AGDAA. Artículos de Investigación

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Acceso abierto
Hidrodestilación asistida con microondas (MWHD) para la extracción de hidrolatos de plantas aromáticas
(2015-07) Guarín Villamizar, Oscar Darío; Barajas Solano, Andrés Fernando
En este estudio, se evalúa la eficiencia de extracción de un sistema de hidrodestilación asistida por microondas para la obtención de hidrolatos a partir de tres plantas aromáticas (Eucalyptus Globulus, Mentha Viridis y Cymbopogon Citratus). Los resultados obtenidos demuestran que, para obtener una mayor cantidad de hidrolato (yerbabuena del 42, limonaria 36 y ecualipto 33%), es necesario emplear tiempos de extracción cercanos a los 45 minutos y concentraciones de biomasa de 160 g; Además, a partir del balance de energía se obtiene que, para obtener 0,98 g de hidrolato son necesarios 1158,952 KJ; por otra parte, teniendo en cuenta los resultados obtenidos, es posible determinar que, el impacto generado al medio ambiente por la operación unitaria empleada es alto; teniendo en cuenta el gasto de 1,650 kWh se tiene una huella de carbono de entre 1320-220 g de CO2.
Acceso abierto
Effect of carbon-nitrogen ratio for the biomass production, hydrocarbons and lipids on botryoccus braunii UIS 003.
(2016-04) Barajas Solano, Andrés Fernando; Guzmán Monsalve, Alexander; Kafarov, Viatcheslav
The genus Botryococcus compiles a variety of green microalgae which accumulate large quantities of hydrocarbons, this genus is classified in four types or races (A, B, L and R) based on chemical structure of hydrocarbons. Race B has been acknowledge due to its hability to accumulate triterpene hydrocarbons C30- C37 best known as botriococene and methylated squalene C31-C34 which are considerate as candidates for biofuels production; however, one of the main problems that face biofuels production using this alga as feedstock is the continuous production, both lipids and hydrocarbons; that is why it’s mandatory to find the best carbon and nitrogen source that maximizes biomass and total lipid production. It was found that by adjusting the carbon/nitrogen ratio using sodium carbonate (Na2CO3) it was possible to substantially improve the production of biomass from 1 to 2 g/L in 15 days thus doubling the production of biomass in the same time; however, both the lipids and hydrocarbons production will not be affected positively showing a significant reduction from baseline.
Acceso abierto
Improvement of biomass and dha production on a semi-continuous culture of aurantiochytrium sp NYH-2
(2016-04) Barajas Solano, Andrés Fernando; Yoshida, Masaki; Watanabe, Makoto M
Aurantiochytrium sp has been recognized as one of the most suitable sources of high valuable fatty acids (FA) including docosahexaenoic acid (DHA), docosapentaenoic acid, arachidonic acid, eicosapentaenoic acid (EPA), and saturated FA; however it’s necessary to improve total biomass production and high value FA specially DHA. The aim of this research is to improve the production of biomass and DHA on the novel Aurantiochytrium sp NYH-2 strain via an optimization of culture time (2, 3 and 5 days) and removal of culture (20, 50 and 80% v/v) using a 23 experimental design. It was found that in order to improve biomass production a large amount of culture media must be replaced (>90%), however after the third cycle biomass production was reduced from 10 g/L to 9 g/L; similarly under the same conditions lipids and DHA production increased from 15% to 20% (w/w) and from 3 to 5% (w/w) respectively in the first 3 cycles and then reduced in cycle 5. Finally results suggest that in a semi-continuous process the algae is only functional 3 cycles (9 to 12 days) and in order to improve total biomass lipids and DHA production, a volume of culture media between 80-92% must be removed every 3-4 days.
