Volumetric method for determination of free and bound carbon dioxide in water

Raztopljeni anorganski ogljik (DIC) je prisoten v vseh naravnih vodah v prosti obliki kot raztopljeni ogljikov dioksid in vezani obliki kot hidrogen karbonatni in karbonatni ion. Agresivna ogljikova kislina je v vodi prisotna kadar imamo preseženo količino CO2. Raztopljeni CO2 je glavna spremenljivka v kemiji vod in je običajno glavna kislina v celinskih vodah na katere ni vplival kisli dež ter je glavni krivec za raztapljanje karbonatnih kamnin. Te reakcije pretvorijo raztopljeni CO2 v HCO3- in CO32- ione, kar vpliva na alkaliteto vode. Alkaliteta je zelo pomemben parameter pri ovrednotenju kemijskega stanja naravnih vod. Pomeni sposobnost vode, da nevtralizira povečano koncentracijo H3O+ ionov. Ugotovitve dokazujejo, da klasičnih izračunov alkalitete za površinske naravne vode ne moremo uporabiti za geotermalne vode, podtalnice in deževnice. V diplomskem delu je prikazana volumetrična analiza (odprt sistem) prostega in vezanega CO2, katerega vsebnosti so odvisne od temperature in pH vode. Rezultati volumetrične metode kažejo, da količina CO2 v obliki ogljikove kisline z naraščanjem pH pada. Vsebnost hidrogen karbonatnih ionov do pH 8,2 narašča, kjer koncentracija doseže vrh, z nadaljnjim naraščanjem pH se vsebnost HCO3- začne nižati, viša pa se koncentracija CO32- ionov. Nadalje se je izkazalo, da na količino posameznih vrst CO2 vpliva tudi temperatura. Z višanjem temperature se v vodi raztaplja manjša količina CO2, kar lahko ima za posledico izločanje apnenca. Pri primerjavi rezultatov, ki mo jih pridobili pri približno enakih temperaturah, pride do odstopanja vsebnosti ogljikovih vrst, pri čemer je potrebno upoštevati, da so vzorci bili odvzetih na različnih mestih z različno geološko sestavo tal.Dissolved inorganic carbon (DIC) is present in all natural waters in free form as dissolved carbon dioxide and in bound form as hydrogen carbonate and carbonate ion. Aggressive carbonic acid is present in water when we have an excess of CO2. Dissolved CO2 is the main variable in chemical water and is usually the main acid in inland waters that have not been affected by acid rain and is the main cause of carbonate rock dissolution. These reactions convert dissolved CO2 into HCO3- and CO32- ions, which affects alkaline waters. Alkalinity is a very important parameter in the assessment of the chemical status of natural waters. It denotes the ability of water to neutralize the increased concentration of H3O+ ions. The results prove that the classically calculated alkalinities for natural surface waters cannot be used for geothermal waters, groundwater and stormwater. The thesis presents a volumetric analysis of free and bound CO2, both of which are temperature dependent in the pH of water. The results of the volumetric forms show that the amount of CO2 in carbonic acid increases with increasing pH. The content of hydrogen carbonate ions increases up to a pH of 8.38, where the concentration peaks. As the pH continues to increase, the content of HCO3- begins to decrease and the concentration of CO32- ions increases. In addition, it turns out that any type of CO2 affects the temperature. As the temperature increases, a smaller amount of CO2 dissolves in the water, which can lead to precipitation of limestone. Based on the results obtained at approximately the same temperatures, the content of carbon species differs, considering that the samples were taken at different locations with a very different geological composition