• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 27
  • 17
  • 8
  • 7
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 67
  • 15
  • 14
  • 12
  • 12
  • 9
  • 8
  • 8
  • 7
  • 7
  • 6
  • 6
  • 5
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Fate and biotransformation of PCP in anaerobic fluidized-bed reactors and anaerobic digesters /

Magar, Victor S. January 1996 (has links)
Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [310]-318).
2

The bioremediation of contaminated soils with mushroom compost

Duncombe, Tracey Elizabeth January 1999 (has links)
No description available.
3

A Novel Microextraction Method for Determining the Presence of Pentachlorophenol in an Ongoing In-Situ Groundwater Remediation

Stratton, Julianna Nicole 12 August 2016 (has links)
Pentachlorophenol (penta) is a pollutant of concern worldwide. This study looks at a site that has been under remediation for the last 16 years due to penta contamination. The site has been air- and bio-sparged, phytoremediated and undergone in-situ chemical oxidation treatment in attempts to clean the ground water of penta. This thesis explores a novel microextraction method that has the promise of being more sensitive using less sample and fewer hazardous chemicals than conventional methods. Groundwater samples were extracted for phenolic compounds using a novel modified liquid microextraction protocol. Comparing our results with monitoring information from 2014, our method determined that penta is limited to a single monitoring well. However, our report was unable to determine exact quantitative results of penta concentration, due to loss of extraction solvent during the retrieval process.
4

Integrated treatment of pentachlorophenol by adsorption using magnetite-immobilized chitin and photocatalytic oxidation. / CUHK electronic theses & dissertations collection

January 2007 (has links)
Chitin is known as an effective biosorbent, which is used to preconcentrate PCP for further treatment. In order to reuse and recover the biosorbent, magnetic separation is a cost-effective alternative to separate the PCP-adsorbed biosorbent (i.e. chitin) from the treated water. Therefore, chitin is immobilized by magnetite prior PCP adsorption. From the immobilization results, the solution pH, temperature, agitation rate do not show great effect on the immobilization of chitin and magnetite. Second, magnetite-immobilized chitin can be formed as quickly as 5 min. Moreover, the interaction of chitin and magnetite is very strong since it is not easy to separate by vigorous shaking, high temperature and changing pH. Although the underlying mechanism of magnetite and chitin is still obscure, the biosorbent is proved to have high stability and reusability. In addition, both Langmuir and Freundlich models indicate that immobilization of chitin by magnetite is favorable with the Langmuir model being the major one. / For PCP adsorption study, it is found that magnetite-immobilized chitin can retain the PCP adsorption ability as free chitin. In accordance with the results, the PCP adsorption of magnetite-immobilized chitin is influenced by altering the parameters of biosorbent concentration, solution pH, temperature, agitation rate, contact time and initial PCP concentration. In general, higher amount of biosorbent gives higher removal efficiency (RE) but lower removal capacity (RC) as more binding sites are available for PCP. The PCP removal is enhanced by lowering pH since uncharged PCP is favorable for adsorption. It is speculated that hydrophobic interaction, hydrogen bonding and electrostatic interaction are involved. In addition, the biosorption efficiency is impeded by high temperature. Evidence shows that the adsorption might be due to the exothermic force such as hydrogen bonding. The biosorption is described as biphasic mechanism with the fast initial phase followed by slow equilibrium phase. For the PCP (10 mg/L) adsorption, the optimized conditions are: 1,500 mg/L of magnetite-immobilized chitin, initial pH 6, 25°C, 200 rpm and 60 min. The RE is 57.9% and RC is 5.4 mg/g. However, the increase in the amount of immobilized chitin (24,000 mg/L) can increase the RE up to 98%. By considering the Langmuir and Freundlich isotherms, the adsorption might be heterogenous, as the correlation coefficient from Freundlich model is higher. / Pentachlorophenol (PCP), a highly chlorinated aromatic organic compound, was widely used as a biocide and is now restrictly used as a wood preservative. PCP is toxic and ubiquitous environmental pollutant. In the present study, integrated treatment of biosorption and photocatalytic oxidation (PCO) using magnetite-immobilized chitin is employed to completely degrade PCP. / To thoroughly remove PCP, PCO is also employed after the biosorption. One hundred % of PCP removal is achieved after 5 h irradiation time, in 100 mL solution at initial pH 9 with 20 mM of H2O2 and 200 mg/L of TiO2. The intermediates of PCP are identified as 2,3,5,6-tetrachlorohydroquinone (TeHQ) and 2,3,5,6-tetrachlorophenol (TeCP) by GC/MS analysis. In addition, the toxicity of sample is monitored by the solid-phase and aqueous-phase Microtox RTM tests, which the toxicity increases and then decreases along the irradiation time. The biosorbent shows no great changes on chitin content and functional groups after PCO. In addition, the results imply that magnetite-immobilized chitin has a good potential to be reused at least for four cycles with high RE and DE. Therefore, the combination of biosorption and PCO treatment was feasible for PCP removal and the system is economic and convenient for repeated use. / by Pang, King Man. / "Oct 2007." / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4636. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 186-212). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
5

Bioremediation of low-permeability, pentachlorophenol-contaminated soil by laboratory and full-scale processes

Havighorst, Mark B. 30 January 1998 (has links)
Ex-situ bioremediation of saturated soil contaminated with pentachlorophenol and 2,3,5,6-TeCP is commonly accomplished by landfarming or by treatment in a bioreactor. Treating saturated, low-permeability soils in bioreactors, without pre-treatment requires a reactor capable of promoting anaerobic and/or aerobic removal of chlorophenols without transferring these contaminants to the aqueous phase. A pilot-scale bioreactor was designed to treat 3.7 cubic meters of contaminated soil with a saturated hydraulic conductivity of 0.12 cm/day. The bioreactor demonstrated significant removal of chlorophenols when soil was infused with a treatment mixture containing imitation vanilla flavoring as an electron donor for reductive dechlorination and primary substrate for aerobic cometabolism. Bench scale studies showed greater overall removal when feed mixtures included an inoculated biomass, or when treatment mixtures were maintained anaerobically prior to use. The combined results of these studies suggest that concentrations of pentachlorophenol and 2,3,5,6-TeCP in soil can be significantly reduced using fill and draw batch reactors, operated for three to five week long cycles, using a variety of treatment mixtures. / Graduation date: 1998
6

The effect of environmental conditions on the reductive dechlorination of pentachlorophenol by a mixed, methanogenic culture

Stuart, Sheryl L. 28 October 1996 (has links)
Graduation date: 1997
7

The extraction of pentachlorophenol from pressure treated wood using supercritical carbon dioxide

Yi, Jung-Seok 30 November 1993 (has links)
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
8

The influence of depth of immersion on end penetration in Douglas fir heartwood when cold-soaked in pentachlorophenol /

Raphael, Harold James. January 1949 (has links)
Thesis (M.S.)--Oregon State College, 1950. / Typescript. Mounted photographs. Includes bibliographical references (leaves 49-52). Also available on the World Wide Web.
9

Toxicity of pentachlorophenol to trout alevins /

Chapman, Gary Adair. January 1969 (has links)
Thesis (Ph. D.)--Oregon State University, 1969. / Typescript. Includes bibliographical references (leaves 82-87). Also available on the World Wide Web.
10

Sorption of pentachlorophenol to humic acids and subsequent effects on biodegradation and solvent extraction /

Crane, Cynthia E., January 1992 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 77-80). Also available via the Internet.

Page generated in 0.0647 seconds