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The impacts of chlorination on methylparaben (MP) removal, as well as of bromide and ammonia on the MP elimination kinetics, were studied. Bromide and ammonia react with chlorine and are promptly transformed into bromine and chloramines, respectively. Rate constants of chlorine, bromine, and monochloramine with MP were determined under different pH conditions. At pH 8.5, the apparent second-order rate constants of MP reactions with chlorine and bromine were found to be 3.37(±0.50) × 101 and 2.37 (±0.11) × 106 M-1.s-1 for kChlorine/MP and kBromine/MP, respectively, yet there was low reactivity with monochloramine ( $$ {\mathrm{k}}_{{\mathrm{NH}}_2\mathrm{Cl}/\mathrm{MP}} $$ = 0.045 M-1.s-1). Regarding chlorination and bromination, in order to gain further insight into the observed pH-dependence of the reaction, the elementary reactions were considered and the corresponding second-order rate constants were calculated. The experimental and modeled values were quite consistent under these conditions. Then, chlorination experiments with different bromide and/or ammonia concentrations were performed to assess the impact of inorganic water content on MP elimination and a kinetic model was designed to assess MP degradation. Under these conditions, MP degradation was found to be enhanced in the presence of bromide whereas it was inhibited in the presence of ammonia, and the overall impact was pH dependent.

With questions emerging on the presence and risks associated with metabolites and transformation products (TPs) of organic contaminants in the aquatic environment, progress has been made in terms of monitoring and regulation of pesticide metabolites. However, less interest is shown for pharmaceutical residues, although their pseudo-persistence and adverse effects on non-target organisms are proven. This study provides original knowledge about the contamination of ten sites located along three French rivers (water, sediments, biofilms, clams) by pharmaceutical metabolites and TPs, as well as a preliminary environmental risk assessment. Studied compounds included carbamazepine with five metabolites and TPs, and diclofenac with three metabolites and TPs. Results show that metabolites and TPs are present in all studied compartments, with mean concentrations up to 0.52 µg L-1 in water, 229 ng g-1 in sediments, 2153 ng g-1 in biofilms, and 1149 ng g-1 in clams. QSAR estimations (OECD toolbox) were involved to predict the studied compounds ecotoxicities. QSAR models showed that diclofenac and its metabolites and TPs could be more toxic than carbamazepine and its metabolites and TPs to three aquatic species representing green algae, invertebrates, and fish. However, real ecotoxicological effects are still to be determined. The environmental risk assessment showed that hydroxydiclofenac, 2-[(2-chlorophenyl)-amino]-benzaldehyde and dibenzazepine could present a greater risk than other studied compounds for aquatic organisms. In addition, the risk associated with a mixture of diclofenac and its related metabolites and TPs has been found to be greater than that of the compounds considered individually.

In this study, aqueous solutions of gallic acid (GA) were irradiated in an electron beam (EB) accelerator under different experimental conditions (various initial GA concentrations, presence or absence of oxidant and oxygen). For an initial GA concentration of 50 μM, complete GA degradation was achieved with an absorbed dose of 850 Gy in the presence of dissolved oxygen. Both GA removal and mineralization are favored when oxygen is present. The addition of persulfate anions (S2O82−) or hydrogen peroxide (H2O2) also increased the efficiency of GA degradation and mineralization. For an absorbed dose of 14 kGy, GA mineralization reached approximately 45%, 55%, and 72% for the EB, EB/H2O2, and EB/S2O82−systems, respectively. Three transformation products were tentatively identified in the presence of oxygen, these are the result of hydroxylation and ring opening reactions. No specific transformation product was found for the sulfate radical anion (SO4–●) reaction. Four additional compounds, including a dimer, were identified in oxygen-free solutions. These findings demonstrate that water radiolysis based on EB irradiation is an efficient process to activate H2O2 and S2O82− anions and is an advanced oxidation process (AOP).

This study focused on the presence of three biocidal products specific to healthcare facilities, i.e. chlorhexidine digluconate (CHD), bis(aminopropyl)laurylamine (BAPLA), and didecyldimethylammonium chloride (DDAC), in a hospital sewage system. Five sampling campaigns were conducted in 2016 and 2017 throughout the entire Poitiers University Hospital sewage system. DDAC concentrations ranging from 933 ± 119 to 3250 ± 482 μg/L were detected in 24-h composite samples, while lower concentrations (both within the same range) were detected for the two other compounds (i.e. 25 ± 5 to 97 ± 39 μg/L for CHD and 18 ± 3 to 142 ± 16 μg/L for BAPLA). Based on these findings, a mass balance was determined for these discharged compounds to compare the quantities detected in discharges to the amounts used for healthcare in the hospital. Hence, 60–90% of the quantities of DDAC used were found to be present at the hospital sewage outfall. Higher percentages of CHD (100–242%) were noted because of the high presumably quantities used for antiseptic applications, which were not considered in mass balance calculation. Finally, only 10–30% of BAPLA quantities used were detected at the site outfall. Analysis of the results for the different sampling points revealed the nature of the emission sources. For surface applications of DDAC and BAPLA, management of hospital linen is thus a major source of discharged biocidal products, probably following the washing of biocide-soaked textiles used for hospital facility maintenance. Moreover, discharge of biocidal products from a healthcare establishment depends especially on biocide handling practices in the emitting establishment. For BAPLA, compliance with hospital recommended dosages and practices whereby operators are required to prepare tailored quantities of detergents and disinfectants for each specific task could largely explain the limited release of this compound.

The degradation of acetic acid in aqueous solution by ionizing radiation was studied. The radiolysis of acetic acid solution induces the almost complete degradation and mineralization of this compound. The high yield of acetic acid mineralization is explained by the degradation of oxalic acid by solvated electron. The degradation of acetic acid depends on the pH of the solution. The best degradation is observed at pH 4.5 due to the higher rate constant of reaction of acetate with hydroxyl radicals and the competitive reactions of inorganic carbon which occur at higher pH. The influence of persulfate ion (S 2 O 8 2− ) addition that forms the sulfate radical (SO 4 − ) during irradiation in solution was examined. The persulfate addition induces an almost constant degradation of acetic acid whatever the initial pH of the solution. The decrease of pH during the persulfate radiolysis partly explains the high degradation observed. But the additional radicals formed by the persulfate introduction also improve the degradation.

These days, the use of persulfate in advanced oxidation processes (AOPs) has gained more attention as an emerging clean and efficient technology to degrade the organic pollutants. The objective of this study was to investigate the effect of the addition of persulfate on the oxidation of benzotriazole (BT) and humic acids (HAs) by irradiation. The degradation of BT (3.7 μM) was followed under the influence of persulfate addition (200–500 μM) in combination with a fixed radiation dose (15 Gy) in the absence and presence of HA (5 and 20 mg/L) in deionized water. The main results obtained in this study on the degradation of BT in the presence of HA showed a different effect of S 2 O 8 2− addition during irradiation, depending on whether HA are oxidized or not-oxidized. (1) An inhibitory effect of S 2 O 8 2− was observed in the presence of non-oxidized HA. (2) The removal of BT was generally more important during irradiation in the presence of S 2 O 8 2− when HA is pre-oxidized. This could be explained by the different structures of humic acids. These differences of structures of HA were identified by physico-chemical parameters such as the absorbance in the UV (254 nm), the fluorescence and the SUVA measurement.

The radiolysis of persulfate (S2O82−) aqueous solution was studied for the enhancement of electron beam process applied to water treatment. It was shown that the persulfate ion reacts with aqueous electron and produces additional radical species in aqueous solution. The oxidative radical species formed (sulfate radical SO4− ) is a very strong oxidant able to react with various recalcitrant pollutants. A model of the evolution of persulfate concentration in solution was performed. It was shown that the presence of persulfate induces a decrease of pH and also an increase of dissolved oxygen concentration in solution during irradiation. Moreover the interest of persulfate addition for the improvement of an organic compound degradation by radiolysis was shown.

