Sodium aluminate silicon tshem tawm yog ib qho tshuaj lom neeg coagulation -adsorption co- txheej txheem nag lossis daus. Nws cov ntsiab lus suav tsis yog kev sib raug zoo stoichiometric yooj yim, tab sis yog ib txoj hauv kev ua haujlwm raws li kev sim, tso siab rau qhov piv txwv, thiab xav tau kev hloov kho.
I. Silicon Tshem Tawm Mechanism
Hydrolysis: Sodium aluminate (NaAlO₂ lossis NaAl (OH)₄) sai hydrolyzes ntxiv rau dej, tsim cov amorphous aluminium hydroxide (Al(OH)₃) colloids nrog rau thaj tsam loj loj thiab muaj zog adsorption muaj peev xwm.
NaAlO₂ + 2H₂O → Al(OH)₃↓ + NaOH
Adsorption thiab coprecipitation: Qhov zoo them Al(OH)₃ colloid tsim neutralizes tus nqi ntawm cov active silica nyob rau hauv dej (xws li HSiO₃⁻, SiO₃²⁻, feem ntau yog sawv cev li SiO₂). Los ntawm adsorption thiab complexation, nws tsim insoluble aluminosilicate complexes los yog swept rau hauv floc thiab co-precipitates.
Al(OH)₃ + x HSiO₃⁻ → Al(OH)₃·(SiO₂)ₓ (Schematic process, non-} qauv tshuaj tiv thaiv formula)
Cov txheej txheem no txiav txim siab tias qhov sib piv ntawm cov tshuaj siv tshuaj (qhov hnyav piv ntawm sodium aluminate rau silica) tsis yog tus nqi theoretical ruaj khov, tab sis yog qhov muaj txiaj ntsig ntawm ntau yam cuam tshuam los ntawm ntau yam.
II. Kev txiav txim siab Chemical Consumption Ratio (R Value)
Tag nrho cov kev suav rov qab nyob ib ncig ntawm qhov tseem ceeb empirical piv, R:
R=Sodium aluminate ntau npaum li cas (mg/L NaAlO₂) / Tus nqi ntawm silicon raug tshem tawm (mg/L SiO₂)
1. Kev txiav txim siab cov ntaub ntawv yooj yim
Raw dej silicon concentration [Si]₀: SiO₂ concentration ntawm cov qauv dej ua ntej kho (mg / L).
Target silicon concentration [Si]ₜ: Qhov xav tau SiO₂ concentration tom qab kho (mg/L).
Tus nqi ntawm silicon yuav raug tshem tawm Δ[Si]: Δ[Si]=[Si]₀ - [Si]ₜ (mg/L SiO₂).
2. Qhov tseem ceeb Empirical Ratio (R)
Qhov no yog qhov tseem ceeb tshaj plaws hauv kev suav thiab yuav tsum tau txais kev sim.
Fluoride thiab Silicon Tshem Tawm Case Study - Nanjing Danheng Technology Co., Ltd.
Feem ntau: Kev xyaum ua haujlwm dav dav qhia tau hais tias tus nqi R feem ntau yog nyob nruab nrab ntawm 8 thiab 20. Qhov no txhais tau tias rau txhua txhua 1 mg ntawm SiO₂ tshem tawm, 8 mg rau 20 mg ntawm sodium aluminate yuav tsum tau ntxiv.
Vim li cas thiaj muaj ntau yam? Vim tias tus nqi R muaj kev cuam tshuam loj heev los ntawm cov hauv qab no thiab yuav tsum tau txiav txim siab los ntawm kev sim beaker:
pH tus nqi: Qhov zoo tshaj pH qhov rais rau kev tshem tawm silica yog nqaim heev, feem ntau ntawm 6.5 thiab 7.5 (tsis muaj zog acidic rau nruab nrab). Yog tias pH tsawg dhau (<6.0), Al(OH)₃ colloids will dissolve into Al³⁺, losing their adsorption capacity; if the pH is too high (>8.0),
Al(OH)₃ yuav yaj mus rau AlO₂⁻, ua rau cov colloids tawg. Qhov zoo tshaj pH point txawv me ntsis nyob ntawm seb cov dej zoo.
Dej kub: Qhov kub thiab txias nce ntxiv molecular thermal zog, accelerates cov tshuaj tiv thaiv tus nqi, thiab txhawb kom zoo dua floc tsim, uas yuav tsim nyog txo tus nqi R.
Coexisting ions hauv dej: Hardness (Ca²⁺, Mg²⁺) txhawb kev flocculation thiab tej zaum yuav txo tus nqi R; thaum cov organic teeb meem sib tw nrog lossis encapsulates colloids, muaj peev xwm nce R tus nqi.
