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The global occurrence of micropollutants in water bodies has raised concerns about potential negative effects on aquatic ecosystems and human health. EU regulations to mitigate such widespread pollution have already been implemented and are expected to become increasingly stringent in the next few years. Catalytic wet peroxide oxidation (CWPO) has proved to be a promising alternative for micropollutant removal from water, but most studies were performed in batch mode, often involving complex, expensive, and hardly recoverable catalysts, that are prone to deactivation. This work aims to demonstrate the feasibility of a fixed-bed reactor (FBR) packed with natural magnetite powder for the removal of a representative mixture of azole pesticides, recently listed in the EU Watch Lists. The performance of the system was evaluated by analyzing the impact of H2O2 dose (3.6–13.4 mg L−1), magnetite load (2–8 g), inlet flow rate (0.25–1 mL min−1), and initial micropollutant concentration (100–1000 µg L−1) over 300 h of continuous operation. Azole pesticide conversion values above 80% were achieved under selected operating conditions (WFe3O4 = 8 g, [H2O2]0 = 6.7 mg L−1, flow rate = 0.5 mL min−1, pH0 = 5, T = 25 °C). Notably, the catalytic system showed a high stability upon 500 h in operation, with limited iron leaching (< 0.1 mg L−1). As a proof of concept, the feasibility of the system was confirmed using a real wastewater treatment plant (WWTP) effluent spiked with the mixture of azole pesticides. These results represent a clear advance for the application of CWPO as a tertiary treatment in WWTPs and open the door for the scale-up of FBR packed with natural magnetite. [ABSTRACT FROM AUTHOR]

The combination of photocatalysis with membrane separation technology allows to mitigate potential membrane fouling while degrading the organic micropollutants in water. This work is focused on the immobilization of a g-C 3 N 4 promising photocatalyst, in the form of a g-C 3 N 4 -PVDF polymeric membrane, for the elimination of representative pharmaceutical substances from complex water matrices in a continuous flow mode under visible light irradiation. Metoprolol (MTP), venlafaxine (VEN) and diclofenac (DCF) in a mixture (at 250 μg L−1 each) were fed to the system at room temperature. The adsorption of these substances on the membrane was negligible (< 5%) in the dark. Removals of 89%, 92% and 72% for MTP, VEN and DCF, respectively, were achieved in deionized water using visible-light emitting diodes (LEDs) as light source. Moreover, the permeate flux remained constant throughout the experiments (89.5 L m−2 h−1). The membrane system was then assessed using urban wastewater treatment plant effluent, surface and tap waters, spiked with the target analytes. As expected, a worse performance was observed with these matrices, although still high removals were achieved in tap water (73%, 61% and 75%, respectively for MTP, VEN and DCF). Accordingly, the impact of the occurrence of humic acid as representative species of natural organic matter, as well as inorganic ions such as chlorides, sulphates, phosphates and carbonates, was evaluated in more detail. Clearly, humic acid and sulphates were the most impactful on the treatment performance. Finally, different scavengers were used to understand the photocatalytic mechanism, suggesting that superoxide radicals and photogenerated holes were the main active species involved in the removal of the studied micropollutants. [Display omitted] • g-C 3 N 4 -PVDF membrane was successfully applied for continuous micropollutant removal. • High pharmaceutical removal yields were achieved in deionized water with constant flux. • Less effective performance in real water matrices but still high activity in tap water. • Humic acid and sulphates had significant negative impact on treatment performance. • Superoxide radicals and photogenerated holes are behind the photocatalytic mechanism. [ABSTRACT FROM AUTHOR]

This work aims to develop highly stable iron oxide foams for the continuous Catalytic Wet Peroxide Oxidation (CWPO) of micropollutants in a structured fixed-bed reactor. Homogeneity and adhesion of the active phase were achieved by adjusting the preparation methodology. Three structured catalysts based on Al 2 O 3 , SiC and ZrO 2 foams were obtained with Fe content of 2.5%, 2.1% and 0.90% wt., respectively. The catalytic foams were tested in the CWPO of a mixture of three pharmaceuticals (metronidazole (MNZ), sulfamethoxazole (SMX) and carbamazepine (CBZ)), with a concentration of 100 µg L−1 each. The catalysts resulted active and stable up to 200 h of CWPO carried out at ambient conditions, with the exception of Fe/ZrO 2 , which showed a progressive deactivation due to the iron leaching from the solid. An increase in space time led to an enhanced performance achieving remarkable conversion levels of 73%, 83% and 90% for MNZ, SMX and CBZ, respectively. The effect of H 2 O 2 dose was also evaluated revealing the development of competing side reactions for supra - stoichiometric dosages. Moreover, the scavenging effect of the water matrix was assessed operating in presence of humic acid as representative natural organic matter (NOM). In this case, the conversion levels for SMX and CBZ resulted alike to the ones obtained for ultrapure water and only a slight decrease in MNZ removal rate was detected. After 400 h of usage at different steady-state conditions, the outstanding catalytic performance of Fe/Al 2 O 3 and Fe/SiC was sustained in the long-term operation. [Display omitted] • Innovative iron oxide foams based on Al 2 O 3 , SiC and ZrO 2 were developed. • The structured catalysts were tested in the continuous flow CWPO of persistent micropollutants. • Fe/Al 2 O 3 and Fe/SiC catalytic foams showed an outstanding activity and stability for 400 h. • The H 2 O 2 dose revealed competing reactions for supra-stoichiometric doses. • The versatility of the system was demonstrated in the presence of NOM. [ABSTRACT FROM AUTHOR]

