M. W. Donida

University of Campinas, Conceição de Campinas, São Paulo, Brazil

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Publications (10)7.93 Total impact

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    ABSTRACT: Polymeric coating has been applied to particles for several reasons, which goes from enhancing product esthetics to control the release of chemicals. Spouted beds are among the equipments widely used to coat particles. Its choice is justified by the cyclic movement of the particles in stable spouting resulting in product homogeneity and good solid–fluid contact with high heat and mass transfer rates. Also, the spouted bed with inert particles is an alternative to drying pastes due to its low cost and applicability to low scale production. This work presents results of coating and drying efficiencies for different systems that combine 04 different solids and 03 formulations of suspensions. Materials having different surface tension were chosen and suspensions with varying surface tensions were formulated, resulting in different wettabilities (quantified by contact angles measurements). The results show the direct influence of these properties on the coating and drying performances.On applique un revêtement polymérique aux particules pour plusieurs raisons, qui vont de l'amélioration de l'esthétique du produit jusqu'au contrôle du rejet de substances chimiques. Les lits en jaillissement sont parmi les équipements les plus couramment utilisés pour revêtir les particules. Leur choix se justifie par le mouvement cyclique des particules dans des conditions de jaillissement stable, qui donne en bout de ligne une homogénéité du produit et un bon contact entre les solides et les fluides et des coefficients élevés de transmission de chaleur et de transfert de masse. De plus, le lit de jaillissement alimenté de particules inertes est une solution de rechange au séchage des pâtes en raison de son faible coût et de ses possibilités d'application à la production à petite échelle. Cet ouvrage présente les résultats relativement aux rendements du revêtement et du séchage de différents systèmes combinant quatre solides différents et trois formulations de suspensions. On a choisi des matériaux qui ont une tension superficielle différente et on a formulé des suspensions ayant diverses tensions superficielles, ce qui a donné lieu à des mouillabilités différentes (quantifiées par les mesures des angles de contact). Les résultats montrent l'influence directe de ces propriétés sur les rendements du revêtement et du séchage.
    The Canadian Journal of Chemical Engineering 09/2009; 87(5):695 - 703. · 1.00 Impact Factor
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    ABSTRACT: Recently, some research groups have been developing studies aiming to apply spouted beds of inert particles for production of dried herbal extracts. However, mainly due to their complex composition, several problems arise during the spouted bed drying of herbal extracts such as bed instability, product accumulation, particle agglomeration, and bed collapse. The addition of drying carriers, like colloidal silicon dioxide, to the extractive solution can minimize these unwanted effects. The aim of this work was to study the influence of the addition of colloidal silicon dioxide on enhancement of the performance of the drying of hydroalcoholic extract of Bauhinia forficata Link on a spouted bed of inert particles. The physical properties of the herbal extract and of its mixture with colloidal silicon dioxide at several concentrations (20% to 80% related to solids content) were quantified by determination of the surface tension, rheological properties, density, pH, and contact angles with the inert surfaces. Drying performance was evaluated through determination of the elutriation ratio, product recovery ratio, and product accumulation. The product was characterized through determination of the thermal degradation of bioactive compounds and product moisture content. The results indicated that the rheological properties of the extracts and their preparations, the contact angle with inert material, and the work of adhesion play important roles in the spouted bed drying of herbal extracts. Higher concentration of the drying carrier significantly improved the spouted bed drying performance.
    Chemical Engineering Communications 03/2009; 196(3):391-405. · 1.05 Impact Factor
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    K. Tannous, M. W. Donida, L. A. Obata
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    ABSTRACT: The entrainment of heterogeneous particles in a gas-fluidized bed for particle mixtures of categories A and B according to the Geldart classification was conducted in this study. The experiments were carried out in an acrylic column of 0.092 m diameter. The distributors were perforated plates of up to 5.9% free area fraction. Measurements of pressure gradients were made using 24 pressure taps. Glass beads with particle diameters from 60 to 400 μm were used. The mixtures were described using the Rosin-Rammler-Bennet granulometric distribution model. The transport disengaging height (TDH) heights were obtained using the Geldart methodology. A 25 experimental design was applied relating the dispersion index, mean diameter, solid mass, superficial gas velocity, and free area fraction of the distributor to obtain the TDH heights. Slugging and transition for turbulence regimes characterized the behaviors of fluidized beds. The results showed that TDH heights for heterogeneous particles were dependent on the solid mass and superficial gas velocity.
    Particulate Science And Technology 05/2008; 26(3):222-234. · 0.44 Impact Factor
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    ABSTRACT: The aim of this work is to analyze the resulting process: coating or drying, and the respective fluid dynamic behavior, by bottom-spraying polymeric suspensions on a spouted bed of inert particles. Glass beads, ABS®, polypropylene (PP), and polystyrene (PS) were chosen as inert particles and were analyzed and characterized by their physicochemical properties. The polymeric suspensions were characterized by density, surface tension, rheology, and wettability. The fluid dynamic behavior of the bed was correlated with the particles and suspensions characteristics for each process: coating and drying. Each process performance was correlated with the polymeric suspension-particle work of adhesion.
    Drying Technology 02/2007; 25(2):319-326. · 1.81 Impact Factor
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    ABSTRACT: The courses of environmental engineering have increasingly become more common in Brazil. In spite of the common legislation that defines the subjects of basic, professional and specific graduation, there has been a variation in the focus given in the list of subjects of these courses, which have been strongly influenced by the vocation of the Institution of Undergraduate Teaching (IES). The objective of this essay is to present the structure, the curricular emphasis and the approaches used by the pedagogic project of the environmental engineering of UNIPINHAL, from Espírito Santo do Pinhal – SP. There are two curricular emphases that guide the course: technology for the environment and environmental planning and managing. These emphases have been given in a way to connect subjects, research, laboratories and extension projects, showing the vocation of the region and of the course, which is strongly agricultural.
    Engenharia Ambiental : Pesquisa e Tecnologia. 01/2006;
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    ABSTRACT: Among the several unit operations that seek the modification of superficial characteristics of solid particles, the spouted bed appears as efficient technology for coating of coarse particles (dp >1 mm). This work aimed at investigating the fluid-dynamics of the conventional spouted bed during a coating process, using several inert particles such as polystyrene, polypropylene, polyethylene of low density, ABS®, placebo tablet and glass beads, and analyze the influence of the physical properties of the particles and of the polymeric coating suspension on the fluid dynamics. The suspension was characterized by the surface tension, density, rheology, and contact angle between the suspension and the solid surface. It was verified that the particles having a high contact angle with the suspension (polystyrene, polypropylene, and low-density polyethylene) were not coated, and drying of the suspension was obtained in these cases. For the other particles (ABS, tablet, and glass beads), coating efficiencies in the range of 76–90% were obtained. The shape, angle of repose, and density of particles affected the fluid-dynamic during the coating, and also the inter-particle friction and the particle circulation velocity in the bed.
    Drying Technology - DRY TECHNOL. 01/2004; 22(5):1069-1085.
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    ABSTRACT: This work is a study of the influence of the coating suspensions and particle properties in a conventional spouted bed during the coating process. The inert particles, glass beads, were coated at fixed operating conditions with different formulations of aqueous polymeric coating suspensions in a spouted bed of laboratory scale. The wettability of solid by liquid was quantified by contact angle measurements and surface tension of the coating suspensions. The results of coating efficiency and particle growth were correlated with the adhesion of the coating suspension on the inert particle, which is a function of the solid and liquid characteristics. The physical properties of the coated particles: particle mean diameter, sphericity, bulk, true and apparent densities, porosity and flow velocity were determined and compared with the inert particle properties.
    Drying Technology 01/2004; 23:217-224. · 1.81 Impact Factor
  • Marta W. Donida, Sandra C. S. Rocha
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    ABSTRACT: In this work, a process of coating of urea with polymeric film was developed and analyzed experimentally in a two-dimensional spouted bed. An experimental design was utilized to investigate the effects of operational variables, e.g., air flow rate, air temperature, atomizing air pressure and coating suspension flow rate, on the efficiency of the process, particles growth, particles growth kinetics and physical properties. The results showed that the efficiency of the process and particle growth characteristics were strongly influenced by the operational variables. Coating of the polymeric suspension of Eudragit® improved up to four times the moisture holding capacity of coated urea in relation to uncoated urea. The bulk density, grain size and sphericity were found to be independent of operational conditions.
