39.Dab tsi yog dej acidity thiab alkalinity?
Lub acidity ntawm dej yog hais txog tus nqi ntawm cov khoom muaj nyob rau hauv cov dej uas yuav neutralize lub hauv paus muaj zog. Muaj peb hom tshuaj uas tsim cov kua qaub: cov kua qaub uas muaj zog uas tuaj yeem sib cais tag nrho H + (xws li HCl, H2SO4), tsis muaj zog acids uas ib nrab dissociate H + (H2CO3, organic acids), thiab ntsev uas muaj zog acids thiab tsis muaj zog hauv paus (xws li. NH4Cl, FeSO4). Acidity yog ntsuas los ntawm titration nrog lub hauv paus muaj zog daws. Lub acidity ntsuas nrog methyl txiv kab ntxwv raws li qhov taw qhia thaum lub sij hawm titration yog hu ua methyl txiv kab ntxwv acidity, nrog rau cov acidity tsim los ntawm thawj hom muaj zog acid thiab peb hom muaj zog acid ntsev; Lub acidity ntsuas nrog phenolphthalein raws li qhov ntsuas yog hu ua phenolphthalein acidity, Nws yog cov lej ntawm cov saum toj no peb hom acidity, yog li nws tseem hu ua tag nrho acidity. Cov dej ntuj feem ntau tsis muaj acidity, tab sis muaj cov carbonates thiab bicarbonates uas ua rau cov dej alkaline. Thaum muaj acidity hauv dej, nws feem ntau txhais tau hais tias cov dej tau kis los ntawm cov kua qaub.
Nyob rau hauv sib piv rau acidity, dej alkalinity yog hais txog tus nqi ntawm cov khoom nyob rau hauv dej uas yuav neutralize muaj zog acids. Cov tshuaj uas tsim cov alkalinity muaj xws li cov hauv paus muaj zog (xws li NaOH, KOH) uas tuaj yeem sib cais OH-, cov hauv paus tsis muaj zog uas ua rau OH- (xws li NH3, C6H5NH2), thiab ntsev uas muaj cov hauv paus muaj zog thiab tsis muaj zog acids (xws li Na2CO3, K3PO4, Na2S) thiab lwm yam peb pawg. Alkalinity yog ntsuas los ntawm titration nrog cov kua qaub muaj zog. Lub alkalinity ntsuas siv methyl txiv kab ntxwv raws li qhov taw qhia thaum lub sij hawm titration yog cov sum ntawm saum toj no peb hom alkalinity, uas yog hu ua tag nrho alkalinity los yog methyl txiv kab ntxwv alkalinity; Lub alkalinity ntsuas siv phenolphthalein raws li qhov taw qhia yog hu ua phenolphthalein puag. Degree, suav nrog alkalinity tsim los ntawm thawj hom muaj zog puag thiab ib feem ntawm alkalinity tsim los ntawm peb hom muaj zog alkali ntsev.
Cov kev ntsuas ntawm acidity thiab alkalinity muaj xws li acid-base indicator titration thiab potentiometric titration, uas feem ntau hloov mus rau hauv CaCO3 thiab ntsuas hauv mg / L.
40.Qhov pH ntawm dej yog dab tsi?
Tus nqi pH yog qhov tsis zoo logarithm ntawm hydrogen ion kev ua hauv cov dej ntsuas ntsuas, uas yog, pH = -lgαH +. Nws yog ib qho ntawm cov kev ntsuas feem ntau siv hauv cov txheej txheem dej phwj tuaj. Nyob rau hauv 25oC tej yam kev mob, thaum tus nqi pH yog 7, cov dej num ntawm hydrogen ions thiab hydroxide ions nyob rau hauv dej yog sib npaug, thiab cov concentration yog 10-7mol / L. Lub sijhawm no, cov dej nruab nrab, thiab pH tus nqi> 7 txhais tau hais tias cov dej yog alkaline. , thiab pH tus nqi<7 means the water is acidic.
Tus nqi pH qhia txog acidity thiab alkalinity ntawm dej, tab sis nws tsis tuaj yeem qhia ncaj qha rau acidity thiab alkalinity ntawm dej. Piv txwv li, acidity ntawm 0.1mol / L hydrochloric acid tov thiab 0.1mol / L acetic acid tov kuj yog 100mmol / L, tab sis lawv cov pH qhov tseem ceeb yog txawv heev. Tus nqi pH ntawm 0.1mol / L hydrochloric acid tov yog 1, thaum pH tus nqi ntawm 0.1 mol / L acetic acid tov yog 2.9.
