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Farmaceutici su tvari koje se koriste zbog svoje specifične biološke aktivnosti, a zbog potencijalne toksičnosti te bioakumulacije u okolišu i organizmima mogu predstavljati opasnost za živi svijet. Konvencionalni sustavi za obradu otpadnih voda nisu se pokazali kao dovoljno učinkoviti za uklanjanje takvih onečišćivala. Jedna od mogućih metoda za rješenje tog problema upravo kemijska oksidacija primjenom ferata (VI). Prednost njihove upotrebe odnosi se na činjenicu da se upotrebljavaju kao oksidacijsko, ali i koagulacijsko sredstvo te se tako gotovo simultano odvijanjem dvaju procesa može povećati ukupna učinkovitost uklanjanja onečišćivala. Cilj ovoga rada bio je istražiti učinkovitost primjene ferata, odnosno željeza oksidacijskog stanja (VI) za uklanjanje triju farmaceutika (diklofenaka - DCF, deksametazona - DXM i karbamazepina - CBZ) iz vode u jednokomponentnom, ali i trokomponentnom sustavu. Primjenom statističkog planiranja eksperimenta i metode odzivnih površina određeni su optimalni uvjeti za uklanjanje pojedinog farmaceutika iz sustava. Učinkovitost uklanjanja farmaceutika praćena je tekućinskom kromatografijom visoke djelotvornosti. Određeni su okolišni pokazatelji, KPK (kemijska potrošnja kisika), BPK5 (biološka potrošnja kisika) te akutna toksičnost u odnosu na slatkovodne račiće Daphnia magna. Utvrđeno je kako se procesom primjene Fe (VI) uklanjanje DCF i DXM može opisati kinetičkim modelom prvog reda s pripadajućim konstantama brzine, kobs(DCF)=8.47*10^-2 s^-1 i kobs(DXM)=2.894 s^-1, a uklanjanje CBZ kinetičkim modelom nultog reda s pripadajućom konstantom brzine kobs1(CBZ)=3.0181 M*s^-1. U trokomponentnom sustavu kinetika uklanjanja DCF i DXM može se opisati kinetičkim modelom prvog reda s pripadajućim konstantama brzine kobs(DXM)=6.73*10^-2 s^-1, kobs(DCF)= 6.69 s^-1, a kinetika uklanjanja CBZ kinetičkim modelom nultog reda s pripadajućom konstantom brzine kobs(CBZ)=1,0279 M*s^-1. Uzorci DCF i DXM nakon obrade feratima (VI) pokazali su se biorazgradivima, dok su uzorci CBZ i mješavine farmaceutika nisu biorazgradivi i nakon obrade feratima, iako se njihova biorazgradivost poboljšala u odnosu na modelne otopine. Akutna toksičnost uzoraka nakon obrade feratima (VI) smanjila se u odnosu na modelne otopine, isključivo u slučaju DCF-a gdje se toksičnost povećala što upućuje na nastanak razgradnih produkata veće toksičnosti. Pharmaceuticals are chemical compunds that are being used due to their biological activity, and because of potential toxicity nature they can pose a risk in the environment. Conventional wastewater treatment plants is not highly efficient due to their low efficiency of removal for those pollutants. Chemical oxidation with application of ferrates (VI) proved to be efficient for the removal of that type of pollutants in the environment. The advantage of using the ferrates (VI) asoxidation as well as coagulation agent almost simultaneously, could possibly enhance overall efiiciency of removal of pollutants. The aim of this study was to investigate the efficiency of using the ferrate (VI) as an oxidation agent for removing three pharmaceuticals (diclofenac – DCF, dexamethasone – DXM and carbamazepine – CBZ) from water in one-component as well as a three-component system. Optimal conditions for the removal of pharmaceutics have been determined by implementing the statistic planning of experiments and a responce surface methodology (RSM). The efficiency of removing of pharmaceutics has been monitored using chromatographic analytical method and determination of certain environmental indicators, COD (chemical oxygen demand), BOD5 (biological oxygen demand) and acute toxicity on the organism Daphnia magna were determined. It has been found that the removal of DCF and DXM can be described with first rate kinetic models with corresponding rate constants, kobs(DCF)=8.47*10^-2 s^-1 and kobs(DXM)=2.894 s^-1, but the removal of CBZ can be described with zero rate kinetic model with corresponding rate constant, kobs1(CBZ)=3.0181 M*s^-1. In the three-component system the kinetics of the removal of DCF and DXM can be described with first rate kinetic models with corresponding rate constants, kobs(DXM)=6.73*10^-2 s^-1, kobs(DCF)= 6.69 s^-1 but the removal of CBZ can be described with a zero rate kinetic model with a corresponding rate constant, kobs(CBZ)=1,0279 M*s^-1. The DCF samples after the ferrate (VI) treatment can be described as biodegradable, while DXM samples as partially biodegradable. CBZ and MIX solutions were still non-biodegradable after the ferrate (VI) treatment, even though their biodegradability increased compared to model solutions. Acute toxicity of samples decreased after the ferrate (VI) treatment compared to model solutions, except in the case of DCF treatment where the higher acute toxicity was obtained suggesting the possible development of degradation products of higher toxicity. |