Acceso abierto
Evaluation of a two-phase extraction system of carbohydrates and proteins from chlorella vulgaris utex 1803
(2016-04) García Martínez, Janet Bibiana; Ayala Torres, Edinson; Reyes Gómez, Oscar; Zuorro, Antonio; Barajas Solano, Andrés Fernando; Barajas Ferreira, Crisóstomo
Microalgae are a valuable source of high-value products and biofuels, however the high-energy cost required for the extraction of their metabolites has kept questioning on possible industrial upgrading. The aim of this study was to evaluate the effect of temperature, solvent/biomass, NaOH concentration and thermal pretreatment of the biomass in a 2-cycle carbohydrate and protein extraction system. Results shown that best conditions for carbohydrates extraction are achieved at a solvent concentration of 3.67 M, 55°C and a solvent/biomass ratio of 30mL/g. On the other side, the best conditions for protein were 3 M, 85°C and 45 mL/g. The efficiencies achieved under these conditions were 95% for carbohydrates and 98% for proteins. Using the best extraction conditions for each metabolite a thermal pre-treatment was performed at 25°C, 75°C and 105ºC. Results indicate that highest efficiencies were achieved with dry biomass pretreated at 105°C, with values of 95% for carbohydrates and 98% for proteins.
Acceso abierto
Evaluation of the efficiency of bio-polymers derived from desertic plants as flocculation agents
(2016-05-20) Daza, Rina; Barajas Solano, Andrés Fernando; Epalza Contreras, Jesús-Manuel
In the treatment of wastewater, flocculation is one of the most used processes, which aims to eliminate colloidal particles cannot be removed by other methods; Traditionally it has been used aluminum or iron salts and synthetic polymer, which generate little biodegradable sludge; moreover biopolymers, have coagulation and flocculation properties which can remove over 80-90% of solids contaminated; additionally, the use of natural polymers produce sludge increased biodegradability. The present work analyzes the efficiency of a biopolimer based on 6 endemic plants (Opuntia dilleni, Stenocereus griseus, Cereus forbesii, Melocactus sp. Aloe arborescens and Aloe vera) found at the desertic indian reservation “Kululumana”.
Acceso abierto
Passive microalgae immobilization for wastewater treatment : Study of residual glycerol consumption
(2016-05-20) Blanco Suarez, Vanessa E.; Villamizar Sanchez, Susan S.; Peralta Ruiz, Yeimmy Yolima; González-Delgado, Ángel Darío; Barajas Solano, Andrés Fernando; Ardila Álvarez, Ana María
The aim of the present study is to evaluate the viability of glycerol as carbon source on immobilized algae cultures coupled with a modification on nitrogen (NO3-) and phosphate (PO4) concentration for the production of high valuable compounds (carbohydrates, proteins and lipids). it was determined that the conditions who favour the deposition of carbohydrates are 3-5% (v/v) of glycerol and 0.37 (g/L) of NaNO3. On The other hand, for obtain higher amounts of lipids, a 3% (v/v) of glycerol coupled with a limitation in the nitrogen source (0.04 g/L) are needed. Finally, in order to improve deposition of total proteins, larger concentrations of glycerol (5% v/v), NaNO3 (>0.37 g/L) and phosphate are needed.
Acceso abierto
Microalgae immobilization using hydrogels for environmental applications : Study of transient photopolymerization
(2016-05-20) González-Delgado, Ángel Darío; Barajas Solano, Andrés Fernando; Peralta Ruiz, Yeimmy Yolima
Immobilization of microalgae has emerged as a useful technique for effective environmental applications as removal of undesirable compounds from water, culture collection handling for CO2 capture, development of biosensors, and production of clean energy among others. In this work, polymerization of hydrogels is evaluated in order to generate adequate nanoporous morphology for microalgae immobilization via use of transient light intensity. Hydrogels were polymerized using a UV light intensity range between 140 and 700 mW/cm2 during 0.8 h and characterized using rheology evaluation using an angular frequency of 1 rad/s for defined monomer, initiator and solvent amounts. Results shows that transient light polymerization has a significant effect on average pore size and pore size distribution, obtaining different gel points between 1,300 and 1,700 s and modules between 4,000 and 13,000 Pa, allowing to adjust nanoporous morphology of hydrogels improving the attach viability of species of microalgae with variable sizes and shapes, and allowing to develop better hydrogels for novel microalgae immobilization-based applications.
