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The degradation of a mixture of ibuprofen, naproxen, and diclofenac in various effluents by UVC/H 2 O 2 or UVC/S 2 O 8 2- was studied to assess the impact of the matrix composition and of the oxidant precursor on process efficiency. Experiments were carried out in a 20-L laboratory pilot (a scaled-down version of a full-scale pilot). In effluents collected during dry weather, the rural constructed wetland effluent allowed faster degradation than the urban conventional WWTP effluent, regardless of the nature of the targets or of the oxidant precursor. This was mainly attributed to a three-times higher chemical oxygen demand in the urban effluent, likely to quench the oxidative species. UV fluences to reach 90% degradation of the three compounds were 3,800 and 5,500 mJ cm -2 in the rural effluent, whereas they were 6,600 and 6,100 mJ cm -2 in the urban effluent with H 2 O 2 and S 2 O 8 2- , respectively. After a rainfall event, the rural effluent composition was not significantly affected compared to that of the urban effluent that underwent the dilution effect. Therefore, the stability of the rural effluent composition allowed comparable degradation efficiency, whereas the dilution effect led to a significant increase in the degradation rate constants in the urban effluent (up to four times higher).

In this work, UVA radiation that is part of solar light is taken as the irradiation source and radicals (HO, SO 4 - and HO 2 ) are generated through activation of hydrogen peroxide (H 2 - ) are generated through activation of hydrogen peroxide (H 2 O 2 ), sodium persulfate (Na 2 S 2 O 8 ) and Bismuth catalyst (BiOCl), respectively. The distinguished performance in removing acetaminophen (ACTP), a model pharmaceutical pollutant, by these three radicals was compared for the first time. Effect of pH, halide ions concentration and interfacial mechanism have been investigated in detail. Interestingly, results show that heterogeneous UVA/BiOCl process has higher degradation efficiency than homogeneous UVA/H 2 O 2 and UVA/Na 2 S 2 O 8 systems whatever the solution's pH. To explain these results, second order reaction rate constant (k radical, ACTP ) have been determined with laser flash photolysis (LFP) or radical scavenging experiments. The strongly interfacial-depended HO 2 /O 2 - radicals have the lowest second order rate constant with ACTP but highest steady state concentration. BiOCl is much easier activated by UVA, and outstanding ACTP mineralization can be achieved. Combination of BiOCl and Na 2 S 2 O 8 exhibits synergistic effects rather than antagonism effects with H 2 O 2 . This study highlights the relative effective utilization of solar light through interfacial directed BiOCl photocatalysis and its synergistic effects with traditional oxidants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This review paper describes briefly the cloud aqueous phase composition and deeply its reactivity in the dark and mainly under solar radiation. The role of the main oxidants (hydrogen peroxide, nitrate radical, and hydroxyl radical) is presented with a focus on the hydroxyl radical, which drives the oxidation capacity during the day. Its sources in the aqueous phase, mainly through photochemical mechanisms with H 2 O 2 , iron complexes, or nitrate/nitrite ions, are presented in detail. The formation rate of hydroxyl radical and its steady state concentration evaluated by different authors are listed and compared. Finally, a paragraph is also dedicated to the sinks and the reactivity of the HO • radical with the main compounds found in the cloud aqueous phase. This review presents an assessment of the reactivity in the cloud aqueous phase and shows the significant potential impact that this medium can have on the chemistry of the atmosphere and more generally on the climate.

While the use of transition metal oxides in catalyzing advanced oxidation reactions has been widely investigated, very few reports have focused on how the preliminary contact of oxides with target compounds may affect the succession of reaction. In this study, we examined the adsorption and electron transfer reactions of two fluoroquinolones, flumequine (FLU), and norfloxacin (NOR), with goethite (α-FeOOH) or manganese (Mn) oxide, and their impact on the subsequent mineralization of target compounds using H 2 O 2 or S 2 O 8 2- under UVA irradiation. Intriguingly, higher total organic carbon (TOC) removal was achieved when antibiotics and metal oxides were allowed for preequilibration before starting the oxidation reaction. The rate and extent of TOC removal are strongly dependent on the molecule structure and the redox-active mineral used, and much less on the preequilibration time. This high efficiency can be ascribed to the presence of reduced metal ions, chemically or photochemically generated during the first stage, onto oxide minerals. Oxide-bound Mn II plays a crucial role in catalyzing oxidant decomposition and then producing greater amounts of radical species through a photoassisted redox cycle, regardless of the underlying surface, Mn IV O 2 or Mn III OOH. This finding will be of fundamental and practical significance to Mn-based oxidation reactions and wastewater treatment processes.

