Chris Griggs

Relationship of surface changes to metal leaching from tungsten composite shot exposed to three different soil types

Physical changes that occur on the surface of fired shots due to firing and impact with soil may increase the dissolution of muniton metals. Increased metal dissolution could potentially increase metal transport and leaching, affecting metal concentrations in surface and groundwater. This research describes the relationship between the surface changes on fired tungsten-nickel-iron (94% W:2% Ni:4% Fe) composite shots and metals leaching from those shots. Tungsten composite shot was fired into, and aged in, three soil types (Silty Sand, Sandy Clay, and Silt) in mesoscale rainfall lysimeters to simulate live-fire conditions and subsequent interactions between the metals of the composite and soil. Leachate, runoff, and soil samples were collected from the lysimeters and analyzed for metal content. The shots were analyzed using scanning electron microscopy (SEM) to evaluate surface changes. SEM results indicated that a soils particle size distribution initially affected the amount of metal that was sheared from the surface of the fired W-composite shots. Shearing was greatest in soils with larger soil particles (sand and gravel); shearing was least in soils composed of small soil particles (fines). Increased metallic shearing from the shots surface was associated with increased W dissolution, compared to controls, following a simulated 1 year soil aging.

Evaluation of the Destruction of the Harmful Cyanobacteria, Microcystis aeruginosa, with a Cavitation and Superoxide Generating Water Treatment Reactor

Cyanobacterial/Harmful Algal Blooms are a major issue for lakes and reservoirs throughout the U.S.A. An effective destructive technology could be useful to protect sensitive areas, such as areas near water intakes. The study presented in this article explored the use of a reactor called the KRIA Water Treatment System. The reactor focuses on the injection of superoxide (O2−), which is generated electrochemically from the atmosphere, into the water body. In addition, the injection process generates a significant amount of cavitation. The treatment process was tested in 190-L reactors spiked with water from cyanobacterial contaminated lakes. The treatment was very effective at destroying the predominant species of cyanobacteria, Microcystis aeruginosa, organic matter, and decreasing chlorophyll concentration. Microcystin toxin concentrations were also reduced. Data suggest that cavitation alone was an effective treatment, but the addition of superoxide improved performance, particularly regarding removal of cyanobacteria and reduction of microcystin concentration.

An integrated theoretical and experimental investigation of insensitive munition compounds adsorption on cellulose, cellulose triacetate, chitin and chitosan surfaces

This manuscript reports results of combined computational chemistry and batch adsorption investigation of insensitive munition compounds, 2,4-dinitroanisole (DNAN), triaminotrinitrobenzene (TATB), 1,1-diamino-2,2-dinitroethene (FOX-7) and nitroguanidine (NQ), and traditional munition compound 2,4,6-trinitrotoluene (TNT) on the surfaces of cellulose, cellulose triacetate, chitin and chitosan biopolymers. Cellulose, cellulose triacetate, chitin and chitosan were modeled as trimeric form of the linear chain of 4C1 chair conformation of β-d-glucopyranos, its triacetate form, β-N-acetylglucosamine and D-glucosamine, respectively, in the 1➔4 linkage. Geometries were optimized at the M062X functional level of the density functional theory (DFT) using the 6-31G(d,p) basis set in the gas phase and in the bulk water solution using the conductor-like polarizable continuum model (CPCM) approach. The nature of potential energy surfaces of the optimized geometries were ascertained through the harmonic vibrational frequency analysis. The basis set superposition error (BSSE) corrected interaction energies were obtained using the 6-311G(d,p) basis set at the same theoretical level. The computed BSSE in the gas phase was used to correct interaction energy in the bulk water solution. Computed and experimental results regarding the ability of considered surfaces in adsorbing the insensitive munitions compounds are discussed.

Scalable Chitosan-Graphene Oxide Membranes: The Effect of GO Size on Properties and Cross-Flow Filtration Performance

Chitosan (CS)-graphene oxide (GO) composite films were fabricated, characterized, and evaluated as pressure-driven water filtration membranes. GO particles were incorporated into a chitosan polymer solution to form a suspension that was cast as a membrane via evaporative phase inversion allowing for scale-up for cross-flow testing conditions. Morphology and composition results for nano and granular GO in the CS matrix indicate that the particle size of GO impacts the internal membrane morphology as well as the structural order and the chemical composition. Performance of the membranes was evaluated with cationic and anionic organic probe molecules and revealed charge-dependent mechanisms of dye removal. The CSGO membranes had rejections of at least 95% for cationic methylene blue with mass balances obtained from measurements of the feed, concentrate, and permeate. This result suggests the dominant mechanism of removal is physical rejection for both GO particle sizes. For anionic methyl orange, the results indicate sorption as the dominant mechanism of removal, and performance is dependent on both GO particle size and time, with micrometer-scale GO removing 68–99% and nanometer-scale GO showing modest removal of 29–64%. The pure water flux for CSGO composite membranes ranged from 2–4.5 L/m2 h at a transmembrane pressure of 344 kPa (3.44 bar), with pure water permeance ranging from 5.8 × 10–3 to 0.01 L/m2 h kPa (0.58–1.3 L/m2 h bar). Based on the 41 μm membrane thickness obtained from microscopy, the hydraulic permeability ranged from 0.24–0.54 L μm/m2 h kPa (24.4–54.1 L μm/m2 h bar).

Uptake of Cesium (Cs+) by Building Materials in Aqueous Batch Systems

Cesium-137 (C137) is a radioactive source that could be utilized in the construction of a radioactive dispersal device (RDD). The objective of this study was to examine the uptake of Cs+ by common structural materials in the presence of water by using batch experiments with nonradioactive cesium chloride (CsCl133) as a surrogate for the radionuclide. Uptake kinetics and adsorption isotherms of Cs+ were measured on a diverse set of building materials, as were the effects of pH on the sorption processes. The results showed that wood materials, metal filings, and organic building materials and supplies did not sorb significant amounts of Cs+, but red brick, concrete block, drop ceiling panels, and clay materials retained Cs+ strongly. Adsorption kinetics were fast, and sorption isotherms could be characterized as linear. The solution pH did not have a significant effect on Cs+ sorption.

Evaluation of sulfide emissions from a hydraulic system at the Blue River Dam

Hydrogen sulfide releases occurred during a routine maintenance process in a hydraulic oil system at Blue River Dam, Oregon. The project worked under the hypothesis that the sulfide emissions most likely resulted from reductive biological processes. Hydraulic oil samples were collected from the Blue River Dam, and from two other nearby dams with similar hydraulic systems, Hills Creek Dam, and Cougar Dam. Water samples from the reservoir were also collected. Sulfur was found in all the oil and water samples, however, no patterns with sulfur to other parameters (such as percent water or acid neutralization number) were found in the oil samples. A microscopic review of hydraulic filters did not show any evidence of biofilm accumulation. The use of sulfate reductive bacterial genetic probes did not find any microbial activity expected to form sulfide. These results rejected the hypothesis that the sulfide production was from microbial activity. The Authors now hypothesize that the sulfide reaction was from abiotic reactions of an additive, Zinc Dialkyldithiophosphate (ZDDP). DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR.