No abstract

The indiscriminate use of films as synthetic primary packaging, for the conservation and transport of fruit and vegetable products in postharvest, causes disposal problems. In the present work, films based on sodium alginate were synthesized and characterized, with alginate as a biopolymer matrix, glycerol (plasticizer), oleic acid (control of hydrophilicity), and calcium chloride (cross-linking agent). The dynamic mechanical, thermal, structural, and hydrophobicity properties were studied. In the case of dynamic mechanical properties, they were analyzed at a temperature of −50°C, because food packaging goes through storage during its cold chain, showing biofilm stability under these conditions. On the other hand, infrared spectroscopy analysis showed that the carboxylate and carboxy functional groups serve as a link for all the components, and oleic acid is also serving as a plasticizer and, to a lesser degree, as a hydrophilicity controller.

The feasibility of employing a porous polyurethane-keratin hybrid membrane for the removal of hexavalent chromium was investigated. Keratin was extracted from chicken feathers and incorporated onto a synthetic polyurethane polymer to synthesize a hybrid membrane. Keratin supply active sites to bioadsorb Cr (VI) and polyurethane play an important role as the support to protein. Also, polyurethane-keratin biofiber membranes were synthesized. Biofibers obtained from chicken feathers were modified to activate their surface. The effective pore in membranes is less than 50 nm, which places these materials in the mesopore range. Scanning electron microscopy (SEM) was used to study the morphology of membranes, and mechanical dynamical analysis (DMA) was used to evaluate the viscoelastic properties. NH, C=O, S-S and C-S were determined via Fourier-transform infrared (FTIR) analysis as functional groups of keratin, which participate in the linking sorption of hexavalent chromium. Adsorption of Cr(VI) was carried out in a filtering system at low contact time in continuous flux; the maximum removal reached was 38% at neutral pH of chromium solution. Results indicate that the isoelectric point of keratin is relevant in the adsorption process. pH of keratin solution above the isoelectric point brings about higher adsorption of heavy metals, whereas lower pH causes minor adsorptions, due to the functional groups' ion charges. Based on the results, keratin extracted from feathers is a natural biosorbent that can be incorporated onto synthetic polymers to develop novel membranes and improve its applications in the heavy metal separation process.

Porous material was processed by the mixing, molding and pressing the ceramic material, afterward burnout and sintering; through the forming porous, using corn flour at different concentration (10, 15 and 20 wt.%) as a pore forming agent; in order to determinate the influence of porous on the mechanical, morphological and structural properties. The effect of the volume fraction of corn flour in the mullite matrix, at various sintering temperature from 1100, 1200, 1300 and 1500 o C were tested by Diffraction X ray, showing changes in crystalline phases of mullite (3Al 2 O 3-2SiO 2), as result of sintered temperatures. Presence of talcum powder in formula, also cause the formation of the cordierite and cristobalite crystalline phases, giving stability and adhesion to the structure of ceramic material. When sintering at temperatures between 1300 to 1500 o C, and it was used the concentration of corn flour 15-20 wt.% as forming agent porous, it was found the better mechanical properties. The scanning electron microscopy analysis shows the presence of open porosity and anisotropy.

Este trabajo presenta el análisis de tecnologías registradas y en desarrollo de empaques inteligentes y películas antibacterianas para quesos, con la finalidad de proporcionar una visión general sobre los esfuerzos realizados a través del tiempo por investigadores que proponen envases más sostenibles. El análisis, se basa en una investigación de tipo exploratoria utilizando la vigilancia tecnológica para la búsqueda, filtrado y síntesis de la información en artículos científicos y patentes, identificando factores como: origen de materiales, materias primas, en qué alimentos se han aplicado, entre otros. El objetivo fue cruzar información y obtener clasificaciones que permitieron estratificar patrones, similitudes y diferencias a través del tiempo; obteniendo como resultado de este análisis una tendencia al desarrollo de mezclas poliméricas naturales. Se llevó a cabo la caracterización de empaques comerciales través de espectroscopía infrarroja identificando que el 90% de sus componentes son polímeros sintéticos. Lo anterior coadyuvará a situar la importancia de investigaciones de películas usando polímeros naturales para quesos desarrollados en investigaciones paralelas.

