Advanced oxidation of antihypertensives losartan and valsartan by photo-electro-Fenton at near-neutral pH using natural organic acids and a dimensional stable anode-gas diffusion electrode (DSA-GDE) system under light emission diode (LED) lighting

Abstract

In this work photo-electro-Fenton (PEF) processes using a dimensionally stable anode-gas diffusion electrode (DSA-GDE) system under light emission diodes (LED)-type radiation were used in the degradation of the angiotensin-II-receptor antagonists (ARA II), valsartan (VAL), and losartan (LOS), which are used in the treatment of hypertension diseases, and are considered among the emerging contaminants (ECs). Organic acids as citric, tartaric, and oxalic acids were used as complexing agents of iron ions in order to maintain the performance of the Fenton reaction at near-neutral pH value. The results show that at 3.42 mA/cm after 90 min of electro-Fenton (EF) treatment, degradation of 70% of VAL and 100% of LOS were observed. Total degradation of VAL and LOS was reached with a PEF process at the same time with mineralization of 30%. When citric and tartaric acids were used instead of oxalic acid, similar results were obtained, i.e., total degradation of both compounds, LOS and VAL, after 90 min of treatment. The degradation performance can be attributed to the increase of the initial dissolved iron in the system, facilitating the Fe/Fe turnover in the catalytic photo-Fenton reaction and consequently, hydroxyl radical (OH) production. In addition, the increased photo-activity of the complexes can be associated with their high capability to complex Fe and to promote ligand-to-metal charge transfer, which is of key importance to feed Fe to the Fenton process. The results show that the system evaluated was more efficient to eliminate sartan family compounds using LED lighting in comparison with traditional UV-A lamps used in this kind of work. Moreover, three transformation products of VAL degradation and two transformation products of LOS degradation were identified by high-resolution mass spectrometry (HRMS) using hybrid quadrupole-time-of-flight (QTOF) MS and, at the end of the PEF system, the several organic compounds accumulated and no mineralized were effectively treated in a subsequent aerobic biological system.

Remediation of Emerging Contaminants

“…The main disadvantage of the method is however the high consumption of electrical energy. Martínez-Pachón et al (2019) studied the advanced oxidation of antihypertensives losartan and valsartan by photo-electro-Fenton at near-neutral pH using natural organic acids and a dimensional stable anode-gas diffusion electrode system under light emission diode lighting. Valsartan and losartan are used in the treatment of hypertension diseases, and are considered among the emerging contaminants that are difficult to treat.…”

“…Moreover, three transformation products of valsartan degradation and two transformation products of losartan degradation were identified by high-resolution mass spectrometry using hybrid quadrupole-time-of-flight mass spectrometry. The several organic compounds still present at the end of the photo-electro-Fenton treatment were effectively treated in a subsequent aerobic biological system (Martínez-Pachón et al 2019).…”

An Efficient Simultaneous Degradation of Sulfamethoxazole and Trimethoprim by Photoelectro-Fenton Process Under Non-Modified pH Using a Natural Citric Acid Source: Study of Biodegradability, Ecotoxicity and Antibacterial Activity

“…The solution was irradiated with a white light LED radiation source wrapped around the cell (United Kingdom; 3.8 W) with 60 LEDs (1.0 m). The PEF system was previously described (Martínez-Pachón et al 2018;Martínez-Pachón et al 2019). The experiments were carried out at neutral pH and a 3.0x10 − 5 mol/L of citric acid was added from either the analytical grade reagent or the extraction of the natural source.…”

Ecotoxicity and genotoxicity assessment of losartan after UV/H2O2 and UVC/photolysis treatments

“…Since conventional processes were not designed to total removal of micropollutants, such as pharmaceuticals (Kosek et al 2020 ), several technologies have been used for degradation and/or removal LOS in waters and effluents. In this context, advanced oxidation processes (AOPs) such as UVC/photolysis and UV/H 2 O 2 (Starling et al 2019 ; Kaur and Dulova 2020 ), UV/Fe 2+ - activated persulfate (Kaur and Dulova 2020 ), heterogeneous catalysis with peroxymonosulfate (PMS) (de Andrade et al 2020 ), UVC/S 2 O 8 −2 (Starling et al 2019 ), photo-electro-Fenton (Martínez-Pachón et al 2019 ), and electrochemical oxidation (Salazar et al 2016 ) have recently been studied as an alternative for removing LOS. However, partial oxidation can generate more toxic by-products than the parent compound (Rizzo 2011 ; Utzig et al 2019 ).…”