41. Cov kev ntsuas pH feem ntau siv li cas?
Hauv kev tsim khoom tiag tiag, txhawm rau txhawm rau nrawm thiab yooj yim nkag siab cov kev hloov pauv hauv pH tus nqi ntawm cov dej khib nyiab nkag mus rau hauv cov dej khib nyiab, txoj kev yooj yim tshaj plaws yog ntsuas nws nrog pH daim ntawv xeem. Rau cov dej khib nyiab uas tsis muaj xim tsis muaj kev tshem tawm impurities, cov txheej txheem colorimetric kuj siv tau. Tam sim no, kuv lub teb chaws tus txheej txheem rau kev ntsuas pH tus nqi ntawm cov dej zoo yog txoj kev potentiometric (GB 6920-86 iav electrode method). Nws feem ntau tsis cuam tshuam los ntawm xim, turbidity, colloidal tshuaj, oxidants, thiab txo cov neeg ua haujlwm. Nws tseem tuaj yeem ntsuas pH ntawm cov dej huv. Nws tseem tuaj yeem ntsuas pH tus nqi ntawm cov dej khib nyiab hauv kev lag luam rau ntau qib. Qhov no kuj yog ib txoj kev siv dav los ntsuas pH tus nqi hauv feem ntau cov chaw kho dej khib nyiab.
Lub hauv paus ntsiab lus ntawm kev ntsuas potentiometric ntawm pH tus nqi yog kom tau txais lub peev xwm ntawm qhov taw qhia electrode, uas yog, tus nqi pH, los ntawm kev ntsuas qhov sib txawv ntawm cov iav electrode thiab cov khoom siv electrode uas muaj peev xwm paub. Kev siv hluav taws xob feem ntau siv calomel electrode lossis Ag-AgCl electrode, nrog rau calomel electrode yog feem ntau siv. Lub hauv paus ntawm pH potentiometer yog DC amplifier, uas ua kom muaj peev xwm tsim tau los ntawm cov hluav taws xob thiab qhia nws ntawm lub taub hau 'meter' nyob rau hauv daim ntawv ntawm cov lej lossis cov taw qhia. Potentiometers feem ntau yog nruab nrog lub ntsuas kub them nyiaj los kho qhov ntsuas kub ntawm cov electrodes.
Lub hauv paus ntsiab lus ua haujlwm ntawm pH meter online siv hauv cov chaw kho dej khib nyiab yog txoj hauv kev potentiometric, thiab kev ceev faj rau kev siv yog qhov zoo ib yam li cov pH ntsuas pH. Txawm li cas los xij, vim tias cov hluav taws xob siv tau txuas ntxiv mus rau hauv cov dej khib nyiab los yog lub tso tsheb hlau luam thiab lwm qhov chaw uas muaj cov roj ntau lossis cov kab mob rau lub sijhawm ntev, ntxiv rau qhov yuav tsum tau siv cov pH meter yuav tsum tau nruab nrog lub tshuab ntxuav tsis siv neeg rau cov electrodes, phau ntawv qhia. Kev ntxuav kuj tseem yuav tsum tau ua raws li cov dej zoo thiab kev ua haujlwm. Feem ntau, pH meter siv nyob rau hauv dej nkag los yog aeration tank yog manually ntxuav ib zaug ib lub lim tiam, thaum lub pH meter siv nyob rau hauv cov dej effluent yuav manually ntxuav ib hlis ib zaug. Rau cov ntsuas pH uas tuaj yeem ntsuas qhov ntsuas kub ib txhij thiab ORP thiab lwm yam khoom, lawv yuav tsum tau tswj xyuas thiab tswj raws li kev siv ceev faj txog kev ntsuas kev ua haujlwm.
42.Dab tsi yog kev ceev faj rau kev ntsuas pH?
⑴ Lub potentiometer yuav tsum tau khaws cia qhuav thiab plua plav pov thawj, ua haujlwm tsis tu ncua rau kev saib xyuas, thiab cov khoom siv lead ua kev sib txuas ntawm cov electrode yuav tsum tau ceev kom huv si kom tsis txhob muaj dej, plua plav, roj, thiab lwm yam. Xyuas kom zoo hauv av thaum siv AC fais fab. Portable potentiometers uas siv cov roj teeb qhuav yuav tsum hloov cov roj teeb tsis tu ncua. Nyob rau tib lub sijhawm, potentiometer yuav tsum tsis tu ncua calibrated thiab zeroed rau calibration thiab txij nkawm. Thaum debugged kom raug, xoom point ntawm lub potentiometer thiab calibration thiab positioning regulators tsis tuaj yeem tig ntawm lub siab nyiam thaum lub sijhawm kuaj.
