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Kontinuirano povećavanje upotrebe pesticida u suvremenoj poljoprivredi postaje neizbježno zbog učinkovitije proizvodnje hrane i samog porasta svjetske populacije. No, s druge strane sve je veća zabrinutost javnih institucija zbog štetnosti pesticida na ljude, druge organizme (domaće životinje, korisne insekte, pčele, ptice, ribe i dr.) i njihovu bio akumulaciju u samome tlu i svim vodenim ekosustavima. Stoga je u ovom radom analizirana fotolitička i fotokatalitička razgradnja s fotokatalizatorima titan dioksid (TiO2) i nanokompozitom titan doksida i ugljikovih nanocjevčica (TiO2/CNT) imidakloprida u pilot reaktoru s paraboličnim zrcalima (eng. compound parabolic collector, CPC). Prema kinetici razgradnje prvog reda, određene su približne konstante brzine fotolitičke razgradnje imidakloprida (k=0,0058 min-1) i fotokatalitičke razgradnje imidakloprida s TiO2 (k=0,0058 min-1) i s TiO2/CNT (k=0,00934 min-1). Primjenom TiO2/CNT fotokatalizatora može se postići brža razgradnja imidakloprida za 3,6 sati, u odnosu na fotokatalitičku razgradnju sTiO2. Analizom razgradbenih produkata, utvrđena su tri (m/z=212,0585; m/z=209,0589 te m/z= 211,0745) od četiri najčešća fotolitički razgradbena produkta imidakloprida, dok je svega jedan razgradbeni spoj (m/z= 274,0518) imidakloprida utvrđen pri fotokatalitičkoj razgradnji na TiO2 i TiO2/CNT fotokatalizatorima. To ukazuje na potrebu detaljnije analize, budući da su se eksperimenti provodili pri realnim uvjetima sunčeva zračenja. The continuous increase in the usage of pesticides in modern agriculture is becoming inevitable due to more efficient food production and the increase in world population. On the other hand, harmful effects of pesticides on humans and other organisms (domestic animals, beneficial insects, bees, birds, fish, etc.) cause concerns of public institutions due to their bio accumulation effect on the soil and aquatic ecosystems. Therefore, in this paper, the photolytic and photocatalytic degradation with photocatalysts titanium dioxide (TiO2) and nanocomposite of titanium dioxide and carbon nanotubes (TiO2/CNT) of imidacloprid in a pilot reactor with compound parabolic mirrors (CPC) was analysed. According to the kinetics of the pseudo first-order degradation, the apparent rate constants of the photolytic degradation of imidacloprid (k=0.0058 min-1) and the photocatalytic degradation of imidacloprid with TiO2 (k=0.0058 min-1) and with TiO2/CNT (k=0.00934 min-1) were determined. Faster degradation (3.6 hours) of imidacloprid can be achieved using TiO2/CNT photocatalyst in comparison to the usage of TiO2. The analysis of the degradation products revealed three (m/z=212.0585; m/z=209.0589 and m/z= 211.0745) out of the four most common photolytic degradation by-products of imidacloprid, while only one degradation compound (m/z = 274.0518) of imidacloprid was determined during photocatalytic degradation on TiO2 and TiO2/CNT photocatalysts. It indicates the need for a more detailed analysis since the experiments were carried out under the actual conditions of solar radiation. |
