The valorization
of olive oil mill solid wastes (OMW) has been
addressed by considering it as a possible source of humic-like substances
(HLSs), to be used as auxiliary substances for photo-Fenton, employing
caffeine as a target pollutant to test the efficiency of this approach.
The OMW-HLS isolation encompassed the OMW basic hydrolysis, followed
by ultrafiltration and drying. OMW-HLS structural features have been
investigated by means of laser light scattering, fluorescence, size
exclusion chromatography, and thermogravimetric analysis; moreover,
the capability of OMW-HLS to generate reactive species under irradiation
has been investigated using spin-trap electronic paramagnetic resonance.
The caffeine degradation by means of photo-Fenton process driven at
pH = 5 was significantly increased by the addition of 10 mg/L of OMW-HLS.
Under the mechanistic point of view, it could be hypothesized that
singlet oxygen is not playing a relevant role, whereas other oxidants
(mainly OH
•
radicals) can be considered as the key
species in promoting caffeine degradation.
Humic-like substances (HLS) extracted from urban wastes have been tested as auxiliaries for the photo-Fenton removal of thiabendazole (TBZ) under simulated sunlight. Experimental design methodology based on Doehlert matrices was employed to check the effects of hydrogen peroxide concentration, HLS amount as well as TBZ loading; this last parameter was studied in the range 25-100 mg/L, to include values below and above the limit of solubility at pH = 5. Very satisfactory results were reached when TBZ was above solubility if HLS and HO amounts were high. This could be attributed to an interaction of HLS-TBZ that enhances the solubility of the pollutant. Additional evidence supporting the latter interaction was obtained by fluorescence measurements (excitation emission matrices) and parallel factor analysis (PARAFAC).
A methodology combining experimental design methodology, liquid chromatography, excitation emission matrixes (EEM) and bioassays has been applied to study the performance of O3 and O3/UVA-vis in the treatment of a mixture of eight phenolic pollutants. An experimental design methodology based on Doehlert matrixes was employed to determine the effect of pH (between 3 and 12), ozone dosage (02-1.0 g/h) and initial concentration of the pollutants (1-6 mg/L each). The following conclusions were obtained: a) acidic pH and low O3 dosage resulted in an inefficient process, b) increasing pH and O3 amount produced an enhancement of the reaction, and c) 2 interaction of basic pH and high amounts of ozone decreased the efficiency of the process. The combination of O3/UVA-vis was able to enhance ozonation in those experimental regions were this reagent was less efficient, namely low pH and low ozone dosages. The application of EEM-PARAFAC showed four components, corresponding to the parent pollutants and three different groups of reaction product and its evolution with time. Bioassys indicated important detoxification (from 100% to less than 30% after 1 min of treatment with initial pollutant concentration of 6 mg/L, pH = 9 and ozone dosage of 0.8 g/h) according to the studied methods (D. magna and P. subcapitata). Also estrogenic activity and dioxin-like behavior were significantly decreased.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.