Nowadays the removal of organic micropollutants is one of the major challenges of water and wastewater treatment plants. The objective of this study was to investigate the influence of persulfate addition on micropollutants degradation by ionizing radiation. In this system, the radicals SO4 −/OH can be present simultaneously due to persulfate reaction with solvated electrons. Ibuprofen (IB), progesterone (Pg) and benzotriazole (BT) have been selected for this study. The degradation of micropollutants was followed at various radiation doses and under the influence of persulfate (S2O82−) addition at a fixed dose (30 Gy), in deionized and tap water. In deionized water the addition of 500 μM persulfate improved the degradation of BT, IB and Pg by 17%, 36% and 24% respectively and the removal of micropollutants was increased when the concentration of persulfate ions increased. No influence of the presence of persulfate ions was observed in tap water. Contrary to tap water experiments, the persulfate (500 μM) increases the elimination of BT slightly in the presence of bicarbonate ions. In the case of IB and Pg the influence of persulfate addition is significant even in the presence of bicarbonate ions which indicate that the bicarbonate ions do not completely inhibit the influence of persulfate addition in tap water. Even if the bicarbonate ions have an inhibitory effect on the irradiation system, it was suggested that the inhibition could be explained by the presence of nitrate ions, which would prevent the formation of sulfate radicals.

International audience; This work aims at envisaging the use of a solid catalyst in the catalytic ozonation process to avoid the separation step needed after the treatment for catalyst recovery when powdered material is involved. This work devoted to the removal of succinic acid (SA), a low molecular weight refractory organic acid whose heterogeneous catalytic ozonation was previously studied using powder form catalysts. Heterogeneous catalytic ozonation of succinic acid was carried out in a reactor fitted with a recirculation loop. This study investigated if the location of the solid catalyst, i.e. inside the reactor in the zone of ozone transfer or in a cartridge placed on the recirculation loop, had an influence on the amount of SA removed or on the elimination rate expression. No influence of the catalyst location was detected. The rates of SA removal by catalytic ozonation were found to depend on both the catalyst concentration and the initial SA concentration for weak SA initial concentrations, but only on the catalyst concentration for greater initial SA concentrations. The pattern of SA concentration from modelization closely matched the experimental results. This implementation of the catalytic ozonation process with solid catalyst is of interest for the application at industrial scale. The 1.8 ratio between the rates of SA and DOC removal showed that mineralization to CO2 did not occur simultaneously with SA removal.

International audience; The aim of this study was to assess the impact of chlorination on the degradation of one of the most commonly used UV filters (benzophenone-3 (BP-3)) and the effects of bromide and ammonia on the kinetics of BP-3 elimination. Bromide and ammonia are rapidly converted to bromine and chloramines during chlorination. At first, the rate constants of chlorine, bromine and monochloramine with BP-3 were determined at various pH levels. BP-3 was found to react rapidly with chlorine and bromine, with values of apparent second order rate constants equal to 1.25(±0.14) × 10(3) M(-1)·s(-1) and 4.04(±0.54) × 10(6) M(-1)·s(-1) at pH 8.5 for kChlorine/BP-3 and kBromine/BP-3, respectively, whereas low monochloramine reactivity was observed (kNH2Cl/BP-3 = 0.112 M(-1)·s(-1)). To assess the impact of the inorganic content of water on BP-3 degradation, chlorination experiments with different added concentrations of bromide and/or ammonia were conducted. Under these conditions, BP-3 degradation was found to be enhanced in the presence of bromide due to the formation of bromine, whereas it was inhibited in the presence of ammonia. However, the results obtained were pH dependent. Finally, a kinetic model considering 18 reactions was developed using Copasi to estimate BP-3 degradation during chlorination in the presence of bromide and ammonia.

This study has been undertaken to determine the conditions of formation of organoiodinated compounds responsible for medicinal tastes and odors frequently observed after chlorination of waters containing iodides. It has been shown that iodoform was formed in the presence of chloramines, in a region where the formation of the most classical chlorinated and brominated THMs is usually unfavored. Reactions would take place between monochloramine, organic matter, and iodides to yield iodoform. These interactions are favored when iodide ions are replaced by iodine. Oxidation by iodine alone in the presence of ammonia and without monochloramine does not explain the yield of the iodinated THMs observed. However, nitrogenated molecules such as amines and amino acids would take part during chlorination in the production of organoiodinated compounds to a small extent.

