Estudio de las variables de proceso mediante superficie de respuesta para la optimización de la producción de biodiesel utilizando aceite de palma africana (Elaeis guineenis Jacq) como materia prima.

El aceite de palma africana (Elaeis guineensis Jacq) representa una opción atractiva para emplearse como materia prima en la fabricación de biodiesel. El Objetivo de este trabajo fue maximizar el rendimiento de biodiesel sintetizado a partir de oleína cruda de palma africana en el laboratorio. La síntesis de biodiesel se realizó en dos etapas: a) una esterificación ácida realizada con ácido sulfúrico y b) una transesterificación alcalina empleando hidróxido de sodio. Para hallar las condiciones óptimas en la tapa de transesterificación, se empleó un diseño central rotatorio compuesto. Se establecieron como factores de estudio la temperatura de reacción, la concentración de catalizador y el tiempo de reacción; el rendimiento de biodiesel fue la variable de respuesta. El análisis de varianza mostró que la temperatura y tiempo de reacción, la concentración de catalizador, y las interacciones concentración de catalizador*temperatura de reacción y concentración de catalizador*tiempo de reacción fueron los factores que tuvieron efecto significativo en el rendimiento de biodiesel. Las condiciones óptimas para la etapa de esterificación se establecieron en 2.5 % peso de ácido sulfúrico, 150 min de reacción y 64.5 °C. Para la etapa de transesterificación las condiciones óptimas fueron: 0.65 % peso para la concentración de catalizador, 56 °C para la temperatura de reacción y 110 min de tiempo de reacción. Bajo estas condiciones de reacción se tuvieron rendimientos de 90 % peso con un tiempo global de 260 min. El control de calidad de biodiesel y de mezclas diesel/biodiesel es de suma importancia, por lo que es necesario contar con técnicas eficientes, rápidas y económicas. En este trabajo se construyeron modelos de calibración basados en la tecnología UV-visible y FTIR para determinar la concentración de biodiesel en mezclas con petrodiesel. Para determinar la robustez de los modelos se realizó una validación interna y una validación externa. Con seis PCs, el modelo de calibración PLS-UV-visible presentó un error estándar de calibración (SEC)=1.41 y un error estándar de validación (SEV)=1.84; los valores del coeficiente de correlación de calibración fue (r Cal)=0.998 y del coeficiente de correlación de validación (r Val)=0.999. Para el modelo de calibración PLS-FTIR los valores fueron (SEC)=1.81, (SEV)= 1.94, (r Cal)= 0.998 y (r Val)=0.998. Los resultados muestran que ambos modelos de calibración, son métodos analíticos que se pueden usar para predecir la concentración de biodiesel de palma en mezclas con petrodiesel en un rango de concentraciones de 0-100 % peso. _______________ ABSTRACT: The African crude palm oil (Elaeis guineensis Jacq) represents a viable option for use as a raw material in the manufacture of biodiesel. The objective of this study was to maximize the yield of synthesized biodiesel from African crude palm oil in the laboratory. The synthesis of biodiesel was realized in two stages: a) an esterification performed with sulfuric acid, and b) an alkaline transesterification using sodium hydroxide. A central composite rotatable design was used to find the optimum conditions in the transesterification stage. Reaction temperature, catalyst concentration and the reaction time were established as study factors, whereas the yield of biodiesel was the response variable. The analysis of variance showed that the reaction temperature, catalyst concentration, reaction time, as well as the catalyst concentration*reaction temperature and the catalyst concentration*reaction time interactions were the factors having significant effect on the yield of biodiesel. The optimum conditions for the esterification stage were set at 2.5 wt % of sulfuric acid, a 150 min reaction time and 64.5 °C to the reaction temperature. For the transesterification stage, the optimum conditions were: 0.63 wt% for the catalyst concentration, 56 °C for the reaction temperature and 110 min reaction time. A 90 wt % yield was obtained under these reaction conditions in a total time of 260 min. The quality control of biodiesel and the blends diesel/biodiesel is extremely important; hence, it is necessary to have efficient, fast and economical techniques. In this work were built models calibration based on UV-visible and FTIR spectroscopy, to determine the concentration of palm biodiesel in blends with petrodiesel. To determine the robustness of the prediction models were realize an internal and external validation. The calibration model PLS-UV-visible with six PCs have a standard error of calibration (SEC)=1.41, and the standard error of validation (SEV)=1.84; the value of the correlation coefficient of calibration was (r Cal)=0.998 and the correlation coefficient of validation (r Val)=0.999. The calibration model PLS-FTIR was (SEC)=1.81, (SEV)=1.94, (r Cal)=0.998 and (r Val)=0.998. The results showed that both calibration models are practical analytical methods that can be used to predict the concentration of palm biodiesel in blends with petrodiesel in a concentration range from 0 to 100 % weight.Tesis (Doctorado en Ciencias por Investigación).- Colegio de Postgraduados, 2013.Secretaría de Educación Pública (SEP). Universidad Autónoma del Carmen (UNACAR)

