Txiv qaub plays ib tug multifunctional, economical, thiab npaum chemical lub hauv paus lub luag hauj lwm nyob rau hauv industrial wastewater kho, nws muaj nuj nqi txuas mus deb tshaj tej yam yooj yim acid- puag hloov. Nws cov txiaj ntsig tseem ceeb nyob hauv kev hloov cov kuab paug hauv dej rau hauv cov khoom tsis sib haum los ntawm cov txheej txheem tshuaj lom neeg thiab lub cev, yog li ua tiav kev sib cais thiab kev huv.
1. Kev hloov pH thiab nag lossis daus tshwm sim
Cov khoom tseem ceeb ntawm cov txiv qaub yog calcium oxide (CaO) lossis calcium hydroxide (Ca(OH) ₂), uas tsim cov alkaline ib puag ncig zoo thaum yaj hauv dej. Qhov no yog lub hauv paus ntawm tag nrho nws cov haujlwm.
Nws tuaj yeem tshem tawm cov dej khib nyiab sai sai rau qhov nruab nrab lossis alkaline, tsim cov xwm txheej tsim nyog rau kev kho mob tom ntej thiab nag lossis daus hlau.
Nyob rau hauv cov xwm txheej alkaline, nws tuaj yeem ua rau muaj ntau yam hlau ions hauv dej los ua dej -insoluble hydroxides lossis ntsev precipitates. Piv txwv li:
Kev tshem tawm cov hlau hnyav (xws li tooj liab, nickel, zinc, chromium): Cu²⁺ + Ca(OH)₂ → Cu(OH)₂↓ + Ca²⁺
Kev tshem tawm Phosphorus: Cov tshuaj tiv thaiv nrog orthophosphate los ua hydroxyapatite precipitate: 5Ca²⁺ + 3PO₄³⁻ + OH⁻ → Ca₅(PO₄)₃(OH)↓
Kev tshem tawm cov tshuaj fluoride: Tsim cov calcium fluoride precipitate: Ca²⁺ + 2F⁻ → CaF₂↓
2. Coagulation -coagulant synergistic nyhuv
Txiv qaub tsis tsuas yog muab ib puag ncig alkaline, tab sis cov calcium ions (Ca²⁺) nws tsim thiab precipitate nws tus kheej muaj cov nyhuv physicochemical synergistic:
Ca²⁺ tuaj yeem ua rau cov hluav taws xob ob txheej ntawm cov khoom siv colloidal hauv cov dej khib nyiab, txo lawv cov kev ruaj ntseg thiab txhawb kev coagulation colloidal.
Lub generated calcium hydroxide microsolubles thiab lawv cov flocs, thaum lub sij hawm tsim thiab sedimentation, ua zoo li ib tug nplua net, mechanically encapsulating, adsorbing, thiab cheb tawm cov zoo tshem tawm hais, organic pigments, thiab ib co colloidal tshuaj nyob rau hauv dej, ua rau lawv nyob rau hauv sib haum xeeb. Cov txheej txheem no ua tau zoo txhim kho qhov kev tshem tawm ntawm turbidity thiab xim.
3. Muaj peev xwm kho tau zoo rau cov pa phem tshwj xeeb
Hauv qee qhov kev lag luam dej khib nyiab, txiv qaub ua lub luag haujlwm tseem ceeb:
Demulsification thiab Roj Tshem Tawm: Rau oily thiab emulsified cov dej khib nyiab, ib puag ncig pH siab tuaj yeem cuam tshuam qhov cuam tshuam ruaj khov ntawm cov roj emulsified, txhawb cov roj demulsification thiab sib cais.
Saponification: Nws muaj peev xwm saponify fatty acids thiab lwm yam organic teeb meem nyob rau hauv cov dej khib nyiab, tsim insoluble calcium soaps, uas yog yooj yim mus tshem tawm.
Chemical Solidification: Rau cov dej khib nyiab uas muaj sulfides, arsenates, thiab lwm yam, nws tuaj yeem tsim cov calcium ntsev ntau ruaj khov, txo lawv cov toxicity thiab tsiv teb tsaws.
4. Kev tshem tawm Hardness
Txiv qaub yog qhov zoo tshaj plaws ntawm kev tshem tawm "carbonate hardness" (piv txwv li, calcium thiab magnesium hardness khi rau bicarbonate ions). Cov tshuaj tiv thaiv tseem ceeb yog "alkalization nag lossis daus ntawm bicarbonate":
Tshem tawm calcium hardness: Ca(OH)₂ + Ca(HCO₃)₂ → 2CaCO₃↓ + 2H₂O
Cov tshuaj tiv thaiv no tseem ceeb heev: sab nraud qhia txog calcium ions (los ntawm txiv qaub) hnov qab nrog calcium bicarbonate hauv dej los tsim calcium carbonate precipitate. Txoj kev xav, tshem tawm 1 molecule ntawm calcium bicarbonate yuav tsum muaj 1 molecule ntawm txiv qaub thiab tsim 2 molecules ntawm calcium carbonate precipitate.
Tshem tawm magnesium hardness: Mg(HCO₃)₂ + 2Ca(OH)₂ → Mg(OH)₂↓ + 2CaCO₃↓ + 2H₂O
Magnesium tshem tawm yuav tsum muaj pH siab dua (feem ntau siab dua 10.5) vim magnesium hydroxide muaj qis solubility. Txiv qaub ua ntej hloov magnesium carbonate rau hauv magnesium hydroxide precipitate, thaum tib lub sij hawm hloov cov bicarbonate ions txuam rau hauv calcium carbonate precipitate.
Hauv cov ntawv thov uas xav tau kev sib sib zog nqus ntawm cov dej khib nyiab (ib txhij tshem tawm ob qho tib si carbonate thiab tsis yog -carbonate hardness), "cov kua qaub- cov txheej txheem dej qab zib" feem ntau yog siv.
Txiv qaub (Ca(OH)₂): Tshem tawm cov carbonate hardness (raws li tau piav qhia saum toj no).
Soda tshauv (Na₂CO₃): Tshem tawm tsis yog{0}} carbon hardness. Piv txwv li:
CaCl₂ + Na₂CO₃ → CaCO₃↓ + 2NaCl
MgSO₄ + Na₂CO₃ + Ca(OH)₂ → Mg(OH)₂↓ + CaCO₃↓ + Na₂SO₄
Cov txheej txheem ua ke no tuaj yeem txo tag nrho hardness mus rau qib qis ntawm pH haum.