Ukulawulwa kwezimo zokuhlaziya i-COD ekuhlanzeni indle
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1. Isici esibalulekile—ukumelela isampula
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Njengoba amasampula amanzi aqashwe ekuhlanzeni indle ekhaya engalingani ngokwedlulele, isihluthulelo sokuthola imiphumela enembile yokuqapha i-COD ukuthi amasampula kufanele amele. Ukufeza le mfuneko, amaphuzu alandelayo adinga ukuqashelwa.
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1.1 Gubha isampula yamanzi kahle
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Ukuze kulinganiswe amanzi aluhlaza ① namanzi ahlanzekile ②, ibhodlela lesampula kufanele lixhunywe ngokuqinile futhi linyakaziswe kahle ngaphambi kokuthatha isampula ukuze kuhlakazwe izinhlayiya kanye nezinto eziqinile ezimiswe okwesikhashana kusampula yamanzi ngangokunokwenzeka ukuze isampula elifanayo nelimele likwazi etholiwe. Kunamanzi. Kulahlwa ③ kanye ④ osekucace kakhudlwana ngemva kokwelashwa, amasampula amanzi kufanele futhi anyakaziswe kahle ngaphambi kokuthatha amasampuli ukuze akalwe. Lapho kulinganiswa i-COD enanini elikhulu lamasampula amanzi okuthuthwa kwendle, kwatholakala ukuthi ngemva kokuzamazama okwanele, imiphumela yokulinganisa yamasampula amanzi ayijwayele ukuphambuka okukhulu. Kubonisa ukuthi amasampula amele kakhulu.
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1.2 Thatha isampula ngokushesha ngemva kokunyakazisa isampula yamanzi
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Njengoba indle iqukethe inani elikhulu lezinto eziqinile ezimisiwe ezingalingani, uma isampula lingathathwa ngokushesha ngemva kokuzamazama, izinto eziqinile ezimisiwe zizocwila ngokushesha. Ukuhlushwa kwesampula yamanzi, ikakhulukazi ukwakheka kwezinto eziqinile ezimisiwe, ezitholakala ngokusebenzisa ithiphu ye-pipette ukuze kuthathwe isampula ezindaweni ezihlukene phezulu, maphakathi nangaphansi kwebhodlela lesampula kuyoba okuhluke kakhulu, okungakwazi ukumela isimo sangempela sokukhucululwa kwendle, futhi imiphumela elinganisiwe ayimeleli. . Thatha isampula ngokushesha ngemva kokunyakazisa ngokulinganayo. Nakuba amabhamuza enziwa ngenxa yokuzamazama (amanye amabhamuza azoshabalala phakathi nenqubo yokukhipha isampula yamanzi), umthamo wesampula uzoba nephutha elincane enanini eliphelele ngenxa yokuba khona kwamabhamuza asele, kodwa leli yiphutha lokuhlaziya elibangelwa ukuncipha kwenani eliphelele alinakwa uma kuqhathaniswa nephutha elibangelwe ukungahambisani kokumele isampula.
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Ukuhlolwa kokulawulwa kokulinganisa amasampula amanzi ashiywe izikhathi ezihlukene ngemva kokuzamazama kanye nokuthathwa kwamasampula okusheshayo nokuhlaziya ngokushesha ngemva kokunyakazisa amasampula kutholwe ukuthi imiphumela elinganiswe ngaphambilini ichezuke kakhulu ezimeni zangempela zekhwalithi yamanzi.
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1.3 Ivolumu yesampula akufanele ibe mncane kakhulu
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Uma inani lesampula lilincane kakhulu, izinhlayiya ezithile ezibangela ukusetshenziswa okuphezulu kwe-oksijeni emanzini, ikakhulukazi amanzi aluhlaza, angeke asuswe ngenxa yokusatshalaliswa okungalingani, ngakho imiphumela ye-COD elinganisiwe izohluka kakhulu esidingweni sangempela se-oxygen ye-sewage. . Isampula efanayo ihlolwe ngaphansi kwezimo ezifanayo kusetshenziswa amavolumu amasampula angu-2.00, 10.00, 20.00, kanye no-50.00 mL. Kwatholakala ukuthi imiphumela ye-COD elinganiswa ngo-2.00 mL wamanzi aluhlaza noma amanzi angcolile okugcina ngokuvamile ayengahambelani nekhwalithi yangempela yamanzi, futhi ukujwayela kwedatha yezibalo nakho kwakumpofu kakhulu; I-10.00 yasetshenziswa, ukujwayela kwemiphumela yesilinganiso sesampula samanzi esingu-20.00mL kuye kwathuthukiswa kakhulu; ukujwayela kwemiphumela ye-COD yesilinganiso sesampula samanzi esingu-50.00mL kuhle kakhulu.
