Evaluation of the synthetic methods for preparing metal organic frameworks with transition metals

In this study, preparation of metal-organic frameworks (Cu3BTC2, Fe3BTC2, Ni3BTC2 and Co3BTC2) (BTC = benzene-1,3,5-tricarboxylate) was performed by five different synthetic methods (solvothermal under autoclave, reflux, domestic microwave, ultrasonic, and mechanochemical conditions) and the results were compared in order to evaluate the advantages and disadvantages of each method with a focus on the domestic microwave method. All the results showed correlations between the reaction conditions and the yield, morphology, crystalline phases, and specific surface area. Characterization of the samples was performed by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and physisorption analysis. Experimental results have shown that the conventional method is a good choice for the preparation of M-BTCs, but it takes a long time and requires high temperature. With this work, we show that the domestic microwave is the best choice because it promotes the same MOF structures in a shorter time while achieving high purity, high specific area, and good quantitative yield. Notably, these transition metal-BTCs are promising candidates to be applied as catalysts in further studies

Mechanical recycling of tags and labels residues using sugarcane bagasse ash

Abstract In this study, an alternative method for recycling residues of labels and stickers (parings) containing biaxically oriented polypropylene (BOPP) and polyurethane-based glue was discussed. The recycling of this type of material is complicated, once the separation and the milling processes are difficult to be accomplished, due to the presence of a large amount of glue. In this study, sugarcane bagasse ash was used to enable the milling process of stickers residues. Composites were prepared with post-consumer polypropylene extrusion with different polypropylene/parings ash ratio. These materials were analyzed by tensile, three point flexural, hardness, density, water absorption, Izod impact tests, thermogravimetric analysis, environmental exposure and scanning electron microscopy. Addition of sticker residues/ash to the polypropylene matrix makes the material more rigid and does not affect significantly thermal and degradation properties. Thus, the recycling process proposed in this paper is environmentally and economically viable

Influence of addition of silanized nanosilica and glycerol on hydrophobicity of starch using a factorial design

Abstract The thermoplastic starch (TPS) is regarded as a promising material for manufacturing packaging and products with biodegradable properties. This study aimed at obtaining hydrophobic starch using silanized silica nanoparticles (nSS) with hexamethyldisilazane. A factorial design 22 with central point was developed to evaluate the influence of glycerol (plasticizer) and nSS addition on the properties of water absorption, solubility and TPS contact angle. The materials morphology was also evaluated by means of scanning electron microscopy. The amount of glycerol and nSS influenced on starch hydrophobic character, for the increase of the glycerol dosage contributed to the increase of absorption and solubility of TPS in water. On the other hand, nSS has greater influence on the characteristics related to the TPS surface, favoring an increase of up to 27% in the contact angle values. Therefore, the sample with the greatest hydrophobic character was obtained by using lowest amounts of glycerol (30%) and highest amounts of nSS (5%)

Unprecedented Low-Cost Hybrid Material for CO 2 and CH 4 Separation

Abstract: The zeolite synthesis using waste as silicon source is a promising low-cost process. Sugarcane bagasse ash is a hazardous solid waste generated in large amounts in the sugar industry. Thus, development of new procedures for its productive reuse is relevant. Therefore, this waste was used to prepare a new ZCNT (zeolite/carbon nanotube material). In this work, ZCNT was applied in a CO 2 /CH 4 separation. The adsorption took place at 303 K under pressure of 0.1 until 20 bar and the data were fitted by Langmuir, Toth and Freundlich equations. The adsorbed amount at 20 bar found was 4.7 mmol of CO 2 /g and 4.1 mmol of CH 4 /g; at 3 bar the adsorbed amount was 4.1 mmol of CO 2 /g and 1.2 mmol of CH 4 /g. This result indicates that ZCNT has potential application in CO 2 /CH 4 separation at low pressures