Tammy P. Taylor

Surfactant enhanced recovery of tetrachloroethylene from a porous medium containing low permeability lenses 1. Experimental studies

A matrix of batch, column and two-dimensional (2-D) box experiments was conducted to investigate the coupled effects of rate-limited solubilization and layering on the entrapment and subsequent recovery of a representative dense NAPL, tetrachloroethylene (PCE), during surfactant flushing. Batch experiments were performed to determine the equilibrium solubilization capacity of the surfactant, polyoxyethylene (20) sorbitan monooleate (Tween 80), and to measure fluid viscosity, density and interfacial tension. Results of one-dimensional column studies indicated that micellar solubilization of residual PCE was rate-limited at Darcy velocities ranging from 0.8 to 8.2 cm/h and during periods of flow interruption. Effluent concentration data were used to develop effective mass transfer coefficient (Ke) expressions that were dependent upon the Darcy velocity and duration of flow interruption. To simulate subsurface heterogeneity, 2-D boxes were packed with layers of F-70 Ottawa sand and Wurtsmith aquifer material within 20-30 mesh Ottawa sand. A 4% Tween 80 solution was then flushed through PCE-contaminated boxes at several flow velocities, with periods of flow interruption. Effluent concentration data and visual observations indicated that both rate-limited solubilization and pooling of PCE above the fine layers reduced PCE recovery to levels below those anticipated from batch and column measurements. These experimental results demonstrate the potential impact of both mass transfer limitations and subsurface layering on the recovery of PCE during surfactant enhanced aquifer remediation.

Beryllium in the Environment: A Review

Abstract Beryllium is an important industrial metal because of its unusual material properties: it is lighter than aluminum and six times stronger than steel. Often alloyed with other metals such as copper, beryllium is a key component of materials used in the aerospace and electronics industries. Beryllium has a small neutron cross-section, which makes it useful in the production of nuclear weapons and in sealed neutron sources. Unfortunately, beryllium is one of the most toxic elements in the periodic table. It is responsible for the often-fatal lung disease, Chronic Beryllium Disease (CBD) or berylliosis, and is listed as a Class A EPA carcinogen. Coal-fired power plants, industrial manufacturing and nuclear weapons production and disposal operations have released beryllium to the environment. This contamination has the potential to expose workers and the public to beryllium. Despite the increasing use of beryllium in industry, there is surprisingly little published information about beryllium fate and transport in the environment. This information is crucial for the development of strategies that limit worker and public exposure. This review summarizes the current understanding of beryllium health hazards, current regulatory mandates, environmental chemistry, geochemistry and environmental contamination.

Surfactant enhanced recovery of tetrachloroethylene from a porous medium containing low permeability lenses. 2. Numerical simulation.

A numerical model of surfactant enhanced solubilization was developed and applied to the simulation of nonaqueous phase liquid recovery in two-dimensional heterogeneous laboratory sand tank systems. Model parameters were derived from independent, small-scale, batch and column experiments. These parameters included viscosity, density, solubilization capacity, surfactant sorption, interfacial tension, permeability, capillary retention functions, and interphase mass transfer correlations. Model predictive capability was assessed for the evaluation of the micellar solubilization of tetrachloroethylene (PCE) in the two-dimensional systems. Predicted effluent concentrations and mass recovery agreed reasonably well with measured values. Accurate prediction of enhanced solubilization behavior in the sand tanks was found to require the incorporation of pore-scale, system-dependent, interphase mass transfer limitations, including an explicit representation of specific interfacial contact area. Predicted effluent concentrations and mass recovery were also found to depend strongly upon the initial NAPL entrapment configuration. Numerical results collectively indicate that enhanced solubilization processes in heterogeneous, laboratory sand tank systems can be successfully simulated using independently measured soil parameters and column-measured mass transfer coefficients, provided that permeability and NAPL distributions are accurately known. This implies that the accuracy of model predictions at the field scale will be constrained by our ability to quantify soil heterogeneity and NAPL distribution.

