Date of Award

8-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Environmental Engineering and Science

Advisor

Karanfil, Tanju

Committee Member

Schlautmann , Mark

Committee Member

Carraway , Elizabeth

Abstract

The main objective of this study was to conduct a systematic investigation of various approaches to mitigate the competition of dissolved organic matter (DOM) on the adsorption of synthetic organic contaminants (SOCs) by activated carbons. TCE and atrazine were selected as the target SOCs because they are known to adsorb in different pore size regions. TCE adsorbs in the primary micropore region (i.e., <10 ) which is inaccessible to the majority of the DOM components, while atrazine adsorbs in the secondary micropore region (i.e., 10-20 ) which is partially accessible to some DOM components. The adsorbents used in this study consisted of four activated carbons (OLC, CRC, F400He, and HD4000ST) and one activated carbon fiber (ACF: ACF10). All sorbents were basic and hydrophobic in nature and represented a set of activated carbons with gradually widening pore size distribution, from the extremely microporous carbons (ACF10 and OLC) to carbons with some amount of mesopores (CRC and F400He) and finally a predominantly mesoporous (HD4000ST) carbon.
Isotherms were performed as single solute and after preloading with a dissolved organic matter (5 mg DOC/L and 20 mg DOC/L) for both TCE and atrazine and using the five activated carbons. Single solute isotherm results showed that (i) the adsorbents with higher volume in pore sizes around the dimensions of the adsorbate molecule exhibited higher uptakes, probably due to the higher adsorption energies resulting from multiple contact points between the adsorbate molecule and the pore surface and (ii) BET surface area and total pore volume were not the primary factors controlling the adsorption. The preloading isotherm results indicated that for TCE, the SOC adsorbing primarily in pores <10 , highly microporous GACs (i.e., activated carbons having high volumes in pores <10  and minimal volumes in pores larger than 10 ) exhibited the least preloading effect and the best results for controlling DOM competition. For atrazine with optimum adsorption region in pores > than 10  (i.e., partly overlapping with that of background DOM components), activated carbons with broad pore size distribution (i.e., mesoporous) or high pore volume in the optimum adsorption pore size region of atrazine (i.e., 10-20 ) showed the lowest degree of DOM preloading effect. Finally, a limited number of kinetic experiments were also carried out in this study. The mesoporous carbons demonstrated faster adsorption as compared to the microporous carbons for both TCE and atrazine in the presence or absence of background DOM

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