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PublicationCharacterization and evaluation of antioxidant and antimicrobial capacity of prepared liquid smoke-loaded chitosan nanoparticles( 2022-04-01)
;Monteza J. ;Ruiz-Pacco G.A. ;Espinoza – Suarez J.B. ;Osorio – Anaya A.M. ;Valderrama – Negrón A.C. ;ALARCON CAVERO, HUGO ARTUROThe combined application of chitosan (CS) and liquid smoke (LS) leads to the development of a suitable material with synergistic properties and promising potential for use as an efficient preservative for the conservation of food products. The present work investigates the development and characterization of liquid smoke-loaded chitosan nanoparticles (LS-CS/NPs) with the optimization of the preparation conditions using response surface methodology and the analysis of the antioxidant and antibacterial properties of the nanoparticles as well as the controlled release of the liquid smoke. The nanoparticles were prepared by the ionic gelation method and were characterized by DLS, zeta potential, FT-IR, SEM, and EDS. The analysis of antioxidant activity of LS-CS/NPs was performed by the free radicals scavenging method (DPPH and ABTS) while the study of the total phenolic content of the particles was conducted via the application of the Folin-Ciocalteau method with some modifications. The analysis of antimicrobial activity of the LS-CS/NPs was performed using the minimum inhibitory concentration method involving the growth of Gram-positive (S. aureus and B. cereus) and Gram-negative (E. coli and Salmonella spp) bacteria. The analysis of the controlled release of liquid smoke was conducted at 4 °C using the Korsmeyer-Peppas model. The results obtained showed that the nanoparticles prepared using CS and LS in the ratio 1.5: 0.583, respectively (F′2), which had an average size of 205 nm and zeta potential of 45 mV, exhibited good antioxidant (%DPPH: 92.7% and %ABTS: 93%) and antibacterial activities, with an efficient, gradual controlled release of liquid smoke (release rate = 0.042 min−1). -
PublicationMixed metal oxide Bi2O3/Bi2WO6 thin films for the photoelectrocatalytic degradation of histamine(Elsevier B.V., 2022-08-15)
;Aranda-Aguirre A. ;Corzo A. ;Garcia-Segura S.Alarcon H.Photoelectrocatalytic technologies emerge as competitive strategy to manage increasing histamine concentrations. This work explores the synergistic benefits induced in the formation of mixed oxide semiconductor in solid solution. Photoelectrocatalytic films of Bi2O3, WO3, and their hybrid metal mixed oxide composition Bi2O3/Bi2WO6 were synthesized and characterized. Results demonstrate that Bi2O3/Bi2WO6 structure increases stability of charge carriers and enhances degradation performance. Applied bias potential was identified as driving variable that induces effective charge carrier stabilization for accelerated degradation of histamine in aqueous solution. Scavenger experiments identified •OH and O2•- as the main oxidant species produced during photoelectrocatalytic treatment. -
PublicationPhotoelectrocatalytic degradation of 2,4-dichlorophenol in a TiO2 nanotube-coated disc flow reactor(Elsevier Ltd, 2021-04-01)
;ALARCON CAVERO, HUGO ARTURO ;Corzo A. ;Westerhoff P.Garcia-Segura S.Photoelectrocatalytic (PEC) water treatment is a promising technology for organic pollution abatement. Much of the prior research focused on material discovery and optimization. However, challenges exist in scaling-up PEC processes and are associated with designing reactors with effective light irradiation on electrode surfaces and, simultaneously, efficient electrode configurations. We design and demonstrate key reactor design principles, which influence reaction mechanisms, for a reactor using a TiO2 nanotube-coated disc flow reactor. Degradation of organochlorinated 2,4-dichlorophenol was studied as representative carcinogenic micropollutant. The synergistic photoelectrocatalytic process showed 5-fold faster degradation kinetics than solely electrocatalytic treatment or a greater than 2-fold enhancement over photocatalysis alone. Applicability of photoelectrocatalytic treatment was demonstrated over a wide range of micropollutant concentrations with almost complete abatement even at concentrations up to 25 mg L−1 of 2,4-dichlorophenol. Mechanistically, the increase in applied current density efficiency for degradation of 2,4-dichlorophenol was due to stabilization of charge carriers and higher oxidants production rates in the PEC system. Carboxylic acids were identified as the main by-products formed from cleavage of the phenolic ring moieties in 2,4-dichlorophenol. However, very importantly we achieved dehalogenation photoelectrocatalysis with evidence of chlorine heteroatoms released as innocuous chloride anions. Overall, this research demonstrates the importance of PEC reactor design and how properly orientated TiO2 nanotube-coated disc flow reactors leverage both novel material designs and reactor architectures to achieve pollutant degradation. -
PublicationScaling up photoelectrocatalytic reactors: A TiO2 nanotube-coated disc compound reactor effectively degrades acetaminophen( 2019-01-01)
;Cotillas S. ;ALARCON CAVERO, HUGO ARTURO ;Westerhoff P.Garcia-Segura S.Multiple discs coated with hierarchically-organized TiO2 anatase nanotubes served as photoelectrodes in a novel annular photoelectrocatalytic reactor. Electrochemical characterization showed light irradiation enhanced the current response due to photogeneration of charge carriers. The pharmaceutical acetaminophen was used as a representative water micropollutant. The photoelectrocatalysis pseudo-first-order rate constant for acetaminophen was seven orders of magnitude greater than electrocatalytic treatment. Compared against photocatalysis alone, our photoelectrocatalytic reactor at <8 V reduced by two fold, the electric energy per order (EEO; kWh m-3 order-1 for 90% pollutant degradation). Applying a cell potential higher than 8 V detrimentally increased EEO. Acetaminophen was degraded across a range of initial concentrations, but absorbance at higher concentration diminished photon transport, resulting in higher EEO. Extended photoelectrocatalytic reactor operation degraded acetaminophen, which was accompanied by 53% mineralization based upon total organic carbon measurements. This proof of concept for our photoelectrocatalytic reactor demonstrated a strategy to increase photo-active surface area in annular reactors.