Estudo comparativo de processos de secagem de solidos granulados com e sem assistencia de microondas. / Comparative study of the drying processes of granulated solids with and without microwave.

AUTOR(ES)

Michele Nenhemy Berteli

DATA DE PUBLICAÇÃO

2005

RESUMO

Microwave energy is an unusual source of energy because it generates heat inside dielectric materials. Thus, an alternative way of drying could be the use of microwaves as the energy source, resulting in shorter processing times with greater performance, usually producing a higher quality product when compared to those obtained by the conventional drying techniques. The objective of the present work was to study the drying kinetics of a pharmaceutical granule that is the basis of the drug hydrochlorthiazide (HCT), from the initial moisture content of about 42 % (d.b.) to the final moisture content of 3 % (d.b.). The product temperature was not allowed to exceed 70oC in order to preserve the effective drug principle (HCT). Experiments were carried out using bench scale driers of the tray type, one using hot air convection and the other applying microwaves combined with hot air convection (adapted domestic ovens). Other experiments were run in a microwave assisted vacuum drier, as well as drying with microwaves in a fluidized bed, which was installed inside an adapted microwave oven where it was possible to operate with or without microwaves. The microwave assisted vacuum process showed the shortest drying times when compared to the tray drier processes, with and without the application of microwaves. The samples from this process were submitted to compression in order to verify the physical characteristics of the corresponding tablets, which were shown to comply with the required specifications. Of all the processes studied, fluidized bed drying provided the shortest drying times, although it was not possible to carry out a more conclusive study of the drying parameters and of the influence of microwaves on the process, since incompatibility was found between the physical characteristics of the sample and the electrical features of the microwave application system.

ASSUNTO(S)

microwave calor - convecção secagem convection drying microondas

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