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Abstract Aqueous-phase catalytic hydrodechlorination (HDC) has been scarcely explored in the literature for the removal of chlorinated micropollutants. The aim of this work is to prove the feasibility of this technology for the fast and environmentally-friendly degradation of such kind of compounds. Diclofenac (DCF), a highly consumed anti-inflammatory drug, has been selected as the target pollutant given its toxicity and low biodegradability. The commercial Pd/Al 2 O 3 (1% wt.) catalyst has been used due to its prominent role on this field. Complete degradation of DCF was achieved in a short reaction time (20 min) under ambient conditions (25 °C, 1 atm) at [DCF] 0 = 68 μM; [Pd/Al 2 O 3 ] 0 = 0.5 g L−1 and H 2 flow rate of 50 N mL min−1. Remarkably, the chlorinated intermediate (2-(2-chloroanilino)-phenylacetate (Cl-APA)) generated along reaction was completely removed at the same time, being the chlorine-free compound 2-anilinophenylacetate (APA) the only final product. A reaction scheme based on this consecutive pathway and a pseudo-first-order kinetic model have been proposed. An apparent activation energy of 43 kJ mol−1 was obtained, a comparable value to those previously reported for conventional organochlorinated pollutants. Remarkably, the catalyst exhibited a reasonable stability upon three successive uses, achieving the complete degradation of the drug and obtaining APA as the final product in 30 min. The evolution of ecotoxicity was intimately related to the disappearance of the chlorinated organic compounds and thus, the final HDC effluents were non-toxic. The versatility of the system was finally demonstrated in different environmentally-relevant matrices (wastewater treatment plant effluent and surface water). Graphical abstract Image 1 Highlights • HDC is a fast and environmentally-friendly technology for the removal of diclofenac. • The commercial Pd/Al 2 O 3 catalyst showed a high activity and a reasonable stability. • A kinetic model based on a consecutive reaction pathway fitted the experimental data. • Non-toxic effluents were achieved at the end of reaction. • The versatility of the system was proved in environmentally-relevant water matrices. [ABSTRACT FROM AUTHOR]

The removal of micropollutants in wastewater treatment plants (WTTPs) is a challenging issue which requires the development of effective but also green and low-cost strategies. In this work, we explore the capability of naturally-occurring magnetite combined with H 2 O 2 for the degradation of the highly persistent antibiotic sulfamethoxazole (SMX). A complete operating condition study has been performed to evaluate the effect of initial pH (3–7), temperature (15–50 °C), magnetite concentration (0.5–2 g L −1 ) and H 2 O 2 dose (12.5–100 mg L −1 ), using an initial SMX amount of 5 mg L −1 . Remarkably, complete removal of the target pollutant and the aromatic intermediates was achieved operating under ambient-like conditions (25 °C) and circumneutral pH (pH 0 = 5) using the stoichiometric dose of H 2 O 2 (25 mg L −1 ) and a catalyst load of 1 g L −1 . The mineralization yield was above 50%, being the final oxidation products short-chain organic acids. The oxidation pathway of SMX was accordingly proposed. The stability of magnetite was confirmed upon three sequential runs, where a similar catalytic activity and negligible iron leaching (<0.15% wt) were observed. As a proof of concept, the performance of the catalytic system was also evaluated in different real aqueous matrices, such as WWTP effluent, surface water and hospital wastewater. Although the catalyst did not show any sign of deactivation, partial inhibition of the oxidation reaction was observed due to scavenging effects. [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]