Dithizone, feem ntau hu ua cov hlau lead reagent, tuaj yeem tsim cov txheej txheem nrog cov hlau ions thiab hloov xim. Nws yog tus tsim cov organic ntau tshaj plaws hauv kev tsom xam colorimetric. Nws tuaj yeem siv los txiav txim siab qhov hnyav hlau ions, xws li pb2 ntxiv, hg2 ntxiv, zn2 ntxiv, thiab cd2 ntxiv. Cov mis mos molecular yog c6h5nhnhcsn=nc6h5. Nws yog ib hom xiav-dub crystalline hmoov tov thiab shaken nrog aqueous tov ntawm hlau los tsim hlau complex ntsev nyob rau hauv aqueous theem, uas yog pauv mus rau cov organic hnyav txheej thiab muaj cov xim tseem ceeb. Raws li cov xim thiab qhov tob ntawm cov hlau complex ntsev, nws tuaj yeem siv los txiav txim siab qee cov kab hlau, xws li mercury, lead, zinc, thiab cadmium, rau kev sib koom ua ke titration thiab ua tus taw qhia hlau rau kev txiav txim siab mercury, lead, zinc thiab cadmium. . Nws yog ib qho yooj yim los qhia, uas tseem hu ua lead reagent. Noj yuam kev tuaj yeem ua rau mob ntshav qab zib.
Synthetic method ofDithizone reagent: txias qhov sib tov ntawm phenylhydrazine thiab toluene kom qis dua 0 degree, ntxiv carbon disulfide nyob rau hauv nplawm thiab tswj qhov ntxiv ceev kom tswj cov tshuaj tiv thaiv kub ntawm 60 ~ 70 degree, tso rau ntau tshaj 10min, ces kub rau 90. ~ 95 degree, crystallize thiab yaj thiab pib cov tshuaj tiv thaiv. Thaum muaj coob tus crystals yog precipitated, thiab cov lead acetate reagent yog me ntsis xim av, cov lus teb yog tiav, txias, thiab lim, thiab cov muaju.
Lawv ntxuav nrog txias toluene thiab ethanol. Qhov tshwm sim dawb siv lead ua yog phenylthiocarbamide. Tom qab ntawd, diphenylcarbazide ntxiv rau cov tshuaj methanol ntawm poov tshuaj hydroxide, rhuab thiab refluxed rau 5 ~ 10min, txias rau li 30 degree nrog dej khov, lim tawm cov teeb meem insoluble, stirred, thiab ntxiv nrog 0.5mol / l sulfuric acid aqueous tov rau cov lim kom txog thaum cov lus teb tsuas yog acidic rau Congo liab daim ntawv xeem. Cov crystals tau txais tom qab pom yog ntxuav nrog dej txias, ces yaj nrog 5 feem pua sodium hydroxide tov, lim tawm cov teeb meem insoluble, thiab cov lim dej txias nrog dej khov; Nyob rau tib lub sijhawm, acidify Congo liab daim ntawv xeem nrog txias 0.5mol / l sulfuric acid kom txog thaum nws tsuas yog acidic, lim tom qab tag nrho cov nag lossis daus, ntxuav lub lim dej nrog dej khov kom txog thaum42- ion yog tsim nyog, thiab qhuav. nws ntawm 40 degree tom qab tso dej kom tau tiav Diphenylthiocarbazone. Cov txheej txheem tshuaj tiv thaiv yog:
Cov kauj ruam ua haujlwm rau kev txiav txim siab cov ntsiab lus txhuas hauv cov qauv los ntawm nws cov Spectrophotometry.
(1) Qauv ua ntej kho
Ntxiv nrog rau kev ua pov thawj tias kev zom thiab kho cov qauv dej tsis tsim nyog, piv txwv li, cov dej hauv av tsis muaj cov khib nyiab thiab cov dej huv huv tuaj yeem txiav txim ncaj qha. Txwv tsis pub, pretreatment yuav tsum tau ua raws li ob yam hauv qab no.
