Rolando Barrera Zapata

Evaluación de biochar como alternativa de sustrato en cultivos de tomate

La transformacion termoquimica de biomasa para generar potencia electrica produce como residuo solido el biochar, material que de acuerdo a sus propiedades puede ser utilizado en diversas aplicaciones, entre ellas la mejora de los suelos de cultivo. En el presente trabajo se evaluan dos tipos especificos de biochar como potencial sustitutos de sustrato en cultivos de pequena escala a cielo abierto. Tomando como referencia un cultivo de Solanum lycopersicum (tomate) se observo el efecto sobre el desarrollo de las plantas y la cosecha (cantidad, diametro y peso de los frutos) al sustituir el sustrato comercial por biochar en proporciones de 0, 20, 50, 80 y 100%. Se observo que con sustituciones del 20% y el 50% de sustrato por biochar, las plantas tienen un desarrollo normal y la produccion de tomate es comparable al obtenido en ausencia de biochar; sin embargo al sustituir el 80% o el 100% del sustrato por el biochar, el efecto en el crecimiento de las plantas es negativo, aparentemente por la ausencia de nutrientes. Estos resultados vistos desde un enfoque economico y ambiental son bastante satisfactorios, pues usar 20% o 50% de biochar pueden representar ahorros significativos para el agricultor (menor uso de sustratos) a la vez que dan utilidad a desechos agroindustriales (biochar)

Uso de cáscara de piña como adsorbente de rojo 40 (típico de la industria alimentaria)

The effect of different operating parameters on the adsorption of R40 (diluted in an aqueous matrix) on pineapple peels was studied. It was found that pineapple peels can remove up to 84% of the colorant, a value lower than that achieved using commercial activated carbon as adsorbent (removal close to 99%), but with the advantage that pineapple peels do not require chemical neither thermal processes for their manufacture, and represent the valuation of agroindustrial wastes. The variables analyzed inlcuded the amount and particle size of the adsorbent, the operating time and temperatura. The higher percentages of dye removal were adquired by using 150 mg of adsorbent, particle sizes between 0.125 and 180 mm and 5 h of operation. Apparently the temperature does not have a significant effect on the phenomenon within the ranges analyzed (25-45 ° C). It is expected that the results obtained contribute to the development of agroindustrial processes where there is a valuation and rational use to agroindustrial wastes such as pineapple peels.

Evaluación preliminar del uso de residuos del cultivo de papa como fuente de solanesol

During potato’s harvest, a relatively high volume of leaves (residues) is generated per hectare. According to the literature, these leaves may contain secondary metabolites such as solanesol, a substance of high added value and wide applicability in pharmaceutical and cosmetic industries. The present contribution describes the extraction of solanesol from potato leaves harvested in Antioquia by means of organic solvents, and the use of indirect iodometric titration for solanesol quantification, corresponding to a relative inexpensive and easy implementation technique. Yields between 0.23 and 0.32% wt/wt of solanesol relative to the dry material were obtained. This resultas ares comparable with other techniques (i.e., microwave assisted extraction) and other raw materials (i.e., tobacco leaves), commonly used to obtain the metabolite. The present research constitutes a contribution for the extraction and characterization of the solanesol for marketing purposes).

Cinética de la Transesterificación del Aceite de Palma con Metóxido de Calcio. (The Kinetic Palm Oil Transesterification with a Calcium Methoxide.)

In this study, two new kinetic models for the palm oil transesterification with methanol, by using calcium oxide, are proposed. The first model, which includes the alcohol and the oil’s adsorption on the catalyst, is carried out by the Langmuir-Hinshelwood mechanisms, while the second model only considers the alcohol adsorption on the solid, through the Eley-Rideal mechanisms. The Kinetic parameters were determined, by using the initial reaction rates method (t < 30 min), while the data taken for longer times (until 240 min) were used for the models validation. For the proposed models’ deduction, it was studied the alcohol/oil molar ratio’s variation effect (4.9-8.9), of the catalyst%w/w (0.3-0.7) and the temperature (328-338 K) on the reaction speed. The kinetic parameters were determined using the initial reaction rates method (t < 30 min), while the data taken for longer times (until 240 min) were used for models validation. It was found aUniversidad Industrial de Santander, Bucaramanga, Santander. bGrupo CERES, Facultad de Ingenieria, Universidad de Antioquia, UdeA, Medellin, Colombia. cCentro de Investigaciones en Catalisis, Escuela de Ingenieria Quimica, Facultad de Ingenierias Fisicoquimicas, Universidad Industrial de Santander, Bucaramanga, Santander. *Correo electronico: juancardozo_0121@hotmail.comIn this study, two new kinetic models for the palm oil transesterification with methanol, by using calcium oxide, are proposed. The first model, which includes the alcohol and the oil’s adsorption on the catalyst, is carried out by the Langmuir-Hinshelwood mechanisms, while the second model only considers the alcohol adsorption on the solid, through the Eley-Rideal mechanisms. The Kinetic parameters were determined, by using the initial reaction rates method (t < 30 min), while the data taken for longer times (until 240 min) were used for the models validation. For the proposed models’ deduction, it was studied the alcohol/oil molar ratio’s variation effect (4.9-8.9), of the catalyst %w/w (0.3-0.7) and the temperature (328-338 K) on the reaction speed. The kinetic parameters were determined using the initial reaction rates method (t < 30 min), while the data taken for longer times (until 240 min) were used for models validation. It was found that the proposed models represent, an acceptable experimental data, according to the squared residuals’ sum < 0.045. The models contribute to this catalytic system understanding, by introducing the adsorption/desorption concepts, on the reaction kinetics.