Margarita Mercedes González Brambila

From 1950 to the present, plastic production and use have increased mainly because plastics possess qualities like stability, light weight, versatility, and decreasing production costs. However, most plastics are not biodegradable, and only a small portion is recycled worldwide. Bioplastics serve as an alternative if they are biodegradable and derived from residual materials, promoting a circular economy. PHB is a polymer with characteristics similar to some commercial plastics. It was discovered in the 1920s and has been examined by researchers and engineers since then due to its potential as a biodegradable bioplastic. Some microorganisms can produce PHB under controlled conditions. In this work, PHB production was analyzed using two strains, Bacillus subtilis and Bacillus megaterium, and two byproducts—whey and glycerol—as substrates and varying the culture media compositions. Both byproducts and both strains are suitable for PHB production; the absence of nitrogen and trace element sources enhances PHB yield. Additionally, bacterial growth, substrate uptake, and PHB production were modeled using logistic growth and the Luedeking–Piret models.

From 1950 to the present, plastic production and use have increased mainly because plastics possess qualities like stability, light weight, versatility, and decreasing production costs. However, most plastics are not biodegradable, and only a small portion is recycled worldwide. Bioplastics serve as an alternative if they are biodegradable and derived from residual materials, promoting a circular economy. PHB is a polymer with characteristics similar to some commercial plastics. It was discovered in the 1920s and has been examined by researchers and engineers since then due to its potential as a biodegradable bioplastic. Some microorganisms can produce PHB under controlled conditions. In this work, PHB production was analyzed using two strains: Bacillus subtilis and Bacillus megaterium. Using two byproducts—whey and glycerol—as substrates and varying the culture media compositions. Both byproducts and both strains are suitable for PHB production; the absence of nitrogen and trace element sources enhances PHB yield. Additionally, bacterial growth, substrate uptake, and PHB production were modeled using logistic growth and the Luedeking-Piret models.

Article Communication Regarding Articles from the 2023 International Engineering Conference (IEC-2023), held in Zacatecas City, Mexico, from September 18–23, 2023, already published in the International Journal of Chemical Reactor Engineering in 2024 was published on March 11, 2025 in the journal International Journal of Chemical Reactor Engineering (volume 0, issue 0).

Atrazine is a triazine organochlorine herbicide used commonly in some countries like Mexico, however it is hazardous for human, vegetable and animal life. Atrazine reaches groundwater drinking sources, causing serious illnesses in the population. Understanding the mineralized atrazine biodegradation process is a crucial issue in dealing with soils containing atrazine. Bioremediation of soil and water contamination involves a complex interplay between mass transport and biological processes. Soil adsorption, solubility, and interfacial transport limit the availability of contaminants to microorganisms. This review summarizes the recent studies about metabolic pathways and enzymes to degrade atrazine to carbon dioxide, ammonia, water and biomass carried out by some bacteria and fungi species. The biodegradation of atrazine was analyzed, considering the different metabolic pathways of bacteria and fungi. Biodegradation of atrazine by bacteria is well studied, but the fungal metabolism of this compound remains less clear. Some species of white-rot fungi can naturally biodegrade complex compounds, such as lignin, an aromatic polymer that is a major component of plant cell walls. The lignin has a polyphenolic structure that presents similarities with many aromatic pollutants and herbicides like atrazine. A deep understanding of the mechanisms involved is a successful tool for the design of new strategies for biodegrading. A comparison of the rates of degradation between physicochemical and biological processes is included, and some recommendations for the microorganism species and conditions.

This Special Issue of the International Journal of Chemical Reactor Engineering (IJCRE) presents selected manuscripts from the International Energy Conference 2023 (IEC 2023), which took place in Zacatecas, Mexico, from September 18 to 22, 2023. As a biennial event, the IEC fosters research and discussions on global energy challenges. The 2023 edition of the conference focused on the role of sustainable processes in addressing energy and climate change. Key topics included energy efficiency, life-cycle assessments, sustainability strategies, public policies, and energy awareness. Beyond these themes, the IEC 2023 provided a platform for knowledge exchange, critical discussions, and reflections on the influence of both fossil fuels and renewable energy sources on the global energy landscape.

