Rapid extraction of sediment contaminants by pressure cycles.

Sediment contamination is a significant issue. Assessment, management, and monitoring of contaminated sediment require routine analyses of a large volume of sediment samples, which require significant preparation time including extraction of contaminants from samples prior to analysis. This work tested a new method of extracting contaminants from sediment based on the use of rapid, successive pressurization cycles, which involve compression of a gas into the extractive solvent in contact with the sediment immediately followed by decompression via venting. The technique improved extraction amounts and shortened preparation time. Tested were PCB and PAH contaminated sediment samples from various locations of the US, including the Passaic River, St. Louis River, Waukegan Harbor, and Wells National Estuarine Research Reserve. The results were compared to those of Soxhlet extraction. Specifically, the extraction of 15 g of sediment with 50 mL of hexane-acetone (1:1) mixture at room temperature using 10 rapid, successive pressure cycles with N(2) attaining 1.0 MPa during compression was complete within 15 min. Using the new technique, consistently more PAHs and PCBs were extracted from the sediments in comparison to Soxhlet extraction. Extraction was evaluated according to key factors including the number of compression-decompression cycles, compression pressure, sample amount, moisture, and pressurizing gas type. The heightened extraction performance was explained by cyclic changes in gas solubility during repetitive compression and decompression steps, which introduce mechanisms to fragment sediment aggregates resulting in increased contaminant exposure and extraction.

Pressure-assisted ozonation of PCB and PAH contaminated sediments.

Sediment contamination by recalcitrant organics such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) is prevalent and of a great concern. Remediation efforts are hampered by the hydrophobic nature of the contaminants that limits their availability as well as by the sediment matrix that limits their exposure to treatment agents. Using contaminated sediment samples from the Passaic River, St. Louis River, Waukegan Harbor, and Wells National Estuarine Research Reserve, this research demonstrated a new ozonation technique that incorporates rapid, successive cycles of pressurization (690 kPa) and depressurization, enabling more effective treatment than conventional ozonation would. Conventional ozonation reached maximum 60% and 40% removal of PAHs from the Passaic River (40 mg kg(-1) initially) and St. Louis River sediment (520 mg kg(-1) initially), respectively, in 1h; however, removals ceased despite prolonged treatment for 2h. The pressure-assisted technique removed 96% of PAHs from both river sediments within 1h; it completely removed both PAHs (16 mg kg(-1) initially) and PCBs (5.1 mg kg(-1) initially) from the Waukegan Harbor sediment in 0.5 h. The heightened treatment is explained by soil aggregate fracturing upon pressure cycles that exposes the contaminants as well as by the confluence of hydrophobic contaminants and O(3) at the gas-liquid interface in the presence of microbubbles. The technique is expected to accelerate O(3) treatment of a wide range of organic contaminants, and it may provide treatment to dredged and stored contaminated sediment.

Adenovirus type 5 intrinsic adsorption rates measured by surface plasmon resonance.

Intrinsic adsorption rates of whole adenovirus type 5 (Ad5) onto a diethylaminoethyl (DEAE) anion exchange surface are measured for the first time by surface plasmon resonance (SPR). Fitting SPR sensorgrams to a two-compartment mass transport reaction model distinguishes intrinsic adsorption rates from slow diffusive Ad5 mass transport. Ad5 is a widely used viral vector for gene therapy that binds electrostatically to surfaces of cells and synthetics such as membranes, chromatographic resins, and glass. Increasing NaCl concentration from 4.8 to 14.4mM shifts binding of whole Ad5 from diffusion control to a regime where both sorption and diffusion affect binding. Intrinsic adsorption rates for Ad5-DEAE interaction are 16 times faster than intrinsic adsorption rates for Ad5 fiber knob interacting with soluble extracellular domain of coxsackievirus adenovirus receptors (s-CAR).