Endaweni esihlala kuyo, ukuphepha kwekhwalithi yamanzi kuyisixhumanisi esibalulekile. Kodwa-ke, ikhwalithi yamanzi ayibonakali ngaso sonke isikhathi, futhi ifihla izimfihlo eziningi esingenakuzibona ngqo ngamehlo ethu angenalutho. Isidingo se-chemical oxygen (COD), njengepharamitha ebalulekile ekuhlaziyweni kwekhwalithi yamanzi, sifana nombusi ongabonakali ongasisiza ukubala nokuhlola okuqukethwe kokungcola okungokwemvelo emanzini, ngaleyo ndlela kwembule isimo sangempela sekhwalithi yamanzi.
Cabanga uma indle ekhishini lakho ivaliwe, ingabe kuzoba nephunga elibi? Lelo phunga empeleni likhiqizwa ukubiliswa kwezinto eziphilayo endaweni engenawo umoya-mpilo. I-COD isetshenziselwa ukukala ukuthi kudingeka umoya-mpilo ongakanani lapho lezi zinto eziphilayo (nezinye izinto ezikwazi ukukhiqizwa, njenge-nitrite, usawoti we-ferrous, i-sulfide, njll.) zifakwa emanzini. Kalula nje, lapho inani le-COD liphakeme, kulapho amanzi engcoliswa kakhulu yizinto eziphilayo.
Ukutholwa kwe-COD kubaluleke kakhulu. Kungenye yezinkomba ezibalulekile zokulinganisa izinga lokungcoliswa kwamanzi. Uma inani le-COD liphezulu kakhulu, kusho ukuthi i-oxygen encibilikisiwe emanzini izodliwa ngobuningi. Ngale ndlela, izinto eziphilayo zasemanzini ezidinga i-oxygen ukuze ziphile (njengezinhlanzi nezimfanzi) zizobhekana nenkinga yokusinda, futhi zingase ziholele ngisho nasesimeni "samanzi afile", okubangela ukuthi yonke indawo ibhidlike. Ngakho-ke, ukuhlolwa njalo kwe-COD kufana nokwenza ukuhlolwa ngokomzimba kwekhwalithi yamanzi, ukuthola nokuxazulula izinkinga ngesikhathi esifanele.
Ungayithola kanjani inani le-COD lamasampula amanzi? Lokhu kudinga ukusetshenziswa "kwezikhali" ezithile zobungcweti.
Indlela evame ukusetshenziswa kakhulu yindlela ye-potassium dichromate. Kuzwakala kuyinkimbinkimbi, kodwa empeleni isimiso silula kakhulu:
Isigaba sokulungiselela: Okokuqala, sidinga ukuthatha inani elithile lesampula yamanzi, bese sifaka i-potassium dichromate, "i-super oxidant", bese sifaka i-silver sulfate njenge-catalyst ukuze senze ukusabela kube kuphelele. Uma kukhona ama-ion e-chloride emanzini, kufanele avikelwe nge-mercuric sulfate.
Ukufudumala kwe-reflux: Okulandelayo, fudumeza lezi zingxube ndawonye bese uzivumela ukuthi zisabele ku-sulfuric acid ebilayo. Le nqubo ifana nokunikeza isampula yamanzi "isauna", iveze ukungcola.
Ukuhlaziywa kwe-Titration: Ngemva kokuphela kokusabela, sizosebenzisa i-ammonium ferrous sulfate, "i-reducing agent", ukuze sinciphise i-potassium dichromate esele. Ngokubala ukuthi ingakanani i-reducing agent esetshenziswayo, singakwazi ukwazi ukuthi ingakanani i-oxygen eyasetshenziswa ukuze i-oxidize ukungcola emanzini.
Ngaphezu kwendlela ye-potassium dichromate, kunezinye izindlela ezifana nendlela ye-potassium permanganate. Zinezinzuzo zazo, kodwa inhloso iyafana, okuwukulinganisa ngokunembile inani le-COD.
Njengamanje, indlela ye-rapid digestion spectrophotometry isetshenziswa kakhulu ukuthola i-COD emakethe yasekhaya. Lena indlela yokuthola i-COD ngokushesha esekelwe endleleni ye-potassium dichromate, futhi isebenzisa indinganiso yenqubomgomo ethi “HJ/T 399-2007 Water Quality Demand of Chemical Oxygen Demand Rapid Digestion Spectrophotometry”. Kusukela ngo-1982, uMnu. Ji Guoliang, umsunguli weLianhua Technology, uthuthukise i-COD rapid digestion spectrophotometry kanye nezinsimbi ezihlobene nayo. Ngemva kweminyaka engaphezu kwengu-20 yokukhuthazwa kanye nokuthandwa, ekugcineni yaba indinganiso kazwelonke yezemvelo ngo-2007, iletha ukutholwa kwe-COD enkathini yokuthola okusheshayo.
I-COD rapid digestion spectrophotometry eyenziwe yiLianhua Technology ingathola imiphumela ye-COD enembile zingakapheli imizuzu engama-20.
1. Thatha u-2.5 ml wesampula, engeza i-reagent D kanye ne-reagent E, bese unyakazisa kahle.
2. Shisisa umshini wokugaya we-COD kuma-degrees angu-165, bese ufaka isampula bese uyigaya imizuzu eyi-10.
3. Ngemva kokuba isikhathi sesiphelile, khipha isampula bese uyipholisa imizuzu emi-2.
4. Engeza u-2.5 ml wamanzi acwengekile, shukumisa kahle bese uwapholisa emanzini imizuzu emi-2.
5. Faka isampula ku-I-photometer ye-CODukuze kusetshenziswe umbala. Akukho ukubalwa okudingekayo. Imiphumela iboniswa ngokuzenzakalelayo futhi iphrintwe. Kulula futhi kuyashesha.
Isikhathi sokuthunyelwe: Julayi-25-2024
