Browsing by Autor "Wilson Aguilar"

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Degradation of an Antibiotic from the Fluoroquinolone Group by Photocatalysis with a New Carbon Nitride Compound
(Universidad Técnica de Manabí, 2023) Alejandro Altamirano-Briones; Iván Cóndor Guevara; Katherine Terán; Isabel Espinoza; Luis A. Ramos; Wilson Aguilar; Christian Sandoval‐Pauker; Paul Vargas Jentzsch; Florinella Muñoz
Ofloxacin (OFL), a fluoroquinolone, is an antibiotic found in hospital wastewater, groundwater, and other water bodies. Its occurrence in water results in several environmental problems, such as the emergence of antibiotic-resistant bacteria. This research is focused on determining the viability of removing and mineralizing OFL by photocatalysis under visible radiation with a graphitic carbon nitride photocatalyst (GCNP) synthesized from the pyrolysis of urea and calcium oxalate at 600°C. The photocatalyst was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the point of zero charge (PZC) of the photocatalyst was determined, and the adsorption isotherms were obtained. The photocatalytic activity of this new material was tested with a synthetic aqueous solution of OFL (20 mg/L) exposed to visible radiation. Three pH values (5, 7, and 10) and three doses of H2O2 (41.7, 83.3, and 333.2 mg/L) were considered. The achieved mineralization was evaluated through the decrease in the content of total organic carbon (TOC). The highest degradation of OFL was 23.9% after 40 min, with an initial concentration of H2O2 of 83.3 mg/L and a pH value of 10. It was confirmed that the reaction follows a kinetics of pseudo-first order.
Enzymatic hydrolysis of Canna indica, Manihot esculenta and Xanthosoma sagittifolium native starches below the gelatinization temperature
(Wiley, 2012) Daysi Perez‐Rea; Cinthia Carola Rojas; Sergio Carballo; Wilson Aguilar; Björn Bergenståhl; Lars Nilsson
Abstract The susceptibility to enzymatic hydrolysis of starch extracted from raw roots of Canna indica , Manihot esculenta and Xanthosoma sagittifolium , grown in Bolivia, were studied below the gelatinization temperature. The granule size and amylose content were as followed: C. indica > M. esculenta > X. sagittifolium . The hydrolysis showed a rapid rate at the initial stage, followed by a progressive decrease thereafter. At 30, 40 and 50°C, during the initial stage, the rate of hydrolysis was observed to be influenced by the size of the granules, being the highest for the small sized granules X. sagittifolium , followed by the medium sized granules M. esculenta and the lowest rate was for the large sized granules C. indica starch. During the slow phase, A‐type M. esculenta and B‐type C. indica showed higher hydrolysis rates than A‐type X. sagittifolium . At 60°C, a positive correlation was found between the amylose content and the rate of hydrolysis among the starches. Microscopic observations showed a pattern of attack by the enzyme towards C. indica starch granules, suggesting that high amylose content is concentrated around the hilum.