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A primary pollution source by pharmaceuticals is hospital wastewater (HWW). Herein, the methods involved in the action of a biological system (BS, aerobic activated sludge) or a sonochemical treatment (US, 375 kHz and 30.8 W), for degrading four relevant pharmaceuticals (azithromycin, ciprofloxacin, paracetamol, and valsartan) in HWW, are shown. Before treatment of HWW, the correct performance of BS was assessed using glucose as a reference substance, monitoring oxygen consumption, and organic carbon removal. Meanwhile, for US, a preliminary test using ciprofloxacin in distilled water was carried out. The determination of risk quotients (RQ) and theoretical analyses about reactive moieties on these target substances are also presented. For both, the degradation of the pharmaceuticals and the calculation of RQ, analyses were performed by LC-MS/MS. The BS action decreased the concentration of paracetamol and valsartan by ∼96 and 86%, respectively. However, a poor action on azithromycin (2% removal) was found, whereas ciprofloxacin concentration increased ∼20%; leading to an RQ value of 1.61 (high risk) for the pharmaceuticals mixture. The analyses using a biodegradation pathway predictor (EAWAG-BDD methodology) revealed that the amide group on paracetamol and alkyl moieties on valsartan could experience aerobic biotransformations. In turn, US action decreased the concentration of the four pharmaceuticals (removals > 60% for azithromycin, ciprofloxacin, and paracetamol), diminishing the environmental risk (RQ: 0.51 for the target pharmaceuticals mixture). Atomic charge analyses (based on the electronegativity equalization method) were performed, showing that the amino-sugar on azithromycin; piperazyl ring, and double bond close to the two carbonyls on ciprofloxacin, acetamide group on paracetamol, and the alkyl moieties bonded to the amide group of valsartan are the most susceptible moieties to attacks by sonogenerated radicals. The LC-MS/MS analytical methodology, RQ calculations, and theoretical analyses allowed for determining the degrading performance of BS and US toward the target pollutants in HWW.•Biological and sonochemical treatments as useful methods for degrading 4 representative pharmaceuticals are presented.•Sonochemical treatment had higher degrading action than the biological one on the target pharmaceuticals.•Methodologies for risk environmental calculation and identification of moieties on the pharmaceuticals susceptible to radical attacks are shown., Competing Interests: 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., (© 2023 The Author(s).)

Mid-high-frequency ultrasound (200-1000 kHz) eliminates organic pollutants and also generates H 2 O 2 . To take advantage of H 2 O 2 , iron species can be added, generating a hybrid sono-Fenton process (sF). This paper presents the possibilities and limitations of sF. Heterogeneous (a natural mineral) and homogeneous (Fe 2+ and Fe 3+ ions) iron sources were considered. Acetaminophen, ciprofloxacin, and methyl orange were the target organic pollutants. Ultrasound alone induced the pollutants degradation, and the dual competing role of the natural mineral (0.02-0.20 g L -1 ) meant that it had no significant effects on the elimination of pollutants. In contrast, both Fe 2+ and Fe 3+ ions enhanced the pollutants' degradation, and the elimination using Fe 2+ was better because of its higher reactivity toward H 2 O 2 . However, the enhancement decreased at high Fe 2+ concentrations (e.g., 5 mg L -1 ) because of scavenger effects. The Fe 2+ addition significantly accelerated the elimination of acetaminophen and methyl orange. For ciprofloxacin, at short treatment times, the degradation was enhanced, but the pollutant complexation with Fe 3+ that came from the Fenton reaction caused degradation to stop. Additionally, sF did not decrease the antimicrobial activity associated with ciprofloxacin, whereas ultrasound alone did. Therefore, the chemical structure of the pollutant plays a crucial role in the feasibility of the sF process.

