The goal of this thesis was to develop a process of producing small monodisperse
alginate gel beads. The phenomenon of controlled jet break-up of alginate solution jet
with assisted vibration was used to form uniform sodium alginate droplets which were
subsequently crosslinked with divalent calcium ion to form gel beads. Producing uniform
alginate beads below 500 microns has been a problem which previous researchers have
faced. Also, there is no commercially viable system available which can produce
microbeads of uniform size. This study was an attempt to solve some of these problems.
Vibration was applied to the alginate solution jet in both axial and transverse
direction to cause jet break-up. Also, different modes of transmitting the vibration to the
jet, like vibrating the full assembly or vibrating a diaphragm, were investigated. This
resulted in construction of different types of bead generator apparatus. The droplet
formation involves the formation of a jet through an orifice and superposition of vibration
in order to control the break-up the jet. Both of these fluid flow phenomena depend on the
properties of the liquid used to form the droplets. Specifically, the viscoelastic properties
of the liquid play a major role in determining the break-up dynamics of the jet. The
rheology of the Keltone LV (alginate) solutions (1-2% w/v) was studied using a rotational
Bohlin CS-50 Rheometer and a Clark High Shear Capillary Viscometer.
The best results were obtained by using the axial vibrating diaphragm droplet
generator. Good monodispersed beads (160-1000 microns) were produced by using two
different size orifices 100 micron and 200 microns. The vibration frequency range used
was 200-6000 Hz and the flowrate range was 2-7 ml/min. The alginate droplets were crosslinked in 0.1 M calcium chloride and the shrinkage of the alginate droplets due to gelation was studied over a period of 7 days. Based on our study a design for producing sub-100 micron size beads has been proposed which uses a piezoceramic crystal for producing high frequency vibrations. / Graduation date: 1997
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34523 |
| Date | 04 October 1996 |
| Creators | Gill, Hardeepak (Happy) Singh |
| Contributors | Rochefort, Willie E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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