p. Medellín, Colombia Universidad de Medellín * Artículo escrito en el marco del proyecto de investigación Estudio de tejidos vegetales como adsorbentes naturales para la remoción de colorantes en medio líquido desarrollado en el año 2016 con recursos del Programa de
Objective: To determine the optimum pH at which the pineapple peel can adsorb the greatest amount of copper. Design/methodology/approach: Sorbent material. The size of the pineapple peel was reduced to 0.250 mm; it was chemically modified with 0.2 M NaOH and 0.2 M CaCl2. Point of zero charge (PZC). Six solutions were prepared with 0.5 g of sorbent in an aqueous medium (with a 3-8 pH range), they were stirred at 225 rpm for 48 h. The derivative method was used to plot the initial pH versus final pH, in order to determine the PZC. Copper adsorption. CuSO4 solutions were prepared in 2, 4, 6, 8 10 mg/L concentrations; 0.1 g of pineapple biomass was added adjusting the pH to 5. The solutions had a contact time of 0 to 24 h. Results: The pineapple peel had a 5.0 point of zero charge (PZC) value, which indicates that pH values higher than the PZC are required to obtain an adsorbent with a negatively charged surface and favor the copper adsorption. A 50% copper removal was obtained in all concentrations after a 1 h contact time. Limitations on study/implications: This research had no limitations. Findings/conclusions: The point of zero charge is a reliable parameter that allows the adsorption process to take place and provides a greater certainty to the metal adsorption process. Meanwhile, pineapple peel can be used as an adsorbent material, consequently reducing its accumulation in open dumps.
Reaction of [Me3SiNPPh2CH3] 1 with ZnCl2 yields the dimer [ClZn(mu-Cl)(Me3SiNPPh2CH3)]2 2 whereas treatment of 1 with AlCl3 in THF leads to the monomeric N adduct [Cl3Al(Me3SiNPPh2CH3)] 3. Compounds 2 and 3 were found to be thermally stable and were fully characterized by NMR spectroscopy, X-ray diffraction, and elemental analysis. On the other hand, treatment of phosphinimine 1 with (n)BuLi/ZnCl2 or (CH3)2CHMgCl yields the zinc and magnesium complexes [M4(Me3SiNPPh2CH2)4(mu4-O)(mu2-Cl)2] 5 (M = Zn) and 6 (M = Mg), respectively. These compounds can be considered as new examples of inverse crown ethers in which the oxygen atom is encapsulated by polar organometallic complexes in a tetrameric arrangement. In contrast, reaction of 1 with nBuLi/AlCl3 in Et2O under inert atmospheric conditions leads to the formation of the dimeric species [Cl2Al(Me3SiNPPh2CH2O)]2 7, which displays oxygen insertion into the C-Al bond, while the same reaction in the presence of air yields the compound [mu-(AlCl2)(NPPh2CH3)]2 8 with loss of ClSiMe3 and without oxygen insertion into the C-Al bond.
Objetivo: Obtener y caracterizar un material biodegradable, utilizando como materia prima el almidón del fruto del pan de sopa (Artocarpus altillis (s. park) fosberg) Diseño/metodología/aproximación: Se extrajo el almidón del fruto del pan de sopa por el método húmedo. El almidón seco, se mezcló con glicerol, agua y HCl 1N aproximadamente a 75 °C hasta obtener un bioplástico, el cual se caracterizó por espectroscopia de FT-IR y SEM-EDX. Resultados: El mayor contenido de almidón se obtiene en la etapa intermedia de desarrollo del fruto (verde-maduro) con un 10% de rendimiento. Se realizaron pruebas de infrarrojo y SEM-EDX, tanto del almidón como del bioplástico obtenido. El SEM-EDX mostró que para el almidón el diámetro de granulo promedio es entre 2.5 ± 0.2 a 8.4 ± 0.2 µm con una geometría de tipo esférica, con cortes en direcciones aleatorias. Limitaciones del estudio/implicaciones: No se observan limitaciones tecnológicas importantes, pero si implicaciones que impactan en el desarrollo acelerado del comercio de bioplásticos. Hallazgos/conclusiones: Se aisló almidón del fruto pan de sopa y se caracterizó con técnicas de Infrarrojo y SEM-EDX. Se obtuvo un material bioplástico a partir del almidón, empleando como plastificante glicerol y agua, encontrándose que la proporción (1:10, almidón:agua) genera un material con las mejores características de termoplástico.
Objective: To produce Serrano peppers using a new cultivation technique that mixes the best of hydroponic cultivation and traditional cultivation. Design/methodology/approach: We set up a growing system where the Serrano pepper grew from seedling to its full-fledged state, in a growbag containing sand (as support material), potassium polyacrylate (as water retention material), and a nutrient solution for vegetable gardens, under greenhouse conditions. The humidity level of the growbag is controlled by adding as much water with nutrient solution as needed. This technique has generated 100% harvestable plants (total: 20 plants); more than 90% of the water can be saved in comparison to regular and hydroponic cultivation. Results: Once the harvest began, at least 22.857 kg of Serrano pepper were obtained in 3 m2 of soil in a system with a pyramidal structure in which the 20 plants were placed. If we extrapolated this data, approximately 93,000 kg of Serrano pepper could be harvested from a 1 ha system. Study Limitations/implications: This technique tries to tackle the water access limitations that may exist in some areas of Mexico. However, it does not mitigate the initial costs of a greenhouse system. Nevertheless, this technique can be reused up to 10 times without requiring maintenance. Findings/conclusions: Experience has shown that hydroponic crops are truly profitable, despite their vast water requirements, which is precisely what prevents their global expansion. However, our modification of this method saves more than 90% of the water, using potassium polyacrylate as a retention agent and sand as a support material. Therefore, this technique could be implemented even in places where water is scarce
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