[Display omitted] • HDC is an effective technology for the removal of chlorinated azole pesticides. • HDC effluents are non-toxic, with only chlorine-free compounds as reaction products. • Intermediates were identified and the reaction mechanism was proposed. • The Pd/Al 2 O 3 catalyst shows a relatively high stability upon consecutive applications. • The process versatility was proved in relevant aqueous matrices (DWTP and tap water). Catalytic hydrodechlorination (HDC) is regarded as a promising purifying technology for drinking water treatment. So far, it has proved to be highly effective for the removal of different groups of chlorinated micropollutants including pharmaceuticals, neonicotinoid pesticides, personal care products or chloroacetic acids. The azole pesticides, recently included in the EU Watch Lists (Decisions 2020/1161 and 2022/1307), are a group of micropollutants of particular concern for drinking water given their high toxicity, persistence, and bioaccumulation potential. In this work, the feasibility of HDC for the removal of a representative group of chlorinated azole pesticides tebuconazole (TEB), tetraconazole (TET), prochloraz (PCZ), penconazole (PEN), metconazole (MET) and imazalil (IMZ)) is demonstrated, and their reactivity is compared with that observed for other halogenated micropollutant groups. Notably, all the pesticides investigated in this work (100 μg L−1) were completely dechlorinated within 30 min under ambient conditions using a 1 wt% Pd/Al 2 O 3 catalyst concentration of 0.25 g L−1 and a H 2 feeding of 50 mL N min−1. The experimental data were accurately described by a pseudo-first order kinetic equation and rate constant values in the range from 1.08 to 2.60 L g cat −1 min−1 were obtained. These values are quite close to those achieved for the most reactive neonicotinoid pesticides and significantly higher than the obtained for chloroacetic acids and most pharmaceuticals (e.g. diclofenac, sertraline or chlorpromazine). From the identification of the generated reaction intermediates and the final non-chlorinated products, sequential reaction pathways were proposed for each pollutant. Remarkably, despite the high toxicity exhibited by the azole pesticides tested, with LC 50 values within the 0.4–7.0 mg L−1 range using A. salina , HDC effluents were non-toxic in all cases. Furthermore, the catalyst showed a remarkable stability upon three consecutive runs. Finally, the versatility of the process was demonstrated in the treatment of real aqueous matrices such as DWTP and tap water, where no significant differences were found either in terms of activity or stability. [ABSTRACT FROM AUTHOR]

This work aims at evaluating the role of nature, size, age, and natural organic matter (NOM) fouling of realistic microplastics (MPs) on the adsorption of two persistent micropollutants (diclofenac (DCF) and metronidazole (MNZ)). For such goal, four representative polymer types (polystyrene (PS), polyethylene terephthalate (PET), polypropylene (PP) and high-density polyethylene (HDPE)) were tested. MPs were obtained by cryogenic milling of different commercial materials (disposable bottles, containers, and trays), and fully characterized (optical microscopic and SEM images, FTIR, elemental analysis, water contact angle and pH slurry). The micropollutants hydrophobicity determined to a high extent their removal yield from water. Regardless of the MP's nature, the adsorption capacity for DCF was considerably higher than the achieved for MNZ, which can be related to its stronger hydrophobic properties and aromatic character. In fact, aromatic MPs (PS and PET) showed the highest adsorption capacity values with DCF (~100 μg g−1). The MP size also played a key role on its adsorption capacity, which was found to increase with decreasing the particle size (20–1000 μm). MPs aging (simulated by Fenton oxidation) led also to substantial changes on their sorption behavior. Oxidized MPs exhibited acidic surface properties which led to a strong decrease on the adsorption of the hydrophobic micropollutant (DCF) but to an increase with the hydrophilic one (MNZ). NOM fouling (WWTP effluent, river water, humic acid solution) led to a dramatic decrease on the MPs sorption capacity due to sorption sites blocking. Finally, the increase of pH or salinity of the aqueous medium increased the micropollutants desorption. [Display omitted] • The capacity of PS, PET, PP and HDPE realistic microplastics for DCF and MNZ uptake was evaluated. • Hydrophobic interactions governed the adsorption, being DCF adsorbed to a higher extent. • MPs oxidation led to their surface acidification, modifying their adsorption performance. • NOM fouling led to a decrease on MPs adsorption capacity due to sorption sites blocking. • The increase of pH or salinity increased the desorption of micropollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Pd-based catalytic membrane reactor with controlled feeding of H 2 was developed. • The Pd/CMR was tested in continuous flow HDC under ambient conditions. • The Pd/CMR showed an outstanding activity and stability for up to 200 h. • The activity of the catalytic system was not affected by the initial DCF concentration. • The versatility of the system was successfully demonstrated in a tap water matrix. This work is focused on the development of a Pd-based catalytic membrane reactor (Pd/CMR) for its application in continuous flow hydrodechlorination (HDC) of chlorinated micropollutants. A cylindrical inert porous alumina membrane was decorated on the outer with well-dispersed Pd nanoparticles (0.2 % wt.). The Pd/CMR was fully characterized by different techniques. The catalytic system was applied for the degradation of the persistent anti-inflammatory drug diclofenac (DCF) under ambient conditions. A remarkable stability was observed upon long-term HDC reaction, with a reasonable DCF conversion (60 %). Notably, as the process could be described by pseudo-first order kinetic, the initial concentration did not affect the final conversion achieved. Finally, the versatility of the system was successfully demonstrated using a real aqueous matrix (tap water). All in all, Pd/CMR exhibited a remarkable feasibility for the implementation of the HDC technology on a larger scale, showing an extraordinary catalytic performance for up to 200 h. [ABSTRACT FROM AUTHOR]