Browsing by Author "Sepulveda, Pamela"

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    Elimination of sulfamethoxazole by anodic oxidation using mixed metal oxide anodes
    (2023) Lauzurique, Yeney; Miralles-Cuevas, Sara; Godoy, Mariel; Sepulveda, Pamela; Bollo, Soledad; Cabrera-Reina, Alejandro; Huilinir, Cesar; Malato, Sixto; Oller, Isabel; Salazar-Gonzalez, Ricardo
    The degradation of sulfamethoxazole (SMX) was studied by anodic oxidation (AO) process using mixed metal oxide (MMO) electrodes with different Ru/Ir ratios. Each electrode was characterized morphological and electrochemically. The electrolyzes were performed in NaCl and Na2SO4 applying two current densities (10 and 50 mA cm-2). The electrode with the highest composition of Ir, Ru/Ir (30/70), showed greater SMX degradation and generation of oxidizing species and was used to treat the antibiotic by AO and AO assisted by solar energy in natural water and actual municipal wastewater effluents.The efficiency in SMX degradation depends on the type of electrode used (MMO) and electrolytic medium. All MMO electrodes, reached almost total degradation of SMX in chloride medium. However, 60 % degradation of SMX in sulfate medium was achieved with anode with lower Ru/Ir ratio. Additionally, degradation of SMX in complex matrices can be successfully carried out by solar-assisted AO and AO processes, without the need to adjust the pH, at room temperature and using anode with lower Ru/Ir ratio. Finally, the AO process assisted by solar energy reduced electrolysis times and the cell's potential, leading to lower energy consumption.
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    Fast simultaneous electrochemical detection of Bisphenol-A and Bisphenol-S in urban wastewater using a graphene oxide-iron nanoparticles hybrid sensor
    (2023) Pina, Samuel; Sepulveda, Pamela; Garcia-Garcia, Alejandra; Moreno-Barcenas, Alejandra; Toledo-Neira, Carla; Salazar-Gonzalez, Ricardo
    In this work, a novel and sensitive electrochemical sensor was developed for the simultaneous determination of low concentration levels of Bisphenol-A (BPA) and Bisphenol-S (BPS) in a secondary effluent from a wastewater treatment plant and surface water. The sensor design involved the utilization of a glassy carbon electrode that was modified with hybrid iron nanoparticles and a nanostructure of graphene oxide. The synthesized material displayed a stable heterostructure, facilitating efficient electronic transfer and exhibiting impressive electro-catalytic capacity. Furthermore, the sensor successfully detected anodic signals of BPA and BPS with a peak separation of 0.28 V, confirming its excellent performance. For method optimization, a chemometric tool based on a Central Composite Face (CCF) design response surface was employed. The optimized conditions yielded an analytical curve with a linear range of 15.0 to 120.0 mu mol L-1 for BPA, represented by the equation Iap (mu A)=-0.088 + 0.044 (mu A L mu mol-1) [cBPA], and 20.0 to 70.0 mu mol L-1 for BPS, represented by the equation Iap (mu A)=-0.367 + 0.025 (mu A L mu mol-1) [cBPS]. The detection and quantification limits for BPA were established at 12.05 and 36.51 mu mol L-1, respectively. Similarly, for BPS, the corresponding values were determined to be 11.63 and 35.24 mu mol L-1. The electrochemical method developed was validated by comparing it with the high-performance liquid chromatography coupled to diode array detector (HPLC-DAD) technique. Notably, the electrochemical method demonstrated to be successful in the simultaneous detection and quantification of BPA and BPS in a secondary effluent and surface water.