The influence of factors on the content of low-volatile lipophilic substances in water

V diplomskem delu smo preučevali vpliv temperature, časa in konzerviranja na vsebnost težkohlapnih lipofilnih snovi (TLS) v vzorcih industrijskih odpadnih vod. TLS so nepolarne ali šibko polarne snovi, ki imajo temperaturo vrelišča nad 250 °C. Gre za mineralna, rastlinska in živalska olja, maščobe, masti in voske. Po drugi definiciji gre za vsoto ekstrahiranih nepolarnih ogljikovodikov, ki so določeni z gravimetrično metodo po sušenju na temperaturi 80 °C. Vsebnost TLS smo določili z gravimetrično metodo, ki je temeljila na standardni metodi SIST ISO 11349:2011. Vzorec odpadne vode smo homogenizirali, ekstrahirali s heksanom, nato smo topilo odparili s pomočjo rotacijskega vakuumskega uparjalnika in vzorec stehtali. Rezultati kažejo, da se vsebnost TLS spreminja pod vplivom temperature in časa, medtem ko 7-dnevno konzerviranje pri temperaturi 4 °C in dodatek H2SO4 ohranita vsebnost TLS. Uporabljena metoda je tako primerna za analize, ki se izvedejo v roku 7 dni. Koncentracija TLS se poveča z dvigom temperature na 40 °C (višja ekstrakcijska hitrost) in zmanjša s časom (poteče proces oksidacije). V kislem mediju pri pH<2 poteče kislinska hidroliza lipofilnih snovi. Ugotovili smo, da na vsebnost TLS vplivata tudi čas tehtanja in stabilnost emulzij.The influence of temperature, time and preservation on the content of low-volatile lipophilic substances (LLS) was investigated in the thesis. LLS are unpolar or weakly polar substances, with a boiling temperature above 250 °C, and include mainly mineral oils, vegetable oils, animal oils, fat, greases and waxes. A second definition determines LLS as the sum of substances extractable by non-polar hydrocarbons, determined gravimetrically after drying at 80 °C. The gravimetric method, based on SIST ISO 11349:2011, was used in the thesis. Firstly, the water sample was homogenized and exctracted with hexane, then the solvent was evaporated and finally the sample was weighed. As the results show, temperature and time influence the content of LLS, while 7-day preservation at 4 °C and addition of H2SO4 mantain the same value of LLS. The analysis of samples must be done within 7 days. The concentration of LLS is higher with a rise in temperature to 40 °C (higher extraction rate) and lower over time because of the oxidation process. The acid hydrolysis of LLS occured at pH