This work considered the sonochemical degradation (using a bath-type reactor, at 375 kHz and 106.3 W L -1 , 250 mL of sample) of three representative halogenated pharmaceuticals (cloxacillin, diclofenac, and losartan) in urine matrices. The action route of the process was initially established. Then, the selectivity of the sonochemical system, to degrade the target pharmaceuticals in simulated fresh urine was compared with electrochemical oxidation (using a BDD anode, at 1.88 mA cm -2 ), and UVC/H 2 O 2 (at 60 W of light and 500 mol L -1 of H 2 O 2 ). Also, the treatment of cloxacillin in an actual urine sample by ultrasound and UVC/H 2 O 2 was evaluated. More than 90% of the target compounds concentration, in the simulated matrix, was removed after 60 min of sonication. However, the sono-treatment of cloxacillin in the real sample was less efficient than in the synthetic urine. The ultrasonic process achieved 43% of degradation after 90 min of treatment in the actual matrix. In the sonochemical system, hydroxyl radicals in the interfacial zone were the main degrading agents. Meanwhile, in the electrochemical process, electrogenerated HOCl was responsible for the elimination of pharmaceuticals. In turn, in UVC/H 2 O 2 both direct photolysis and hydroxyl radicals degraded the target pollutants. Interestingly, the degradation by ultrasound of the pharmaceuticals in synthetic fresh urine was very close to the observed in distilled water. Indeed, the sonodegradation had a higher selectivity than the other two processes. Despite the sono-treatment of cloxacillin was affected by the actual matrix components, this contrasts with the UVC/H 2 O 2 , which was completely inhibited in the real urine. The sonochemical process led to 100% of antimicrobial activity (AA) elimination after 75 min sonication in the synthetic urine, and ∼ 20% of AA was diminished after 90 min of treatment in the real matrix. The AA decreasing was linked to the transformations of the penicillin nucleus on cloxacillin, the region most prone to electrophilic attacks by radicals according to a density theory functional analysis. Finally, predictions of biological activity confirmed that the sono-treatment decreased the activity associated with cloxacillin, diclofenac, and losartan, highlighting the positive environmental impact of degradation of chlorinated pharmaceuticals in urine., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Losartan is a highly consumed antihypertensive worldwide and commonly found in effluents of municipal wastewater treatment plants. In the environment, losartan can promote harmful effects on organisms. Thus, an option to face this pollutant is the treatment by photochemical advanced oxidation processes. This dataset has two main components: 1) theoretical calculations on reactivity indexes for losartan, and 2) degradation of the pollutant throughout TiO 2 -photocatalysis and UVC/persulfate (UVC/PS). The first part of the work presents the data about HOMO and LUMO energies, optimized geometry, dipolar moment, HOMO/LUMO energy gap and total density distribution, in addition to ionization energy, electron affinity, chemical potential, hardness, softness and electrophilicity for losartan. Meanwhile, the second one depicts information on the routes involved in the degradation of the pharmaceutical by the oxidation processes, mineralization, toxicity evolution and losartan removal from a complex matrix (synthetic fresh urine). The data reported herein may be utilized for further researches related to elimination of pharmaceuticals in primary pollution sources such as urine. Moreover, this work also provides experimental and theoretical data useful for the understanding of the response of losartan to oxidative and photochemical processes., (© 2020 The Authors.)

This work presents the treatment of selected emerging concern pharmaceuticals in real hospital wastewater (HWW) from Tumaco-Colombia by combination of a biological system with a sonochemical process. Fifteen compounds, commonly present in HWW, were considered: acetaminophen, diclofenac, carbamazepine, venlafaxine, loratadine, ciprofloxacin, norfloxacin, valsartan, irbesartan, sulfamethoxazole, trimethoprim, clarithromycin, azithromycin, erythromycin and clindamycin. Initially, HWW was characterized in terms of global parameters and the pharmaceuticals content. HWW contained a moderate amount of organic matter (i.e., total organic carbon: 131.56 mg L -1 (C)) mainly associated to biodegradable components. However, the most of pharmaceuticals were found at levels