Acceso abierto
Segment scale typology for colombian andean rivers
(2017-04) Gutiérrez, Juan David; Ospina-Torres, Rodulfo; Álvarez, Juan Pablo; Riss, Wolfgang; Guarín Villamizar, Oscar Darío
This paper presents a method for establishing segment scale typology for the Andean rivers of Colombia. The method incorporates physical and ecological aspects and combines inferences of structural stability and metabolic activity. The classification of river segments is based on the assignment of two non-dimensional descriptors. The first descriptor involves aspects related to structural stability of the channel, whereas the second descriptor includes factors that affect the metabolic activity of planktonic communities in the water column and biotic communities on the bed. Each descriptor can adopt values that are divided into two categories, high and low. Both descriptors are organized orthogonally. A bidimensional 2 × 2 matrix is created, where the x-axis represents the current structural stability of the channel and the y-axis represents the metabolic activity. A case study that combines a set of thematic layers using GIS is presented for the Cundinamarca region in Colombia. Most of the river segments (97%) in Cundinamarca correspond to type 2 or 4. We provide data from macroinvertebrate samples to compare the obtained types with the actual biological communities present in the region. This method, which can be useful for scientists, managers and water planners, compares similarities and differences between water body systems, compiles basic information in a brief and clear manner and locates monitoring and reference sites for bioassessment studies.
Acceso abierto
Producción de biomasa y proteínas de Chlorella vulgaris Beyerinck (Chlorellales: Chlorellaceae) a través del diseño de medios de cultivo selectivos
(2017-09) Barajas Solano, Andrés Fernando; Ardila Álvarez, Ana María; González Delgado, Ángel Darío
En los últimos años se ha vuelto cada vez más frecuente el uso de medios de cultivo basados en fuentes de fósforo, nitrógeno y microelementos como alternativa a los medios tradicionales. Por lo tanto, en este trabajo se diseñaron dos medios de cultivo mixotróficos con diferentes concentraciones de nitrato de sodio, fosfato de potasio, acetato de sodio y carbonato de amonio (estos últimos como fuente de carbono), a fin de evaluar la producción de biomasa y proteínas a partir de la microalga Chlorella vulgaris. Se realizaron diagramas de Pareto y superficies de respuesta a fin de conocer la influencia de las variables de estudio sobre la producción de proteínas. Los resultados mostraron que las mayores producciones de biomasa (3,72 para el cultivo con acetato y 2,17 g/L para el cultivo con carbonato) están directamente relacionadas con el nitrato de sodio (1,96 mM) y el fosfato de potasio (2,11 mM). Además, los máximos porcentajes de proteínas obtenidos fueron 60% y 34% para los cultivos con acetato y carbonato, respectivamente, ambos con 2,94 mM de nitrato de sodio. Finalmente, con base en el diagrama de Pareto obtenido, se encontró que para el medio de cultivo con acetato no existieron variables significativas que influyeran sobre la producción de proteínas, mientras que, en el medio de cultivo con carbonato, el nitrato de sodio y el fosfato de potasio influyeron significativamente en la producción de este metabolito.
