Browsing by Author "Isaacs Casanova, Mauricio Alejandro"

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    A ternary eutectic solvent for cellulose nanocrystal production: exploring the recyclability and pre-pilot scale-up
    (2023) Mariño, Mayra A. ; Paredes Gutierrez, Maria Gabriela; Martinez Ahumada, Natalia del Pilar; Millan, Daniela ; Tapia, Ricardo A. ; Ruiz, Domingo ; Isaacs Casanova, Mauricio Alejandro; Pavez Guerrero, Paulina Isabel
    Deep eutectic solvents (DES) formed using choline chloride (ChCl), p-toluenesulfonic acid (pTSA) of stoichiometry ChCl: pTSA (1:1) and (1:2), and its ternary eutectic mixtures with phosphoric acid (PA) 85% as an additive (ChCl: pTSA: PA) were evaluated for cellulose nanocrystal (CNC) isolation. Initially, the hydrolytic efficiency to produce CNC of each DES was compared before and after adding phosphoric acid by Hammett acidity parameters and the Gutmann acceptor number. Moreover, different DES molar ratios and reaction time were studied at 80°C for CNC optimization. The nanomaterial characteristics were analyzed by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The ternary eutectic mixture ChCl: pTSA: PA molar ratio (1:1:1.35) was chosen as a suitable recyclable ternary system at the laboratory scale. A CNC yield of about 80% was obtained from the hydrolysis of commercial cellulose in five cycles of recovery, but it dropped to 35% in pre-pilot scaling. However, no variation in the average size of the resulting CNC was observed (132 ± 50 nm x 23 ± 4 nm), which presented high thermal stability (Tmax 362°C) and high crystallinity of about 80% after 3 h of reaction time.
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    Improved ammonia production using Cu2O@poly-carbazole electrocatalysts in the electrochemical reduction of molecular nitrogen and nitrogen oxoanions
    (2024) Herrán Maldonado, Luis Alberto; Véliz-Silva, Diego F.; Poblete Baeza, Colin; Leiva Farias, Elías Guillermo; Honores Sotelo, Jessica Scarlet; Landaeta Campos, Esteban Alonso; Sancy Velásquez, Mamie Odette; Del Río Quero, Rodrigo Rafael; Sáez Navarrete, César Antonio; Dalchiele, Enrique; Isaacs Casanova, Mauricio Alejandro
    In the present study, a Cu2O@PCz electrode for the nitrogen reduction reaction is proposed; this electrode takes advantage of the catalytic properties of Cu2O in conjunction with conducting polymers such as polycarbazole (PCz). This combination demonstrates an improvement in the catalytic activity and higher stability of this metal oxide in nitrogen electro-reduction reaction (NRR) and nitrogen oxoanion electro-reduction reaction (NORR) processes under aqueous conditions. On this basis, the material synthesized on FTO (SnO2 : F), Cu2O@PCz, exhibits a faradaic efficiency of around 38.83%, together with an NH3 productivity of 1.83 μg h−1 cm−2 in NRR type processes, on applying a potential of −0.8 V (V vs. Ag/AgCl). Similarly, in NORR type processes, the material exhibits NH3 and N2H4 productivity. The latter is the most relevant in terms of the yields obtained. Specifically, using nitrite (NO2−), an efficiency of around 77.72% was obtained, together with a formation rate of 37.02 μg h−1 cm−2 at a potential of −0.8 V (V vs. Ag/AgCl). Although N2H4 is a by-product of ammonia formation, this molecule can be considered an intermediate, which broadens the scope of this study for future research into the production of green chemicals. Finally, this research presents promising new routes for the production of NH3 at room temperature, highlighting the potential of low-cost materials, easy synthesis, and enhanced stability.
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    Synthesis of cyclic carbonates from CO2 and epoxide catalyzed by Co, Ni and Cu complexes in ionic liquids
    (2019) Honores Sotelo, Jessica Scarlet; Quezada, Diego; Chacón, Gustavo; Martínez‑Ferraté, Oriol; Isaacs Casanova, Mauricio Alejandro