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Diethyl phthalate (DEP) is a pollutant which can be found on soils as a result of its widespread application in plastic industry. Soil contaminated with DEP requires the application of different chemical methods to attain its remediation. Among these methods, ozonation has proven to be effective against toxic soil pollutants. The presence of metal oxides in soil is a possible source of catalytic effect. In this study, it was analyzed the catalytic effect of goethite (α-FeOOH), hematite (α-Fe2O3), and gibbsite (γ-Al(OH)3) in combination with O3 to achieve DEP decomposition. The DEP elimination efficiency by ozonation on the sand increased according to the following order: without catalyst

The carbamazepine (CBZ) abatement is herein evaluated using catalytic ozonation at different NiO concentrations as catalyst: 100, 300, and 500 mg L−1, revealing its total destruction after 5 min of reaction either by conventional or catalytic ozonation. The NiO incorporation in the reactor does not increase the destruction rate, but the catalyst presence enhances the partial mineralization of the contaminant by conversion into oxalic and formic acids and the removal of total organic carbon (TOC) associated with the formation of oxidant species such as hydroxyl radical. Evidence for this behavior is the accumulation rate of the above acids which rise proportionally to the NiO concentration. The highest NiO concentration (500 mg L−1) reached a maximum TOC removal of 79.2%, which exceeds by 50% the outcome of the conventional treatment. The accumulation-decomposition profiles of oxalic and formic acids suggest the occurrence of simultaneous reaction mechanisms (hydroxyl radicals and complex formations) on the catalyst during CBZ ozonation. According to XPS analysis, the presence of nitrogen species in the NiO-ozonated was attributable to byproducts of CBZ decomposition. The toxicity bioassay based on Lactuca sativa seeds demonstrate that ozonated samples attained similar plant germination than the reference substance (water) after 120 min of treatment. This result is comparable with or without the catalyst presence, indicating the formation of non-toxic accumulated byproducts at the end of the ozonation reaction.

This study evaluates naproxen (NP) degradation efficiency by ozonation using nickel oxide films (NiO(F)NiO(F)) as a catalyst. The NiO films were synthesized by chemical vapor deposition and characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. NP degradation was conducted for 5 min using 10 films of NiO(F) comparing against ozonation using 100 mg/L NiO powder in suspension (NiO(s)NiO(S)) and conventional ozonation (O3-conv). Total organic carbon analysis demonstrated a mineralization degree of 12% with O3O3-conv, 35% with NiONiO as powder and 22% with NiO(F)NiO(F) after 60 min of reaction. The films of NiO(F)NiO(F) were sequentially used 4 times in ozonation demonstrating the stability of the synthesized material, as well as its properties as a catalyst for ozonation. A proposed modeling strategy using robust parametric identification techniques allows the comparison of NP decomposition pseudo-monomolecular reaction rates.

In this work, the degradation of terephthalic acid (TA) by vanadium oxide (VxOy) supported on zinc oxide (ZnO) was evaluated in a photocatalytic ozonation treatment based on two UV-A LEDs distribut...

This work evaluated the inhibition effect of low molecular weight alcohol (ethanol) on naproxen (NAP) degradation by conventional and catalytic ozonation. The reaction system considered the ethanol as complementary organic matter in water. The conventional ozonation and in the presence of nickel oxide (O3–NiO) achieved 98% NAP degradation during the first 15 min of reaction despite the presence of ethanol. However, NAP degradation presented a delaying effect during the first minutes of treatment with this alcohol. The latter phenomenon indicates that ethanol concentration played a meaningful role in ozonation effectiveness in comparison with the presence of NiO catalyst. The presence of NiO did not generate differences in the byproducts in comparison with conventional ozonation. The intermediates were detected using the Electrospray Ionization Mass Spectrometry technique and have only one aromatic ring in their chemical structure. In samples without ethanol, these byproducts appeared only in the first 5 min of reaction. The TOC study demonstrated the increment of 25% in the mineralization degree with the presence of NiO due to the formation of ·OH species.

