Production of biopowder from alginate: Experimental design and particle sizing

Lim, Tek Kaun (2011) Production of biopowder from alginate: Experimental design and particle sizing. Masters thesis, Universiti Malaysia Sabah.


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Alginate is extracted from brown seaweed and commonly used as biopolymer due to its biocompatibility, abundance in source, and low prices. There are various existing methods to produce alginate hydrogel particles, yet none of the methods are able to produce particles over a wide range of mean size, from 50 to 2300 IJm. This work attempted to use an air-atomization method at low air-to-liquid flow rate ratio (m air/m liq) that could allow the production of wide range of particle mean size. The first part of this study investigated the effect of process conditions on the size, size distribution and shape of alginate particles. It was found the liquid mass flow rate must not be more than 1100 times the air mass flow rate for atomization to take place. The (m air/m liq) ratio was found to have a significant influence on particle size with a critical value 0.25. An increase in Weber number decreased the particle size and increased the coefficient of variance whereas average sphericity factor was found to decrease with an increase in the Weber number. The subsequent work involved drying of the wet particles by oven and freeze drying to form dry powder. The effect of drying parameters on the drying kinetics, the kinetic parameters and the particle properties were studied. In oven drying, the drying temperature, intermittent mixing and sample thickness were found to affect the drying kinetics whereas the particle size (i.e 110 µm and 1360 µm) did not show a significant effect on the drying kinetics. The developed moisture ratio prediction model for alginate particles drying was shown to follow logarithmic model. Effective moisture diffusivity value for alginate particles was ranged from 8.0 x 10-11 to 5.4 X 10-10 m2/s while the activation energy for alginate particles was 17.05 kJ/mol. The smaller particles before drying (i.e 110 µm) showed an increase in size due to agglomeration phenomenon after oven-drying but the larger particles (i.e 1360 µm) showed a reduction in particle size. Freeze-drying resulted in a reduction in particle size regardless of particle size before drying. In conclusion, a method using atomization at low air-to-liquid flow rate ratio to produce hydrogel particles in a wide range of mean size has been verified and the properties of the particles before and after drying were characterized.

Item Type: Thesis (Masters)
Uncontrolled Keywords: biopowder, alginate, brown seaweed, biopolymer, particle sizing, hydrogel particle, atomization, low air-to-liquid flow rate ratio
Subjects: T Technology > TP Chemical technology
Divisions: SCHOOL > School of Engineering and Information Technology
Date Deposited: 09 Jul 2013 03:40
Last Modified: 11 Oct 2017 06:58

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