This study aimed to produce biochar with an energy value in the range of sub-bituminous carbon by investigating the effect of oxidative and non-oxidative torrefaction on the torrefaction yield and fuel properties of wheat straw. Three independent variables were considered at different levels: temperature (230, 255, 280, 305 °C), residence time (20, 40, 60 min), and reaction atmosphere (0, 3, 6 vol% O₂; N₂ balance); and three dependent variables: mass yield, energy yield, and percentage increase in higher heating value (HHV). The results showed that it is possible to produce a sub-bituminous carbon type C biochar using oxidative torrefaction, significantly reducing time and temperature compared with non-oxidative torrefaction. The optimum torrefaction conditions were 287 °C–20 min–6.0% O₂, which increased the HHV of wheat straw from 13.86 to 19.41 MJ kg⁻¹. The mass and energy yields were 44.11 and 61.78%, respectively. The physicochemical and fuel properties of the obtained biochar were improved compared with the raw biomass. The atomic O/C ratio was reduced from 1.38 to 0.86. In addition, the hydroxyl groups in the lignocellulosic structure decreased and the hemicellulose content decreased from 26.08% to 1.61%. This improved grindability, thermal stability, porosity, and hydrophobicity.

The capacity of untreated cotton stalk to remove and adsorb Cu²⁺ ions in synthetic and natural aqueous solutions was evaluated. The influence of three sensitive parameters of the adsorption process—solution pH, adsorbent dosage, and contact time—on the percentage of Cu²⁺ removal in agricultural wastewater, livestock wastewater, and synthetic samples was studied. Physicochemical and morphological properties were studied using thermogravimetry, Fourier infrared spectrophotometry, and scanning electron microscopy. The elemental composition, proximal composition, zero charge point, and acid–base sites were determined. In addition, kinetic studies were performed, and the adsorption equilibrium was analyzed. The optimum conditions for Cu²⁺ adsorption were the following: solution pH = 5.5, adsorbent dosage of 0.6 g, and contact time of 60 min. Under these conditions, the percentage of Cu²⁺ removal in synthetic samples was 66.5% when the initial copper concentration was 50 mg/L. The removal percentage in agricultural and livestock wastewater samples was 87.60% and 85.05%, respectively, when the initial copper concentration was 25 mg/L. The adsorption data are consistent with the Freundlich isotherm model, which achieved a quadratic fit of 0.991 compared to 0.5542 for the Langmuir model. The experimental results indicate that the adsorption adequately fits the pseudo-second-order kinetic model. The results suggest that cotton stalks are a promising adsorbent for the ecological and economical removal of Cu²⁺ in wastewater. This research, therefore, provides relevant information that contributes to the sustainable management of agricultural waste and instills hope for a reduction in water pollution from heavy metals derived from agricultural activities.

Selenium is an essential micronutrient which is found in many foods and beverages in low concentrations. Craft beer, one of the most widely consumed fermented beverages globally, presents a strategic opportunity for selenium intake through organic nanoparticles. This study aimed to confirm the presence of selenium nanoparticles in the fermentation process of an ale-style beer using S. boulardii yeast selenized with Na₂SeO₃ (74 ppm), through spectroscopic analysis and TEM. The yeast accumulated 5.92 mg/g of dry cell mass, and the beer contained 0.642 mg/g of selenium. UV-VIS detected nanoparticles with a peak at 300 nm and FT-IR at a wavelength of 1398.85 cm⁻¹. The particle size ranged between 74 to 175 nm, with a maximum ζ-potential of −4.2 mV, an electrophoretic mobility of −0.3492 μm × cm Vs⁻¹, and a conductivity of 2.656 mS cm⁻¹. TEM analysis revealed that the nanoparticles exhibited circular/ovoid shapes. The fermentation process, combined with the ingredients used to produce ale-type craft beer, proved to be a feasible method for the biosynthesis of selenium nanoparticles using S. boulardii, offering a reliable option for developing and innovating functional craft beers.

The world’s energy matrix can be diversified with biodiesel from castor and jatropha oil. Hence, the objective of this study was to assess a conversion path for the valorization of castor and jatropha seeds. The results showed the maximum extraction of castor oil at 90 °C, 2 rpm, and 6 mm nozzle, achieving a yield of 36.97% and for jatropha oil at 100 °C, 1.5 rpm, and 10 mm nozzle, achieving a yield of 20.11%. The acid value and cloud point of castor and jatropha oil were 0.797 and 23.44 mg KOH/g, 10±1 °C and 12±0.55 °C, respectively; while the pour point was -3 °C for both. The acid value and cloud point for biodiesels ranged from 0.26-0.43 mg KOH/g, and -12.50-6.10 °C, respectively. The viscosity of oils and biodiesel ranged from 0.02-1.3 P. GC-MS indicated 66.38% of methyl ricinoleate in castor biodiesel and 31.64% of methyl oleate in jatropha biodiesel. The HHV for castor and jatropha biodiesel ranged from 32.37-40.25 MJ/kg.

El reúso de aguas residuales tratadas en la agricultura constituye una alternativa viable para enfrentar la escasez hídrica en regiones áridas y semiáridas, siempre que se garantice su calidad conforme a criterios técnicos y normativos. El objetivo de este estudio fue evaluar la calidad fisicoquímica, microbiológica y de metales pesados del agua residual tratada generada en la Planta de Tratamiento de Aguas Residuales del Instituto de Ciencias Agrícolas de la Universidad Autónoma de Baja California, y analizar su aptitud para el riego de cultivos forrajeros en el Valle de Mexicali. Se analizaron parámetros como pH, temperatura, grasas y aceites, demanda química de oxígeno (DQO), sólidos suspendidos totales (SST), Escherichia coli, nitrógeno y fósforo totales, así como metales pesados (As, Cd, Hg, Pb, Cr, Ni, Cu y Zn), comparando los valores obtenidos con los límites establecidos en la NOM-003-SEMARNAT-1997 y la NOM-001-SEMARNAT-2021.