upper than their predicted no effect concentration (PNEC). Then, a conventional biological treatment was applied to the HWW. After 36 h, such process mainly removed biodegradable substances, but had a limited action on the pharmaceuticals. The resultant biotreated water was submitted to the sonochemical process (375 kHz and 88 W L -1 , 1.5 h), which due to its chemical (i.e., radical attacks) and physical (i.e., suspended solids disaggregation) effects induced a considerable pharmaceuticals degradation (pondered removal: 58.82%), demonstrating the complementarity of the proposed combination. Afterwards, Fe 2+ (5 ppm) and UVC light (4 W) were added to the sonochemical system (generating sono-photo-Fenton process), which significantly increased up to 82.86% the pondered pharmaceuticals removal. Subsequently, to understand fundamental aspects of the pharmaceuticals degradations, a model compound (norfloxacin) in distilled water was treated by sonochemical system, sono-photo-Fenton process and their sub-systems (i.e., sono-Fenton and UVC alone). This allowed proving the hydroxyl radical action in sonochemical treatment, plus the contribution of Fenton reaction and direct photodegradation in the pharmaceuticals removal by sono-photo-Fenton. Finally, it was found that 91.13% of the initial pharmaceuticals load in HWW was removed by the biological/sono-photo-Fenton combination. The high pollutants abatement evidenced that this combination is a powerful alternative for removing pharmaceuticals from complex-matrix waters, such as raw HWW., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Ampicillin (AMP) is an antibiotic widely used in hospitals and veterinary clinics around the world for treating infections caused by bacteria. Therefore, it is common to find traces of this antibiotic in wastewater from these entities. In this work, we studied the mineralization of this antibiotic in solution as well as the elimination of its antimicrobial activity by comparing different electrochemical advanced oxidation processes (EAOPs), namely electro-oxidation with hydrogen peroxide (EO-H 2 O 2 ), electro-Fenton (EF), and photo electro-Fenton (PEF). With PEF process, a high degradation, mineralization, and complete elimination of antimicrobial activity were achieved in 120-min electrolysis with high efficiency. In the PEF process, fast mineralization rate is caused by hydroxyl radicals (·OH) that are generated in the bulk, on the anode surface, by UV radiation, and most importantly, by the direct photolysis of complexes formed between Fe 3+ and some organic intermediates. Moreover, some products and intermediates formed during the degradation of the antibiotic Ampicillin, such as inorganic ions, carboxylic acids, and aromatic compounds, were determined by photometric and chromatographic methods. An oxidation pathway is proposed for the complete conversion to CO 2 .

In this work, the photo-Fenton process at near-neutral pH was applied for the removal of the β-lactam antibiotic oxacillin (OXA) in water using artificial and sunlight. Initially, the main variables of the process (Fe(II), H 2 O 2 , and light power) were optimized by a statistical factorial design (2 3 with center points). The experimental design indicated that 90 μmol L -1 of Fe(II), 10 mmol L -1 of H 2 O 2 , and 30 W of power light were the favorable conditions for degradation of OXA at 203 μmol L -1 . In the photo-Fenton system, the H 2 O 2 alone, UV-light/H 2 O 2 , and Fe(II)/H 2 O 2 subsystems presented a significant participation on antibiotic removal. Moreover, based on the primary organic transformation products, a mechanism of OXA degradation was proposed. Under the favorable operational conditions, both the pollutant and the antimicrobial activity were eliminated after 50 min of process application. Although at 480 min of treatment, only 5% of mineralization was achieved, the level of biodegradability of the solutions increased from 0.08 to 0.98. Interestingly, the presence of pharmaceutical additives (glucose, isopropanol, and oxalic acid) had a moderate interference on the efficiency of the pollutant removal. Additionally, the treatment at pilot scale of the β-lactam antibiotic in a pharmaceutical complex matrix using solar radiation allowed the complete removal of the pollutant and its associated antimicrobial activity in a very short time period (5 min). These results evidenced the applicability of the photo-Fenton process to treat wastewaters from pharmaceutical industry loaded with β-lactam antibiotics at near neutral pH values efficiently.

