Molecular weight determinations of biosolubilized coals

Conference · Wed May 01 04:00:00 EDT 1991

OSTI ID:5747677

Linehan, J C; Clauss, S; Bean, R; Campbell, J

We have compared several different methods for determining the molecular weight of biosolubilized coals: Aqueous gel permeation Chromatography (GPC), organic GPC, preparative GPC, dynamic laser light scattering (LLS), static LLS, static LLS, mass spectrometry, vapor phase osmometry (VPO) and ultrafiltration. We have found that careful consideration must be given to the molecular weight result obtained from each method. The average molecular weight and the molecular weight distribution were found to be dependent upon many factors, including the technique used; molecular weight standards, pH, and the percentage of sample analyzed. Weight average molecular weights, M{sub w}, obtained for biosolubilized leonardite range from 800,000 daltons for neutral pH aqueous GPC based on polyethylene glycol molecular weight standards to 570 daltons for pH 11.5 buffered aqueous GPC based on a fulvic acid standard. It is clear that the state of association of the biocoal analyte, as well as the interactions of sample with the separation matrix, can have large influence of the observed result, and these must be understood before reliable GPC measurements can be made. Furthermore, a uniform set of molecular weight standards for biodegraded coals is needed. 10 refs., 1 tab.

• Research Organization: Pacific Northwest Lab., Richland, WA (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 5747677
• Report Number(s): PNL-SA-19427; CONF-910528--1; ON: DE91012921
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010405* -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
550700 -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
BIOCONVERSION
CARBONACEOUS MATERIALS
CHROMATOGRAPHY
COAL
COMPARATIVE EVALUATIONS
ENERGY SOURCES
FILTRATION
FOSSIL FUELS
FUELS
MASS SPECTROMETERS
MATERIALS
MEASURING INSTRUMENTS
MOLECULAR WEIGHT
SEPARATION PROCESSES
SPECTROMETERS
ULTRAFILTRATION