The present work describes, for the first time, the use of a new and strong complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS) in the homogeneous Fenton process. The effect of H(2)O(2) concentration, Fe(III)-EDDS concentration, pH value, and oxygen concentration on the homogeneous Fenton degradation of bisphenol A (BPA) used as a model pollutant, was investigated. Surprisingly, the performance of BPA oxidation in an EDDS-driven Fenton reaction was found to be much higher at near neutral or basic pH than at acidic pH. Inhibition and probe studies were conducted to ascertain the role of several radicals (e.g., (•)OH, HO(2)(•)/O(2)(•-)) on BPA degradation. This unexpected effect of pH on Fenton reaction efficiency could be due to the formation of HO(2)(•) or O(2)(•-) radicals and to the presence of different forms of the complex Fe(III)-EDDS as a function of pH. Indeed, the reduction of Fe(III)-EDDS to Fe(II)-EDDS is a crucial step that governs the formation of hydroxyl radical, mainly responsible for BPA degradation. In addition to its ability to maintain iron in soluble form, EDDS acts as a superoxide radical-promoting agent, enhancing the generation of Fe(II) (the rate limiting step) and therefore the production of (•)OH radicals. These results are very promising because they offer an important new treatment option at higher range of pH values and more particularly at pHs encountered in natural conditions.

The main disadvantage of using iron mineral in Fenton-like reactions is that the decomposition rate of organic contaminants is slower than in classic Fenton reaction using ferrous ions at acidic pH. In order to overcome these drawbacks of the Fenton process, chelating agents have been used in the investigation of Fenton heterogeneous reaction with some Fe-bearing minerals. In this work, the effect of new iron complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS), on heterogeneous Fenton and photo-Fenton system using goethite as an iron source was tested at circumneutral pH. Batch experiments including adsorption of EDDS and bisphenol A (BPA) on goethite, H(2)O(2) decomposition, dissolved iron measurement, and BPA degradation were conducted. The effects of pH, H(2)O(2) concentration, EDDS concentration, and goethite dose were studied, and the production of hydroxyl radical ((•)OH) was detected. The addition of EDDS inhibited the heterogeneous Fenton degradation of BPA but also the formation of (•)OH. The presence of EDDS decreases the reactivity of goethite toward H(2)O(2) because EDDS adsorbs strongly onto the goethite surface and alters catalytic sites. However, the addition of EDDS can improve the heterogeneous photo-Fenton degradation of BPA through the propagation into homogeneous reaction and formation of photochemically efficient Fe-EDDS complex. The overall effect of EDDS is dependent on the H(2)O(2) and EDDS concentrations and pH value. The high performance observed at pH 6.2 could be explained by the ability of O (2) (•-) to generate Fe(II) species from Fe(III) reduction. Low concentrations of H(2)O(2) (0.1 mM) and EDDS (0.1 mM) were required as optimal conditions for complete BPA removal. These findings regarding the capability of EDDS/goethite system to promote heterogeneous photo-Fenton oxidation have important practical implications for water treatment technologies.

The processes of Fe(III) activated persulfate (PS) and H 2 O 2 modified by catechin (CAT) had been shown to be effective in degrading contaminants. In this study, the performance, mechanism, degradation pathways and products toxicity of PS (Fe(III)/PS/CAT) and H 2 O 2 (Fe(III)/H 2 O 2 /CAT) systems were compared using atenolol (ATL) as a model contaminant. 91.0% of ATL degradation was reached after 60 min in H 2 O 2 system which was much higher than that in PS system (52.4%) under the same experimental condition. CAT could react directly with H 2 O 2 to produce small amounts of HO• and the degradation efficiency of ATL was proportional to CAT concentration in H 2 O 2 system. However, the optimal CAT concentration was 5 μM in PS system. The performance of H 2 O 2 system was more susceptible to pH than that of PS system. Quenching experiments were conducted indicating that SO 4 •- and HO• were produced in PS system while HO• and O 2 •- accounted for ATL degradation in H 2 O 2 system. Seven pathways with nine byproducts and eight pathways with twelve byproducts were put forward in PS and H 2 O 2 systems respectively. Toxicity experiments showed that the inhibition rates of luminescent bacteria were both decreased about 25% after 60 min reaction in two systems. Although the software simulation result showed few intermediate products of both systems were More toxic than ATL, but the amounts of them were 1–2 orders of magnitude lower than ATL. Moreover, the mineralization rates were 16.4% and 19.0% in PS and H 2 O 2 systems respectively. [Display omitted] • Comparative studies were done in Fe(III)/H 2 O 2 /CAT and Fe(III)/PS/CAT system. • The performance of ATL degradation was efficient in Fe(III)/H 2 O 2 /CAT system. • The ATL degradation rates were slightly affected by pH in Fe(III)/PS/CAT system. • Degradation pathways of ATL in two systems were proposed and compared. • Several byproducts showed less toxicity in two systems. [ABSTRACT FROM AUTHOR]

