Cov txheej txheem kev khiav hauj lwm rau kev siv thiab tu cov pH ntsuas
Lub ntsuas acidity yog hu ua pH meter, uas muaj ob ntu: electrode thiab lub ntsuas hluav taws xob. Yog tias cov electrodes tuaj yeem tswj tau qhov tsim nyog, cov txheej txheem tsis haum tuaj yeem npaj tau raws li qhov yuav tsum tau ua, thiab lub ntsuas hluav taws xob tuaj yeem ua haujlwm raug thaum siv, qhov yuam kev ntawm pH qhia tau txo qis, yog li txhim kho kev ntseeg siab ntawm kev sim tshuaj thiab tshuaj xyuas kev kho mob. cov ntaub ntawv.
ib qho, siv thiab tu cov electrodes kom raug
Cov electrodes tam sim no siv nyob rau hauv lub chaw soj nstuam yog composite electrodes, uas muaj qhov zoo ntawm kev siv tau yooj yim, tsis cuam tshuam los ntawm oxidizing los yog txo cov tshuaj, thiab muaj kev sib npaug ceev ceev. Thaum siv, tshem lub tes tsho roj hmab ntawm lub electrode filling chaw nres nkoj thiab lub tes tsho roj hmab hauv qab kawg kom tswj tau qhov sib txawv ntawm qhov sib txawv ntawm cov tshuaj potassium chloride hauv cov electrode. Cov hauv qab no yog cov lus qhia luv luv rau kev siv thiab tu cov electrodes:
1. Thaum tsis siv cov hluav taws xob sib xyaw, nws tuaj yeem ua tiav hauv 3M potassium chloride tov. Tsis txhob ntub nrog cov kua ntxhua khaub ncaws los yog lwm yam dej-absorbing agents.
2. Ua ntej siv, xyuas lub teeb ntawm lub hauv ntej kawg ntawm lub iav electrode. Raws li ib txwm muaj, lub electrode yuav tsum pob tshab tsis muaj kab nrib pleb; lub teeb yuav tsum tau ntim nrog kev daws tsis muaj cua npuas.
3. Thaum ntsuas cov kev daws teeb meem siab, txo lub sij hawm ntsuas kom ntau li ntau tau, thiab ntxuav nws kom zoo tom qab siv los tiv thaiv cov kua ntsuas los ntawm adhering rau electrode thiab polluting electrode.
4. Tom qab ntxuav cov electrode, tsis txhob so lub iav daim nyias nyias nrog cov ntawv lim, tab sis siv cov ntawv lim kom qhuav, kom tsis txhob muaj kev puas tsuaj rau cov iav membrane, tiv thaiv kev sib kis, thiab cuam tshuam rau kev ntsuas qhov tseeb.
5. Thaum lub sij hawm ntsuas, xyuam xim rau cov nyiaj-silver chloride sab hauv siv electrode ntawm cov electrode yuav tsum tau muab tso rau hauv cov tshuaj chloride tsis nyob rau hauv lub teeb kom tsis txhob muaj qhov tshwm sim ntawm cov dhia dhia hauv cov khoom siv hluav taws xob. Thaum siv, xyuam xim rau maj mam co lub electrode ob peb zaug.
6. Cov electrode tsis tuaj yeem siv rau hauv cov kua qaub, muaj zog alkali lossis lwm yam kev daws teeb meem corrosive.
7. Nws yog nruj me ntsis txwv tsis pub siv nyob rau hauv lub cev qhuav dej nruab nrab xws li kiag li ethanol, poov tshuaj dichromate, thiab lwm yam.
Qhov thib ob, kev npaj thiab khaws cia ntawm tus qauv tsis zoo
1. Cov khoom siv pH yuav tsum muab cia rau hauv qhov chaw qhuav. Piv txwv li, cov khoom sib xyaw phosphate pH tus qauv yuav deliquesce thaum huab cua av noo siab. Thaum deliquescence tshwm sim, tus qauv pH tsis tuaj yeem siv.
2. Secondary distilled dej los yog deionized dej yuav tsum tau siv los npaj pH txheem tov. Yog tias nws siv rau 0.1 qib pH meter ntsuas, cov dej distilled zoo tib yam siv tau.
⒊ Cov txheej txheem pH npaj yuav tsum tau diluted nrog lub khob me me kom txo cov pH txheej txheem kev daws teeb meem rau ntawm phab ntsa beaker. Ntxiv nrog rau kev tshem tawm cov hnab yas lossis lwm lub thawv uas khaws cov khoom pH txheem, lawv yuav tsum tau muab yaug nrog dej distilled ob peb zaug, thiab tom qab ntawd muab nchuav rau hauv cov txheej txheem pH npaj los xyuas kom meej tias cov txheej txheem pH npaj tau raug.
4. Cov txheej txheem kev daws teeb meem feem ntau tuaj yeem khaws cia rau 2-3 hli. Yog tias pom muaj turbidity, pwm lossis nag lossis daus, nws yuav siv tsis tau ntxiv lawm.
5. Alkaline txheem tov yuav tsum tau muab kaw thiab khaws cia rau hauv lub raj mis polyethylene. Tiv thaiv cov pa roj carbon dioxide los ntawm kev tsim cov pa roj carbonic acid tom qab nkag mus rau cov txheej txheem kev daws teeb meem thiab txo nws cov nqi pH.
Peb, qhov tseeb calibration ntawm pH meter
Muaj ntau hom pH ntsuas vim qhov sib txawv ntawm cov ntsuas hluav taws xob, thiab lawv cov kauj ruam ua haujlwm txawv. Yog li ntawd, kev ua haujlwm ntawm pH meter yuav tsum tau ua nruj me ntsis raws li nws phau ntawv qhia. Hauv kev ua haujlwm tshwj xeeb, calibration yog ib kauj ruam tseem ceeb hauv kev ua haujlwm ntawm pH meters. Cov ntaub ntawv hauv Table 1 yog qhov ntsuas qhov ntsuas ntawm qhov ntsuas pH tsis tau ntsuas thiab ntsuas pH nrog qhov tseeb ntawm qib 0.01 thiab dhau qhov ntsuas ntsuas ntsuas, uas peb tuaj yeem pom qhov tseem ceeb ntawm calibration.
