1. Hluav taws xob
Anode
Cov anode thiab cathode muaj cov haujlwm sib txawv thiab muaj cov khoom siv sib txawv.
Muab faib ua ob pawg: soluble thiab insoluble. Nyob rau hauv electrolytic hlwb rau refining tooj liab, cov khoom siv anode yog soluble blister tooj liab yuav refined. Nws yaj mus rau hauv cov tshuaj thaum lub sij hawm electrolysis kom ntxiv cov tooj liab uas tawm ntawm cov tshuaj ntawm lub cathode. Nyob rau hauv electrolytic hlwb siv los electrolyze aqueous daws (xws li cov dej ntsev tov), cov anodes yog insoluble thiab lawv yeej tsis hloov thaum lub sij hawm electrolysis txheej txheem, tab sis lawv feem ntau muaj ib tug catalytic nyhuv ntawm cov tshuaj tiv thaiv anode nqa tawm nyob rau hauv lub electrode nto. Hauv kev lag luam tshuaj, insoluble anodes feem ntau yog siv.
Ntxiv rau qhov ua tau raws li qhov yuav tsum tau ua ntawm cov khoom siv hluav taws xob dav dav (xws li conductivity, catalytic kev ua lub zog, kev ua haujlwm, qhov chaw, nqi), cov ntaub ntawv anode yuav tsum yog insoluble thiab non-passivated nyob rau hauv muaj zog anodic polarization thiab siab dua-kub anolytes. , nrog siab stability. Graphite tau ntev tau siv cov khoom siv anode. Txawm li cas los xij, graphite yog ntxeem tau, muaj lub zog tsis zoo, thiab yooj yim oxidized rau hauv carbon dioxide. Nws yog tas li corroded thiab tev tawm thaum lub sij hawm electrolysis txheej txheem, ua rau lub electrode nrug maj mam nce thiab lub cell voltage nce. Thaum siv rau electrolysis ntawm ntsev dej tov, lub overpotential ntawm chlorine evolution ntawm graphite electrode kuj siab.
Cov hlau oxide electrode tsim los ntawm txheej ruthenium oxide thiab titanium oxide ntawm titanium puag tau npaj los ntawm H. Beer hauv xyoo 1960 yog ib qho kev tsim kho tshiab hauv cov khoom siv anode. Ruthenium dioxide muaj kev ua haujlwm zoo catalytic rau qee qhov kev cuam tshuam anode xws li chlorine evolution thiab oxygen evolution, thiab tuaj yeem ua haujlwm ntawm qhov ceev tam sim no nrog cov xov tooj ntawm tes tsis tshua muaj. Qhov tseem ceeb tshaj plaws yog tias nws muaj tshuaj lom neeg ruaj khov thiab nws lub neej ua haujlwm ntev dua li ntawm graphite anodes. Piv txwv li, nyob rau hauv diaphragm electrolyzers siv nyob rau hauv chlor-alkali ntau lawm, lawv lifespan yuav ncav cuag ntau tshaj 10 xyoo. Vim tias nws tsis yooj yim rau corrode thiab yog qhov ruaj khov, nws yog hu ua dimensionally ruaj khov anode. Txhawm rau hloov mus rau cov kev xav tau sib txawv thiab kev siv, lwm yam khoom siv tuaj yeem muab ntxiv rau txheej txheej. Piv txwv li, ntxiv tin thiab iridium tuaj yeem ua rau muaj zog tshaj ntawm cov pa oxygen thiab txhim kho kev xaiv ntawm cov anode. Ntxiv platinum tuaj yeem txhim kho kev ruaj ntseg ntawm cov electrode. Tam sim no, muaj nuj nqis hlau-coated hlau anodes tau nthuav dav hauv kev lag luam tshuaj.
Nyob rau hauv molten ntsev electrolyzers, vim hais tias qhov kub ntawm electrolysis yog ntau dua li nyob rau hauv aqueous kua electrolyzers, cov kev cai rau cov ntaub ntawv anode yog nruj dua. Rau electrolysis ntawm molten sodium hydroxide, hlau, npib tsib xee thiab lawv cov alloys feem ntau yog siv. Rau electrolysis ntawm molten chloride, tsuas graphite siv tau.
Cathode
Thaum cov hlau los yog hlau yog siv los ua cov cathode, vim nws ua haujlwm ntawm qhov muaj peev xwm tsis zoo, feem ntau nws tuaj yeem ua lub luag haujlwm hauv kev tiv thaiv cathodic thiab tsis tshua muaj corrosive, yog li cov khoom siv cathode yooj yim dua los xaiv. Nyob rau hauv ib tug aqueous electrolytic cell, lub cathode feem ntau tsim ib tug hydrogen evolution cov tshuaj tiv thaiv thiab muaj ib tug siab overpotential. Yog li ntawd, kev txhim kho tseem ceeb ntawm cov khoom siv cathode yog txo cov hydrogen evolution overpotential. Tsuas yog thaum siv sulfuric acid ua cov electrolyte, txhuas lossis graphite yuav tsum tau siv los ua cathode, cov hlau tsis tshua muaj hlau yog cov khoom siv cathode. Txhawm rau txo qis kev siv hluav taws xob, ntau txoj hauv kev tam sim no tau siv los npaj cov cathodes nrog thaj chaw siab tshwj xeeb thiab kev ua haujlwm catalytic, xws li ntxeem tau npib tsib xee plated cathodes.
