Kev txiav txim siab ntawm av pH tus nqi (potentiometric method)
Txheej txheem txheej txheem: Cov txheej txheem potentiometric yog siv los txiav txim cov av pH los ntawm kev ntxig pH iav electrodes thiab calomel electrodes rau hauv av tshem tawm los yog leachate, ntsuas lawv cov nqi hluav taws xob electromotive, thiab tom qab ntawd hloov mus rau pH qhov tseem ceeb. Tus nqi pH tuaj yeem nyeem ncaj qha tom qab txiav txim siab los ntawm cov txheej txheem kev daws teeb meem ntawm acidity meter. Qhov sib piv ntawm cov av thiab dej muaj qhov cuam tshuam tseem ceeb ntawm tus nqi pH, tshwj xeeb tshaj yog rau cov nyhuv dilution ntawm calcareous av. Nws yog ib advisable mus nqa ib tug me me av rau dej ratio. Txoj cai no teev cov av rau dej piv nrog av pH ntawm 1: 1. Nyob rau tib lub sijhawm, ntxiv rau kev ntsuas pH tus nqi ntawm cov dej hauv av, pH tus nqi ntawm ntsev rau hauv av yuav tsum tau ntsuas hauv cov av acidic, uas yog 1mol / L ˉ Soak av H + hauv cov tshuaj potassium chloride thiab ntsuas nws. siv txoj kev potentiometric.
Txoj kev no siv tau rau kev txiav txim siab pH qhov tseem ceeb hauv ntau hom av.
3 Cov cuab yeej tseem ceeb thiab khoom siv
① Acidity ntsuas;
② PH iav electrode;
③ Saturated calomel electrode;
④ Lub tshuab nqus tsev.
4 reagents
① 1molL ˉ 1. Potassium chloride tov: Nyhav 74.6 ɡ Dissolve potassium chloride (chemically pure) hauv 800ml dej, kho pH ntawm cov tshuaj batch rau 5.5-6.0 nrog dilute poov tshuaj hydroxide thiab hydrochloric acid, thiab dilute rau 1L;
② PH 4.01 (25 degree) standard buffer solution: Nyhav 10.21 potassium hydrogen phthalate, uas tau qhuav ntawm 110-120 degree rau 2-3 teev, thiab yaj hauv dej. Hloov nws mus rau 1L ntim ntim, ua kom ntim nrog dej, thiab khaws cia rau hauv lub raj mis polyethylene;
③ PH 6.87 (25 degree) standard buffer solution: Nyhav 3.533g ntawm disodium hydrogen phosphate thiab 3.388g ntawm poov tshuaj dihydrogen phosphate, uas tau qhuav ntawm 110-130 degree rau 2-3 teev, thiab yaj lawv hauv dej . Hloov lawv mus rau 1L volumetric hwj, ua kom ntim nrog dej, thiab khaws cia rau hauv lub raj mis polyethylene;
④ PH 9.18 (25 degree) txheem buffer tov: Nyhav 3.800g ntawm balanced borax (Na2B4O7 · 10H2O) thiab yaj nyob rau hauv CO2 dawb dej. Hloov nws mus rau 1L ntim ntim, ua kom ntim nrog dej, thiab khaws cia rau hauv lub raj mis polyethylene;
Kev sib npaug ntawm kev kho mob ntawm borax: Muab borax tso rau hauv lub tshuab ziab khaub ncaws uas muaj cov tshuaj saturated aqueous ntawm sucrose thiab ntsev kom sib npaug rau ob hnub thiab hmo ntuj;
⑤ Distilled dej kom tshem tawm CO2.