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Ngakho-ke, emanzini aluhlaza anenani elikhulu le-COD, indlela yokunciphisa ivolumu yesampula akufanele isetshenziswe ngokungaboni ukuze kuhlangatshezwane nezidingo zenani le-potassium dichromate engeziwe kanye nokugxila kwe-titrant esilinganisweni. Kunalokho, kufanele kuqinisekiswe ukuthi isampula inevolumu eyanele yokusampula futhi imele ngokugcwele. Isisekelo siwukulungisa inani le-potassium dichromate elingeziwe kanye nokugxiliswa kwe-titrant ukuze kuhlangatshezwane nezidingo ezikhethekile zekhwalithi yamanzi yesampula, ukuze idatha elinganisiwe izonemba.
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1.4 Guqula ipayipi bese ulungisa uphawu lwesikali
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Njengoba usayizi wezinhlayiyana zama-solids amisiwe kumasampula amanzi ngokuvamile mkhulu kunobubanzi bepayipi lokuphuma le-pipette, kuhlale kunzima ukususa izinto eziqinile ezimisiwe kusampula yamanzi lapho usebenzisa i-pipette evamile ukudlulisa amasampula emfucumfucu yasekhaya. Okukalwa ngale ndlela kuphela inani le-COD lendle elisuse ingxenye eqinile emisiwe. Ngakolunye uhlangothi, ngisho noma ingxenye yezinto eziqinile ezimisiwe zisusiwe, ngenxa yokuthi ichweba lokumunca i-pipette lincane kakhulu, kuthatha isikhathi eside ukugcwalisa isikali, futhi okuqinile okumisiwe okuye kwanyakaziswa ngokulinganayo endle kancane kancane kuyacwila. , futhi impahla ekhishiwe ayilingani ngokwedlulele. , amasampula amanzi angameli izimo zangempela zekhwalithi yamanzi, imiphumela elinganiswe ngale ndlela izoba nephutha elikhulu. Ngakho-ke, ukusebenzisa i-pipette enomlomo omuhle ukumunca amasampula emfucumfucu yasekhaya ukukala i-COD akukwazi ukunikeza imiphumela enembile. Ngakho-ke, lapho ufaka amasampula amanzi okuthuthwa kwamanzi asekhaya, ikakhulukazi amasampula amanzi anenani elikhulu lezinhlayiya ezinkulu ezimisiwe, i-pipette kufanele iguqulwe kancane ukuze ikhulise ububanzi be-pores ukuze okuqinile okumisiwe kuhoxiswe ngokushesha, bese umugqa wesikali kufanele ube. kulungisiwe. , okwenza ukulinganisa kube lula.
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2. Lungisa ukugxila kanye nevolumu yama-reagents
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Endleleni yokuhlaziya ye-COD ejwayelekile, ukugcwala kwe-potassium dichromate kuvamise ukuba ngu-0.025mol/L, inani elingezwe ngesikhathi sokukalwa kwesampula ngu-5.00mL, kanye nevolumu yesampula yokukhuculula indle ngu-10.00mL. Uma ukugcwala kwe-COD kokukhucululwa kwendle kuphezulu, indlela yokuthatha amasampuli amancane noma amasampuli okuhlanjululwa ngokuvamile isetshenziselwa ukuhlangabezana nemikhawulo yokuhlola yezimo ezingenhla. Kodwa-ke, u-Lian Huaneng uhlinzeka ngama-COD ama-reagents amasampula wokugxila okuhlukile. Ukugxila kwalawa ma-reagents kuyaguqulwa, ukugxila kanye nevolumu ye-potassium dichromate kuyalungiswa, futhi ngemva kwenani elikhulu lokuhlola, ahlangabezana nezidingo zokuthola i-COD yazo zonke izigaba zokuphila.
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Ukufingqa, lapho uqapha futhi uhlaziya i-COD yekhwalithi yamanzi emanzini asekhaya, isici sokulawula esibucayi kakhulu ukumelela isampula. Uma lokhu kungenakuqinisekiswa, noma noma isiphi isixhumanisi esithinta ukumelela ikhwalithi yamanzi sizitshwa, imiphumela yokulinganisa neyokuhlaziya izobe inemba. amaphutha aholela eziphethweni eziyiphutha zobuchwepheshe.
OkusheshayoUkutholwa kwe-CODIndlela eyakhiwe yi-Lianhua ngo-1982 ingathola imiphumela ye-COD phakathi nemizuzu engama-20. Umsebenzi uqondiswa futhi ithuluzi selivele lisungule ijika, lisusa isidingo se-titration nokuguqulwa, okunciphisa kakhulu amaphutha abangelwa ukusebenza. Le ndlela iye yaqondisa ukusungulwa kwezobuchwepheshe emkhakheni wokuhlolwa kwekhwalithi yamanzi futhi yenza iminikelo emikhulu.
Isikhathi sokuthumela: May-11-2024
