Title Fotokatalitička razgradnja neonikotinoidnog insekticida u modelnoj otpadnoj vodi Title (english) Photocatalytic degradation of neonicotinoid insecticid in model waste water Author Tatjana Baković Mentor Vesna Tomašić (mentor)Committee member Vesna Tomašić (predsjednik povjerenstva)Committee member Irena Škorić (član povjerenstva)Committee member Vanja Kosar (član povjerenstva)Granter University of Zagreb Defense date and country 2019-09-20, Croatia Scientific / art field, TECHNICAL SCIENCES Abstract Otpadne vode ekološki su problem zbog prisutnosti različitih organskih spojeva koji negativno utječu na zdravlje ljudi, kao i na ekosustav u cjelini. Stoga se prije ispuštanja u okoliš moraju obraditi primjenom različitih metoda, kao što su mehaničko uklanjanje krutog onečišćenja te fizikalnim, biološkim i kemijskim metodama. Napredni oksidacijski procesi koji, između ostalog, uključuju fotokatalitičke procese pokazuju veliku učinkovitost za obradu otpadnih voda i tema su brojnih istraživanja. U ovom radu proučavana je fotokatalitička aktivnost titanijevog dioksida, TiO2, kao potencijalnog fotokatalizatora za fotorazgradnju neonikotinoidnog insekticida imidakloprida. Istraživanja su provedena u pločastom fotoreaktoru s imobiliziranim slojem fotokatalizatora s recirkulacijom reakcijske smjese primjenom UVA zračenja uz prethodnu obradu fotokatalizatora. Reakcija je provedena pri različitim reakcijskim uvjetima, kao što su volumen i protok recirkulacije reakcijske smjese te ukupna površina fotokatalitičkog sloja izloženog zračenju i intenzitet zračenja. Stupanj razgradnje imidakloprida određen je mjerenjem koncentracije imidakloprida prije i nakon provedene reakcije primjenom tekućinske kromatografije visoke djelotvornosti. Međuprodukti fotorazgradnje imidakloprida identificirani su QTof analizom. Predložen je kinetički model i model reaktora, provedena je ocjena prihvatljivosti modela te su procijenjeni parametri modela. Rezultati ispitivanja pokazali su da učinkovitost fotorazgradnje raste s porastom protoka reakcijske smjese, veličine ozračene površine fotokatalizatora odnosno s porastom intenziteta UVA zračenja. Primjenom QTof analize identificirani su glavni međuprodukti fotorazgradnje imidakloprida koji uključuju: hidroksi-imidakloprid, 6-klor-nikotinsku kiselinu, imidakloprid-desnitro-olefin te nepoznatu komponentu čiji sastav nije precizno utvrđen, ali pretpostavljeno je da nastaje otvaranjem imidazolidinskog prstena ili iz odgovarajućeg mono- ili di-hidroksi-imidakloprida. Nađeno je da pri relativno visokim koncentracijama imidakloprida u odnosu na ukupnu aktivnu površinu fotokatalitičkog sloja brzina fotorazgradnje ne ovisi o promjeni koncentracije reaktanta. Zbog toga se brzina fotokatalitičke razgradnje pri uvjetima korištenim u ovom radu može opisati empirijskim kinetičkim modelom za reakciju pseudo-nultog reda.
Abstract (english) Wastewaters are an ecological issue because of the presence different organic compounds which have negative impact on human health, as well as the ecosystem as whole. Before discharging them into the effluent they must be treated properly using different methods, such as mechanical removal of solid contamination, as well as physical, biological and chemical methods. Advanced oxidation processes involving, among other, photocatalytic processes have shown great efficiency for wastewater treatment and have been the topic of much research. In this work, the photocatalytic activity of titanium dioxide, TiO2, was studied as a potential photocatalyst for the photodegradation of neonicotinoid insecticide imidacloprid. The studies were performed in a plate photoreactor with immobilized photocatalyst layer with recirculation of the reaction mixture using UVA radiation with previously pretreated photocatalyst. The reaction was carried out under different reaction conditions, such as the volume and flow rate of the reaction mixture and the total surface area of the photocatalytic layer exposed to irradiation and the intensity of the irradiation. Imidacloprid conversion was determined by measuring imidacloprid concentrations before and after degradation using high performance liquid chromatography. The byproducts of imidacloprid photodegradation were identified by QTof analysis. A kinetic model and reactor model were proposed, validation of the proposed reactor model was performed and model parameters were estimated. The obtained results showed that the efficiency of photodegradation increases with the increase of the flow rate of reaction mixture, with the increase of the irradiated photocatalyst's surface and with the increase of the UVA irradiation intensity. The main byproducts of imidacloprid photodegradation were identified by QTof analysis which include: hydroxy imidacloprid, 6-chloro-nicotinic acid, imidacloprid desnitro olefin and an unknown component whose composition is not well established but it was assumed to be formed by opening an imidazolidine ring or formed from appropriate mono- or di-hydroxy imidacloprid. It was found that at relatively high concentrations of imidacloprid relative to the total active surface of the photocatalytic layer, the rate of photodegradation does not depend on the change in the reactant concentration. Therefore, the rate of photocatalytic degradation under the conditions used in this work can be described by an empirical kinetic model for the pseudo-zero order reaction.
Keywords
heterogena fotokataliza
imidakloprid
titanijev (IV) oksid
pločasti fotoreaktor
kinetika reakcije
reakcijski međuprodukti
Keywords (english)
heterogeneous photocatalysis
imidacloprid
titanium (IV) oxide
plate photoreactor
reaction kinetics
reaction byproducts
Language croatian URN:NBN urn:nbn:hr:149:818704 Project Number: IP-2018-01-8669 Study programme Title: Chemical Engineering - Graduate study Type of resource Text File origin Born digital Access conditions Access restricted to students and staff of home institution Terms of use Created on 2022-02-16 12:19:59
