Currently, catalytic pyrolysis has become a versatile and highly useful technology in the treatment of different plastic wastes. Thus, the development of selective catalysts to carry out cracking reactions and obtain a greater fraction of the desired products is essential. This study focuses on the synthesis of monometallic (Ni) and bimetallic (Ni-Zn) catalysts supported on ZSM-5 zeolite using an impregnation and co-impregnation method, respectively. The obtained catalysts were characterized by FTIR spectroscopy, N₂ adsorption/desorption measurements, scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDS), temperature programmed NH₃ desorption (TPD-NH₃) and thermogravimetric analysis (TGA). In this way, a mixture of polystyrene and polypropylene recycled with a catalyst/plastic waste ratio of 1:500 was used for pyrolysis tests. The best results were obtained using the Ni-Zn/ZSM-5 catalyst, which included better impregnation, increased surface acidity, decreased dispersion and a shorter reaction time in the catalytic pyrolysis process. Under the optimized conditions, catalytic pyrolysis showed an excellent performance to generate hydrocarbons of greater industrial interest.

The pyrolysis process is a thermochemical recycling process that in recent years has gained importance due to its application in plastic waste, which is one of the biggest environmental problems today. Thus, it is essential to carry out kinetic and thermodynamic analyses to understand the thermocatalytic degradation processes involved in plastic waste mixtures. In this sense, the main objective of this study is to analyze the degradation kinetics of the specific mixture of polypropylene (25%) and polystyrene (75%) with 10% mass of regenerated FCC catalyst which was recovered from conventional refining processes using 3 heating rates at 5, 10 and 15 K min⁻¹ by thermogravimetric analysis (TGA). The obtained TGA data were compared with the isoconversional models used in this work that include Friedman (FR), Kissinger Akahira Sunose (KAS), Flynn–Wall–Ozawa (FWO), Starink (ST) and Miura–Maki (MM) in order to determine the one that best fits the experimental data and to analyze the activation energy and the pre-exponential factor; the model is optimized by means of the difference of minimum squares. Activation energy values between 148 and 308 kJ/mol were obtained where the catalytic action has been notorious, decreasing the activation energy values with respect to thermal processes.

El alofán es una nanopartícula natural presente en suelos de origen volcánico como los andisoles, que se encuentran distribuidos alrededor de todo el mundo en países con actividad volcánica. En Ecuador, los andisoles constituyen el 30% del territorio en zonas altas y húmedas de la región sierra-norte. El alofán se puede obtener de los andisoles a través de procesos físicos y químicos, o a su vez se puede sintetizar. Este nanomaterial posee múltiples propiedades para varias aplicaciones en diferentes áreas. Existen muchas investigaciones de estas nanopartículas y de este tipo de suelos, pero no se han estudiado aún en el Ecuador. En este artículo se presentan las características estructurales, propiedades, la formación, aislamiento, síntesis y usos del alofán, con el fin de generar conocimiento e incentivar la investigación de estos suelos que son fuente de la mencionada nanopartícula. La búsqueda de literatura se realizó en bases de datos de Science Direct y Google Académico, y se utilizaron artículos de alto impacto relacionados con investigaciones de alofán natural o sintético. Las características particulares que tiene el alofán le permite ser usadocomo remediador ambiental, bactericida, antiinflamatorio, ignífugo, soporte de enzimas, pero además se ha estudiado en catálisis, fotocatálisis y electrocatálisis. Al considerar el área cubierta por el alofán en el territorio ecuatoriano y su disponibilidad, este se puede aprovechar para realizar investigaciones basadas en los estudios internacionales que se han desarrollado para aprovechar en el área ambiental y médica.

This study aimed to synthesize a magnetic biochar@ZIF-8 composite derived from almond shell biomass for the adsorption of fluoroquinolones (FQs) from aqueous media. The biochar was prepared under different pyrolysis conditions using a central composite design (CCD) based on temperature and residence time, with biochar yield (%) and ofloxacin adsorption capacity selected as the response variables. Subsequently, the composite was obtained by combining KOH-activated biochar with ZIF-8 and magnetic particles, producing a hierarchically porous material with enhanced surface area and functional groups favorable for adsorption. The physicochemical and morphological properties of the composite were characterized by SEM–EDS, FTIR, BET, TGA, and XRD analyses, confirming the successful incorporation of ZIF-8 and magnetic phases onto the biochar surface. The adsorption performance was systematically evaluated by studying the effects of pH and contact time. The kinetic data fitted well to the pseudo-second-order model, suggesting that chemisorption predominates through π–π stacking, hydrogen bonding, and coordination interactions between FQ molecules and the active sites of the composite. Furthermore, the material exhibited high reusability, maintaining over 84% of its adsorption capacity after four cycles, with efficient magnetic recovery without the need for filtration or centrifugation. Overall, the magnetic biochar@ZIF-8 composite demonstrates a sustainable, cost-effective, and magnetically separable adsorbent for water remediation, transforming almond shell waste into a high-value material within the framework of circular economy principles.

El presente estudio tiene como objetivo determinar de la cinética química de la reacción de degradación térmica del polietileno de alta densidad (HDPE) post consumo mediante análisis termogravimétrico (TGA) a tasas de calentamiento de 5, 10 y 15 ºC min-1, usando atmósfera de nitrógeno a un flujo de 20 mL min-1, en condiciones dinámicas desde 25 a 900 ºC. A partir de ello se obtuvieron los datos de degradación (masa vs tiempo) y su primera derivada, que a su vez fueron aplicados en tres modelos cinéticos para determinar la energía de activación: Friedman (FR), Kissinger–Akahira–Sunose (KAS) y Flynn–Wall–Ozawa (FWO), tomando el modelo de reacción conocido como Esfera de Contracción (R2) característica para este tipo de plásticos. Se deduce cada uno de los modelos para el tratamiento del termoplásticos, establecienndo que el modelo que describe mejor la cinética de degradación para HDPE es el de Friedman obteniendo valores de energía de activación de 281, 248 y 232 kJ kmol-1 para las tasas de 5, 10 y 15 ºC min-1 respectivamente