Browsing by Author "Torres Palma, Ricardo A."
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Item Electroquímica, un enfoque verde para la sociedad del S.XXI(Editorial USC, 2019) Morales Morales, Jimmy Alexander; Amatore, Christian; Feliu, Juan Miguel; González Martínez, Ignacio; Rivera Iturbe, Fernando Felipe; García Ochoa, Esteban Miguel; Torresi, Roberto Manuel; Córdoba Torresi, Susana Inés; Orozco Holguín, Jahir; Torres Palma, Ricardo A.; Loaiza, Oscar Andrés; Calderón, Jorge A.; Meléndez, Ángel M.; Dector, Andrés; Quesada-Plata, Fabián E.; Pimi, Luca; Palma Goyes, Ricardo Enrique; Stiefvater, Robert; Casadiego Leal, Natalia Isabel; de Oliveira Junior, Renato Prado; Salazar Duque, Carlos Alberto;Item Laser Ablation for the Synthesis of Cu/Cu2O/CuO and Its Development as Photocatalytic Material for Escherichia coli Detoxification(MDPI, 2024) Quintero, Marcy; Manrique Moreno, Marcela; Riascos, Henry; Torres Palma, Ricardo A.; Castro Narvaez, Sandra; Ávila Torres, Yenny P.Advanced Oxidation Processes (AOPs) offer promising methods for disinfection by generating radical species like hydroxyl radicals, superoxide anion radicals, and hydroxy peroxyl, which can induce oxidative stress and deactivate bacterial cells. Photocatalysis, a subset of AOPs, activates a semiconductor using specific electromagnetic wavelengths. A novel material, Cu/Cu2O/CuO nanoparticles (NPs), was synthesized via a laser ablation protocol (using a 1064 nm wavelength laser with water as a solvent, with energy ranges of 25, 50, and 80 mJ for 10 min). The target was sintered from 100 °C to 800 °C at rates of 1.6, 1.1, and 1 °C/min. The composite phases of Cu, CuO, and Cu2O showed enhanced photocatalytic activity under visible-light excitation at 368 nm. The size of Cu/Cu2O/CuO NPs facilitates penetration into microorganisms, thereby improving the disinfection effect. This study contributes to synthesizing mixed copper oxides and exploring their activation as photocatalysts for cleaner surfaces. The electronic and electrochemical properties have potential applications in other fields, such as capacitor materials. The laser ablation method allowed for modification of the band gap absorption and enhancement of the catalytic properties in Cu/Cu2O/CuO NPs compared to precursors. The disinfection of E. coli with Cu/Cu2O/CuO systems serves as a case study demonstrating the methodology’s versatility for various applications, including disinfection against different microorganisms, both Gram-positive and Gram-negative.Item Manganese Dioxide Nanoparticles Prepared by Laser Ablation as Materials with Interesting Electronic, Electrochemical, and Disinfecting Properties in Both Colloidal Suspensions and Deposited on Fluorine-Doped Tin Oxide(2022-11) Corrales, Jhonatan; Acosta, Jorge; Castro, Sandra; Riascos, Henry; Serna Galvis, Efraim; Torres Palma, Ricardo A.; Ávila Torres, YennyNanoparticles (NPs) of α-MnO2 have high applicability in photoelectrochemical, heterogeneous photocatalysis, optical switching, and disinfection processes. To widen this panorama about MnO2 NPs, the formation of this material by laser ablation and deposition by dip-coating on fluorine-doped tin oxide (FTO), were considered in this study. The optical, spectroscopic, electrochemical characterization, and the evaluation of the antimicrobial activity, plus the photocatalytic response, were measured herein in colloidal media and deposited. For the deposition of NPs on FTO sheet, an anode is produced with a pseudocapacitive behavior, and 2.82 eV of band gap (GAP) in comparison with colloidal NPs for a value of 3.84 eV. Both colloidal suspension and deposited NPs have intrinsic antibacterial activity against two representative microorganisms (E. coli and S. aureus), and this biological activity was significantly enhanced in the presence of UVA light, indicating photocatalytic activity of the material. Thus, both the colloidal suspension and deposited NPs can act as disinfecting agents themselves or via light activation. However, an antibacterial behavior different for E. coli and S. aureus was observed, in function of the aggregation state, obtaining total E. coli disinfection at 30 min for deposited samples on FTO.Item Photochemical and photocatalytical degradation of antibiotics in water promoted by solar irradiation(Elsevier, 2020-01-24) Torres Palma, Ricardo A.; Serna Galvis, Efraím A.; Ávila Torres, YennySunlight is able to induce processes utilizable for the degradation of organic pollutants in water. In this chapter, the use of solar irradiation for the treatment of