⑵ Cov dej siv los npaj cov txheej txheem buffer tov thiab yaug cov electrode yuav tsum tsis txhob muaj CO2, muaj pH tus nqi ntawm 6.7 thiab 7.3, thiab ib tug conductivity ntawm tsawg tshaj li 2 μs / cm. Dej kho nrog anion thiab cation txauv resin tuaj yeem ua tau raws li qhov yuav tsum tau ua tom qab boiling thiab cia nws txias. Cov txheej txheem kev daws teeb meem yuav tsum tau muab kaw thiab khaws cia rau hauv lub khob iav tawv los yog lub raj mis polyethylene, thiab tom qab ntawd muab cia rau hauv lub tub yees ntawm 4oC txhawm rau txuas lub neej kev pab cuam. Yog tias khaws cia rau hauv qhov chaw qhib cua lossis hauv chav tsev kub, qhov kev pabcuam lub neej feem ntau tsis tuaj yeem tshaj 1 Lub Hlis, cov khoom siv tsis tuaj yeem rov qab mus rau lub raj mis kom rov siv dua.
⑶ Ua ntej ntsuas kev cai, ua ntej xyuas seb lub ntsuas hluav taws xob, hluav taws xob, thiab cov qauv tsis zoo li qub. Thiab pH meter yuav tsum tau calibrated tsis tu ncua. Feem ntau lub voj voog calibration yog ib lub hlis twg los yog ib nrab xyoo, thiab ob lub ntsiab lus calibration yog siv rau calibration. Ntawd yog, raws li tus nqi pH ntau ntawm cov qauv yuav tsum tau kuaj, ob qhov kev daws teeb meem tsis zoo uas nyob ze nws raug xaiv. Feem ntau, pH tus nqi sib txawv ntawm ob qhov kev daws teeb meem tsis zoo yuav tsum yog tsawg kawg yog ntau dua 2. Tom qab tso nrog cov tshuaj thawj zaug, sim cov tshuaj thib ob dua. Qhov sib txawv ntawm cov khoom tshwm sim ntawm potentiometer thiab tus qauv pH tus nqi ntawm tus txheej txheem thib ob yuav tsum tsis txhob siab dua 0.1 pH unit. Yog tias qhov ua yuam kev ntau dua 0.1 pH chav tsev, yuav tsum tau siv cov txheej txheem thib peb rau kev sim. Yog tias qhov yuam kev tsawg dua 0.1 pH units nyob rau lub sijhawm no, feem ntau yuav muaj teeb meem nrog kev daws teeb meem thib ob. Yog tias qhov yuam kev tseem ntau dua 0.1 pH chav tsev, muaj ib yam dab tsi tsis ncaj ncees lawm ntawm cov electrode thiab cov electrode yuav tsum tau ua tiav lossis hloov nrog ib qho tshiab.
⑷ Thaum hloov cov qauv tsis zoo lossis qauv, cov electrode yuav tsum tau muab yaug nrog dej distilled, thiab cov dej txuas nrog cov electrode yuav tsum tau nqus nrog cov ntawv lim, thiab tom qab ntawd yaug nrog cov tshuaj ntsuas kom tshem tawm kev sib nrig sib cuam tshuam. Qhov no yog qhov tseem ceeb rau kev siv cov tsis muaj zog buffers. Qhov no tseem ceeb tshwj xeeb tshaj yog thaum siv cov kev daws teeb meem. Thaum ntsuas pH tus nqi, cov tshuaj aqueous yuav tsum tau nplawm kom tsim nyog kom cov tshuaj sib npaug thiab ua tiav electrochemical equilibrium. Thaum nyeem ntawv, lub stirring yuav tsum tau nres thiab tso cai rau sawv ntsug ib pliag kom tso cai rau kev nyeem ntawv kom ruaj khov.
⑸ Thaum ntsuas, ua ntej yaug ob lub electrodes ua tib zoo nrog dej, tom qab ntawd yaug nrog cov qauv dej, tom qab ntawd muab cov electrodes tso rau hauv lub khob me me uas muaj cov qauv dej, co lub beaker kom zoo zoo nrog koj txhais tes kom ua kom cov dej coj los sib xws, thiab sau cov ntaub ntawv. pH tus nqi tom qab nyeem ntawv ruaj khov.
Post lub sij hawm: Oct-26-2023