A novel physical process to obtain graphene nanoplatelets consisting of two principal steps, steam explosion and ultrasonic exfoliation, is proposed. This approach requires only water; nevertheless, the pressure and temperature conditions in the steam explosion equipment contribute to the delamination of the graphite complemented with an ultrasonic step. Moreover, two kinds of source material were tested: highly pyrolytic oriented graphite and a lower oriented graphite. Infrared and energy dispersive x‐ray spectroscopies analysis confirmed additional functional groups were not generated in any of the treated materials. X‐ray diffraction showed that graphene nanoplatelets obtained in this work are conformed by 20–30 nm of thickness, also corroborated with atomic force microscopy. According to Raman results, graphene nanoplatelets possess a high structural quality which is similar to the initial graphite. Hence, this process represents a viable option to obtain graphene nanoplatelets through an easy, green and large‐scalable route.

Green ceramic bodies based on mullite were infiltrated with SiO 2 (TEOS precursor) solution using a sol-gel technique and sintered at 1,300°C. Previously, the green bodies had been prepared with the molding method, using corn flour as the pore-forming agent with a concentration in mass percent of 10, 15, and 20, and then they were sintered. Infiltrated ceramic material was evaluated to determine the relationship between, morphology, porosity, thermal properties, and crystalline characteristics by scanning electron microscopy, X-ray diffraction, porosimetry by N 2 at 77 K, and thermal analysis using laser flash technique. The presence of SiO 2 together with magnesium (talc powder) gives a cordierite crystalline phase, which is considered presenting thermal stability. Infiltration process changes the surface area, which is reduced by 93 %, and the pore size value reaches 1.98 nm, changing from open to closed structure. In spite of porosity change, thermal conductivity increases in the majority of the samples. This phenomenon obeys the complex system involved in the study, such as closed porosity, microstructure, tortuosity, geometry, and the anisotropy of mullite bonds, accompanied by the infiltrant liquid (SiO 2 ).

Polymers and specifically hybrid polymeric membranes have been identified as effective formulations in adsorption processes. Nevertheless, the adsorption mechanisms associated with their thermodynamics and kinetics are not fully understood, particularly when these polymeric membranes are used to adsorb 2-Phenylethanol (2-PE) to intensify its production in a specific bioconversion process. This work was aimed at giving phenomenological insights on the adsorption of 2-PE on a set of novel porous hybrid membranes based on polyurethane and keratin biofiber obtained from chicken feathers. Feathers, considered as a waste by-product of the poultry industry, represent an alternative source of keratin, a biopolymer that can be used to design low-cost materials from natural resources. Two types of hybrid membranes were prepared. i. e. composite and copolymer. Firstly, these materials were characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) (before and after the adsorption process) and X-Ray (WAXD) analysis. Secondly, these materials, including the reference ones (keratin biofiber and polyurethane), were evaluated during the removal of 2-PE, relating their adsorption capabilities to physiochemical properties elucidated during the characterization. Particularly a composite with 0.1 g of chicken-feather-keratin (C1) presented the highest removal percentage (60.68%), a significant initial adsorption rate (0.2340 mgPE.h−1.gA −1), the maximum adsorption capacity (12.13 mgPE.gA −1) and the best stability and mechanical properties at studied operating conditions. In comparison with results reported in literature, in this composite carbonyl functional groups from polyurethane showed rather major affinity to 2-PE than amino groups from the keratin biofiber. To this end, parameters associated with its industrial application were obtained, namely thermodynamic and kinetic information was obtained from a proper design of experiments and phenomenological models based on adsorption macroscopic fundamentals.