The present work describes, for the first time, the use of a new and strong complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS) in the homogeneous Fenton process. The effect of H2O2 concentration, Fe(III)-EDDS concentration, pH value, and oxygen concentration on the homogeneous Fenton degradation of bisphenol A (BPA) used as a model pollutant, was investigated. Surprisingly, the performance of BPA oxidation in an EDDS-driven Fenton reaction was found to be much higher at near neutral or basic pH than at acidic pH. Inhibition and probe studies were conducted to ascertain the role of several radicals (e.g., •OH, HO2•/O2•-) on BPA degradation. This unexpected effect of pH on Fenton reaction efficiency could be due to the formation of HO2• or O2•- radicals and to the presence of different forms of the complex Fe(III)-EDDS as a function of pH. Indeed, the reduction of Fe(III)-EDDS to Fe(II)-EDDS is a crucial step that governs the formation of hydroxyl radical, mainly responsible for BPA degradation. In addition to its ability to maintain iron in soluble form, EDDS acts as a superoxide radical-promoting agent, enhancing the generation of Fe(II) (the rate limiting step) and therefore the production of •OH radicals. These results are very promising because they offer an important new treatment option at higher range of pH values and more particularly at pHs encountered in natural conditions. [ABSTRACT FROM AUTHOR]

In the present work we investigate the activation efficiency of H 2 O 2 and S 2 O 8 2− using UVA and UVB radiation. Bisphenol-A (BPA) is used as model pollutants to estimate the oxidative process efficiency in simulated and real sewage treatment plant waters. Particular attention is paid to the BPA removal efficiency and to the radical mechanism involvement considering the effect of typical inorganic water constituents (carbonates and chloride ions) and organic matter. Despite a detrimental effect observed when carbonate ions are in solution using both hydrogen peroxide and persulafate, the presence of high chloride ions concentration was found to improve BPA removal using S 2 O 8 2− as radical precursor. This enhancement, investigated combining chemical kinetic model approach and laser flash photolysis experiments, is attributed to the formation of hydroxyl radical and chlorine radical species from sulfate radical. Different transformation products are identified by means of GC–MS and HPLC-MS analyses. Moreover, experiments using sewage treatment plant water (STPW) spiked with BPA are performed in order to assess the efficiency of oxidative processes in a simulated treatment systems activated using UVA + UVB radiations. [ABSTRACT FROM AUTHOR]

Abstract: The photochemical behaviour of H2O2 in cloud aqueous phase was investigated from a large amount of in situ cloud droplet sampling data. Then we performed laboratory irradiation experiments of real cloud samples, free from gaseous chemistry, in order to factorise between gas phase and liquid phase photochemical reactions. H2O2 was revealed to be sensitive to solar radiation, with higher concentrations during the day. H2O2 was dependent on the degree of air mass pollution with anthropogenic influences leading to lower values of aqueous H2O2. We observed higher differences between day and night of H2O2 concentrations for air masses influenced by anthropogenic activities (mainly Northern direction) compared to those form remote areas (oceanic). Contrary to this field diurnal trend, during laboratory irradiation experiments of the cloud aqueous phase, the concentration showed a regular linear decrease leading to the conclusion that photolysis is more important than photoproduction in cloud aqueous phase. So the diurnal cycle observed during field measurements is due to the high mass transfer from gas phase to liquid phase favoured by the high dispersion of liquid phase and the high solubility of hydrogen peroxide. As a consequence, H2O2 can act as a photochemical source of ls in cloud aqueous phase. [Copyright &y& Elsevier]