En el presente trabajo se evaluaron catalizadores bifuncionales mono y bimetálicos de Ni, Pd y Pt, empleando cargas metálicas totales menores al 3 % en peso soportados en arcillas pilareadas modificadas con cationes de circonio en la reacción de hidrodeoxigenación de eugenol a condiciones medias de presión y temperatura, 3 MPa y 573 K. Los catalizadores fueron sintetizados a través del método de impregnación en estado sólido y se caracterizaron textural y estructuralmente a través de fisisorción de N2 y difracción de rayos X. El catalizador monometálico que presentó mayor actividad fue el de Pd con un contenido de metal del 1 % peso, k= 4.94 x10-2 min-1, además alcanzó una conversión del 99.98 % a los 75 min de reacción y selectividades a 4-propilfenol y propil-ciclohexano de 22 y 29 % molar, respectivamente. Para el caso de los catalizadores bimetálicos, el más activo fue 1Ni1Pd, k= 3.83 x10-2 min-1 con una conversión del 99.6 % a los 105 min y selectividades a 4-propilfenol y propil-ciclohexano de 14 y 31 % molar, respectivamente, proveniente de las reacciones de desmetoxilación e hidrodeoxigenación. Además, se encontró que la relación molar H/C empleando el catalizador 1Pt fue igual a 1.93 cercana a la encontrada en combustibles de aviación comerciales (1.98) o incluso mayor a la de biocombustibles de aviación reportados en la literatura (1.37).

Article Preface of the special issue dedicated to the International Energy Conference, IEC 2021: sustainable energy as a platform for post-pandemic economic recovery was published on March 22, 2023 in the journal International Journal of Chemical Reactor Engineering (volume 0, issue 0).

Cellulose can be used to produce biofuels and many other products like pharmaceutical goods, food supplements, cosmetics, bio-plastics, etc. Lignocellulosic materials, like O . ficus indica residuals, are a heterogeneous biopolymer formed mainly by lignin, hemicellulose and cellulose. Lignin provides protection to the plants against chemical and microbial degradation, but it can be degraded by white rot fungi species, like Pycnoporus cinnabarinus . Since cellulose molecules are arranged in regular bundles enveloped by hemicellulose and lignin molecules, it is necessary to brake lignin and hemicellulose molecules to recover cellulose for its use in bioprocess. In this work, a biotechnological process for cellulose recovery from cactus waste through depolymerization of lignin by P . cinnabarinus , is presented. The delignification is carried out by aerobic culture in batch stirred bioreactors, with a liquid culture medium enriched with nutrients and minerals with O . ficus indica residuals as the unique carbon source, during eight-day span under continuous feeding of oxygen. A factorial design of experiments (DOE) for eight sets of factor values was selected for this study. The factors were: particle size, pH level, and process temperature. For each experiment, biomass, total reducing carbohydrates (TRC) and dissolved oxygen (DO) concentrations were measured every 24 h. At the end of each experiment, the percentage of delignification, and cellulose recovery was measured by Infrared (IR) spectroscopy. Up to 67% of delignification and 22% of cellulose recovery were obtained by the process. These results were analyzed by a factorial DOE in order to maximize each response individually and to optimize both responses together. The delignification of Opuntia ficus indica thorns has not been previously reported to our knowledge.

Atrazine is a commonly used herbicide in the Mexican agricultural industry even though it is hazardous for human and animal health. Before reaching its mineralization, this herbicide infiltrates through soil, producing toxic compounds and contaminating groundwater sources. Considering that Aspergillus niger (A. niger) is a filamentous fungus that degrades pectin, cellulose, and other organic polymers, this study analyzes its use to accelerate atrazine mineralization under optimal parameters of temperature, soil humidity, and a co‐substrate for bio‐stimulation. Different atrazine concentrations were used, from 0 ppm to 1000 ppm, in order to measure the growth of its filaments. Glucose and Opuntia ficus indica residues were analyzed as co‐substrates for A. niger biodegradation improvement. A DOE analysis was used to establish optimal treatment conditions. The findings in this study show that a 10 wt% of O. ficus indica as a co‐substrate with 80% humidity achieved atrazine biodegradation in the order of 70% to 75% in 6 days.