A new methodology to assess the performance of AOPs in complex samples: Application to the degradation of phenolic compounds by O3 and O3/UV-A–Vis

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.

Investigations on Ozone-Based and UV/US-Assisted Synergistic Digestion Methods for the Determination of Total Dissolved Nitrogen in Waters

“…According to the commonly used oxidants in water treatment [33], besides the PS and H 2 O 2 , ozone (O 3 ) may be a compromised alternative for N-compounds digestion, and which can generate •OH by self-decomposition in basic medium or under certain conditions such as UV, ultrasound (US) and microwave (MW) [34,35]. Although ozone has been widely used in water treatment as disinfectant and oxidant, in which transformation of organic micropollutants occurs via direct reaction with O 3 or indirect reaction with hydroxyl radicals [36][37][38][39][40], fewer studies have reported its use for digestion and determination of TDN in waters. Considering the oxidation capacity, safety, self-degradability, removal ability and convenience of oxidant, O 3 was selected as the oxidant for digestion of N-compounds, and then will use UV and/or US to intensify its digestion ability in this study.…”

Emerging Photochemical Processes Involving Iron for Wastewater Treatment

“…EEM-PARAFAC is still in constant improvement, with its application with real-time continuous monitoring [133], machine learning [134], or even for laboratory-scale fluorescence of CECs simultaneous degradation analysis employing AOPs: from heavy polycyclic aromatic hydrocarbons [135], polyphenols [136] to FQs antibiotics [119,137], the latter shown in the Results and Discussion chapter. Therefore, besides from the simultaneous monitoring of the several parent pollutants that can be obtained in a simple, economical and fast way, it can also be elucidated the plausible molecular changes when observing new deconvoluted components corresponding to oxidation by-products.…”

“…2.1, where Lac is the accumulated irradiation (W min), Vi the irradiated volume (m 3 ), Si the irradiated surface (m 2 ) and VT the total volume (m 3 ). The accumulated light is therefore normalized by the solar average intensity, L, which is reported to be 30 W m -2 in Southern Spain [140,141].…”

“…This is a useful procedure commonly employed to normalize the amount of hydrogen peroxide added to the reaction medium and to ensure that the process is not stopped because of the exhaustion of this reagent [191]. The same conditions were employed for photo-Fenton experiments (in both studied pHs, 2.8 and natural 7.7), but with the addition of 5 mg/L of Fe(II) added from a stock solution prepared with FeSO4•7H2O, which is a concentration that has been shown to be effective according to previous works [140,191], and it is also the maximum recommended level for treated wastewater according to the FAO [192]. In the experiments involving Magnox, the desired amount of this solid catalyst was added directly into the pilot plant, leaving 10 min before turning on the UVC lamp to ensure complete homogenization.…”

“…Until now, only a few examples of application of this technique on FQs can be found in chemometrics [201,202] or to describe chemical interactions of these substances [203]. In addition, there are very few examples on the application of this technique to gain further insight into the efficiency of advanced oxidation processes [135,136,140]. Finally, bioassays based on the inhibition halo of E. coli and S. aureus have been used to estimate the antibacterial activity of the effluents derived from the different treatments, relating the results with all the above mentioned methodologies.…”