International audience; This work was carried out to investigate the fate of the antibiotic levofloxacin upon oxidation with ozone and hydroxyl radicals. A kinetic study was conducted at 20 degrees C for each oxidant. Ozonation experiments were performed using a competitive kinetic method with carbamazepin as competitor. Significant levofloxacin removal was observed during ozonation and a rate constant value of 6.0 x 10(4) M-1 s(-1) was obtained at pH 7.2. An H2O2/UV system was used for the formation of hydroxyl radicals HO.. The rate constant of HO was determined in the presence of a high H2O2 concentration. The kinetic expressions yielded a k(Ho/LVF) value of 4.5 x 10(9) M-1 s(-1) at pH 6.0 and 5.2 x 10(9) M-1 s(-1) at pH 7.2. These results were used to develop a model to predict the efficacy of the ozonation process and pharmaceutical removal was estimated under different ozonation conditions (i.e. oxidant concentrations and contact times). The results showed that levofloxacin was completely degraded by molecular ozone during ozonation of water and that hydroxyl radicals had no effect in real waters conditions. Moreover, LC/MS/MS and toxicity assays using Lumistox test were performed to identify ozonation transformation products. Under these conditions, four transformation products were observed and their chemical structures were proposed. The results showed an increase in toxicity during ozonation, even after degradation of all of the observed transformation products. The formation of other transformation products not identified under our experimental conditions could be responsible for the observed toxicity. These products might be ozone-resistant and more toxic to Vibrio fisheri than levofloxacin

The aim of this work was to study the mechanism of oxidation of dicarboxylic acids by hydroxyl radicals resulting from the photolysis of hydrogen peroxide. Experiments have been carried out with aqueous solutions (Co ≈ 1 mmol.L−1) of malonic acid, hydroxymalonic, ketomalonic, succinic, malic and tartaric acids. Results showed that in the presence of dissolved oxygen, OH• reacts with hydroxyacids by H-abstraction at the carbon atom carrying the hydroxyl group. The radical formed fixes one oxygen molecule and then releases one HO2 • radical. On the other hand, the reaction of OH• radicals with the unsubstituted analogues leads to a C-C bond cleavage. In each case, the mechanism proposed involves oxygen consumption.

The effect of phenolic compounds (phenol and p-nitrophenol) on the removal of chlorite in aqueous solution (50 mg/L; pH=7.2; 20 o C) by filtration though granular activated carbon beds (3.0g of CECA 40 activated carbon) was examined. No reaction between chlorite and phenol or p-nitrophenol was observed in the absence of activated carbon. The presence of phenol or p-nitrophenol in solution or preadsorbed on carbon decreased the capacity of activated carbon to remove chlorite. High-performance liquid chromatography, total organic halogen, and gas chromatography/mass spectrometry analyses showed that many organic byproducts such as chlorophenols, p-benzoquinone, dimerization, and carboxylation products were formed on the surface of activated carbon

The removal of phenol (Co = 100 μM) during electron beam irradiation was studied in pure water and in the presence of HCO 3 − and Br − ions. It was found that the introduction of S 2 O 8 2− ions (1 mM), by generating SO 4 − radicals increases the radiation yield of phenol removal. 90% removal of phenol was obtained with radiation doses 600 and 1200 Gy with and without S 2 O 8 2− ions respectively. This system induced smaller oxygen consumption with smaller concentration of catechol and hydroquinone found in the solution. HCO 3 − and Br − have an inhibiting effect in the presence as in the absence of S 2 O 8 2− . In most cases, the introduction of S 2 O 8 2− ions in water radiolysis system can advantageously increase the yield of organic compounds removal by oxidation.

The photolysis of S(2)O(8)(2-) was studied for the removal of acetic acid in aqueous solution and compared with the H(2)O(2)/UV system. The SO(4)(-) radicals generated from the UV irradiation of S(2)O(8)(2-) ions yield a greater mineralization of acetic acid than the ()OH radicals. Acetic acid is oxidized by SO(4)(-) radicals without significant formation of intermediate by-products. Increasing system pH results in the formation of ()OH radicals from SO(4)(-) radicals. Maximum acetic acid degradation occurred at pH 5. The results suggest that above this pH, competitive reactions with the carbon mineralized inhibit the reaction of the solute with SO(4)(-) and also ()OH radicals. Scavenging effects of two naturally occurring ions were tested; in contrast to HCO(3)(-) ions, the presence of Cl(-) ions enhances the efficiency of the S(2)O(8)(2-)/UV process towards the acetate removal. It is attributed to the formation of the Cl() radical and its great reactivity towards acetate.