Eficiencia económica y organización de la cadena productiva de miel en Campeche, México

The global food market, based on strict sanitary and quality standards, imposes new challenges to production and marketing by small-scale producers in developing countries. In this article the economic efficiency of small-scale beekeepers is examined, as well as the relationships between actors and the functioning of the honey chain in Campeche, Mexico. The information was obtained through in-depth interviews with key informants, and community workshops. The results show that the conventional honey chain is efficient, although it favors large cooperatives and private trading companies due to economies of scale. Small-scale producers and their organizations can increase their competitiveness through differentiation of the product and diversification of the activity, but only if they are capable of establishing new agreements with other actors of the chain. In addition, the government can favor the development of these organizations and promote commercial, technological and institutional innovations between actors of the chain.El mercado mundial de alimentos basados en estrictos estándares sanitarios y de calidad impone nuevos desafíos a la producción y a la comercialización de los pequeños productores en países en desarrollo. En el presente artículo se examinan la eficiencia económica de los pequeños apicultores, las relaciones entre los actores y el funcionamiento de la cadena de miel en Campeche, México. La información se obtuvo a través de entrevistas en profundidad a informantes clave y talleres comunitarios. Los resultados muestran que la cadena de miel convencional es eficiente pero, debido a economías de escala, favorece a las grandes cooperativas y a las empresas comercializadoras privadas. Los pequeños productores y sus organizaciones pueden aumentar su competitividad a través de la diferenciación del producto y la diversificación de la actividad, pero sólo si son capaces de establecer nuevos acuerdos con otros actores de la cadena. Además, el gobierno puede favorecer el desarrollo de estas organizaciones y promover las innovaciones comerciales, tecnológicas e institucionales entre los actores de la cadena

Determination of the Concentration of Heavy Metals in Artisanal Cheeses Produced in the Mexican States of Tabasco and Chiapas

Cheese consumption provides humans with minerals, proteins, carbohydrates, and vitamins. In Mexico, several cheese varieties are produced, each with its texture, scent, and flavor. The artisanal cheeses made in the states of Tabasco and Chiapas—including, among others, the varieties named crema (cream), doble crema (double cream), oaxaca, panela, fresco, bola, poro, cotija, and asadero—have a high demand in the domestic and foreign markets. The intensification of anthropic activity in these states causes an increased emission to the environment of contaminants like heavy metals, which could reach human foodstuffs through the food chains. In particular, heavy metal contents in cheeses consumed daily by these states’ local populations might represent a public health risk. Because of that, our objectives in this work were to determine the concentrations of lead, cadmium, nickel, copper, zinc, and iron in artisanal cheeses produced in the states of Tabasco and Chiapas and to determine the values of the hazard quotient (HQ), total hazard quotient (THQ), and cancer risk total (CRT) for adult and young men and women. The results of our analyses of cheese samples from the states of Tabasco and Chiapas showed that the average concentrations (mg kg−1) of cadmium (0.0023 ± 0.002, 0.0023 ± 0.002 mg kg−1, respectively, for each state), lead (0.0047 ± 0.00, 0.0051 ± 0.002), nickel (0.0039 ± 0.0046, 0.0031 ± 0.0039), copper (0.0199 ± 0.021, 0.0202 ± 0.022), zinc (0.1611 ± 0.18, 0.194 ± 0.21), and iron (61.84 ± 4.23, 65.76 ± 6.61 mg kg−1), the first three values lower than the limits established by the FAO/WHO and Codex Alimentarius. The value of THQ that we obtained was less than one, and that of CRT was within the limits established by the US-EPA, which means that the consumption of artisanal cheeses from Tabasco and Chiapas by humans does not imply a risk of disease or cancer