Acceso abierto
Environmental and socio-economic determinants associated with the occurrence of cutaneous leishmaniasis in the northeast of Colombia
(2017-12) Gutiérrez, Juan David; Martínez Vega, Ruth Aralí; Ramoni Perazzi, Josefa; Díaz Quijano, Fredi Alexander; Gutiérrez, Reinaldo; Ruiz, Freddy J; Botello, Hector A.; Gil, María; González, Juan; Palencia, Mario
Background: Cutaneous leishmaniasis (CL) is a vector-borne disease that is widely distributed in most tropical regions. Colombia has experienced an important increase in its incidence during the last decade. There are CL transmission foci in the Colombian departments of Santander and Norte de Santander. Objectives: To identify environmental and socio-economic variables associated with CL incidence in the municipalities of the northeast of Colombia between 2007 and 2016. Methods: This was an ecological study of CL cases aggregated by municipality. The cases reported during the study period were analyzed with a negative binomial regression to obtain the adjusted incident rate ratio for environmental and socio-economic variables. Findings: During the study period, 10 924 cases of CL were reported, and 110 (86.6%) municipalities reported at least one CL case. The coverages of forest (aIRR 1.05, 95% CI 1.03–1.07), heterogeneous agricultural zones (aIRR 1.04, 95% CI 1.02–1.06) and permanent crops (aIRR 1.07, 95% CI 1.02–1.12) were associated with a higher incidence of CL. Conversely, urban functionality (aIRR 0.95, 95% CI 0.92–0.96), minimal-altitude above sea level (aIRR 0.84, 95% CI 0.79–0.90) and shrub coverage (aIRR 0.98, 95% CI 0.95–1.0) were negatively associated with the incidence of CL in the municipality. Main conclusions: Our results confirm the importance of environmental determinants, such as height above sea level, and coverage of forest, permanent crops and heterogeneous agricultural zones, for the occurrence of CL; these findings also suggest the importance of shrub coverage. Furthermore, urban functionality was a socio-economic determinant independently associated with CL incidence.
Acceso abierto
Design of an electroflotation system for the concentration and harvesting of freshwater microalgae
(2018) Castellanos Estupiñan, Miguel A.; Sánchez Galvis, Edwar M.; García Martínez, Janet Bibiana; Barajas Ferreira, Crisóstomo; Zuorro, Antonio; Barajas Solano, Andrés Fernando
Microalgae are considered as one of the most promising alternatives for the integrated use of agro-industrial water residues and the production of metabolites of high industrial interest. This is due to algae can grow on wastewater which in turn can reduce the emission of nutrients to rivers and lakes. However, the greatest scientific-technological barrier is the concentration and separation of the biomass produced. There are several processes used at different levels (from laboratory to industrial scale) such as flocculation, centrifugation, flotation, etc. These can be very expensive or can (possibly) contaminate the biomass. Unlike the previous ones, electroflotation has been proposed as a cost-efficient method, nevertheless its final efficiency will depend heavily on the type of alga and culture medium. Taking into account the above, the present project aims to design an electroflotation system for the concentration and harvest of microalgae biomass. The effect of several factors (pH, time, voltage and distance between the electrodes) and for types of materials (Copper, Aluminium, Iron and Steel) on biomass recovery efficiency from a culture of Chlorella vulgaris UTEX 1803 was evaluated by the implementation of a Design of experiments (43 non-factorial design) using STATISTICA 7.0. Results show that, the materials with higher concentration efficiency were cooper and aluminium with 40 and 80% respectively, and the most relevant factors were distance between electrodes (1-2 cm), time (>20 min) and Voltage (>15V). In order to increase the efficiency of the overall process a new 43 experimental factorial design was proposed using as factors distance between electrodes, time, voltage and agitation. Results show that agitation positively affects the total efficiency until reaching a total concentration of the biomass (100%). It was found that a voltage close to 50V and a time greater than 25 min positively affect the final efficiency of the copper and aluminium electrodes, however aluminium has the highest efficiency (> 95%) compared to copper (<85%).
Acceso abierto
Production of chlorella vulgaris biomass on uv-treated wastewater as an alternative for environmental sustainability on high-mountain fisheries
(2018) Guiza Franco, Luisa; Orozco Rojas, Luis G.; Sánchez Galvis, Edwar M.; García Martínez, Janet Bibiana; Barajas Ferreira, Crisóstomo; Zuorro, Antonio; Barajas Solano, Andrés Fernando
The sustained expansion of agricultural industry in Colombian high-mountain has led to an increased size of residues, especially untreated wastewater. This untreated water is an urgent matter for public and environmental health, not only by its nutrient concentration (composed especially of food residuals and feces) but also the presence of pathogens (virus, bacteria, etc.) which are discharged to the environment. The overall objective of this work is to evaluate the effect of UV-treated wastewater from a high-mountain fishery as culture media for the production of Chlorella vulgaris as a sustainable method for nutrient and water recirculation on the fishery production system. The UV-canal efficiency was evaluated by the implementation of an experimental factorial design (time, distance of the UV-lamps towards the canal, number of UV-lamps and the sample concentration) using STATISTICA 7.0 software. Results shown that time (3 to 5 minutes) and the number of lamps (3-4) of 15 Watts eliminate completely coliforms from the samples. After UV-treatment the resulting water was test as culture media for C. vulgaris production by the adjustment of C/N ratio (Sodium Carbonate/potassium nitrate) by the implementation of an experimental 23 factorial design. Results shown that higher nitrate concentrations (>0,22 g/L) and moderate carbonate concentrations (1 g/L) increase the final biomass concentration up to 4g/L in 20 days.
Acceso abierto
Tobacco waste ash : A promising supplementary cementitious material
(2018-05-12) Moreno Yáñez, Paalo-Andrea; Fragozo, Rafael; Vesga, Sergio; Gonzalez, Mauricio; Hernández, Liliana; Gamboa, Ivan D.; Delgado Monroy, José-Antonio
According to the European Cement Association, CEMBUREAU, in 2015, the global cement production was 4.6 billion tons. Traditional cement production emits approximately 1 ton of CO2 per ton of cement, which represents almost 80% of the total CO2 emissions of concrete and approximately 6% of the world’s emissions. Among supplementary cementitious materials, the use of agro-waste ash emerges due to its reduced CO2 emissions, chloride diffusion, and materials cost, in addition to its greater compressive strength. In Colombia, the disposal of agro-wastes, such as tobacco waste, is an environmental and economic concern. In this study, ash obtained from tobacco waste (TWA) was studied as a sustainable partial replacement for cement in hydraulic concrete. The TWA was reduced to a particle size of less than 75 μm and was characterized by X-ray florescence. A central composite design was used to study the influence of the ash replacement percentage of cement and the water/binder (w/b) ratio on the compressive strength at 28 days. The results show that it is possible to replace 10% of the cement with TWA using a 0.5 w/b ratio and obtain a 51% higher compressive strength than the control mixture at 28 days. Moreover, the experimental results demonstrated an improvement of 86% in the 7-day compressive strength when TWA was used.
Acceso abierto
Determination of the gelification kinetics of a correction gel of injection profiles by ultraviolet-visible spectroscopy
(2020-08-05) Sanchez, E.; Villamizar, J.; Mantilla, G.; Rodriguez, J.; Roa, M.
Mature wells in which, for a long time, water injection has been used, as a method of recovery they reach a point where the water cut increases or remains constant. thus decreasing the recovered hydrocarbon factor; This phenomenon occurs because the water injected, has preferential recordings in the porous medium, and does not reach the hydrocarbon available in other areas of the formation, in this type of deposits the injection of polyacrylamide gels, crosslinked with acetate of chromium, these gels make a plugging, in areas of high water permeability, causing the change of path of the same, as well as move the hydrocarbon in other areas of the porous medium. At present, the kinetics of gelation of this type of substances is monitored qualitatively by means of the "Syddansk" code, which analyzes its consistency and elasticity, only by observation. Although this method is practical, it is not very descriptive and depends a lot on the opinion and criteria of the observer, being little reproducible. Given this situation, and the increase in chemical recovery projects in the country, a methodology is described that describes the moment of gelation, reproducibly and without the injection of the analyst. During the gelation process, different polyacrylamide-chromium gels were monitored in relationships used in field operations, using ultraviolet-visible spectroscopy, detecting a change in absorbances, of the spectra, which were analyzed to plant a kinetic model of gelation, in addition to generating the approach of a method, to identify the state of gelation based on the variation in absorbance.
Acceso abierto
Geological and physical-chemistry characterization of asphaltite from Colombian Middle Magdalena region
(2020-08-05) Bustos, N.; Jerez, E.; Paez, L.; Roa., M.
