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Química de Superficies y Catálisis

Optimized electrocatalytic degradation of ciprofloxacin using Co3O4 coated stainless steel electrodes

Saleem, MU; Jawad, M; Azad, F; Nawaz, MA; Zaman, WQ; Miran, W
Colloids and Surfaces A-Physicochemical and Engineering Aspects, 681 (2024) 132738

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Ciprofloxacin (CIP) is a fluoroquinolone antibiotic that is widely used across the globe and its release is a serious concern due to its persistent nature, partial degradation, and simple transport through different environmental matrices. Pharmaceuticals have been degraded effectively by electrochemical oxidation. Exploring ways to in-crease the mineralization of these compounds while maintaining low power consumption is important. In this study, the treatability and degradation of CIP were investigated by using cobalt oxide-coated stainless steel (SS) electrodes in a lab-scale electrochemical (EC) reactor. The performance of the electrochemical reactor was determined under various operational conditions. The feed wastewater was synthetically prepared in the laboratory with varying concentrations of CIP ranging from 8 to 41 mg/L and the EC reactor was operated with an applied voltage and airflow rate of 2.6-9.3 volts and 1.6-3.5 L/min, respectively. A 3-factor central composite experimental design (CCD) was developed by using response surface methodology (RSM) in Design-Expert software. At a residence time of 27 min, initial concentration of 25 mg/L, airflow rate of 2.5 L/min, and applied voltage of 6 volts, the EC reactor achieved a removal efficiency of 70.8% for CIP with SS electrodes. On the contrary, the removal efficiency was increased to 91.5% at a reduced residence time of 21 min with cobalt oxide (Co3O4) coated over SS plates. The results indicated that Co3O4@SS electrodes resulted in better removal efficiency of CIP at a lower residence time. This system can be used as a robust benchmark for a single or consortium of antibiotics present in domestic and hospital wastewater.

Enero, 2024 | DOI: 10.1016/j.colsurfa.2023.132738

Química de Superficies y Catálisis

Subnanometric Pt clusters dispersed over Cs-doped TiO2 for CO2 upgrading via low-temperature RWGS: operando mechanistic insights to guide an optimal catalyst design

Torres-Sempere, G; Blay-Roger, R; Luque-Alvarez, LA; Santos, JL; Bobadilla, LF; Pastor-Pérez, L; Centeno, MA; Hernández, WY; Yousef, I; Odriozola, JA; Reina, TR
Journal of Matertials Chemistry A, 12 (2024) 1779-1792

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The RWGS reaction is gathering momentum as an effective route for CO2 valorisation and given its endothermic nature the challenge lies in the design of active low-temperature catalysts. Herein we have designed two catalysts based on subnanometric Pt clusters providing effective CO2 conversion and, more importantly, high CO selectivity in the low-temperature range. The impact of Cs as a dopant in the catalyst's formulation is crucial leading to full selectivity at 300 °C. The reaction mechanisms for the studied systems namely Pt/TiO2 and PtCs/TiO2 are significantly different due to the presence of the alkali promoter. The presence of Cs neutralises the hydroxide groups of the TiO2 surface, changing the reaction pathway. The Pt/TiO2 catalyst follows a redox mechanism where CO2 dissociates to CO in the oxygen vacancies, and then these vacancies are recovered by the migration of H2 by spill over phenomena. On the other hand, the Cs doped catalyst has two possible mechanism pathways: the (ii) formyl/acyl pathway, where –CHO species are formed and, depending on the reaction conditions, evolve to CO gas or oxygenated compounds, and (ii) frustrated Lewis pair (FLP) assisted CO2 reduction route, in which the FLP induces the heterolytic dissociation of H2 and the subsequent hydrogenation of CO2 to CO. The latter route enabled by Cs-doping combined with the subnanometric Pt domains seems to be responsible for the excellent catalytic behaviour leading to fully selective low-temperature RWGS systems and thus unlocking new possibilities for less energy demanding CO2 valorisation units based on RWGS.