The elimination of the antibiotic Nafcillin (NAF), which is usually used in hospitals and veterinary clinics around the world, was assessed through a combination of three advanced electrochemical oxidation processes followed by anaerobic digestion process. In the first stage different electrochemical advanced oxidation processes (EAOPs) were used: electro-oxidation with hydrogen peroxide (EO-H 2 O 2 ), electro-Fenton (EF) and Photo electro-Fenton (PEF). After PEF, almost complete and highly efficient degradation and elimination of NAF was achieved, with the concomitant elimination of the associated antimicrobial activity. The fast degradation rate produced by PEF is explained by the oxidative action of hydroxyl radicals (•OH) together with the direct UV photolysis of complexes formed between Fe 3+ and some organic intermediates. Total removal of NAF occurs after 90min of electrolysis by PEF, with the generation of organic intermediates that remain in solution. However, when this post PEF process solution was treated with an anaerobic biological process, the intermediates generated in the electrochemical degradation of NAF were completely eliminated after 24h. The kinetic degradation of NAF as well as the identification/quantification of products and intermediates formed during the degradation of antibiotic, such as inorganic ions, carboxylic acids and aromatic compounds, were determined by chromatographic and photometric methods. Finally, an oxidation pathway is proposed for the complete conversion to CO 2 ., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The removal of the widely used antibiotic norfloxacin (NOR), the presence of which has been reported in natural water, was evaluated using rice (RH) and coffee (CH) husk wastes as adsorbents. Low particle sizes and natural pH in distilled water favored NOR elimination in both materials. In order to investigate the type of adsorption, the data was adjusted to the Langmuir, Freundlich and Redlich-Peterson isotherms. The best fit for the Langmuir and Redlich-Peterson isotherms suggested a monolayer-type adsorption model. Kinetic models of pseudo first and second order were also evaluated, the latter being the most suitable to represent the NOR adsorption phenomenon. Meanwhile, the intraparticle diffusion model indicated that the adsorption of NOR occurs both at the surface and within the pores of the material. Studies performed on thermodynamic aspects such as activation energy (E a ), enthalpy change (ΔH˚) and Gibbs free energy change (ΔG˚) suggest that the physisorption of the pollutant takes place through a spontaneous endothermic process. Additionally, PZC determination, Boehm method, chemical composition, thermodynamic analysis, and FTIR spectra before and after the adsorption of the antibiotic suggest that in CH adsorbents this occurred mainly through electrostatic interactions, while in RH hydrogen bonds also contributed significantly. Finally, the efficiency of natural adsorbents for the removal of NOR was evaluated in synthetic matrices of municipal wastewater and urine, and promising results were obtained despite the complexity of these matrices. The results presented in this work show the potential application of RH and CH residues as a low-cost alternative for the removal of NOR even in complex matrices. However, despite the similarities between the materials, CH waste showed better properties for the removal of the tested NOR due to its higher surface area, lower PZC and higher number of acid groups., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Taking ciprofloxacin (CIP) as a fluoroquinolone antibiotic model, this work explores the role of common anions (sulfate, nitrate, and chloride) during the application of photoelectro-Fenton (PEF) at natural pH to degrade this type of compound in water. The system was composed of an IrO 2 anode, Ti, or gas diffusion electrode (GDE) as cathode, Fe 2+ , and UV (254 nm). To determine the implications of these anions, the degradation pathway and efficiency of the PEF sub-processes (UV photolysis, anodic oxidation, and electro-Fenton at natural pH) were studied in the individual presence of the anions. The results highlight that degradation routes and kinetics are strongly dependent on electrolytes. When chloride and nitrate ions were present, indirect electro-chemical oxidation was identified by electro-generated HOCl and nitrogenated oxidative species, respectively. Additionally, direct photolysis and direct oxidation at the anode surface were identified as degradation routes. As a consequence of the different pathways, six primary CIP by-products were identified. Therefore, a scheme was proposed representing the pathways involved in the degradation of CIP when submitted to PEF in water with chloride, nitrate, and sulfate ions, showing the complexity of this process. Promoted by individual and synergistic actions of this process, the PEF system leads to a complete elimination of CIP with total removal of antibiotic activity against Staphylococcus aureus and Escherichia coli, and significant mineralization. Finally, the role of the anions was tested in seawater containing CIP, in which the positive contributions of the anions were partially suppressed by its OH radical scavenger action. The findings are of interest for the understanding of the degradation of antibiotics via the PEF process in different matrices containing sulfate, nitrate, and chloride ions.

