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Publicación Acceso abierto Carbon-based nanocatalysts (CnCs) for biomass valorization and hazardous organics remediation(Universidad Cooperativa de Colombia, Facultad de Ingenierías, Ingeniería Mecánica, Medellín y Envigado, 2022-05-14) Giannakoudakis, Dimitrios A.; Zormpa, Foteini F.; Margellou, Antigoni G.; Qayyum, Abdul; Colmenares Quintero, Ramón Fernando; Len, Christophe; Colmenares, Juan Carlos; Triantafyllidis, Konstantinos S.The continuous increase of the demand in merchandise and fuels augments the need of modern approaches for the mass-production of renewable chemicals derived from abundant feedstocks, like biomass, as well as for the water and soil remediation pollution resulting from the anthropogenic discharge of organic compounds. Towards these directions and within the concept of circular (bio)economy, the development of efficient and sustainable catalytic processes is of paramount importance. Within this context, the design of novel catalysts play a key role, with carbon-based nanocatalysts (CnCs) representing one of the most promising class of materials. In this review, a wide range of CnCs utilized for biomass valorization towards valuable chemicals production, and for environmental remediation applications are summarized and discussed. Emphasis is given in particular on the catalytic production of 5-hydroxymethylfurfural (5-HMF) from cellulose or starch-rich food waste, the hydrogenolysis of lignin towards high bio-oil yields enriched predominately in alkyl and oxygenated phenolic monomers, the photocatalytic, sonocatalytic or sonophotocatalytic selective partial oxidation of 5-HMF to 2,5-diformylfuran (DFF) and the decomposition of organic pollutants in aqueous matrixes. The carbonaceous materials were utilized as stand-alone catalysts or as supports of (nano)metals are various types of activated micro/mesoporous carbons, graphene/graphite and the chemically modified counterparts like graphite oxide and reduced graphite oxide, carbon nanotubes, carbon quantum dots, graphitic carbon nitride, and fullerenes.Publicación Acceso abierto Mechanistic and kinetic studies of benzyl alcohol photocatalytic oxidation by nanostructured titanium (hydro)oxides: do we know the entire story?(Universidad Cooperativa de Colombia, Facultad de Ingenierías, Ingeniería Mecánica, Medellín y Envigado, 2023-01) Giannakoudakis, Dimitrios A.; Qayyum, Abdul; Barczak, Mariusz; Colmenares Quintero, Ramón Fernando; Borowski, Piotr; Triantafyllidis, Konstantinos; Colmenares, Juan CarlosSelective upgrade of lignocellulosic biomass-derived aromatic compounds by photocatalytic oxidation is assumed as a prosperous, environmentally friendly, and cost-effective process. We present for the first time the application of various advantageous titanium oxide nano-photocatalysts for the additives-free selective partial oxidation of benzyl alcohol to benzaldehyde at ambient conditions. The two best-performing materials were found titanate nanotubes and nanocores of anatase surrounded by amorphous titanium hydroxide phase. The results obtained by scavenger tests on top of the DFT calculations led us to conclude that various reactions and active species are responsible by a complex way for materials’ photoreactivity. Depending on nanocatalysts’ physicochemical features as well as the light irradiation (ultraviolet vs. royal-blue), different mechanisms/oxidation-pathways are photo-catalyzed. Finally, we show that utilizing organic compounds like benzoquinone as scavenger hides risks due to the interactions with the targeted to be converted organic that results in elevated photolytic decomposition even under royal-blue light.Publicación Acceso abierto Problem based learning and design thinking methodologies for teaching renewable energy in engineering programs: Implementation in a Colombian university context(Universidad Cooperativa de Colombia, Facultad de Ingenierías, Ingeniería Mecánica, Medellín y Envigado, 2023-01-05) Colmenares Quintero, Ramón Fernando; Caicedo Concha, Diana Milena; Rojas, Natalia; Stansfield, Kim E.; Colmenares-Quintero, Juan CarlosThe rapid depletion of fossil fuel reserves, population growth, and increasing environmental pollution have forced a change in the search for alternatives to produce and use energy. Currently, renewable energies (RE) have achieved more efficient advances to produce energy from non-conventional and inexhaustible sources, which can meet the basic needs of society and whose environmental impact is a door of opportunities for all. For this reason, academia has a preponderant role in ensuring that engineers are fully equipped with the necessary skills to provide feasible and contextualised solutions for this era of energy transition framed by the UN Sustainable Development Goals (SDGs). This article explores the impact on the development of the necessary skills for engineers in the renewable energy sector by tracing a route towards the acquisition of renewable energy knowledge with strategically organised work teams of undergraduate students, where two methodologies that are gaining ground in engineering education programs are applied: Problem Based Learning(PBL)and Design thinking (DT).After the validation of these techniques, it is concluded that bringing engineering students closer to real contexts related to renewable energies and above all with an objective of impact on communities, it is the right way to build knowledge in teams, in an immersive and committed way with the institution, which has developed and implemented an innovative pedagogical method based on the application of a critical educational model focused on the development of competencies, where the union of new technologies with the teaching processes on which this research is based is envisioned for the future.Publicación Acceso abierto Producción de acetinas (aditivos para combustibles) a partir de glicerol(Universidad Catolice Luis Amigo, 2021-05-10) Arbeláez Pérez, Oscar Felipe; González Martínez, Cristian David; Guzman Sanchez, Geovanni Alexis; Salazar Henao, DavidThe high production of glycerol, a low-cost by-product, from the biodiesel industry, has posed a threat to both the environment and the economy. The transformation of glycerol into value-added products would contribute positively to the biodiesel economy. In this review article, the valorization routes of glycerol are described; esterification is presented as one of the most promising routes for the transformation of glycerol in additive fuels. This review describes the most relevant results between 2010 and 2020 related to experimental conditions (temperature, molar ratio, and reaction time), heterogeneous catalysts, and catalytic activity (in terms of glycerol conversion and acetins selectivity) for the transformation of glycerol into acetins. (monoacetin, diacetin and triacetin). It is hoped that this review will allow this valuation technique to be addressed in a profitable and environmentally sustainable manner