Enero, 2024 | DOI: 10.1039/D3TA05482A


Materiales de Diseño para la Energía y Medioambiente

Incorporation of bioactive compounds from avocado by-products to ethyl cellulose-reinforced paper for food packaging applications

Acquavia, MA; Benitez, JEJ; Bianco, G; Crescenzi, MA; Hierrezuelo, J; Grife-Ruiz, M; Romero, D; Guzman-Puyol, S; Heredia-Guerrero, JA
Food Chemistry, 429 (2023) 136906

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Reinforced films were fabricated by impregnating paper in ethyl cellulose solutions. After solvent evaporation, the infused ethyl cellulose acted as binder of the paper microfibres and occupied the pores and cavities, thus improving the mechanical and barrier properties. To prepare active films, avocado by-products from guacamole industrial production were extracted in ethyl acetate. Then, the extract (optimized to be rich in phenolic compounds and flavonoids and mainly composed by lipids) was incorporated to the paper reinforced with the highest content of ethyl cellulose. In general, the addition of the avocado by-products extract decreased the water uptake and permeability, improved the wettability, and increased the biodegradability in seawater and the antioxidant capacity. In addition, these films acted as barriers and retainers for Escherichia coli and Bacillus cereus. The potentiality of these materials for food packaging was demonstrated by low overall migrations and a similar food preservation to common low-density polyethylene.

Diciembre, 2023 | DOI: 10.1016/j.foodchem.2023.136906

Química de Superficies y Catálisis

Boosting Low-Temperature CO2 Hydrogenation over Ni-based Catalysts by Tuning Strong Metal-Support Interactions

Ye, RP; Ma, LX; Hong, XL; Reina, TR; Luo, WH; Kang, LQ; Feng, G; Zhang, RB; Fan, MH, Zhang, RG
Angewandte Chemie-International Edition,

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Rational design of low-cost and efficient transition-metal catalysts for low-temperature CO2 activation is significant and poses great challenges. Herein, a strategy via regulating the local electron density of active sites is developed to boost CO2 methanation that normally requires >350 °C for commercial Ni catalysts. An optimal Ni/ZrO2 catalyst affords an excellent low-temperature performance hitherto, with a CO2 conversion of 84.0 %, CH4 selectivity of 98.6 % even at 230 °C and GHSV of 12,000 mL g−1 h−1 for 106 h, reflecting one of the best CO2 methanation performance to date on Ni-based catalysts. Combined a series of in situ spectroscopic characterization studies reveal that re-constructing monoclinic-ZrO2 supported Ni species with abundant oxygen vacancies can facilitate CO2 activation, owing to the enhanced local electron density of Ni induced by the strong metal-support interactions. These findings might be of great aid for construction of robust catalysts with an enhanced performance for CO2 emission abatement and beyond.

Diciembre, 2023 | DOI: 10.1002/anie.202317669

Materiales y Procesos Catalíticos de Interés Ambiental y Energético

Photoreforming of glycerol to produce hydrogen from natural water in a compound parabolic collector solar photoreactor

Villachica-Llamosas, JG; Sowik, J; Ruiz-Aguirre, A; Colón, G; Peral, J; Malato, S
Journal of Environmental Chemical Engineering, 11 (2023) 111216

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To improve TiO2 for H2 generation, one strategy for the separation of photogenerated charges is the formation of heterostructures with other materials. In particular, NiO is a photocatalyst known for its good stability and low cost. However, no studies at pilot scale using solar energy have been described. Consequently, an evaluation of a physical NiO:TiO2 mixture at pilot scale (25 L) with natural irradiation (2.10 m2 of sun-exposed surface) and with simultaneous glycerol photoreforming was explored. NiO:TiO2 50 mg & sdot;L- 1 resulted in the highest hydrogen production, showing an STH = 1.44%, considering only the UV fraction of the solar irradiation. H2 and CO2 production were analysed by on-line GC; Glycerol, dissolved organic carbon, carboxylic acids and nickel leaching were also evaluated. The NiO:TiO2 mixtures rendered a systematically lower H2 production in natural water than in high-purity water. The increase of ionic strength increased the mean size of particle clusters, promoting rapid sedimentation. All this indicates the importance of testing under real field conditions for attaining reliable solar to hydrogen (STH) efficiency.

Diciembre, 2023 | DOI: 10.1016/j.jece.2023.111216