Naphthalene (NA) is a polycyclic aromatic hydrocarbon with toxic properties in aquatic systems. Ozonation (O3) and catalytic ozonation (O3-cat) processes are attractive alternatives of degradation for this kind of compound. NA (20 mg L−1) degradation by conventional and catalytic ozonation in the presence of a cosolvent (ethanol) was the aim of this study. This solution was proposed to simulate some aspects of real wastewaters where not only water acts as solvent. Two proportions of the mixture ethanol/water were selected (30:70 and 50:50) with the purpose of studying the cosolvent effect on NA degradation system by ozonation. O3-cat process used nickel oxide as catalyst (0.1 g L−1). The degradation analysis of NA by O3-cat in two different proportions of cosolvent showed that in the case of 30:70 (ethanol/water), a 95 % of NA elimination in 60 min was obtained, while in the case 50:50 (ethanol/water), only 55 % was achieved. The O3 process showed similar results of degradation to the initial compound in comparison with catalytic system. According to these results, there is an inhibition effect in pollutant removal by ethanol due to the higher ethanol concentration; the lower elimination rate of NA was obtained (by 40 % during the 60 min). The by-products analysis of ozonation process detected oxalic and formic acids. Treatments with NiO presented less production of organic acids in comparison with conventional ozonation process. The high concentration of ethanol has a relevant factor in the elimination of NA and formation of organic acids; samples with 50 % of cosolvent have showed a higher concentration of organic acids. X-ray photoelectron spectroscopy (XPS) study of O3-cat of diluent (O3-NiO control) and O3-NA-NiO showed the presence of –CO3 absorbed on catalyst due to ethanol decomposition.

Ceria films (CeO2(f)) were deposited on glass substrate by a spray pyrolysis method. The catalytic oxidation performance of CeO2(f) was evaluated in the removal of 4-chlorophenol (4-CPh) and 4-phenolsulfonic acid (4-SPh). The catalytic oxidation reactions were carried out in water with ozone as an oxidant agent. Conventional and catalytic ozonation achieved complete removal of both compounds. Furthermore, TOC results showed higher catalytic activity with six CeO2(f) films in comparison with conventional ozonation after 120 min for the oxidation of both 4-CPh and 4-SPh. After five consecutive reuses of CeO2(f), the similar TOC removal for 4-CPh demonstrated the ceria films stability.

Efficient degradation of 2,4-dichlorophenoxyacetic acid (2,4-D, herbicide) aqueous solutions was achieved on NiO/SiO 2 catalysts in presence of ozone. NiO nanoparticles were deposited on the silica surface by impregnation (I) and liquid phase photodeposition (P) in presence of sensitizers (acetone or benzophenone). The most promising method of preparation appears to be the sensitized photodeposition allowing a higher reduction of the precursor (Ni(acac) 2 ) at short irradiation time. The resulting catalysts were characterized by transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDS), and X-ray photoelectron spectroscopy (XPS). It was found from TEM observations, that the size of NiO nanoparticles was smaller than 2 nm for both preparation methods, however the particle size distribution for impregnated catalyst was broader than that of photodeposited catalyst. On the other hand, the surface composition of both catalysts was similar, showing Ni(0), NiO, Ni(OH) 2 as the main species for impregnation, in the case of photodeposition an additional contribution of Ni(acac) 2 were detected. According to the results of catalytic ozonation of 2,4-D, the initial specific activity of the photodeposited catalyst was almost 7 times higher compared with that of impregnation catalyst.

Metallic nanoparticles may be tailored to obtain specific size and morphology. In this work we present the synthesis of Ni/TiO2 catalysts by a photodeposition method. Our investigation included the photochemical and photocatalytic reduction of the nickel organometallic precursor (Ni (II) acetylacetonate) over titania (Degussa P-25) support. The photo-reduction kinetics was followed by UV-Vis and the catalysts were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). According to the results, the photochemical reduction of the Ni precursor was only 30% at λ= 254 nm, whereas, the photocatalytic route was approximately 90 % (λ= 365 nm) yielding Ni nanoparticles with diameter ranging from 10 to 40 nm.