    Drying Technology 01/2002; 20(3):685-704. · 1.81 Impact Factor
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    ABSTRACT: RESUMO Os cursos de Engenharia Ambiental têm se expandido no Brasil de maneira muito acentuada nos últimos anos. Apesar da legislação em comum que define as matérias de formação básica, de formação profissional geral e de formação específica, tem se observado uma variação de enfoques nas grades curriculares desses cursos, os quais têm sido fortemente influenciados pela vocação da Instituição de Ensino Superior (IES). O objetivo do presente trabalho é apresentar a estrutura, as ênfases curriculares e as abordagens empregadas pelo Projeto Pedagógico do curso de Engenharia Ambiental do UNIPINHAL, de Espírito Santo do Pinhal – SP. Duas são as ênfases curriculares que norteiam o curso: tecnologias para o meio ambiente e planejamento e gestão ambiental. Essas ênfases têm sido praticadas de forma integrada no que se refere às disciplinas, pesquisa, laboratórios e projetos de extensão, refletindo a vocação da região e do curso, a qual é fortemente agrícola. ABSTRACT The courses of environmental engineering have increasingly become more common in Brazil. In spite of the common legislation that defines the subjects of basic, professional and specific graduation, there has been a variation in the focus given in the list of subjects of these courses, which have been strongly influenced by the vocation of the Institution of Undergraduate Teaching (IES). The objective of this essay is to present the structure, the curricular emphasis and the approaches used by the pedagogic project of the environmental engineering of UNIPINHAL, from Espírito Santo do Pinhal – SP. There are two curricular emphases that guide the course: technology for the environment and environmental planning and managing. These emphases have been given in a way to connect subjects, research, laboratories and extension projects, showing the vocation of the region and of the course, which is strongly agricultural.
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    ABSTRACT: RESUMO -O objetivo deste trabalho é analisar a fluidodinâmica de um leito de jorro convencional durante operações de recobrimento de partículas e secagem de suspensões. Para realização dos experimentos, foi utilizado um leito de jorro convencional em escala laboratorial, com ângulo da base cônica de 60° e atomização da suspensão na base, contendo partículas inertes de diferentes propriedades físicas: esferas de vidro, ABS ® , polipropileno e poliestireno. Os valores de queda de pressão, vazão de ar de jorro, circulação de sólidos e altura da fonte foram acompanhados durante os processos. O comportamento fluidodinâmico do leito foi correlacionado com as características das partículas e da suspensão em cada processo: recobrimento e secagem. O desempenho do recobrimento da partícula e da secagem de suspensão foi correlacionada com a adesão da suspensão no material. INTRODUÇÃO Secagem de suspensões e recobrimento de partículas são operações similares quando conduzidas em leito de jorro. Em ambos os casos, a suspensão é atomizada sobre leito de partículas movimentadas por ar aquecido, revestindo a superfície das partículas com um fino filme líquido. No processo de recobrimento, o solvente evapora e o material sólido fica depositado sobre as partículas na forma de filme. No processo de secagem, o filme líquido é seco sobre o material inerte e é rompido durante a circulação das partículas, produzindo um pó fino. O principal parâmetro que determina se ocorrerá recobrimento ou secagem é a força de adesão da suspensão com a superfície da partícula. Em casos de forte adesão entre a interface líquido-sólido, as partículas poderão ser recobertas e para uma fraca adesão na superfície sólida, as gotas de líquido poderão secar como pó, ou secar formando um filme sólido que é rompido pelo atrito inter-partículas (Kutsakova, 2004; Donida et al., 2004). A força de adesão é dependente da molhabilidade do sólido pelo líquido e pode ser quantificada a partir do ângulo de contato e da tensão superficial da suspensão (Iveson et al., 2001; Hemati et al., 2003). O objetivo deste trabalho é analisar a fluidodinâmica e o desempenho de um leito de jorro convencional durante processos de recobrimento e secagem, quando uma suspensão polimérica é atomizada pela base sobre partículas inertes.