Effects of ethanol addition on micellar solubilization and plume migration during surfactant enhanced recovery of tetrachloroethene

Alcohol addition has been suggested for use in combination with surfactant flushing to enhance solubilization kinetics and permit density control of dense non-aqueous phase liquid (DNAPL)-laden surfactant plumes. This study examined the effects of adding ethanol (EtOH) to a 4% Tween 80 (polyoxyethylene (20) sorbitan monooleate) solution used to flush tetrachloroethene (PCE)-contaminated porous media. The influence of EtOH concentration, subsurface layering and scale on flushing solution delivery and PCE recovery was investigated through a combination of experimental and mathematical modeling studies. Results of batch experiments demonstrated that the addition of 2.5%, 5% and 10% (wt.) EtOH incrementally increased the PCE solubilization capacity and viscosity of the surfactant solution, while reducing solution density from 1.002 to 0.986 g/cm3. Effluent concentration data obtained from one-dimensional (1-D) column experiments were used to characterize rate-limited micellar solubilization of residual PCE, which was strongly dependent upon flow velocity and weakly dependent upon EtOH concentration. Two-dimensional (2-D) box studies illustrated that minor differences (0.008 g/cm3) between flushing and resident solution density can strongly influence surfactant front propagation. A two-dimensional multiphase simulator, MISER, was used to model the influence of EtOH composition on the aqueous flow field and PCE mass recovery. The ability of the numerical simulator to predict effluent concentrations and front propagation was demonstrated for both 1-D columns and 2-D boxes flushed with EtOH-amended Tween 80 solutions. Results of this study quantify the potential influence of alcohol addition on surfactant solution properties and solubilization capacity, and demonstrate the importance of considering small density variations in remedial design.

Treatability Study of Reactive Materials to Remediate Groundwater Contaminated with Radionuclides, Metals, and Nitrates in a Four-Component Permeable Reactive Barrier

Publisher Summary This chapter presents a treatability study of a shallow multicontaminant plume of 239,240Pu, 241Am, 90Sr, nitrate, and perchlorate in Mortandad Canyon, Los Alamos, New Mexico, by using a multiple permeable reactive barrier consisting of four sequential layers. These layers include a polyelectrolyte-impregnated porous gravel for flocculating colloids, an Apatite II layer for plutonium, americium, and strontium immobilization, a layer of pecan shells as a biobarrier to nitrate and perchlorate; and a limestone gravel layer for any anionic species that may slip through the other layers, especially those of americium-carbonate. The pecan shells sorb strontium very well and the Apatite II remediates nitrate and perchlorate very well. Nitrate, perchlorate, plutonium. americium, and 90Sr concentrations are reduced to below their maximum concentration limits (MCL) and usually to below detection limits in laboratory studies. The materials for this particular multiple barrier are inexpensive and readily available, and thus a large amount can be used to ensure conservative performance. If the barrier performs as well as desired in the field, the total expected inventory of radionuclides in the shallow aquifer is low enough that complete removal by huge of barrier material does not result in activities high enough for the barrier to become a hazardous or radioactive waste. The nitrate and perchlorate are reduced to harmless components and does not cause the barrier to become a hazardous waste.

Beryllium colorimetric detection for high speed monitoring of laboratory environments