In this work, three penicillins (ampicillin "AMP", oxacillin "OXA" and cloxacillin "CLO"), two cephalosporins (cephalexin "CPX" and cephadroxyl "CPD") and three fluoroquinolones (levofloxacin "LEV", norfloxacin "NOR" and ciprofloxacin "CIP") were initially treated by UV 254 and persulfate activated by UV 254 (UV/PS). Significant differences in degradation kinetics under UV 254 irradiation were found. Photodegradation followed the order: OXA > CPX > CPD > CLO > CIP > NOR > AMP ≫ LEV. Then, in order to study the participation of direct photolysis and reactive oxygen species (ROS) in photodegradation a model antibiotic of each class (OXA, CPX and CIP) was considered. OXA and CPX were mainly degraded by direct photolysis, whereas the CIP removal involved ROS and photolysis. On the other hand, the persulfate addition (UV/PS process) improved the removals due to sulfate radical formation, especially, in the case of antibiotics with lower photodegradation levels (i.e. LEV, AMP and NOR). Computational calculations on the representative antibiotics were applied to determine the regions susceptible to electrophilic attacks by degrading agents. The functional groups of OXA and CPX followed the reactivity order: thioether ≫ β-lactam ring > benzene ring. For CIP, the piperazyl moiety presented higher reactivity than the quinolone ring. Also, the antimicrobial activity (AA) evolution during the treatments was tested. In the cases of CPX and CIP, both UV 254 and UV/PS removed the AA; which were associated with structural changes in their reactive moieties: β-lactam ring and piperazyl ring, respectively. However, in the case of OXA only the UV/PS system decreased AA, which was attributed to transformations in its penicillin electron-rich nucleus (thioether + β-lactam). Finally, the applicability of UV 254 and UV/PS was assessed using synthetic hospital wastewater (HWW). The processes comparison showed that for practical purposes, OXA and CIP in HWW should be treated by UV/PS, while CPX in HWW could be treated by both UV 254 and UV/PS., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This paper presents the Staphylococcus aureus inactivation in a simulated wastewater treatment plant effluent by different electrochemical techniques, including the photo-electro-Fenton process. S. aureus, dissolved organic carbon (DOC), total oxidants and H 2 O 2 concentrations, as well as pH, were monitored during the assays. An electrolytic cell, including a UVA lamp, a gas diffusion electrode (GDE) as cathode and an IrO 2 anode, was used to conduct the experiments under galvanostatic conditions (20 mA). Low inactivation (-0.4) and low DOC removal were achieved within 120 min when applying the GDE-IrO 2 system, in which bacteria disinfection was caused by the generated H 2 O 2 . When light was combined with GDE-IrO 2 , the process efficiency noticeably increased (-3.7 log inactivation) due to the synergistic effect between UVA and H 2 O 2 . Introducing iron (5 mg L -1 Fe 2+ ) into the system also produced higher disinfection and DOC mineralization. The electro-Fenton process (GDE-IrO 2 +Fe 2+ ) led to a bacterial reduction of -0.9 log units and DOC reduction of 14%, while with the photo-electro-Fenton process (GDE-IrO 2 +UVA + Fe 2+ ) -5.2 units of bacteria and 26% of DOC were removed. Increasing the current intensity (20 mA, 30 mA and 40 mA) in the photo-electro-Fenton system increased H 2 O 2 production and, consequently, augmented the bacterial inactivation (-5.2 log, -6.2 log and -6.5 log, respectively). However, mineralization extent slightly increased or remained practically the same. When comparing the influence of Fe 2+ and Fe 3+ on photo-electro-Fenton, similar S. aureus inactivation was observed, while DOC removal was higher with Fe 2+ (31%) than with Fe 3+ (19%). Finally, by testing the system with a Ti anode, the direct anodic oxidation contribution of the IrO 2 anode was identified as negligible., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

To provide new insights toward the selection of the most suitable AOP for isoxazolyl penicillins elimination, the degradation of dicloxacillin, a isoxazolyl penicillin model, was studied using different advanced oxidation processes (AOPs): ultrasound (US), photo-Fenton (UV/H 2 O 2 /Fe 2+ ) and TiO 2 photocatalysis (UV/TiO 2 ). Although all processes achieved total removal of the antibiotic and antimicrobial activity, and increased the biodegradability level of the solutions, significant differences concerning the mineralization extend, the pH of the solution, the pollutant concentration and the chemical nature of additives were found. UV/TiO 2 reached almost complete mineralization; while ∼10% mineralization was obtained for UV/H 2 O 2 /Fe 2+ and practically zero for US. Effect of initial pH, mineral natural water and the presence of organic (glucose, 2-propanol and oxalic acid) were then investigated. UV/H 2 O 2 /Fe 2+ and US processes were improved in acidic media, while natural pH favored UV/TiO 2 system. According to both the nature of the added organic compound and the process, inhibition, no effect or enhancement of the degradation rate was observed. The degradation in natural mineral water showed contrasting results according