• Novel activation of oxidants with the new cubic co-doped magnetite nanoparticles. • High stability of the synthesized photocatalyst after 5 cycles of the processes. • 67% of Sulfalene degradation in real wastewater and under the optimum condition. • 85% of Sulfalene mineralization during the UVA/ Fe 2.5 Co 0.3 Zn 0.2 O 4 /PS process. • Production of nontoxic products during the UVA/Fe 2.5 Co 0.3 Zn 0.2 O 4 /PS process. In this work, the cubic cobalt and zinc doped and co-doped magnetite nanocatalysts were synthesized and characterized using different analysis. The so-synthesized photocatalysts were used for the activation of hydrogen peroxide (HP) and persulfate (PS) under UVA irradiation. The integration of Fe 2.5 Co 0.3 Zn 0.2 O 4 improved the activation of PS and HP; wherein, the UVA/Fe 2.5 Co 0.3 Zn 0.2 O 4 /PS process demonstrated higher degradation performance for Sulfalene (SFL) as a veterinary pharmaceutical contaminant in water. Afterward, the effect of different physicochemical parameters was studied and the radicals generated through the process were identified using chemical scavengers. UVA/Fe 2.5 Co 0.3 Zn 0.2 O 4 /PS process brought about 67% of SFL degradation in real wastewater. Moreover, 85% of TOC removal was achieved within 15 h of the above-mentioned process. Eventually, the phototoxicity of the untreated and treated SFL solution after 120 min of the UVA/Fe 2.5 Co 0.3 Zn 0.2 O 4 /PS process was studied using Lemna minor aquatic species. [ABSTRACT FROM AUTHOR]

In this work, the decomposition of phenanthrene (PHE) in mimic and real soil washing (SW) effluents was investigated using UVB light assisted activation of hydrogen peroxide (H 2 O 2) and peroxydisulfate (PDS) oxidation processes. The impact of oxidant concentration, initial pH, and coexisting inorganic anions (Cl−, HCO 3 − and NO 3 −) on PHE removal was evaluated. PHE degradation efficiency under UVB irradiation followed the order of UVB/PDS > UVB/H 2 O 2 > UVB. The increase of PHE decomposition efficiency was observed with increasing oxidant dose in the range of 2–30 mM upon the two processes. It was found Cl− played different roles in the two activation systems depending on the solution pH and Cl− concentration. The influence of HCO 3 − on PHE elimination was negligible in the UVB/PDS process, while an inhibitory effect was observed in the UVB/H 2 O 2 system. Nitrate inhibited the PHE decay in both UVB/H 2 O 2 and UVB/PDS processes at the investigated pH 3.3, 7.1 and 8.6. Finally, the application of the two activation processes to the treatment of real SW effluents indicated that up to 85.0% of PHE degradation could be reached under 6 h UVB irradiation with PDS, indicating UVB/PDS process is a promising alternative for SW effluent treatment. • PDS is more efficient than H 2 O 2 for UVB decay of PHE in soil washing (SW) effluent. • UVB/PDS process is less impacted by the inorganic ions (Cl−, HCO 3 − and NO 3 −). • UVB/PDS is a promising and sustainable process for real SW effluent treatment. [ABSTRACT FROM AUTHOR]