5 Cov kauj ruam tsom xam
① Instrument calibration: Cov kev siv ntawm ntau yam pH meters thiab potentiometers tsis zoo ib yam, thiab kev kho electrode thiab ntsuas ntsuas tau ua raws li phau ntawv ntsuas. Kho cov tshuaj ntsuam xyuas rau tib qhov kub thiab txias raws li cov txheej txheem tsis haum, thiab kho qhov ntsuas kub ntawm qhov ntsuas kub rau qhov ntsuas kub no. Thaum ntsuas qhov ntsuas nrog cov txheej txheem tsis haum, ua ntej ntxig cov electrode rau hauv cov txheej txheem tsis sib xws nrog pH sib txawv ntawm tsis pub ntau tshaj 2 pH ntawm cov qauv kuaj, qhib qhov hloov pauv nyeem ntawv, kho qhov chaw kom nyeem raws nraim pH. tus nqi ntawm cov qauv kev daws teeb meem, thiab rov ua dua ob peb zaug kom ruaj khov rau kev nyeem ntawv. Tshem tawm cov electrode thiab ntxuav nws kom huv. Siv cov ntawv lim dej kom nqus cov dej noo, thiab tom qab ntawd muab tso rau hauv * * cov txheej txheem tsis haum. Qhov tso cai sib txawv ntawm ob txoj kev daws teeb meem yog 0.1 pH unit. Yog tias nws tshaj qhov txwv, xyuas seb puas muaj teeb meem nrog lub ntsuas hluav taws xob lossis cov qauv kev daws teeb meem. Tsuas yog tom qab ntsuas ntsuas ntsuas tau raug, nws tuaj yeem siv los txiav txim tus qauv.
② Kev txiav txim siab ntawm pH ntawm Av Dej Dej Immersion Solution: Nyhav 20g (* * rau 0.1g) ntawm huab cua qhuav qauv dhau los ntawm 2 hli sieve thiab muab tso rau hauv 50ml siab beaker. Ntxiv 20ml dej kom tshem tawm CO2 thiab do rau 1 feeb nrog ib tug stirrer kom tag nrho disperse cov av hais. Tom qab 30 feeb, qhov ntsuas tau ua tiav. Ntxig lub electrode rau hauv cov tshuaj ntsuam xyuas (nco ntsoov tias qhov qis ntawm lub iav electrode qhov muag teev nyob rau hauv qab cov av kua interface, thiab cov calomel electrode tau muab tso rau hauv cov kua dej ntshiab), maj mam co lub beaker kom tshem tawm cov yeeb yaj kiab dej ntawm lub electrode, txhawb nws qhov sib npaug nrawm, cia nws sawv ntsug ib pliag, nias qhov hloov pauv nyeem ntawv, thiab sau tus nqi pH thaum nyeem ntawv ruaj khov. Tso cov ntawv nyeem, tshem tawm cov electrode, ntxuav nws nrog dej, thiab siv cov ntawv lim kom nqus cov dej noo ua ntej ntsuas * * cov qauv. Tom qab kuaj 5-6 cov qauv, nws yog ib qho tsim nyog los xyuas qhov chaw nrog cov qauv kev daws teeb meem.
③ Kev txiav txim siab ntawm pH ntawm cov av poov tshuaj chloride extraction tov: Thaum pH nqi ntawm av immersion yog tsawg tshaj li 7, tus nqi pH ntawm av ntsev extraction tov yuav tsum tau ntsuas. Txoj kev ntsuas yog tshem tawm 1mol L ˉ Tsuas yog hloov CO2 dawb dej nrog cov tshuaj poov tshuaj chloride, cov dej rau av piv yog 1: 1, thiab lwm yam kev ntsuas yog tib yam li kev ntsuas pH hauv dej.
Thaum ntsuas pH tus nqi siv lub ntsuas acidity, pH tus nqi tuaj yeem nyeem ncaj qha yam tsis tas yuav suav.
7 precision parallel results pub rau * * qhov sib txawv: nruab nrab thiab acidic av Tsawg dua los yog sib npaug rau 0.1pH units, alkaline av Tsawg dua los yog sib npaug rau 0.2pH units.\
