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RESUMEN En este trabajo se describe la síntesis de nanoestructuras de seleniuro de cobre, utilizando la técnica de microondas y mecanosíntesis. En la síntesis asistida por microondas, el proceso se realizó en un horno microondas modificado, para ello, a una solución de sulfito de sodio se le añadió selenio en polvo, esta mezcla fue sometida a radiación microondas al 40 % formando así el selenosulfato de sodio para luego agregarle acetato de cobre manteniendo la proporción Cu:Se (1:1) mientras se sometía nuevamente a irradiación, obteniendo al finalizar un precipitado negro de seleniuro de cobre. La otra técnica es la mecanosíntesis, donde se molió polvos de cobre y selenio bajo atmósfera inerte, utilizando un molino SPEX 8000M, obteniendo seleniuro de cobre. Los productos fueron caracterizados mediante DR-X, FRX- ED, MEB, EDX, UV-Vis. Los resultados indican que se formaron las fases Cu2Se, Cu3Se2 y Cu1.8Se. Empleando las ecuaciones de Scherrer y Williamson-Hall se determinó el diámetro promedio del cristalito entre 8 y 83 nm, y con la ayuda del programa OriginPro 2017, se calcularon las microtensiones que estuvieron entre 0.00105 a 0.01031 Pa. La banda de energía prohibida se obtuvo empleando el ploteo de Tauc, obteniendo valores entre 1 y 2 eV. ABSTRACT In this work, the synthesis of copper selenide nanostructures is described, using the microwave and mechanosynthesis technique. In microwave-assisted synthesis, the process was carried out in a modified microwave oven. To this a solution of sodium sulfite was added with selenium powder, this mixture was subjected to microwave radiation at 40 %, thus forming sodium selenosulphate for then add copper acetate maintaining the Cu: Se ratio (1: 1) while undergoing irradiation again, obtaining at the end a black precipitate of copper selenide. The other technique is mecanosynthesis, where copper and selenium powders were ground under inert atmosphere, using a SPEX 8000M mill, obtaining copper selenide. The products were characterized by DR-X, FRX-ED, MEB, EDX, UV-Vis. The results indicate that the Cu2Se, Cu3Se2 and Cu1.8Se phases were formed. Using the equations of Scherrer and Williamson-Hall, the average diameter of the crystallite was determined between 8 and 83 nm, and with the help of the OriginPro 2017 program, microtensions that were between 0.00105 to 0.01031 Pa were calculated. The banned energy band was obtained using the plot of Tauc, obtaining values between 1 and 2 eV.

Fatty acid methyl esters (FAME) produced from vegetable oils or animal fats by transesterification, or from the esterification of fatty acids, with methanol, is labeled as ‘‘Biodiesel”. Current industrial processes for biodiesel production are mainly based on homogeneous catalysis, in presence of an alkali hydroxide or methoxide dissolved in methanol, a large excess of methanol (methanol:oil molar ratio > 6), a temperature around 60 ºC and 1-2 h of reaction. However, this process suffers from different drawbacks, mainly related with the generation of large amount of wastewater associated to the washing and neutralization steps, the non-recovery of the homogeneous catalyst, or the formation of stable emulsions difficult to separate. These problems cause an increase of the overall biodiesel production cost. To overcome them, different approaches have been proposed, such as the use of heterogeneous catalysis, CO2 under supercritical conditions or enzymes, coupled to microwave and ultrasonic systems as alternative to conventional heating. In the present communication, a new mechanochemical reactor is used for the transesterification reaction that promotes the oil-methanol mixing, minimizing the mass transfer problems associated to the immiscibility of reactant mixtures. Moreover, in order to achieve a more sustainable biodiesel production process, a new heterogeneous basic catalyst is prepared from calcium oxide and glycerol, the by-product of biodiesel industry. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech