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).

No abstract

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.

The photodegradation of an aqueous solution of diclofenac (DCF) has been attempted in the presence of hydrogen peroxide and organic/inorganic hybrid magnetic materials under simulated and real solar light. The hybrid magnetic materials have been prepared via coprecipitation synthesis starting from iron(II) and iron(III) inorganic salts in the presence of bioderived organic products (i.e., chitosan or bio-based substances isolated from commercially available composted urban biowastes) acting as stabilizers of the iron-containing phase. In addition to the as prepared hybrid materials, the corresponding materials obtained after a pyrolytic step at low temperature (550 °C) have been tested. The obtained results evidenced the capability of the materials to activate hydrogen peroxide at mild pH promoting DCF (photo) degradation. All the materials feature also as adsorbents since a decrease of DCF is observed also when working in the dark and in the absence of hydrogen peroxide.

Soybean peroxidase (SBP) has been employed for the treatment of aqueous solutions containing pentachlorophenol (PCP) in the presence of hydrogen peroxide at pH range 5-7. Reaction carried out with 1 mg/L of PCP, 4 mg/L of H2O2 and 1.3 x 10 -9 M of SBP, showed a fast initial elimination of PCP (ca. 30% in 20 min), but the reaction does not go beyond the removal of 50% of the initial concentration of PCP.Modification in SBP and PCP amounts did not change the reaction profile and higher amounts of H2O2 were detrimental for the reaction. Addition of Fe(II) to the system resulted in an acceleration of the process to reach nearly complete PCP removal at pH 5 or 6; this is more probably due to a synergetic effect of the enzymatic process and Fenton reaction. However, experiments developed in tap water resulted in a lower PCP elimination, but this inconvenience can be partly overcome by leaving the tap water overnight in an open vessel before reaction.

ElsevierGarcía Ballesteros, S.; Mora Carbonell, M.; Vicente Candela, R.; Sabater Marco, C.; Castillo López, MÁ.; Arques Sanz, A.; Amat Payá, AM. (2016). Gaining further insight into photo-Fenton treatment of phenolic compounds commonly found in food processing industry. a b s t r a c t A mixture of eight phenolic compounds, namely 2,4-dinitrophenol, tannic, ellagic, gallic, protocatechuic, vanillic, syringic and sinapic acids, have been treated by means of a photo-Fenton process under simulated and real sunlight. An experimental design methodology, based in Doehlert matrixes, was employed to check the effect of the concentration of Fe(II) and H O , as well as pH. Response surfaces show that 2 2Keywords: Photo-Fenton Phenolic compounds Doehlert matrixes Toxicity Excitation emission matrix fluorimetry photo-Fenton can be extended to pH values clearly above 2.8, probably due to complexation of iron with the phenolic substances. Experiments performed under solar irradiation at pH = 3.9 showed that complete removal of the monitored pollutants was achieved in less than 3 min; mineralisation was also efficient, although some organics remained in the solution. Toxicity was monitored according to Pseudokirchneriella subcapitata and Daphnia magna bioassays; Recombinant Yeast Assay (RYA) was employed to assess estrogenic and dioxin-like activities. 2,4-Dinitrophenol was demonstrated to be the major concern and, in general, photo-Fenton resulted in a detoxification of the solution. Finally, excitation emission matrix (EEM) fluorimetry was employed to obtain complementary information on the behaviour of organic matter. Most peaks associated with the parent pollutants disappeared after short irradiation periods and, at 12 min of irradiation chromophores were destroyed, what can be associated with the removal of complex molecules.

Commercial steel wool used for Zero Valent Iron and as a source of disolved iron in a combined red-ox processfor pentachlorophenol degradationm in tap water.