfer to a Ioo-ml flask i\IlCl clilutc to tlw mark. Pipct 20 nil of tlic solution into an ion-c:.schan~c column containing nnibcrlitc IRA-400. Acljust tlw rate of flow of tlw sample through the colu~nn to upprosinlntcly 30 drops per min and collect tlw cluatc in a x00-d volunictric flask. Rinse tlw colunin f~efcvolcc!s
p.
2aG
VOL.
21 (1959)
SPECTROPHOTOMETRY
OF
1’
225
with several portions of water. Adcl enough NaOl-3 solution to the flask in order to make the contents I Jf after diluting to the mark. Obtain the ultraviolet absorbance at 270 m/c on a spcctrophotometcr (Cnry Model II) using x-cm cells and I 1V NnOH as refcrencc. Rcacl the concentration of vanadium from a standard working curve. Detevntination
of vnmditrns
in steel
Weigh a x.oooo g sample of the steel sha\Ggs into ;L small he;lkcr and acld IO ml of 6 N I-ICI. I’lacc: t!w beaker on a steam bath and al!ow it to hcilt until the sample Evaporntc the solution to a few ml, being careful not to is dissol\-ccl complctcly. cvaporatc to dryness, and add 2 or ?, drops of nitric acid. FTcat for a few min and transfer to ;L Ioo-ml volumetric flask containing 40 ml of hot 2.5 1V NaOl-I. The iron will prccipitntc illld the vanadium remain in solution as sodium vanxlntc. .4ftcr dilute to tlic mark with wntcr. allowing the solution to cool to room temperature, IXtcr the solution or allow it to stand for in few min during which tinic the prccipitiltc will scttlc out. Rcmo\*c a x0 or zo-ml aliquot clcpcntling on tile concentration of vanadium. Acidify to ~II 2 or less anti continue as given unclcr the clctcrmination of vanadium in ores.
A study of the interfering clcmcnts found in arcs and steel indicated thut chromium was the grcatcst offcnclcr. Chromate ions have a strong absorption at 275 m/dand cause ihlcrcrrccs
p. 226
I<. J. WARMIN,
220
J. 1’. IIAZEL,
w.
VOL.
AI. ?dCSAI3I3
21 (rgsg)
serious intcrfcrcncc. Scpration of chromate was accomplishccl by use’ of an ionacid solutions vanadium is present in tlic forln of czschangc resin. In conccntratccl while the cl~romium is in the form of dichromatc. ‘I’lic vanadium (VCq?-’ and (VO)+:J can 1~ aclsorbcd as a cation on a cation-cxcllang,lc resin or the chromium can lx aclsorlxd as an anion on an anion-cxcliangc resin. ‘I‘llc latter was founcl to be most ‘I’l~c vanadi~lni W;LS difficult to clute from tlic cation resin siltisf:lctfWy for two r(:xsons. and tllc cliromutc rcactccl wit11 tlkc cutioli resin and causccl erroneous results. l’lic proccclurc W;L~tried first Lvith stxntlarcl solutions in the following manner. A stnnclard was passwl tlirough VZlll~lcliltL! solution W:LS xljuStcC1 to pII I . 20 ml of tlic: solution 11<.4-400 in t 1ic: cliloridc form. an pinion-cscliangc column consisting of Amlxrlitc: ‘I’liis was fr,llowctl by 50 ml of clilutc: I-ICI of tlic same pll. ‘1’1~ solution ant1 washings Wc!rc: colh!ctccl ill ;L roe-~111 volilmctric flask :lIId mxdc :llkilliIIc with SocliuIn llyrlro_sitlc. ‘I’IIC IlltrilVi0lC’t through
tlw
SJMXtrllJll
cvluInn.
\ViLS 0bt;iinctl
‘I’llcy
wcrc:
i&:llticill
alltl
comptrcxl
intlicatilig
to tllat nolic
Of ;L St~lltlard
of tlic
ion
not
li;icl lwcn
lxiSScc1
aclsorbcd
‘1’1~ proccdlirc was rcpcatccl risilig IL solution consisting of wit11 tlic rcsiii. sliowcd alxcncc of vxnaclatc and cliromatc ions. ‘II ic resulting spcxtruni of cliromatc and full rccovcry of tlic vanidiiun. or
rc:uAxtl
a misturc
‘l’lic ores usccl in tlic tlctcrmi17;ltions ZlS (.h!
110.
of viiliadiiun
were
of
tlic
same
$$Ilerill
t>y)c
I,
'I'lli? lnctlit~l proposotl is suitalh for a cllliclcroutiiic tlctc1’1ili11;~Lio1~ ~~Ism;rll al1~oiilitSof Villli~tlill~ll in CXrti~ill 0I’cS ;Ltltl StCcl. ‘L’llc intcrfcrclicc of cllmJniuJ31 in tllc fillill clctcrmin;rtion r~f \*;rti:ltlilini ilsiriK tllc ultraviolet spectra was clirrlilliltcil I)y tlic 1i.w of ill1 ion-cxcllan~:c resin. I~cl~ro(llicc;rl)ilit~ r~f rcslllts was fotind Lx> Ix acccl~tal~lt: for ;L cc>lorinictric nicll~orl.
IJnc: nV2Llicxli: cchrindtriquc cst prqxdc laour Ic tlcxap: clu VilllilCli~llll. rapitlc tic cut i'ldnicllt tlails ilcs niincmis ct tics irCicl%. l..c clironic ~61lc; :ulsorplicm slur ilnc rdsinc tl'bcl~uiigc Cl’ioiis.
1%
win1
Still11
wcrtlcii.
cinc
colorirnctriscllc
~JcSC!~lriC!h!ll.
~tl3Y~lll,
tl:lS
Scliiic:ll-ljtrstinlillu~lh' van die
h!Stillllllllll~
stiirt,
ltlcirwll
k;rnn
nii
Xlcnjicii t cincJ33
IZllc pcrnint liti tlos;~gc il l>cllt Ctrc: stip;lrC l,ar
Vcrn;Ltlitlln JC~J3c11;3llstnllscl3~r
in 15rzcn
untl
cntfcrJ3t