Research of microwave drying of natural zeolite granules and its influence on the technological properties

Abstract

Introduction.The wet granulation technique is often used in the preparation of free-flowing granules in the manufacture of tablets and capsules. It is very important that granules obtained by this technology be dried before further processing. And also, it is important that the method of drying is entirely controlled and managed and the result is quite predictable. In recent years, microwave drying of granules make a considerable interest. Microwave drying is especially useful for moisture sensitive materials which are mostly pharmaceutical substances. Microwave drying technology is useful for dosage forms with high purity, since this method provides the possibility of drying in the same container production, which reduces the chance of cross contamination of matter and its direct contact with staff.The aim of this work was to study the effect of microwave radiation on the technological properties of natural zeolite peets compared to traditional convection method and to determine the optimal drying modes and specific humidity of the material.Material & methods. Granules were prepared by wet granulation technology by using a laboratory granulator NG-12. As the humidifier we used potato starch gel and PVP in an amount of 25% by weight of the dry product. The resulting granules were divided into two equal parts and subjected to drying in a microwave oven (Delfa D20MW) of installed capacity (119 W, 280 W, 336 W, 462 W, 595 W and 700 W) and shelf dryer to a residual moisture level of 0.01 g.w./g.d.m. or less. Determination of the specific humidity of granules was carried out by mass loss on drying. Fractional composition of granules was determined using a standard set of sieves with the diameter of the holes 2.0; 1.0; 0.5 and 0.25 mm. The friability of the granules was determined using friabilator Pharma Test PTF 10E / ER, Germany. To characterize the fluidity of granule Carr`s indicator (I_C) and coefficient Hausnera (H_R).

Results & discussion. The results of experimental studies have shown a significant impact of intensity microwave radiation on the rate of drying material. With an increase in power from 119 watts to 700 watts time spent on drying decreased more than twice. Changing the speed of drying material took place in two periods. In the first period (humidity of 0,29-0,05 g.w./g.d.m.) free moisture located mainly on the surface of the granules is removed in the first period, in the second period (0,04-0,05 g.w./g.d.m.) moisture from the inner pores of the material is removed.Type of drying does not significantly affect the distribution of particle size. Different amounts of microwave radiation also not significantly affect the size and rheological properties of the granules. The last one was confirmed by values of Carr`s index and coefficient of Hausner. Both indicators showed that all series of obtained granules have very good flowability.Study of the influence of specific humidity values on the mechanical strength of granules and tablets obtained on the basis showed that its most optimal level, which can be recommended both for granules and for tablets, is based on their range of 0,03-0,05 g.w./g.d.m. Knowing the limits of specific humidity allows to choose optimal modes of power microwave radiation for drying a natural zeolite granules.Conclusion.The effect of microwave radiation on the dynamics of natural zeolite pellets drying on the value of their technological properties. Optimal levels of specific humidity for granules and tablets, providing the best technological properties, is 0,03-0,05 g.w./g.d.m. On the basis of data obtained, the reasonable duration of the process of drying, depending on the power of the microwave radiation, is 3-14 minutes.