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The occurrence of harmful cyanobacterial blooms has unabated increased over the last few decades, posing a significant risk for public health. In this work, we investigate the feasibility of catalytic wet peroxide oxidation (CWPO) promoted by modified natural magnetite (Fe 3 O 4 -R400/H 2 O 2 ), as an inexpensive, simple-operation and environmentally-friendly process for the removal of the cyanotoxins that show the major impact on drinking water: microcystins (MC-LR and MC-RR), cylindrospermopsin (CYN), anatoxin-a (ATX) and saxitoxin (STX). The performance of the system was evaluated under ambient conditions and circumneutral pH (pH 0  = 5) using relevant cyanotoxin concentrations (100-500 μg L -1 ). The nature of the cyanotoxins determined their reactivity towards CWPO, which decreased in the following order: MC-RR > CYN > MC-LR ≫ ATX > STX. In this sense, microcystins and CYN were completely removed in short reaction times (1-1.5 h) with a low catalyst concentration (0.2 g L -1 ) and the stoichiometric amount of H 2 O 2 (2-2.6 mg L -1 ), while only 60-80% conversion was achieved with ATX and STX in 5 h. In these cases, an intensification of the operating conditions (1 g L -1 catalyst and up to 30 mg H 2 O 2 L -1 ) was required to remove both toxins in 1 h. The impact of the main components of freshwaters i.e. natural organic matter (NOM) and several inorganic ions (HCO 3 - , HPO 4 2- , SO 4 2- ) on the performance of the process was also investigated. Although the former led to a partial inhibition of the reaction due to HO· scavenging and catalyst coating, the latter did not show any remarkably effect, and the versatility of the process was finally confirmed in a real surface water. To further demonstrate the effectiveness of the catalytic system, the toxicity of both the initial cyanotoxins and the resulting CWPO effluents was measured with the brine shrimp Artemia salina. Remarkably, all CWPO effluents were non-toxic at the end of the treatment., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

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]

• HDC is an effective technology for the removal of chlorinated micropollutants. • HDC effluents are non-toxic, with only chlorine-free compounds as reaction products. • The Pd/Al 2 O 3 catalyst shows a relatively high stability upon consecutive applications. • The process versatility is proved in relevant aqueous matrices (mineral, surface and tap water). • HDC shows a high potential as polishing step in DWTPs as it also removes THMs. The presence of micropollutants in fresh waters represents an important challenge for drinking water treatment plants (DWTPs). In particular, the chlorinated ones are especially harmful given their high toxicity and strong bioaccumulation potential. The aim of this work is to evaluate the feasibility of catalytic hydrodechlorination (HDC) for the removal of a representative group of chlorinated micropollutants commonly found in the source waters of DWTPs: the antibiotic chloramphenicol (CAP), the anti-inflammatory diclofenac (DCF), the antibacterial agent triclosan (TCL) and the antidepressant sertraline (SRT). The complete degradation of the isolated micropollutants (3 mg L−1) was achieved in 1 h reaction time using a Pd/Al 2 O 3 catalyst load of 0.25 g L−1 and a H 2 flow rate of 50 N mL min−1. The experimental data were properly described by a pseudo-first order kinetic equation, obtaining degradation rate constants in the range of 0.32–1.56 L g cat −1 min−1 and activation energy values within 42–52 kJ mol−1. In all cases, the final reaction products were chlorine-free compounds and thus, HDC effluents were non-toxic (<0.1 TU). Remarkably, the catalyst showed a suitable stability upon five consecutive applications. The versatility of the process was demonstrated in the treatment of the micropollutants mixture in different aqueous matrices (mineral, surface and tap waters). Strikingly, the removal rate was not affected by the presence of co-existing substances, being the micropollutants completely removed in 15 min with 1 g L−1 catalyst concentration. Finally, the potential of HDC for the removal of trihalomethanes, by-products formed along the oxidation step by chlorination in DWTPs, was also demonstrated. [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]

[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]