antibiotics by photolysis, classical heterogeneous photocatalysis, and photocatalysis based on nanomaterials is presented. Initially, the general aspects of antibiotics and their environmental impacts are considered. Then, the direct and mediated actions of sunlight on antibiotics are analyzed, focusing the discussion on aspects such as kinetics, transformations, and matrix effects. Next, some illustrative cases of application of TiO2-photocatalysis to eliminate antibiotics are addressed. The final section is devoted to photocatalysis based on nanomaterials for degrading antibiotics, paying special attention to their preparation, types of nanomaterials, and its application to the treatment of antibiotics in waters. The advantages and limitations of the applicability of photocatalytical systems for antibiotics elimination from water are also considered.Item Treatment of two sartan antihypertensives in water by photo-electro-Fenton using BDD anodes: Degradation kinetics, theoretical analyses, primary transformations and matrix effects(2021) Martínez Pachón, Diana; Serna Galvis, Efraím A.; Ibañez, María; Hernández, Félix; Ávila Torres, Yenny; Torres Palma, Ricardo A.; Moncayo Lasso, AlejandroDegradation of two representative antihypertensives, losartan (LOS) and valsartan (VAL) in water by photo-electro-Fenton (PEF), using a BDD anode in presence of sulfate anion was evaluated. PEF showed a fast elimination of these pollutants (>95% at 30 and 60 min of treatment for LOS and VAL, respectively). The main elimination route was the attacks of radicals produced in the system, having pseudo-first-order rate constants of 0.154 and 0.054 min−1 for LOS and VAL, correspondingly. Theoretical analyses of atomic charges were performed to rationalize the antihypertensives reactivity toward the electrogenerated degrading agents. Afterwards, the primary transformation products were assessed. The transformation products revealed that the degrading species attack the biphenyl-tetrazole, imidazole, and alcohol moieties on LOS. Meanwhile, carboxylic and amide groups, plus the central nucleus, were modified on VAL. These moieties corresponded well with the electron-rich sites indicated by the theoretical calculations. Also, the PEF process removed between 33 and 38% of total organic carbon after 5 h of electrolysis. Finally, it was considered LOS treatment in presence of oxalic acid (a typical organic waste of pharmaceutical industry), in addition to the pollutant degradation in effluents from municipal sewage treatment plants by PEF at pH ∼5. Oxalic acid accelerated LOS degradation. Meanwhile, in the effluent, the process led to 64% of LOS removal after 120 min of treatment, indicating the high potentiality of PEF to degrade antihypertensives in water containing organic and inorganic substancesItem Use of cds from teaching-laboratory wastes as a photocatalyst for the degradation of fluoroquinolone antibiotics in water(2021) Serna Galvis, Efraím A.; Ávila Torres, Yenny; Ibáñez, María; Hernández, Félix; Torres Palma, Ricardo A.Laboratory wastes containing Cd2+ and water polluted by pharmaceuticals represent an environmental concern. In this work, a proof concept, consisting of the use of teaching-laboratory wastes to synthesize CdS and its subsequent use as a photocatalyst to degrade fluoroquinolone antibiotics, was developed. The CdS was prepared by extraction with thioacetamide and calcination (at 450◦C) and characterized using several techniques. The photocatalytic activity of the CdS, to degrade levofloxacin and norfloxacin, was tested, and the routes involved in the process and the primary transformations of the fluoroquinolones were established. Moreover, the ability of CdS-photocatalysis to eliminate levofloxacin in simulated matrices of fresh urine and hospital wastewater was evaluated. The characterization analyses indicated that the CdS semiconductor was synthesized successfully. Effectively, the CdS acted as a photocatalyst toward degradation of levofloxacin, involving the action of superoxide anion radical, holes, and singlet oxygen mainly. The process induced transformations on the methyl-piperazyl moiety, plus hydroxylation of the fluoroquinolone nucleus on levofloxacin. Additionally, CdS-photocatalysis was highly selective for the elimination of the target pollutant in both tested matrices. Our research indicated the good potentiality of recycling teaching-laboratory wastes to generate photocatalysts to degrade organic pollutants. This work was presented at 4◦ Congreso Colombiano de Procesos Avanzados de Oxidación (4CCPAOx).