Satoru Watano

Dry particle coating using magnetically assisted impaction coating: modification of surface properties and optimization of system and operating parameters

Abstract The feasibility of using the magnetically assisted impaction coating (MAIC) device to coat fine silica guest particles onto the surface of larger cornstarch and cellulose host particles was examined. This was done to simultaneously improve the flowability of the host particles, as well as reduce their hydrophilicity, making them more suitable for use in foods and pharmaceuticals. The success of coating achieved by MAIC depends on the degree of “fluidization” of the host/guest particle system caused by the motion of the magnetic particles. To better understand the factors influencing this fluidizing behavior, several critical system and operating parameters were investigated. This was done using a model system consisting of PMMA host particles and alumina guest particles. The system parameters examined were magnetic particle size, mass ratio of magnetic particles to powder (host and guest particles) and guest particle size. The operating parameters were processing time, current (or voltage) and frequency. In addition to varying these parameters, enhanced image processing was used to measure the motion of the magnetic particles in order to study its effect on coating efficiency. The magnetic particles were observed to have both rotational and translational motion.

Image processing for on-line monitoring of granule size distribution and shape in fluidized bed granulation

Abstract A particle image probe comprising a CCD camera and an image processing system has been developed for on-line monitoring of granule size distribution and shape in a fluidized bed granulation. Continuous granule measurements by the image probe were digitized and processed by the image processing system, and granule size distribution and shape were computed in real time. The developed system was applied to the monitoring of granule growth in pharmaceutical granulation and its validity was confirmed. Application of this system to the dynamic control of granule size and shape was also demonstrated.

Microgranulation of fine powders by a novel rotating fluidized bed granulator

A novel rotating fluidized bed system has been developed for fluidizing, granulating and coating cohesive fine powders to tailor their properties and functionalities. The system basically consists of a plenum chamber and a horizontal porous cylindrical air distributor, which rotates around its axis of symmetry inside the chamber. The pressure drop and minimum fluidization velocity of cohesive fine cornstarch powder (mass median diameter of 15 μm, Geldart Group C powder) were measured under various rotating conditions and the fluidization behavior was studied. The system was then used for wet granulation of the cornstarch powder and the effects of operating parameters on the granule properties such as granule size, size distribution, density and flowability were investigated. The experimental results indicated that the flowability of cohesive fine cornstarch was dramatically improved by the microgranulation resulting in spherical granules with a narrow size distribution while inhibiting the size enlargement.

Direct control of wet granulation processes by image processing system

Abstract Recent trend in granulation technology is toward an improvement of process efficiency, stability of product quality and labor-saving. With such improvements and recent temporary increases in demand for granulation technologies, there is a great need for a reliable tool for the process monitoring and control. This paper presents new technologies for measurement and control of granule growth in wet granulation processes. Advanced technologies of image processing realize direct and continuous control of wet granulation processes. This contribution may assist readers who wish to stabilize the product quality and to establish the automated operation system of wet granulation processes.

A fuzzy control system of high shear granulation using image processing

Abstract A novel system has been developed to control granule growth in a high shear (speed) granulation. The system basically consisted of an image processing and a fuzzy control system. An image probe composed of a CCD camera, air purge unit and high energy xenon (Xe) lightning system was also developed to continuously take granule images through the sidewall of the vessel. The images were digitized by the image processing system and granule median diameter and shape factor were calculated automatically. Median diameter and shape factor of granules sampled out during granulation were also calculated by manually, and then compared with the automatically computed ones. Close agreement between both measurements was obtained, showing the developed system could continuously monitor granule growth during high shear granulation. A fuzzy control system using a linguistic algorithm employing if-then rules with a process lag element taken into consideration was developed to control granule growth accurately without any excessive growth (overshoot). This newly developed system was applied to actual high shear granulation of pharmaceutical powders and validity of the system was investigated. It was found that the system could control granule growth with high accuracy, regardless of changes in operating conditions.

Simple and Rapid Synthesis of Magnetite/Hydroxyapatite Composites for Hyperthermia Treatments via a Mechanochemical Route

This paper presents a simple method for the rapid synthesis of magnetite/hydroxyapatite composite particles. In this method, superparamagnetic magnetite nanoparticles are first synthesized by coprecipitation using ferrous chloride and ferric chloride. Immediately following the synthesis, carbonate-substituted (B-type) hydroxyapatite particles are mechanochemically synthesized by wet milling dicalcium phosphate dihydrate and calcium carbonate in a dispersed suspension of magnetite nanoparticles, during which the magnetite nanoparticles are incorporated into the hydroxyapatite matrix. We observed that the resultant magnetite/hydroxyapatite composites possessed a homogeneous dispersion of magnetite nanoparticles, characterized by an absence of large aggregates. When this material was subjected to an alternating magnetic field, the heat generated increased with increasing magnetite concentration. For a magnetite concentration of 30 mass%, a temperature increase greater than 20 K was achieved in less than 50 s. These results suggest that our composites exhibit good hyperthermia properties and are promising candidates for hyperthermia treatments.

Numerical simulation of electrostatic charge in powder pneumatic conveying process

This paper describes a mechanism of electrification of particles in a pneumatic conveying process by both numerical and experimental approaches. A two-dimensional discrete element method (DEM) is used to analyze the particle movement (collision velocity, number of collision, etc.) in a pneumatic conveying process under various operating conditions. By using a simplified model that assumes that the electrification of single particle is proportional to the vertical collision velocity and the number of particle collision against the pipe wall, electrification during the conveying process is numerically computed. The electrification of particles during pneumatic conveying process is practically measured and then compared with the simulated results to confirm the validity of the proposed model.

Feedback control in high shear granulation of pharmaceutical powders.

A novel system has been developed to control granule growth in high shear granulation. The system basically consisted of an image-processing device and a fuzzy control system. A computer-controlled image processor, an air purge unit, a high-energy xenon lighting system and an image probe with a CCD camera comprised the image processing device. A fuzzy control system using a linguistic algorithm employing if-then rules with a process lag element taken into consideration has been developed to accurately control granule growth without any excessive growth. This newly developed system was applied to actual high shear granulation of pharmaceutical powders and validity of the system was investigated. It was found that the system could control granule growth with high accuracy, regardless of changes in physical properties of starting materials and the operating conditions.

Application of a neural network to granulation scale-up

This paper describes a practical method for granulation scale-up by means of a neural network. Wet granulation was conducted using an agitation fluidized bed, and the scale-up characteristics were investigated using a neural network with back-propagation learning. Granule properties obtained by production-scale granulation under various operating conditions were predicted. Extremely good correlation was obtained between the predicted data and the experimental data of agitation fluidized bed granulation. It was found that granulation scale-up could be conducted with high accuracy by a neural network without constructing a mathematical model with a complicated non-linear relationship using a vast amount of experimental scale-up data.

Size control of magnetite nanoparticles by organic solvent-free chemical coprecipitation at room temperature

This study provides a facile single-step coprecipitation method for preparing size-controlled high crystalline magnetite nanoparticles in water system without using any organic solvents. In this method, an iron ions solution and an alkaline solution are simply mixed at room temperature without using any additional heating treatment. The size of obtained magnetite nanoparticles greatly depended on the coexisting anionic species in the starting solution because the coexisting anions greatly influenced both the formation of crystal nuclei and the dispersion stabilisation of formed precipitates. The size control of magnetite nanoparticles having high crystallinity and ferromagnetic property could be successfully achieved by using the effects of coexisting anions. For synthesising finer magnetite nanoparticles, the presence of lactate ion in the starting solution was effective, and coarser ones could be synthesised under higher ferrous/ferric ions molar ratios.