Improving the stability of coal slurries: Final report. [Polygalacturonic acid and gum tragacanth]
Polysaccharides were found to stabilize colloidal dispersions (such as coal particles and polystyrene latex particles) even at high ionic strengths. The stability studies with various kinds of polysaccharides showed that rod-like molecules (such as poly (galacturonic acid) and gum tragacanth) are much more effective stabilizers than highly-branched molecules such as arabinogalactan. This effective stabilization with the rod-like molecules was found to result from the adsorption of polysaccharides on the particles, i.e., the steric stabilization mechanism. The stability depends significantly on the solution pH, the molecular weight and the surface charge of particles. Adsorption isotherms, the zeta potential and the conformation of adsorbed molecules (the steric layer thicknesses) were measured as a function of the solution pH, the molecular weight and the surface charge. Photon correlation spectroscopy studies showed that the conformation of adsorbed molecules is strongly dependent on the solution pH, the molecular weight and the surface charge, suggesting that the dependence of stability on these parameters is due to the change of the conformation of the molecules adsorbed on the surface. In addition, the solution pH has a significant effect on the flocculation behavior of particles and can be modulated to bring about peptization of particles. This type of stabilization is referred to as electrosteric stabilization whereby steric stabilization is induced by changing the electrical properties of the system (the solution pH in this case). 41 refs., 43 figs., 10 tabs.
- Research Organization:
- Michigan Univ., Ann Arbor (USA). Dept. of Chemical Engineering
- DOE Contract Number:
- FG22-85PC80517
- OSTI ID:
- 6641388
- Report Number(s):
- DOE/PC/80517-T12; ON: DE89004644
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
Similar Records
Improving the stability of coal slurries: Quarterly progress report for the period December 15, 1986-March 15, 1987. [Adsorption of gum tragacanth on polystyrene latex spheres]
Improving the stability of coal slurries: Quarterly progress report for the period December 15, 1987-March 15, 1988
Related Subjects
36 MATERIALS SCIENCE
COAL
SURFACE PROPERTIES
FUEL SLURRIES
STABILIZATION
GALACTURONIC ACID
ADSORPTION
POLYSACCHARIDES
SOLUTIONS
PH VALUE
ADSORPTION ISOTHERMS
CHEMICAL COMPOSITION
CHEMICAL PROPERTIES
ELECTROPHORESIS
FLOCCULATION
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
PARTICLES
PROGRESS REPORT
VAN DER WAALS FORCES
WATER
ALDEHYDES
CARBOHYDRATES
CARBONACEOUS MATERIALS
CARBOXYLIC ACIDS
DISPERSIONS
DOCUMENT TYPES
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROGEN COMPOUNDS
HYDROXY ACIDS
ISOTHERMS
MATERIALS
MIXTURES
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PRECIPITATION
SACCHARIDES
SEPARATION PROCESSES
SLURRIES
SORPTION
SUSPENSIONS
010600* - Coal
Lignite
& Peat- Properties & Composition
360603 - Materials- Properties