Drying of Starch Suspension in Spouted Bed with Inert Particles: Physical and Thermal Analysis of Product

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Drying in a spouted bed with inert particles promotes high heat and mass transfer rates due to the gas-solid contact, which in turn is successfully achieved by particles' cyclic movements. Because of its advantages and versatility, spouted bed drying of suspensions on inert particles is a potential alternative to flash and spray drying and has received attention in research and development in recent years. In this context, this article describes the drying process of cassava starch suspension (35% initial solids content) in a laboratory-scale cone-cylindrical spouted bed dryer with polypropylene particles. The setup consists of a cone-cylindrical spouted bed dryer (internal angle of 60 degrees, 20-cm column diameter, and 5-cm inlet orifice diameter) with top feeding of suspension, which is sprayed by a double-fluid atomizer. The study focused on the fluid dynamics of polypropylene particles at inlet air temperatures of 60, 75, and 90 degrees C and the effects of air temperature on dried starch properties, such as gelatinization temperature, pasting temperature, particle size distribution, crystalline profile, and final moisture content. The pressure drop fluid dynamic curves did not allow a proper analysis and assessment of minimum spout air flow when air was atomized in the bed. Therefore, the minimum spout air flow was determined by the visual observation of the fountain height in this case. Inlet air temperatures did not show a significant difference in the minimum spout air flow, but the bed presented dynamic instability with increasing inlet air temperature. The results showed that the spout fluid dynamic regime during drying was stable with air flow around 1.5 times the minimum spout air flow in the range of inlet air temperature studied. Drying air temperature influenced final moisture content of samples, which was lower than 13% for all conditions. However, physical properties of dried starch were not affected by process conditions.281112881296Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FAPESP [06/06268-1, 07/5555-1

Analysis of the drying process of a biopolymer (poly-hydroxybutyrate) in rotating-pulsed fluidized bed

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)A rotating-pulsed fluidized bed (RPFB) dryer was employed to conduct the drying of polyhydroxybutyrate (PHB) cohesive granules. Along the experiments, it was possible to identify, visually, 3 different dynamic regimes that were related with the temperature profile, the drying kinetics and the fluid dynamic behavior. The drying kinetics of PHB showed a short constant drying rate period followed by a decreasing drying rate period. The constant drying rate (N(c)) and final moisture content (dry basis) were related to the rotation frequency (responsible for the pulsation effect), temperature and velocity of the inlet air. Furthermore, measurements of molecular mass (gel permeation chromatography analysis) and Carr Index (flowability test) on PHB samples were done before and after the drying. The RPFB dryer showed to be appropriate to dry the PHB granules, resulting in an excellent fluid dynamic behavior that provided uniform drying of the solid. The best conditions of drying were identified at 7 Hz of rotation frequency, 90 degrees C and 0.55 m/s of inlet air temperature and velocity. At these conditions the dried PHB reached final moisture content of 0.56% (wet basis) after 2 h of drying. (C) 2011 Elsevier B.V. All rights reserved.507623629Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)School of Chemical Engineering of the University of Campinas - UNICAMPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Fluid Dynamics and Drying of Cohesive Particles of a Biodegradable Polymer (Poly-Hydroxybutyrate) in a Rotating Pulsed Fluidized Bed

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)This article presents the results of fluid dynamics and drying of poly-hydroxybutyrate (PHB) granules in a rotating pulsed fluidized bed (RPFB) dryer. Cohesiveness of PHB results in problems when using conventional drying techniques, such as a fluidized bed dryer. The excess surface water on the particles may form agglomerates that damage the flowability of the material inside the dryer. The drying study in RPFB consisted of adjusting mathematical models for predicting the moisture evaporation during the constant drying rate period (linear fit) and the decreasing drying rate period (analytical solution of Fick's second law). The influence of temperature, rotation frequency, and velocity of the drying air on the constant drying rate (Nc), effective diffusivity (Deff), and mass of particles elutriated (me) during drying was evaluated. Particle porosity was analyzed before and after drying and scanning electronic microscopy (SEM) was employed to verify structural changes on the PHB granules after drying. The RPFB dryer proved to be appropriate to dry the PHB granules, resulting in an excellent fluid dynamics behavior of the particles inside the bed and providing uniform drying of the solids. Temperature and velocity of the air had a significant influence on the drying process, but rotation frequency did not affect the process in the ranges analyzed. Fine particle elutriation occurred during the first 10min of drying. After drying, the porosity changed and breakage of the particles was observed due to attrition inside the bed.281112971306Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Multilayer biopolymer membranes containing copper for antibacterial applications

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Chitosan/alginate multilayer dense membranes, with micrometric thicknesses, were produced by casting the solution of each polymer alternately on a Petri dish. Copper ions were also incorporated into these membranes, which were then characterized with regard to morphology, chemical and crystallographic structures, ions diffusivity, and bacteriostatic properties. Results indicate that the casting approach for multilayers production was successful, since the membranes produced were formed by organized and alternated polymer layers. The pH dependence of the metal adsorption resulted in a higher concentration of the copper in the alginate layers, as shown by SEM-EDS (scanning electron microscopy - energy dispersive X-ray spectroscopy) analysis. Fourier transformed infrared spectroscopy confirmed the Coulombic interaction between the chitosan amino groups and sodium alginate carboxyl groups. The copper ions were distributed homogeneously, without the formation of clusters, and were bound mainly to oxygen and nitrogen atoms located on the alginate and chitosan functional groups, respectively, according to extended X-ray absorption fine structure (EXAFS) results. The antibacterial properties of this membrane indicate that this material may hold promise for numerous applications, such as for water treatment or antibacterial functional coatings with controlled release. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 20121261SIE17E24Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Sustainable 3D Printing: Design Opportunities and Research Perspectives

As 3D Printing process, technologies and tools are rapidly becoming pervasive and used both in industrial and in non-industrial contexts, the risk to have new unsustainable printing processes and production’s behaviours is high and, potentially, can led to the increasing of environmental emergency (unsustainable growth). On the other hand, Design for Sustainability works, since late 80’s, on the mitigation of production’s environmental foot-print and, recently, on the development of socio-technical systems and distributed hybrid solutions empowering both environmental aspects and socio-economic ones. This paper investigates the new concept of Sustainable 3D Printing using recent Design for Sustainability’s research theories and design approaches, in order to evaluate, and later describes, promising design opportunities and research perspectives that can be used and taken into account, simultaneously, by designers, researchers, entrepreneurs and policymakers to support the societal transition toward sustainable ways of design, production and consumption