The health consequences of beryllium (Be2+) exposure can be severe. Beryllium is responsible for a debilitating and potentially fatal lung disease, chronic beryllium disease (CBD) resulting from inhalation of beryllium particles. The US Code of Federal Register (CFR), 10 CFR 850, has established a limit of 0.2 microg beryllium/100 cm(2) as the maximum amount of beryllium allowable on surfaces to be released from beryllium work areas in Department of Energy (DOE) facilities. The analytical technique described herein reduces the time and cost of detecting beryllium on laboratory working surfaces substantially. The technique provides a positive colorimetric response to the presence of beryllium on a 30.5 cm x 30.5 cm (1 ft(2)) surface at a minimum detection of 0.2 microg/100 cm(2). The method has been validated to provide positive results for beryllium in the presence of excess iron, calcium, magnesium, copper, nickel, chromium and lead at concentrations 100 times that of beryllium and aluminum and uranium (UO2(2+)) at lesser concentrations. The colorimetric detection technique has also been validated to effectively detect solid forms of beryllium including Be(OH)2, BeCl2, BeSO4, beryllium metal and BeO.

Beryllium Binding by Functionalized Polyethylenimine Water-Soluble Polymers

A series of polyethylenimine (PEI)-based water-soluble polymers (WSPs) were prepared by attaching functional groups (beta-diketones, carboxylic acid, salicylic acids) to the polymer backbone, with the goal of characterizing the interaction between beryllium and the various polymers. The extraction of beryllium from aqueous solutions by the WSPs was examined as a function of pH and ionic strength to evaluate the potential for the WSPs to isolate beryllium from contaminated aqueous waste streams. The loading capacities of these polymers for beryllium at near-neutral pH were unusually high in the absence of ionic strength adjustment compared to that for other +2 cations, suggesting that polynuclear beryllium species were interacting with the polymers. Beryllium loading capacity values were similar for all polymers evaluated in the absence of ionic strength adjustment. However, when the ionic strength of the solutions was adjusted to 0.1 N (NaNO3) the loading capacities were significantly reduced, indicating that electrostatic attraction played a dominant role in the interaction between beryllium and the polymers. The extraction curves of beryllium for all polymers evaluated, even those not designed to be selective for beryllium extraction, were nearly identical irrespective of the nature of the functional groups. Collectively, these results suggest that oligomeric beryllium species were formed, which can bind to the polymers through a combination of electrostatic forces and, potentially, hydrogen bonding.

The Effects of Global Coal Fires

This chapter describes the origin of coal fires and related gases, discussing some of the world’s most problematic coal fires and associated environmental hazards. It also considers techniques used to combat these fires. Environmentally catastrophic effects from coal fires include the emission of noxious gases and particulate matter into the atmosphere and condensation products responsible for stream and soil pollution. Coal fires have killed people, have forced entire communities to abandon their homes and businesses, have destroyed floral and faunal habitats, and are responsible for perilous land subsidence. Mine-related activities, improperly controlled man-made fires, and spontaneous combustion in adjacent materials ignite most coal mine-related fires. It is also caused by forced ignition from sources that include lightning and brush and forest fires. Regardless of origin, coal fires consume a valuable natural resource and constitute a thermodynamic recipe for environmental catastrophe. Fires in China, Pennsylvania, and India exemplify this. Industrial smokestacks and motorized vehicles are usually cited in the news as the primary sources of pollution including acid rain and greenhouse gases. The enormous amount of toxic gases and particulate matter emitted by coal fires burning around the world over many years contributes significantly to the global destruction of the environment and the health of its inhabitants.

An ultra high throughput, double combinatorial screening method of peptide-metal binding

An effective ultra-high throughput, double combinatorial method of screening potential selective ligands based upon oligopeptides is described. This rapid screening of bead-based libraries by Micro X-ray Fluorescence (MXRF) was used to identify selective chelating agents for metals that may be found in radioactive dispersive devices (RDDs). The method has proven to be a powerful tool to rapidly and quantitatively screen metal–ligand interactions. It is a tag-free, sensitive technique, which in a combinatorial approach with peptide libraries (e.g. varying charge, length, hydrophobicity, ligand elements etc.), provides a rapid and quantitative means for identifying metal–ligand interactions.

A high throughput screening method for the selection of zeolites for binding cations

An effective high throughput screening technique is described for the rapid analysis of zeolites as binding agents for cationic sequestration.