Is photoelectrocatalysis an efficient process to degrade endocrine disruptors chemicals?

Endocrine disruptors chemicals (EDCs) pose significant health risks, including cancer, behavioral disorders, and infertility. In this study, we employed the photoelectrocatalysis (PEC) technique with optimized tungsten oxide (WO3) nanostructures as a photoanode to degrade three diverse EDCs: methiocarb, dimethyl phthalate, and 4-tert-butylphenol. PEC degradation tests were carried out for individual contaminants and a mixture of them, assessing efficiency across different EDC families. Ultra High-Performance Liquid Chromatography and Mass Spectrometry was used to control the course of the experiments. For individual solutions, 4-tert-butylphenol and methiocarb were 100% degraded at 1 hour of PEC degradation. Among the tested EDCs, dimethyl phthalate showed the highest resistance to degradation when treated individually. However, when assessed in a mixture with the other EDCs, the degradation efficiency of dimethyl phthalate increased compared to its individual treatment. Furthermore, four degradation intermediates were identified for each contaminant. Finally, toxicity tests revealed that the initial solution was more toxic than the samples treated for all the contaminants tested, except for the phthalate.

Degradation of Methylparaben Using Optimal WO3 Nanostructures: Influence of the Annealing Conditions and Complexing Agent.

In this work, WO3 nanostructures were synthesized with different complexing agents (0.05 M H2O2 and 0.1 M citric acid) and annealing conditions (400 °C, 500 °C and 600 °C) to obtain optimal WO3 nanostructures to use them as a photoanode in the photoelectrochemical (PEC) degradation of an endocrine disruptor chemical. These nanostructures were studied morphologically by a field emission scanning electron microscope. X-ray photoelectron spectroscopy was performed to provide information of the electronic states of the nanostructures. The crystallinity of the samples was observed by a confocal Raman laser microscope and X-ray diffraction. Furthermore, photoelectrochemical measurements (photostability, photoelectrochemical impedance spectroscopy, Mott-Schottky and water-splitting test) were also performed using a solar simulator with AM 1.5 conditions at 100 mW·cm-2. Once the optimal nanostructure was obtained (citric acid 0.01 M at an annealing temperature of 600 °C), the PEC degradation of methylparaben (CO 10 ppm) was carried out. It was followed by ultra-high-performance liquid chromatography and mass spectrometry, which allowed to obtain the concentration of the contaminant during degradation and the identification of degradation intermediates. The optimized nanostructure was proved to be an efficient photocatalyst since the degradation of methylparaben was performed in less than 4 h and the kinetic coefficient of degradation was 0.02 min-1.

Photoelectrocatalyzed degradation of organophosphorus pesticide fenamiphos using WO3 nanorods as photoanode.

In this study, WO3 nanostructures were synthesized by the electrochemical anodization technique to use them on the degradation of persistent organic compounds such as the pesticide fenamiphos. The acids electrolyte used during the anodization were two different: 1.5 M H2SO4 - 0.05 M H2O2 and 1.5 M CH4O3S - 0.05 M H2O2. Once the samples have been manufactured, they have been subjected to different tests to analyze the properties of the nanostructures. With Field Emission Scanning Electron Microscopy (FE-SEM) the samples have been examined morphologically, their composition and crystallinity has been studied through Raman Spectroscopy and their photoelectrochemical behaviour by Photoelectrochemical Impedance Spectroscopy (PEIS). Finally, degradation tests have been carried out using the technique known as photoelectrocatalysis (PEC). The conditions that were applied in this technique were a potential of 1 VAg/AgCl and simulated solar illumination. The degradation process was monitored by UV-Visible and High-Performance liquid Chromatography (HPLC) to control the course of the experiment. The nanostructures obtained with 1.5 M CH4O3S - 0.05 M H2O2 electrolyte showed a better photoelectrochemical behaviour than nanostructures synthesized with 1.5 M H2SO4 - 0.05 M H2O2. The fenamiphos degradation was achieved at 2 h of experiment and the intermediate formation was noticed at 1 h of PEC experiment.

Photoelectrocatalyzed degradation of a pesticides mixture solution (chlorfenvinphos and bromacil) by WO3 nanosheets.

A photoelectrocatalyst consisting of WO3 nanosheets or nanorods has been synthesized by electrochemical anodization under hydrodynamic conditions, and has been used for the degradation of two toxic pesticides: chlorfenvinphos and bromacil. Nanostructures have been characterized by FESEM and Raman spectroscopy. Photoelectrochemical degradation tests have been carried out both for individual pesticide solutions and for a mixture solution, and the concentration evolution with time has been followed by UV-Vis spectrophotometry. For individual pesticides, pseudo-first order kinetic coefficients of 0.402h-1 and 0.324h-1 have been obtained for chlorfenvinphos and bromacil, respectively, while for the mixture solution, these kinetic coefficients have been 0.162h-1 and 0.408h-1. The change in behavior towards pesticide degradation depending on whether individual or mixture solutions were used might be indicative of a competitive process between the two pesticide molecules when interacting with the WO3 nanostructures surface or when approaching the semiconductor/electrolyte interface.