to the antibiotic concentration: US process was enhanced at low concentration of dicloxacillin followed by detrimental effects at high substrate concentrations. A contrary effect was observed during photo-Fenton, while UV/TiO 2 was inhibited in all of cases. Finally, a schema illustrating the enhancement or inhibiting effects of water matrix is proposed as a tool for selecting the best process for isoxazolyl penicillins degradation., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This study evaluates the treatment of the antibiotic cloxacillin (CLX) in water by means of electrochemical oxidation, TiO 2 photocatalysis, and the photo-Fenton system. The three treatments completely removed cloxacillin and eliminated the residual antimicrobial activity from synthetic pharmaceutical wastewater containing the antibiotic, commercial excipients, and inorganic ions. However, significant differences in the degradation routes were found. In the photo-Fenton process, the hydroxyl radical was involved in the antibiotic removal, while in the TiO 2 photocatalysis process, the action of both the holes and the adsorbed hydroxyl radicals degraded the pollutant. In the electrochemical treatment (using a Ti/IrO 2 anode in sodium chloride as supporting electrolyte), oxidation via HClO played the main role in the removal of CLX. The analysis of initial by-products showed five different mechanistic pathways: oxidation of the thioether group, opening of the central β-lactam ring, breakdown of the secondary amide, hydroxylation of the aromatic ring, and decarboxylation. All the oxidation processes exhibited the three first pathways. Moreover, the aromatic ring hydroxylation was found in both photochemical treatments, while the decarboxylation of the pollutant was only observed in the TiO 2 photocatalysis process. As a consequence of the degradation routes and mechanistic pathways, the elimination of organic carbon was different. After 480 and 240 min, the TiO 2 photocatalysis and photo-Fenton processes achieved ∼45 and ∼15 % of mineralization, respectively. During the electrochemical treatment, 100 % of the organic carbon remained even after the antibiotic was treated four times the time needed to degrade it. In contrast, in all processes, a natural matrix (mineral water) did not considerably inhibit pollutant elimination. However, the presence of glucose in the water significantly affected the degradation of CLX by means of TiO 2 photocatalysis.

The electrochemical degradation of the fluoroquinolone antibiotic norfloxacin (NOR) on Ti/IrO 2 anodes, in several aqueous matrices was evaluated. For this purpose, initially the performance and degradation routes of the technology at several pH values (3.0, 6.5, 7.5 and 9.0) and in the presence of some of the most common anions in real water matrices (Cl - , HCO 3 - , SO 4 2- and NO 3 - ) were determined. The results showed that the degradation of NOR can occur through both direct elimination at the electrode surface and mediated oxidation, via the electrogeneration of oxidative agents, such as active chlorine species and percarbonate ions, which come from chloride and bicarbonate oxidation, respectively. Conversely, nitrate ions showed to inhibit the efficiency of the system. Concerning the pH, the efficiency of the process in the presence of chloride ions followed the order: 9.0>7.5>6.5>3.0; showing a strong dependence of the NOR speciation, and being the anionic form of the antibiotic the more susceptible to be oxidized. Furthermore, the identification of three primary NOR by-products demonstrated that the initial attack of the active chlorine species, mainly HOCl, occurred at the secondary amine of the piperazine ring followed by chlorination of the benzene ring. The precedent findings were crucial to understand the efficiency of the technology to eliminate NOR in synthetic complex matrices such as seawater, municipal wastewater and urine. The electrochemical oxidation showed to be promissory to eliminate NOR, and its associated antimicrobial activity, in such complexes matrices. Waters at basic pH containing chloride or bicarbonate ions, such as seawater or municipal wastewater showed to be the most adapted to the application of the technology. Additionally, nitrate ions or urea, found in some matrices like fresh urine, reduce the efficiency of the process., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This work studies the sonochemical degradation of a penicillinic antibiotic (oxacillin) in simulated pharmaceutical wastewater. High frequency ultrasound was applied to water containing the antibiotic combined with mannitol or calcium carbonate. In the presence of additives, oxacillin was efficiently removed through sonochemical action. For comparative purposes, the photo-Fenton, TiO2 photocatalysis and electrochemical oxidation processes were also tested. Therefore, the evolution of the antibiotic and its associated antimicrobial activity (AA) were monitored. A high inhibition was found for the other three oxidation processes in the elimination of the antimicrobial activity caused by the additives; while for the ultrasonic treatment, a negligible effect was observed. The sonochemical process was able to completely degrade the