Toxicology Aspects of the Decomposition of Diuron by Advanced Oxidation Processes

Diuron is a phenylurea-based residual herbicide with toxic and endocrine disrupting effects. The aims of the present work were the comparison of the efficiency of various advanced oxidation processes, such as direct ultraviolet photolysis, ozonation, their combination, and heterogeneous photocatalysis from the point of view of the transformation rate of diuron, rate of mineralisation and dehalogenation, formation of aromatic intermediates, and ecotoxicological effects of the formed multicomponent solutions during the treatments. The initial rates of transformation of diuron are in the order of ozonation < heterogeneous photocatalysis < UV photolysis < combination of UV photolysis and ozonation. Each method provided similar tendencies in the decrease of the concentration of organically bound chlorines (AOX) since, until the diuron was completely degraded, the concentration of AOX decreased almost to zero in each case. However, only heterogeneous photocatalysis was found to be effective in terms of mineralisation. Ecotoxicological results showed that in each case, except for ozonation, the toxicity of the treated solutions changed through a maximum during the transformation of diuron. The maximum value was found to be lower in the case of heterogeneous photocatalysis. Thus, the formation and decomposition of by-products of relatively higher toxicity than diuron can be supposed. Our results confirmed that the amount of the formed (aromatic) intermediates, their quality and specific toxicity strongly depend on the applied processes

Gyógyszernyomok eltávolítása tisztított szennyvizekből nagyhatékonyságú oxidációs eljárásokkal = Removal of trace pharmacuticals form clarified wastewaters by Advanced Oxidation Processes

A projekt megvalósítása során olyan nagyhatékonyságú oxidációs eljárásokon (AOP) alapuló vízkezelési eljárásokat dolgoztunk ki, amelyek alkalmasak biológiailag kezelt szennyvizekben nagyon kicsiny koncentrációban visszamaradó gyógyszernyomok és bomlástermékeik költséghatékony és eredményes eltávolítására. A munkához kellő megbízhatóságú és kimutatási képességű analitikai módszereket fejlesztettünk ki és adaptáltunk. Modellvegyületként ibuprofent, ketoprofent, diklofenakot, naproxent választottunk, de vizsgáltunk antibiotikumot (perfloxacint) is. Az ózon és UV sugárzás kombinációján alapuló módszer jól használható és kellően költség-hatékony az egyszerűen és gazdaságosan üzemeltethető olyan kisnyomású higanygőz-lámpára alapozva, amelynek az ózont termelő 185 nm-es komponensét is hasznosítani tudjuk. Megvizsgáltuk továbbá a vákuum-ultraibolya (VUV) fotolízis és a heterogén fotokatalízis alkalmazhatóságát is. A munkából 12 rangos nemzetközi folyóiratban megjelent dolgozat született (összesített impakt faktor 42,9), 37 előadás hangzott el nemzetközi és hazai konferenciákon, Szabó Rita elkészítette doktori (PhD) dolgozatát, valamint több diplomadolgozat és diákköri dolgozat is készült a tématerületen. | In this project a new wastewater treatment method was developed, based on a novel concept to eliminate toxic organic contaminants of pharmaceutical origin in wastewater effluents and which operates on the principle of combined innovative application of a range of advanced oxidation processes (AOPs). For the reaction kinetic measurements analytical methods with good accuracy, correctness and an unusually low detection limit were developed and adapted, which enables to analyze the components with ppb concentrations. The chosen pharmaceutical compounds were; ketoprofen, ibuprofen, diclophenac, naproxen and one of the antibiotics, the perfloxacin. The combination of ozone and UV-radiation treatment method proved to be the most promising both in terms of cost efficiency and effectiveness. A specific low pressure mercury vapour lamp equipped with a VUV transparent quartz sleeve (transparent to the ozone producing 185 nm component of the light source) was applied. VUV photolysis and heterogeneous photocatalysis also were used in order to compare the applicability of various methods based on the generation of reactive free-radicals. During the elaboration of this project, 12 papers were published (their summarized impact factor is 42.9), 37 conference presentation were held on international and national conferences. Rita Szabó prepared her PhD thesis in this topic and numerous diploma theses were prepared by students worked in this project

Effect of irradiation wavelength on the heterogeneous photocatalytic removal of organic pollutants using TiO2 and ZnO

The efficiency of TiO2 and ZnO was compared during the photocatalytic removal of neonicotinoid pesticides (imidacloprid and thiacloprid) and sulfonamide antibiotics (sulfamethazine and sulfamethoxypyridazine), causing severe environmental and health problems. The differences between LEDs emitting at 365 nm and 398 nm were compared, and removal efficiencies were tested in tap water and biologically treated wastewater matrices. The effect of the most abundant anions, Cland HCO3 on the removal efficiency and •OH formation was also compared. TiO2 was more sensitive to the matrices and the irradiation wavelength. •OH production was higher for TiO2, and 398 nm photons resulted in a higher contribution of •OH. Efficiencies were not reduced by matrix components for ZnO, which is mainly the result of increased •OH-production by Cl- . In the case of TiO2 and 365 nm photons, the formation of CO3 from HCO3 -was assumed. For TiO2, the significant inhibition of matrices could not be explained solely by the effect of anions