Txhawm rau txhim kho cov khoom zoo, cov ntaub ntawv tshwj xeeb cathode kuj tseem siv tau. Piv txwv li, nyob rau hauv lub mercury cathode siv los electrolyze dej ntsev tov los tsim caustic soda siv mercury txoj kev, lub siab overpotential ntawm hydrogen evolution los ntawm mercury yog siv los tawm sodium ions los tsim sodium amalgam, uas yog ces siv nyob rau hauv ib tug tshwj xeeb nyob rau hauv lub khoom siv, sodium amalgam yog decomposed nrog dej los npaj high-purity, high-concentration alkali kua. Tsis tas li ntawd, txhawm rau txuag hluav taws xob, lub cathode siv cov pa oxygen kuj tuaj yeem siv los txo cov pa oxygen ntawm cathode los hloov cov tshuaj tiv thaiv hydrogen evolution. Raws li theoretical xam, lub cell voltage yuav raug txo los ntawm 1.23V.
2. Diaphragm
Txhawm rau tiv thaiv kev sib xyaw ntawm cathode thiab anode cov khoom thiab tsis txhob muaj teeb meem tshwm sim, hauv cov hlwb electrolytic, diaphragms yog siv los cais cov cathode thiab anode chamber. Lub diaphragm yuav tsum muaj qee qhov porosity tso cai rau ions hla dhau yam tsis pub cov molecules lossis npuas hla dhau. Thaum tam sim no ntws los ntawm lub diaphragm, lub ohmic voltage poob ntawm lub diaphragm yuav tsum tsawg. Cov kev ua tau zoo no tseem tsis tau hloov pauv thaum siv, thiab lawv yuav tsum muaj tshuaj lom neeg ruaj khov thiab lub zog ua haujlwm raws li kev ua ntawm cov electrolytes hauv cathode thiab anode chambers. Thaum electrolyzing dej, cov electrolytes hauv cathode thiab anode chambers yog tib yam. Lub diaphragm ntawm electrolytic cell tsuas yog yuav tsum tau cais cov cathode thiab anode chambers kom ntseeg tau tias purity ntawm hydrogen thiab oxygen thiab tiv thaiv kev tawg los ntawm kev sib xyaw hydrogen thiab oxygen. Ib qho teeb meem ntau dua thiab nyuaj yog tias cov electrolyte muaj nyob rau hauv cathode thiab anode chambers ntawm electrolytic cell txawv. Nyob rau lub sijhawm no, lub diaphragm kuj yuav tsum tau tiv thaiv kev sib nrig sib diffusion thiab kev sib cuam tshuam ntawm cov khoom siv hluav taws xob hauv cov electrolytes ntawm cathode thiab anode chambers. Piv txwv li, lub diaphragm nyob rau hauv lub diaphragm electrolytic cell nyob rau hauv chlor-alkali ntau lawm yuav ua rau kom cov hydroxide ions los ntawm lub cathode chamber mus rau lub anode chamber.
Diaphragms yog ua los ntawm cov ntaub ntawv inert, xws li asbestos diaphragms ntev siv nyob rau hauv kev lag luam chlor-alkali. Txawm li cas los xij, kev ua haujlwm ntawm asbestos separators tsis ruaj khov. Thaum lub brine muaj calcium thiab magnesium impurities, hydroxide nag lossis daus yog yooj yim generated nyob rau hauv lub separator, txo cov permeability. Ntawm qhov kub thiab txias thiab nyob rau hauv qhov kev txiav txim ntawm electrolyte, o thiab loosening yuav tshwm sim. Tshem tawm. Rau lub hom phiaj no, resin tuaj yeem muab ntxiv rau asbestos los ua cov khoom siv ntxiv, los yog microporous membrane tuaj yeem ua nrog cov resin ua lub cev tseem ceeb, uas tuaj yeem txhim kho kev ruaj ntseg thiab kev ua haujlwm zoo. Cov cation txauv membrane tsim nyob rau hauv chlor-alkali ntau lawm nyob rau hauv xyoo tas los no yog ib yam tshiab ntawm cov ntaub ntawv membrane. Nws muaj kev xaiv rau ion permeation, uas tuaj yeem tiv thaiv chloride ions los ntawm kev nkag mus rau hauv cathode chamber, kom cov tshuaj alkali nrog cov ntsiab lus sodium chloride tsawg heev tuaj yeem tsim tau.