The massive consumption of fossil hydrocarbons and the absence of new conventional oil reserves, research on unconventional resources is prevalent. The Asphaltite is a substance with high energy value thanks to its composition of high molecular weight hydrocarbons, becomes an energy alternative in the future. In Middle Magdalena region of Colombia, Luna formation emerges with its members Salada, Pujamana, and Galembo of Upper Cretaceous age, which contains a deposit of this type of substances, which can become an economic and energy engine for the region. A representative sample of this asphaltite was taken in the Galembo Member (Top of Luna formation) and a geological description was made about its formation and occurrence in the area. The solubility of asphaltite was evaluated in two characteristic solvents for hydrocarbons, toluene and heptane, the first of aromatic character, with which it was possible to solubilize probably corresponding to the light fractions, while solubilization with heptane generated a precipitate Asphaltene, a nature that was corroborated by tests of visible infrared and ultraviolet spectroscopy, additionally an elementary analysis was performed to determine the concentrations of carbon, hydrogen, sulphur and oxygen. Finally, by means of thermogravimetry and differential scanning calorimetry an analysis was carried out to evaluate its energy potential, according to the results obtained, asphaltite samples are a promising energy resource.
Acceso abierto
Post-consumption foamed polystyrene coatings for surface tension modification
(2020-08-05) Bustos, N.; Gamarra, C.; Ponton, D.; Roa, M.
Foamed polystyrene, commercially known as Icopor, occupies a very important place in the transport systems, and conservation of freight and food, but it is also one of the main polymeric pollutants, due to its low biodegradability, and low reuse. Polystyrene has in its structure aromatic and aliphatic functional groups, which have a high hydrophobicity, which makes them candidates as modifiers of permeability and surface properties, although for this purpose the implementation of solvents is also required. In the following work, polystyrene residues for domestic and food use were used to obtain coatings, which allow surface tension to be modified, on surfaces with high water permeability. For this purpose, the polymeric residue was dissolved in organic type solvents, generating a varnish, which was used to coat the study surface, from which the surface tension with respect to water was previously known by analysing the contact angle; to be compared with those obtained after coating, resulting in an increase in the contact angle, which indicates an increase in surface tension, conferred on the new surface hydrophobicity.
Acceso abierto
Effects of meteorological factors on human leptospirosis in Colombia
(2020-10-10) Gutiérrez, Juan David; GAIA
Leptospirosis is a disease usually acquired by humans through water contaminated with the urine of rodents that comes into direct contact with the cutaneous lesions, eyes, or mucous membranes. The disease has an important environmental component associated with climatic conditions and natural disasters, such as floods. We analyzed the relationship between rainfall and temperature and the incidence of leptospirosis in the top 30 municipalities with the highest numbers of cases of the disease in the period of 2007 to 2016. It was an ecological study of the time series of cases of leptospirosis, rainfall, and temperature with lags of 0, 1, 2, 3, and 4 weeks. A multilevel negative binomial regression model was implemented to evaluate the relationship between leptospirosis and both meteorological factors. In the 30 evaluated municipalities during the study period, a total of 5136 cases of leptospirosis were reported. According to the implemented statistical model, there was a positive association between the incidence of leptospirosis and rainfall with a lag of 1 week and a negative association with temperature with a lag of 4 weeks. Our results show the importance of short-term lags in rainfall and temperature for the occurrence of new cases of leptospirosis in Colombia.
Acceso abierto
Comparative analysis between asphaltites and extra heavy oil asphaltenes
(2020-12-05) Bustos, N.; Diaz, E.; Jerez, E.; Roa, M.