Condición y perspectivas de la meliponicultura en comunidades mayas de la reserva de la biósfera Los Petenes, Campeche, México

Résumé: L'élevage de l'abeille sans aiguillon ko'olel kaab (Melipona beecheii) est une activité ancestrale en voie de disparition dans la réserve Los Petenes, dans l’état de Campeche. De par son importance pour la stratégie de la vie familiale et afin de permettre la conservation de la diversité d'espèces d'abeilles natives, nous avons envisagé l'étude de la situation et perspectives de la méliponiculture de cette aire naturelle protégée. Nous avons employé des enquêtes semi-structurées, des entretiens avec des informateurs essentiels et l’observation participante. Les résultats montrent que seulement six de dix-sept communautés ont recours à l'abeille ko'olel kaab, et que la majorité des méliponiculteurs sont des hommes d’âge mur faiblement organisés pour commercialiser la production du miel. Cependant, la perspective de la méliponiculture est encourageante, car elle se trouve dans une aire naturelle protégée et que la connaissance et le savoir-faire traditionnel persistent encore dans quelques familles mayas, qui produisent du miel pour un usage médicinal et cérémoniel. De plus, le marché et la valeur culturelle de la méliponiculture constituent des facteurs qui peuvent contribuer à sa récupération.Abstract: Raising stingless bee (Melipona beecheii), called ko’olel kaab by the Maya of Campeche in The Petenes Biosphere Reserve, Mexico, is an age-old practice which is in danger of disappearing. Given the importance of meliponiculture to families´ life strategy in this protected natural area, as well as to conservation of the diversity of native bee species, this study aimed to evaluate the current state of meliponiculture in the area through semi-structured questionnaires, interviews and participant observation. Only six of the 17 communities in the study region were found to still manage ko’olel kaab bees, and most keepers of native bees are men over the age of 65. Furthermore, the communities lack the ability to produce and market honey. However, points in favor of meliponiculture among the Maya people of Campeche are that it is being practiced in a protected natural area, that traditional knowledge persists, and that families still raise stingless bees using traditional management techniques to produce honey and other products for medicinal uses and ceremonial use. Increasing the market value of meliponiculture and fomenting appreciation for its cultural value may contribute to its recovery.Resumen: La cría de la abeja sin aguijón ko’olel kaab (Melipona beecheii) es una actividad ancestral en vías de desaparición en la reserva Los Petenes, Campeche. Por su importancia para la estrategia de vida familiar en el área natural protegida y para procurar la conservación de la diversidad de especies de abejas nativas, se planteó el estudio de la situación y las perspectivas de la meliponicultura en dicha área. Se usaron encuestas semiestructuradas, entrevistas a informantes clave y observación participante. Los resultados muestran que solo seis de las 17 comunidades manejan la abeja ko’olel kaab y que los meliponicultores están constituidos mayoritariamente por hombres de edad avanzada con débil organización para comerciar la miel. Sin embargo, la perspectiva de la meliponicultura es alentadora, porque se ubica en un área natural protegida y el conocimiento y el manejo tradicional aún persisten en algunas familias mayas que producen miel para uso medicinal y ceremonial. Además, el mercado y el valor cultural de la meliponicultura son factores que pueden contribuir a su rescate

Removal of an Ethoxylated Alkylphenol by Adsorption on Zeolites and Photocatalysis with TiO2/Ag