① Rau cov dej turbid saum npoo, ntxiv 1ml nitric acid rau txhua 100ml ntawm cov qauv dej, muab tso rau ntawm lub phaj cua sov kom zom rau 10min, lim nws nrog daim ntawv lim sai tom qab txias, thiab ntxuav lub lim. daim ntawv nrog 0.2 feem pua nitric acid tov rau ob peb zaug, thiab ces dilute nws mus rau ib tug tshwj xeeb ntim nrog no acid rau kev txiav txim.
② Rau cov dej saum npoo av lossis cov dej khib nyiab uas muaj ntau cov khib nyiab thiab cov organic teeb meem, ntxiv 5 ml nitric acid rau txhua 1 00 ml ntawm cov qauv dej, tso rau ntawm lub phaj cua sov, zom nws. mus txog 10 ml, txias nws me ntsis, ntxiv 5 ml nitric acid thiab 2 ml perchloric acid, txuas ntxiv cua sov thiab zom, thiab ua kom nws qhuav. Tom qab txias, siv 0.2 feem pua nitric acid tov kom sov thiab yaj cov residue. Tom qab txias, siv cov ntawv lim ceev kom lim. Cov ntawv lim yog ntxuav nrog 0.2 feem pua nitric acid ob peb zaug. Cov filtrate yog diluted nrog cov kua qaub no rau ntim rau kev txiav txim Measurementlank kev ntsuam xyuas yuav tsum tau ua nyob rau hauv parallel rau txhua batch ntawm cov qauv soj ntsuam.
③ Kev ntsuas qhov tseeb yuav tsum tsis pub tshaj 30 μ. Muab tus nqi tsim nyog ntawm cov qauv ntawm G lead rau hauv 250 ml cais funnel, ntxiv dej rau 100 ml, ntxiv 3 tee ntawm 0.1 feem pua thymol xiav qhia daws teeb meem, thiab kho nws nrog 6 mol / l sodium hydroxide tov los yog 6 mol / l hydrochloric. acid tov kom txog thaum ruaj khov daj tshwm. Lub sijhawm no, tus nqi pH ntawm cov tshuaj yog 2.8 rau kev txiav txim.
(2) Qauv txiav txim
① Chromogenic extraction: ntxiv cov hmoov lead rau cov qauv tso rau hauv 250 ml sib cais funnel (cov ntsiab lus txhuas tsis tshaj 30 μ g. Qhov siab tshaj plaws ntim tsis ntau tshaj 100 ml). Ntxiv 10 ml ntawm 20 feem pua nitric acid thiab 50 ml ntawm citrate potassium cyanide txo cov tshuaj, ntsaws nws nruj nreem, co nws zoo thiab txias rau chav tsev kub. Tom qab ntxiv 10 ml ntawmdithizone,ntsuas nws nruj nreem, co lub sib cais funnel hnyav rau 30 s thiab muab tso rau hauv txheej.
② Kev Ntsuas: ntxig ib lub pob me me ntawm cov paj rwb tsis muaj hlau lead rau hauv lub caj dab ntawm qhov sib cais, tso cov theem qis hauv cov organic, pov tseg 1 ~ 2ml ntawm chloroform txheej, thiab tom qab ntawd txhaj rau hauv 10mm cuvette. Nrog chloroform raws li cov ntaub ntawv siv, ntsuas qhov nqus ntawm cov extract ntawm 510nm, txiav tawm qhov khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob
③ Kev kuaj dawb: siv cov dej tsis muaj hmoov txhuas es tsis txhob siv cov qauv, siv tib tus nqi ntawm lwm cov reagents, thiab ua raws li cov kauj ruam saum toj no.
(3) Kev kos duab ntawm calibration nkhaus
Ntxiv {{0}}, 0.50, 1.00, 5.00, 7.50, 10.00, 12.50, thiab 15.00 ml ntawm cov txheej txheem txhuas tov rau ib series ntawm 250 ml separators.Measurementropriate tus nqi ntawm lead-dawb deionized dej mus rau 100ml, thiab ua xim kev loj hlob thiab ntsuas raws li cov qauv txiav txim cov kauj ruam hauv qab no.