The asphaltite material receives many names depending on the country, or area of knowledge, for this reason it is also known as bitumen, asphalt and gilsonite, its composition is a mixture of high molecular weight organic substances, mainly polyaromatic compounds characterized by a black color, and they appear in a semi-solid or solid state. Asphaltenes correspond to the oil fraction with the highest molecular weight, this characteristic provides a high viscosity to hydrocarbons, which contain, in their composition, a concentration equal to or greater than 10%, although the exact structure of this is not known. molecular family, it has been possible to elucidate the functional groups present, such as carbonyl acids, thiols and pyridines, implying the presence of heteroatoms, such as nitrogen, sulfur and oxygen, but the most characteristic part of this type of molecules is their nucleus polyaromatic, which can contain up to 20 or more benzene rings. A sample of Colombian asphaltite was taken and compared with a sample of asphaltenes from a Colombian extra-heavy crude, solubility tests, a spectroscopic characterization by Ultraviolet-Visible, infrared, a thermal evaluation by Thermogravimetry and Differential Scanning Calorimetry were carried out. , in addition to an analysis by X-ray diffraction, in order to determine if the behavior and composition of both The objective of this investigation is to be analyzed by comparing a traditional asphaltite and an asphaltite, if the latter has the same properties and composition, with a view to being used as an energy source .The results obtained reveal that despite the fact that both substances present a similar composition, their glass transitions are different, as well as the crystalline phases present in each of the materials.
Acceso abierto
Gelation kinetics of colloidal dispersion gels by viscoelasticrheological methods
(2020-12-05) Mantilla, G.; Villamizar, J.; Sanchez, E.; Ardila, J.; Roa, M.
Colloidal dispersion gels are one of the methodologies implemented, such as chemical recovery processes, in mature wells, their components are mainly polyacrylamide and aluminum citrate, both aqueous unlike other types of gelling, in this there is an intramolecular process, between the polymer chains and the crosslinker, generating a ball of polyacrylamide of nanometric dimensions. The usual gelling processes increase the viscosity of a fluid because of an increase in the molecular weight of the polymer, but in this case, the viscosity of the fluid decreases to the point of being close to that of the solvent, for this reason a monitoring of its gelation kinetics, in a conventional way is not possible, in view of this problem, this research implements techniques of viscoelastic characterization of fluids, to determine the loss and storage modules G' and G'', as well as the phase angle in the time, in order to learn more about the gelling mechanism, as well as to be able to estimate a reaction speed, from the point of view of viscoelastic variables, the results obtained revealed that despite being gelling, there is a decrease in the storage modulus , to a greater extent than the loss modulus, which implies that the material loses elastic properties, that is, from solid to become a material more viscous or liquid. With this information, an equation was proposed that can be used both in the laboratory and in oil field work. In addition to being extended to fluids with similar behaviors, where the interactions between the polymeric chains and their crosslinker generate a decrease in their elastic properties.
Acceso abierto
The corn cob gasification-based renewable energy recovery in the life cycle environmental performance of seed-corn supply chain: An Ecuadorian case study
(2021-01-05) Martillo Aseffe, José Alfonso; Martínez González, Aldemar; Lesme Jaén, René; Silva Lora, Electo Eduardo; GAIA
The influence of energy recovery from corn cob residues on the environmental performance of the seed-corn supply chain was the main research purpose of this work. An experimental and theoretical analysis as research methods were considered. In this way, an experimental study of corn cob gasification by using air as gasifying agent was conducted, while syngas-based power generation was assessed in a typical gas-ICE. Additionally, life cycle assessment (LCA) of two scenarios (combustion and gasification cases of corn cob residues) for the seed-corn supply chain was accomplished. According to results, a syngas yield in the range of 1.23 and 2.35 Nm3/kg of corn cob was obtained, with LHV close to 5.32 MJ/Nm3. Specific energy recovery from corn cob residues showed, an electricity surplus index of 744 kWh/t corn cob. Moreover, the carbon footprint for both combustion and gasification cases was 913 kg CO2-eq/t seed-corn and 797 kg CO2-eq/t seed-corn, respectively. Integrated thermochemical conversion of corn cob and power generation system represents a technological alternative for its sustainable management. This study provides a holistic inventory, energy balance, and life cycle analysis of corn cob energy utilization. No similar approaches were found in the reviewed literature.

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