Date of Award

5-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Environmental Engineering and Science

Advisor

Karanfil, Tanju

Committee Member

Ladner , David

Committee Member

Lee , Cidy

Abstract

In literature, manufacturer-supplied powdered activated carbon has been ground to produce submicron particles with mean diameter lower than 1µm for use as an adsorbent during water treatment. Superfine powdered activated carbon (SPAC) can be used for removal of natural organic matter as well as synthetic organic chemicals (SOCs) from water. It has been suggested that SPAC has higher adsorption capacity than powdered activated carbon (PAC) due to larger external surface area and mesopore volume. Another advantage of SPAC over PAC is the faster uptake rate for both NOM and SOC during adsorption owing to small particle size. Therefore, understanding SPAC adsorption capacity and kinetics on NOM and SOC is crucial for future studies and usage of it. The main objectives of this study were to: (i) understand the impact of crushing on carbon characteristics; (ii) investigate the SPAC adsorption capacity and rate for selected SOCs in distilled and deionized water (DDW) and natural waters from Myrtle Beach, South Carolina, and compare with PAC adsorption; (iii) evaluate adsorption mechanism of four SOCs, phenanthrene (PNT), atrazine (ATZ) , carbamazepine (CMZ) and 2-phenylphenol (2PP), with different properties planarity, polarity, and hydrogen/electron donor/acceptor ability on SPAC and PAC. One commercial PAC and its SPAC form created using a special mill were used in the study. Isotherm and kinetic experiments were performed in five different waters: DDW, diluted Edisto raw river (DOC=4mg/L), diluted Myrtle Beach raw waters (DOC=4mg/L and 10 mg/L) and Myrtle Beach treated (after conventional treatment) water (DOC=4 mg/L). One week and six hours contact times were used for the isotherm and kinetic experiments. First, the role of carbon characteristics on the adsorption was examined. The characterization of SPAC and PAC samples showed that the crushing process caused some changes in the pore volume distribution and surface acidity of the activated carbon. After pulverization, the pore volume distribution was mainly formed by mesopore and macropore region rather than micropore region. Carbon blending caused an increase of iron, nitrogen and oxygen content. The oxidation of surfaces and pHPZC values were decreased. Then, the SPAC and PAC adsorption capacity and rate for selected SOCs in distilled and deionized water (DDW) and natural waters from Myrtle Beach were investigated. The isotherm results showed that all PAC adsorption capacities were higher than SPAC. However for adsorption kinetics, SPAC exhibited faster uptakes for PNT, ATZ and CMZ in all background solution than PAC did. On the other hand, SPAC was not advantageous for 2PP compared to PAC in both DDW and natural waters. That may result from multiple factors: (i) higher solubility of 2 PP, (ii) the larger third dimension as compared to other molecules, and (iii) the presence of an electron donating (-OH) group on its structure, which makes the molecule slightly negative charge and cause the deduction in interaction with SPAC whose surface is slightly higher negatively charged. The presence of NOM had a small impact on the adsorption rates of four SOCs by SPAC during the first six hours contact time. The difference in the NOM characteristics (MB raw SUVA254=4.4 and MB treated SUVA254=2.1, Edisto SUVA254=2) and NOM concentrations (4 mg/L vs. 10 mg/L) did not significantly impact the adsorption rates. The only exception was observed for atrazine. In summary, these findings indicated that the advantage of using SPAC over PAC at the short contact time can be compound specific; on the other hand, SPAC loses its advantages for small molecular weight compounds at equilibrium conditions

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