• The effect of HA coating on MPs was studied in photo-Fenton-like process. • Humic acid coating enhances the H 2 O 2 and S 2 O 8 2− activation for BPA degradation. • Reactive species were identified (OH and SO 4 –) through scavenging experiments. • The recycling and reuse of MP/HA show no loss of activity. • The efficiency of MP/HA was tested in real wastewater sample. Magnetic particles (MPs) coated with humic acid (HA) prepared under anoxic atmosphere were tested as heterogeneous photo-Fenton catalyst for the activation of hydrogen peroxide (H 2 O 2) and persulfate (S 2 O 8 2−) using Bisphenol A (BPA) as a model pollutant. The role of HA coating, pH value and H 2 O 2 /S 2 O 8 2− concentration were investigated. A positive contribution of HA coating on H 2 O 2 and S 2 O 8 2− activation was found. The highest BPA degradation rates were achieved at acidic conditions (pH 3) with both H 2 O 2 and S 2 O 8 2−, however persulfate showed a significant efficiency even at pH 6, interesting feature in the light of decreasing the wastewater treatment costs. By the addition of selective quenching agents, OH and SO 4 – were identified as the main reactive species involved in the BPA abatement. An important contribution of the S 2 O 8 2− photolysis on the overall BPA transformation was highlighted. The reuse of the catalyst was investigated and similar efficiency using H 2 O 2 and S 2 O 8 2− activation was observed until the third catalytic cycle. Experiments carried out using real wastewater samples, showed a good, even if less efficient compared to pure water, BPA removal. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we investigated the degradation of the rivastigmine drug induced by hydroxyl radical in synthetic and natural waters focusing on both reactivity and photoproducts identification. The hydroxyl radical formation rate was quantified by using terephthalic acid as trapping molecule and it was related with the rivastigmine degradation rate. The second order rate constant between hydroxyl radical and rivastigmine was estimated to be ∼5.8 × 109 M−1 s−1. Irradiation of rivastigmine in three natural waters (rain, lake and river) and comparison with degradation rates observed in synthetic solutions using nitrite, nitrate and hydrogen peroxide suggest that, in addition to hydroxyl radical, also nitroderived radicals (NO/NO2) are responsible for the pollutant degradation in natural media. In fact, the evaluated degradation rates in three natural waters are greatly higher than those estimated considering only the reactivity with photogenerated hydroxyl radical. Using nitrites and nitrates as photochemical OH source, the rivastigmine degradation cannot be described considering only the hydroxyl radical reactivity suggesting that NO and NO2 radicals could play a key role during indirect degradation. Moreover main degradation products have been identified by means of HPLC-MS. Hydroxylation of the aromatic ring as well as carbamate and amino chain oxidation were suggested as main reaction mechanisms, but also nitroderived compounds were characterized. Finally polychromatic irradiations of three rivastigmine doped natural waters (rain, river and lake) underlined the role of the indirect degradation that needs to be considered when direct degradation of selected pollutants is negligible under environmental-like conditions. [Copyright &y& Elsevier]

Abstract: In the first part of the work, we investigated the reactivity toward photogenerated hydroxyl radicals ( OH) of seven monocarboxylic acids and six dicarboxylic acids found in natural cloud water. This leads to the proposition of a schematic degradation pathway linking glutaric acid (C5) to complete mineralization into CO2. We report a detailed mechanism on the succinic acid reactivity toward OH leading to the formation of malonic, glyoxylic and consequently oxalic acids and a comparison with reported pathways proposed by the CAPRAM (Chemical Aqueous Phase RAdical Mechanism) is discussed. We also investigated the photooxidation of formic acid under atmospherically relevant conditions leading to the possible formation of oxalic acid via radical mediated recombination. The second part focuses on the polychromatic irradiation (closed to solar irradiation) of a collected cloud aqueous phase showing that irradiation of cloud water leads to the formation of both formic and acetic acids. Carboxylic acid formation increases in the presence of photogenerated hydroxyl radicals from hydrogen peroxide, showing that photooxidation could play a key role in the formation of carboxylic acids under atmospherically relevant conditions. [Copyright &y& Elsevier]

In the present work, the degradation of three estrogens (17β-estradiol (E2), estrone (E1) and 17α-ethinylestradiol (EE2)) was investigated under photoactivation of hydrogen peroxide and persulfate. Lab-scale irradiation experiments showed that both UVA and UVB radiations are able to photoactivate the oxidant precursors, although UVB is more efficient to generate radicals and therefore to degrade the targets. The efficiency of both oxidant precursors was investigated showing higher efficiency in the system with persulfate. The pseudo-first order degradation rate constants and the second order rate constants between the hydroxyl or the sulfate radicals and estrogens were measured. In order to evaluate the process efficiency in real treatment conditions, the degradation of the estrogens spiked into sewage treatment plant effluent was studied. Measurements of second order rate constants between the radical and the effluent organic matter by laser flash photolysis allowed to understand the involved quenching mechanisms. A Yeast Estrogen Screen (YES) assay was used to follow the decrease in estrogenic activity during the estrogen degradation. This assay permitted to ensure that the studied processes are not only able to degrade the estrogens but also to remove their estrogenic activity. ga1 • H 2 O 2 and S 2 O 8 2- are activated by UVA and UVB radiations generating highly reactive radicals. • Wastewater effluent composition inhibits E1, E2 and EE2 photo-induced degradation. • Species containing organic carbon are the main radical quenchers in wastewater effluent. • Estrogenic activity decline was shown to follow E1, E2 and EE2 concentration decrease. [ABSTRACT FROM AUTHOR]