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BN CHT QU TRNH KH TRNG BNG CLO Cl l mt cht oxi ha mnh, bt c dng no. Khi tc dng vi nc to ra nhiu phn t axit hypoclorit HOCl c tc dng kh trng rt mnh. Qu trnh dit vi khun xy ra qua 2 giai on. u tin cht kh trng khuch tn xuyn qua lp v t bo vi sinh, sau phn ng vi lp men bn trong t bo v ph hoi qu trnh trao i cht dn dn s dit vong ca t bo.
Tc ca qu trnh kh trng tng khi nng ca cht kh trng v nhit nc tng ng thi ph thuc vo dng khng phn ly ca cht kh trng, v qu trnh khuch tn qua v t bo xy ra nhanh hn qu trnh phn ly. Tc kh trng b chm i rt nhiu khi trong nc c cc cht hu c, cn l lng v cc cht kh khc.
2. Cc phn ng ha hc xy ra khi cho Clo vo nc (Clo ha nc)Phn ng c trng ca qu trnh l s thy phn ca Clo to ra axit hypoclorit v axit clohydricCl2 + H2O = HOCl + HClHoc dng phng trnh phn ly:Cl2 + H2O = 2H+ + OCl- + Cl- Khi s dng Clorua vi lm cht kh trng thCa(OCl)2 + H2O = CaO + 2HOCl2HOCl = 2H+ + 2OCl-Kh nng dit trng ca Clo ph thuc vo hm lng ca HOCl. M s phn ly ca HOCl li ph thuc vo nng ion H+ c trong nc hay thuc vo pH ca nc. Kt qu thc nghim cho thy qu trnh thy phn ca Clo xy ra hon ton khi pH>4. Khi pH=6 th HOCl chim 99.5% cn OCL- chim 0.5%Khi pH=7 th HOCl chim 79% cn OCl- chim 21%Khi pH=8 th HOCl chim 259% OCl- chim 75%Khi pH tng, nng HOCl gim l cho hiu qu kh trng gim i tng ng.
Khi trong nc c ammoniac, cc mui amoni hay cc hp cht hu c c cha nhm amoni. Th Clo, axit hypoclorit, ion hypoclorit tham gia vo phn ng vi chng to thnh monocloramin v dicloraminHOCl + NH3 = NH2Cl + H2OHOCl + NH2Cl = NH2Cl + H2OHOCl + NHCL2 = NCl3 + H2O kt hp 1mg clo t do thnh monocloramin cn 0,2 mg ammoniac. Tr s pH cng cao th lng clo kt hp thnh dicloramin cng t v nng monocloramin trong nc cng cao, ng thi kh nng dit trng cng gim i. Kh nng dit trng ca monocloramin thp hn ca dicloramin khong 3 n 5 ln. So vi clo th kh nng dit trng ca dicloramin li thp hn t 20 n 25 ln. Clo kt hp thnh cloramin gi l clo kt hp, tng hm lng ca clo t do , Cl2, HOCl OCl- v Clo kt hp gi l clo hot tnh.Nh vy khi kh trng nc c cha ammoniac v mui amoni, mun t c hiu qu cao nht, cn s dng mt lng clo ln c c lng clo d cn thit l clo t do. m bo cho qu trnh kh trng t c hon ton, sau khi kh trng cn gi li mt lng clo d thch hp. Do kh nng dit trng khc nhau ca clo t do v clo kt hp, lng clo d cn thit cng khc nhau. Lng clo a vo nc c xc nh theo thc nghim.Ti liu: X l nc cp ca TS. Nguyn Ngc DungBottom of Form