Two advanced removal methods (adsorption and photocatalysis) were compared for the elimination of an ethoxylated alkylphenol (nonylphenol polyethylene glycol, NPEG). For the adsorption process, zeolites were used in their natural state, and the process was characterized by DRX (X-ray diffraction) and SEM–EDS (Scanning electron microscopy). The analysis of the results of the adsorption kinetics was carried out using different isotherms to interpret the removal capacity of zeolites. The Temkin kinetic model better predicted the experimental data and was satisfactorily adjusted to models of pseudo-second order (PSO). On the other hand, for photocatalysis, nano-particles of Ag (silver) were deposited on titanium oxide (TiO2) Degussa-P25 by photo-deposition, and the catalyst was characterized by diffuse reflectance and SEM–EDS. The data obtained using the two removal techniques were analyzed by UV–Vis (ultraviolet-visible spectrophotometry) and total organic carbon (TOC). The kinetic data were compared. The photocatalytic process showed the highest efficiency in the removal of NPEG, corresponding to >80%, while the efficiency of the adsorption process was <60%. This was attributed to the recalcitrant and surfactant nature of NPEG

Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and chemometric techniques for the determination of adulteration in petrodiesel/biodiesel blends

We propose an analytical method based on fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy to detect the adulteration of petrodiesel and petrodiesel/palm biodiesel blends with African crude palm oil. The infrared spectral fingerprints from the sample analysis were used to perform principal components analysis (PCA) and to construct a prediction model using partial least squares (PLS) regression. The PCA results separated the samples into three groups, allowing identification of those subjected to adulteration with palm oil. The obtained model shows a good predictive capacity for determining the concentration of palm oil in petrodiesel/biodiesel blends. Advantages of the proposed method include cost-effectiveness and speed; it is also environmentally friendly

Non-Structural Proteins (Nsp): A Marker for Detection of Human Coronavirus Families

SARS-CoV-2 was the cause of the global pandemic that caused a total of 14.9 million deaths during the years 2020 and 2021, according to the WHO. The virus presents a mutation rate between 10−5 and 10−3 substitutions per nucleotide site per cell infection (s/n/c). Due to this, studies aimed at knowing the evolution of this virus could help us to foresee (through the future development of new detection strategies and vaccines that prevent the infection of this virus in human hosts) that a pandemic caused by this virus will be generated again. In this research, we performed a functional annotation and identification of changes in Nsp (non-structural proteins) domains in the coronavirus genome. The comparison of the 13 selected coronavirus pangenomes demonstrated a total of 69 protein families and 57 functions associated with the structural domain’s differentials between genomes. A marked evolutionary conservation of non-structural proteins was observed. This allowed us to identify and classify highly pathogenic human coronaviruses into alpha, beta, gamma, and delta groups. The designed Nsp cluster provides insight into the trajectory of SARS-CoV-2, demonstrating that it continues to evolve rapidly. An evolutionary marker allows us to discriminate between phylogenetically divergent groups, viral genotypes, and variants between the alpha and betacoronavirus genera. These types of evolutionary studies provide a window of opportunity to use these Nsp as targets of viral therapies

Esterification Optimization of Crude African Palm Olein Using Response Surface Methodology and Heterogeneous Acid Catalysis

In this work, the effect of zeolite montmorillonite KSF in the esterification of free fatty acids (FFAs) of crude African palm olein (Eleaias guinnesis Jacq) was studied. To optimize the esterification of FFAs of the crude African palm olein (CAPO), the response surface methodology (RSM) that was based on a central composite rotatable design (CCRD) was used. The effects of three parameters were investigated: (a) catalyst loading (2.6–9.4 wt %), (b) reaction temperature (133.2–166.2 °C), and (c) reaction time (0.32–3.68 h). The Analysis of variance (ANOVA) indicated that linear terms of catalyst loading (X1), reaction temperature (X2), the quadratic term of catalyst loading ( X 1 2 ), temperature reaction ( X 2 2 ), reaction time ( X 3 2 ), the interaction catalyst loading with reaction time ( X 1 * X3), and the interaction reaction temperature with reaction time ( X 2 * X3) have a significant effect (p < 0.05 with a 95% confidence level) on Fatty Methyl Ester (FAME) yield. The result indicated that the optimum reaction conditions to esterification of FFAs were: catalyst loading 9.4 wt %, reaction temperature 155.5 °C, and 3.3 h for reaction time, respectively. Under these conditions, the numerical estimation of FAME yield was 91.81 wt %. This result was experimentally validated obtaining a difference of 1.7% FAME yield, with respect to simulated values