antibiotic, generating solutions without AA. In fact, the elimination of antimicrobial activity showed an excellent performance adjusted to exponential kinetic-type decay. The main sonogenerated organic by-products were determined by means of HPLC-MS. Four intermediaries were identified and they have modified the penicillinic structure, which is the moiety responsible for the antimicrobial activity. Additionally, the possible oxacillin sonodegradation mechanism was proposed based on the evolution of the by-products and their chemical structure. Furthermore, the high-frequency ultrasound action over 120 min readily removed oxacillin and eliminated its antimicrobial activity. However, the pollutant was not mineralized even after a long period of ultrasonic irradiation (360 min). Interestingly, the previously sonicated water containing oxacillin and both additives was completely mineralized using non-adapted microorganisms from a municipal wastewater treatment plant. These results show that the sonochemical treatment transformed the initial pollutant into substances that are biotreatable with a typical aerobic biological system., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This study focuses on the photo-transformation, in presence of humic substances (HSs), of ciprofloxacin (CIP), a commonly-used fluoroquinolone antibiotic whose presence in aquatic ecosystems is a health hazard for humans and other living organisms. HSs from the International Humic Substances Society (Elliott humic acid and fulvic acid, Pahokee peat humic acid and Nordic lake) and a humic acid extracted from modified coal (HACM) were tested for their ability to photodegrade CIP. Based on kinetic and analytical studies, it was possible to establish an accelerating effect on the rate of CIP decomposition caused by the humic substances. This effect was associated with the photosensitized capacity of the HSs to facilitate energy transfer from an excited humic state to the ground state of ciprofloxacin. Except for Nordic lake, which experienced a lower positive effect, no significant differences in the CIP transformation were found among the different humic acids examined. The photochemistry of CIP can be modified by parameters such as pH, CIP or oxygen concentration. The irradiation of this antibiotic in the presence of HACM showed that antimicrobial activity was negligible after 14 h for E. coli and 24 h for S. aureus. In contrast, the antimicrobial activity was only slightly decreased after 24 h of irradiation by direct photolysis. Although mineralization of CIP irradiation in the presence of a HACM solution was not achieved, biodegradability was achieved after 12 h of irradiation, indicating that microorganisms within the environment can easily degrade CIP photochemical by-products., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Synthetic pharmaceutical effluents loaded with the β-lactam antibiotic oxacillin were treated using advanced oxidation processes (the photo-Fenton system and TiO2 photocatalysis) and chloride mediated electrochemical oxidation (with Ti/IrO2 anodes). Combinations of the antibiotic with excipients (mannitol or tartaric acid), an active ingredient (calcium carbonate, i.e. bicarbonate ions due to the pH) and a cleaning agent (sodium lauryl ether sulfate) were considered. Additionally, urban wastewater that had undergone biological treatment was doped with oxacillin and treated with the tested systems. The evolution of antimicrobial activity was monitored as a parameter of processes efficiency. Although the two advanced oxidation processes (AOPs) differ only in the way they produce OH, marked differences were observed between them. There were also differences between the AOPs and the electrochemical system. Interestingly, each additive had a different effect on each treatment. For water loaded with mannitol, electrochemical treatment was the most suitable option because the additive did not significantly affect the efficiency of the system. Due to the formation of a complex with Fe(3+), tartaric acid accelerated the elimination of antibiotic activity during the photo-Fenton process. For TiO2 photocatalysis, the presence of bicarbonate ions contributed to antibiotic activity elimination through the possible formation of carbonate and bicarbonate radicals. Sodium lauryl ether sulfate negatively affected all of the processes. However, due to the higher selectivity of HOCl compared with OH, electrochemical oxidation showed the least inhibited efficiency. For the urban wastewater doped with oxacillin, TiO2 photocatalysis was the most efficient process. These results will help select the most suitable technology for the treatment of water polluted with β-lactam antibiotics., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Fluoxetine (FLX), one of the most widely used antidepressants in the world, is an emergent pollutant found in natural waters that causes disrupting effects on the endocrine systems of some aquatic species. This work explores the total elimination of FLX by sonochemical treatment coupled to a biological system. The biological process acting alone was shown to be unable to remove the pollutant, even under favourable conditions of pH and