20.500.12556/DKUM-77443 Razvoj metode za določevanje ekvivalentne točke pri obarjanju fluoridov iz ekstrakta po obdelavi izrabljenih katodnih ostankov elektrolize aluminija diplomsko delo univerzitetnega študijskega programa I. stopnje Development of a method for determination of the equivalent point of the fluoride precipitation from the extract after leaching of the spent pot linings from alumina smelting process V diplomskem delu smo se osredotočili na razvoj metode, s katero bi najlažje določili ekvivalentno točko obarjanja fluoridnih ionov. Problem izhaja iz raztopine vodnega ekstrakta katodnih ostankov, ki so bili izločeni iz uporabe v proizvodnji aluminija. Za namene recikliranja odpadkov in varovanja okolja pred nevarnimi snovmi je potrebno fluor iz raztopine odstraniti. Ena od metod je obarjanje s kalcijevimi ioni, ki jih uvajamo s suspenzijo kalcijevega hidroksida. Obarjanje poteka po reakciji: Ca(OH)2(s)+2NaF(aq) → CaF2(s) + 2NaOH(aq) Imamo opravka z dvema različnima oborinama, to sta Ca(OH)2 in CaF2. Topnostni produkt drugega (Ksp = 3,9*10-9) je bistveno manjši od prvega (Ksp = 5,5*10-6), kar omogoča uspešno obarjanje CaF2. Tekom raziskovanja je bilo ugotovljeno, da direktno merjenje ekvivalentne točke s pH ali prevodnostjo ni mogoče. V raziskavi je bila ugotovljena pomembna razlika v motnosti posamezne oborine. Na podlagi tega lahko izmerimo ekvivalentno točko obarjanja, kar je bilo ključno pri načrtovanju metode. Izkaže se, da je merjenje motnosti oborin veliko bolj natančna metoda kot merjenje koncentracije fluoridnih ionov, saj je v osnovi merjena raztopina zelo alkalna, ISE za fluor pa zahteva merilno območje pH vzorca med 5 in 8 in tako ne omogoča direktnega merjenja. Ugotovili smo tudi, da se ves fluor ne izobori, saj mu to preprečuje ionsko ravnotežje obarjalne raztopine. Z analizo motnosti smo se približali meritvi ekvivalentne točke, ki smo nato z merjenjem fluora natančno potrdili. In the diploma thesis, we focused on the development of a method that would most easily determine the equivalent precipitation point of fluoride ions. The source of fluoride ions is found in the aqueous extract of spent pot linings that have been eliminated from use in aluminum production. To recycle waste and protect the environment from hazardous substances, fluoride must be removed from the solution. One of the methods is precipitation with calcium ions, which are added with a suspension of calcium hydroxide. A precipitation reaction is as follows: Ca(OH)2(s) + 2NaF(aq) → CaF2(s) + 2NaOH(aq) We are dealing with two different precipitates, namely Ca(OH)2 and CaF2. The solubility product of the second one is (Ksp = 3.9*10-9) significantly lower than the first one (Ksp = 5.5*10-6), which allows successful precipitation of fluorspar. During the study, it was found that direct measurement of the equivalent point with pH or conductivity is not possible. The study found a significant difference in the turbidity of each precipitate. Based on this, we can measure the equivalent precipitation point, which was crucial in the design of the method. It turns out that measuring the turbidity of precipitation is a much more practical method than measuring the concentration of fluoride ions, as the measured solution is very alkaline, and the fluoride ISE requires a pH measuring range between 5 and 8 does not allow direct measurement. We also found that not all fluoride is perticipated due to the ionic balance of the species in the precipitating solution. The turbidity analysis was used to approach the measurement of the equivalent point, which was later confirmed accurately by measuring the concentration of fluoride. obarjanje kalcijev fluorid ekvivalentna točka motnost kalcijev hidroksid precipitation calcium fluoride equivalent point turbidity calcium hydroxide true true false [E. Mihelič] Slovenski jezik Angleški jezik Diplomsko delo/naloga 2020-08-31 13:56:04 2020-10-08 13:31:42 2022-08-09 15:33:55 2020-10-16 03:16:07 2020 0 Maribor 0 Maribor X, 47 str. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 66.066.7:628.316.12(043.2) 32457731 URN:SI:UM:DK:KSOEEAWF UN_Mihelic_Erik_2020.pdf UN_Mihelic_Erik_2020.pdf 1 D40BC353F3D3E423433643C49F2F46AA 60d65e4d23167721242231afefb0f4fd8d2db6e8ecf37e830a8f0e2a7a2698a9 c4d21258-7c11-11eb-bb7a-00155d0001ca 20.500.12556/dkum/e153e01b-4239-4e98-a6f6-85c0a50144ad https://dk.um.si/Dokument.php?lang=slv&id=145025 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0