Initial silica concentration: ntau dua thawj zaug yuav ua rau muaj kev tshem tawm ntau dua ib chav tsev ntawm reagent (R tus nqi yuav zoo li qis dua ntawm qhov ntau).
Cov kev mob tshwm sim: Kev sib xyaw siv, lub sij hawm flocculation, thiab lub sij hawm daws txhua qhov cuam tshuam ncaj qha rau cov nyhuv.
3. Ua kev sim beaker los txiav txim siab R thiab pom pH zoo
Siv cov qauv dej nyoos ntawm tib lub ntim.
Thawj txheej ntawm cov kev ntsuam xyuas (tso pH, qhov sib txawv ntau npaum li cas): Kho cov pH ntawm tag nrho cov qauv dej mus rau tus nqi preset (piv txwv li, 7.0), thiab ntxiv sodium aluminate daws ntawm cov gradients sib txawv (xws li, ntau npaum li cas xam raws li R=5, 10, 15, 20...).
Cov txheej txheem thib ob (taw ntau npaum li cas, pH hloov pauv): Xaiv qhov nruab nrab ntau npaum li cas thiab kho cov pH ntawm cov qauv dej mus rau qhov sib txawv (piv txwv li, 6.0, 6.5, 7.0, 7.5, 8.0).
Ua cov txheej txheem nrawm nrawm (sib tov), qeeb stirring (flocculation), thiab static sedimentation ntawm tag nrho cov qauv dej.
Coj tus supernatant thiab txiav txim siab qhov seem SiO₂ concentration.
Plotting Curves: Plot "Dosage - Residual Silicon" nkhaus kom pom qhov tsawg kawg nkaus uas yuav tsum tau ua kom tiav lub hom phiaj [Si]ₜ. Teeb lub "pH - Residual Silicon" nkhaus kom pom qhov pH zoo tshaj plaws rau kev tshem tawm silicon.
Xam R Tus Nqi: Raws li "Dosage - Residual Silicon" nkhaus, nrhiav qhov ntau npaum C (mg/L NaAlO₂) sib raug rau kev ua tiav lub hom phiaj [Si]ₜ. Ces, R=C/Δ[Si].
4. Kev suav tshuaj noj tiag tiag
Thaum tus nqi R thiab qhov zoo tshaj pH tus nqi tsim nyog rau cov dej zoo tam sim no tau txiav txim siab los ntawm kev sim, cov kev suav rau kev ua haujlwm niaj hnub ua tau yooj yim heev:
Theoretical Dosage (mg/L)=R × Δ[Si]
Qhov twg, Δ[Si] yog xam raws li qhov tiag -lub sij hawm soj ntsuam cov dej nyoos silicon concentration thiab lub hom phiaj tus nqi.
III. Auxiliary laij lej thiab kev hloov kho ua haujlwm
Alkalinity Consumption thiab pH Kho Kev Ntsuas:
Sodium aluminate hydrolysis tsim NaOH, siv cov acidity (H⁺) hauv dej. Qhov no txhais tau hais tias cov kua qaub ntxiv (xws li sulfuric acid los yog hydrochloric acid) feem ntau yuav tsum tau kom ruaj khov pH nyob rau hauv qhov kev pom zoo.
Tus nqi ntawm OH⁻ tsim los ntawm hydrolysis ≈ (mg / L NaAlO₂) / 82) * 1000 (mmol / L)
Cov kua qaub yuav tsum tau (raws li 98% H₂SO₄) tuaj yeem kwv yees li: Acid ntau npaum li cas (mg/L) ≈ [yuav tsum tau OH⁻ (mmol/L) × 49]/0.98/η
(Qhov twg 49 yog qhov molar loj ntawm H₂SO₄, 0.98 yog qhov purity, thiab η yog qhov ua tau zoo coefficient)
Nco tseg: Qhov no yog qhov kwv yees kwv yees. Qhov tseeb ntawm cov kua qaub ntxiv yuav tsum tau tswj hwm los ntawm kev tawm tswv yim pH hauv online thiab cov kua qaub twj tso kua mis hloov ntawm PID tswj.
Aluminium residue xam: Tsis yog tag nrho ntxiv aluminium precipitates; ib txhia tseem nyob hauv dej. Cov ntsiab lus txhuas hauv cov dej ntws yuav tsum tau saib xyuas kom ntseeg tau tias nws ua tau raws li cov qauv dej zoo (feem ntau<0.2 mg/L). Adding too much not only wastes the reagent, but can also lead to excessive aluminum levels.