temperature. However, sonochemical treatment (600 kHz) was shown to be able to remove the pharmaceutical. Several parameters were evaluated for the ultrasound application: the applied power (20-60 W), dissolved gas (air, Ar and He), pH (3-11) and initial concentration of fluoxetine (2.9-162.0 μmol L(-1)). Additionally, the presence of organic (1-hexanol and 2-propanol) and inorganic (Fe(2+)) compounds in the water matrix and the degradation of FLX in a natural mineral water were evaluated. The sonochemical treatment readily eliminates FLX following a kinetic Langmuir. After 360 min of ultrasonic irradiation, 15% mineralization was achieved. Analysis of the biodegradability provided evidence that the sonochemical process transforms the pollutant into biodegradable substances, which can then be mineralized in a subsequent biological treatment., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The photocalytic degradation of dicloxacillin (DXC) using TiO2 was studied in synthetic and natural waters. The degradation route and the effect of different experimental variables such as pH, applied power, and the initial concentrations of DXC and the catalyst were investigated. The best performances were achieved at a natural pH 5.8 and using 2.0 g L(-1) of TiO2 with 150 W of applied power. The photodegradation process followed Langmuir-Hinshelwood kinetics. The water matrix effect was evaluated in terms of degradation efficiency in the presence of organic compounds (oxalic acid, glucose), Fe(2+) ion and natural water. An increase in degradation was observed when ferrous ion was part of the solution, but the process was inhibited with all evaluated organic compounds. Similarly, inhibition was observed when natural water was used instead of distilled water. The extent of degradation of the process was evaluated following the evolution of chemical oxygen demand (COD), antimicrobial activity (AA), total organic carbon (TOC) and biochemical oxygen demand (BOD5). Total removal of DXC was achieved after 120 min of treatment and 95% mineralization was observed after 480 min of treatment. Additionally, the total removal of antimicrobial activity and a high level of biodegradability were observed after the photocalytical system had been operating for 240 min.

The sonochemical degradation of dicloxacillin (DXC) was studied in both synthetic and natural waters. Degradation routes and the effect of experimental conditions such as pH, initial DXC concentration and ultrasonic power were evaluated. Experiments were carried out with a fixed frequency (600kHz). The best performances were achieved using acidic media (pH=3) and high power (60W). The degradation process showed pseudo-first order kinetics as described by the Okitsu model. To evaluate water matrix effects, substrate degradation, in the presence of Fe(2+) and organic compounds such as glucose and 2-propanol, was studied. A significant improvement was achieved with Fe(2+) (1.0mM). Inhibition of the degradation process was observed at a relatively high concentration of 2-propanol (4.9mM), while glucose did not show any effect. Natural water showed an interesting effect: for a low concentration of DXC (6.4μM), an improvement in the degradation process was observed, while at a higher concentration of DXC (0.43mM), degradation was inhibited. Additionally, the extent of degradation of the process was evaluated through the analysis of chemical oxygen demand (COD), antimicrobial activity, total organic carbon (TOC) and biochemical oxygen demand (BOD5). A 30% removal of COD was achieved after the treatment and no change in the TOC was observed. Antimicrobial activity was eliminated after 360min of ultrasonic treatment. After 480min of treatment, a biodegradable solution was obtained., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This paper deals about the sonochemical water treatment of acetaminophen (ACP, N-acetyl-p-aminophenol or paracetamol), one of the most popular pharmaceutical compounds found in natural and drinking waters. Effect of ultrasonic power (20-60 W), initial ACP concentration (33-1323 μmol L(-1)) and pH (3-12) were evaluated. High ultrasonic powers and, low and natural acidic pH values favored the efficiency of the treatment. Effect of initial substrate concentration showed that the Langmuir-type kinetic model fit well the ACP sonochemical degradation. The influence of organic compounds in the water matrix, at concentrations 10-fold higher than ACP, was also evaluated. The results indicated that only organic compounds having a higher value of the Henry's law constant than the substrate decrease the efficiency of the treatment. On the other hand, ACP degradation in mineral natural water showed to be strongly dependent of the initial substrate concentration. A positive matrix effect was observed at low ACP concentrations (1.65 μmol L(-1)), which was attributed to the presence of bicarbonate ion in solution. However, at relative high ACP concentrations a detrimental effect of matrix components was noticed. Finally, the results indicated that ultrasonic action is able to transform ACP in aliphatic organic compounds that could be subsequently eliminated in a biological system., (Copyright © 2014 Elsevier B.V. All rights reserved.)