The extraction of pentachlorophenol (PCP) from pressure treated wood
wafers with supercritical carbon dioxide has been studied. Experimental data
were obtained for the effects of pressure (17.5 - 25.0 MPa), temperature (313 - 353
K), flow rate (1 - 3 ml/min at supercritical conditions), and sample size (0.8 x 10
x 50 mm and 2.2 x 10 x 50 mm) by measuring the effluent concentration versus
time. A fundamental model was developed which includes rates of intraparticle
diffusion, external film mass transfer, desorption and the initial distribution of
PCP between the pore volume (cell lumen) and pore surface (cell wall) of wood
wafers. The intraparticle diffusion and external mass transfer rates are combined
in terms of an overall mass transfer coefficient derived from the assumption of
a parabolic concentration profile of PCP inside the wafer pores. The initial
distribution of PCP between cell lumen and cell wall was determined by fitting
the mathematical model to dynamic extraction rate data. The desorption rate
was very small for all the extraction conditions, and extraction rate increased with
the pressure, temperature, and flow rate because the combined mass transfer
increased. Similar values of mass transfer coefficient were achieved for two
different sample sizes: 0.8 x 10 x 50 mm and 2.2 x 10 x 50 mm. / Graduation date: 1994
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37192 |
| Date | 30 November 1993 |
| Creators | Yi, Jung-Seok |
| Contributors | Levien, Keith L. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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