Physical Sciences and Mathematics Commons^™

Single-Stage, Venturi-Driven Desalination System, Brandon Proetto

Mechanical & Aerospace Engineering Theses & Dissertations

Water demand is increasing at a rapid pace due to population increase, industrial expansion, and agricultural development. The use of desalination technology to meet the high water demands has increased global online desalination capacity from 47 million m^3/d in 2007 to 92.5 million m^3/d as of June 2017 [49]. Membrane and thermal processes are the two mainstream desalination categories used worldwide for desalination plants. Reverse Osmosis (RO) is the most widely used membrane process and it has become the dominant technology for building desalination plants over recent decades. Thermal distillation, however, has become less and less competitive due to its …

Comparison Of Ice Core Dissolved Organic Matter From A Greenland Ice Core By Nanospray Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Joshua Jeremiah Shiloh Marsh

Chemistry & Biochemistry Theses & Dissertations

Recent studies of ice cores have embarked on the task of determining the classes of dissolved organic matter (DOM) present in melt-water from the cores collected in numerous locations in the northern and southern hemispheres. This DOM originally derives from wet precipitation and is thought to reflect atmospheric organic matter derived from anthropogenic and non-anthropogenic sources. Because the amount of DOM is so low, previous studies have necessarily used large sample volumes (greater than 500 mL) to concentrate sufficient ice core DOM necessary for mass spectral analysis. Solid phase extraction (SPE) with C₁₈ resins was followed by evaporative concentration …

Relating Water And Otolith Chemistry In Chesapeake Bay, And Their Potential To Identify Essential Seagrass Habitats For Juveniles Of An Estuarine-Dependent Fish, Spotted Seatrout (Cynoscion Nebulosus), Emmanis Dorval

Biological Sciences Theses & Dissertations

A quantitative understanding of habitat use of estuarine-dependent fishes is critical to the conservation of their most essential habitats. Because recruitment and fitness may be influenced by the quality of juvenile habitats, developing methods to quantify habitat-specific survivorship is pivotal to such understanding. An initial step to quantify survivorship is to validate the habitat-specific natural tags contained in otoliths. To this aim I investigated the variability in the chemistry of surface waters and otoliths of juvenile spotted seatrout, Cynoscion nebulosus, in five seagrass habitats of Chesapeake Bay, namely: Potomac, Rappahannock, York, Island, and Eastern Shore. I measured Mg, Ca, …

Humic Substances As Interferences In The Analysis Of Nitrite In Water, Stephanie Ann Tebault

Chemistry & Biochemistry Theses & Dissertations

Humic substances are of current interest because of their roles in environmental processes involving pollutants. It is also becoming recognized that humic substances may interfere in analysis of environmental samples though the possible adverse effects do not appear to be fully appreciated. The present effort focuses on determining whether humic materials interfere in the analysis of nitrite in water using the Griess reaction. This is a well-known reaction using nitrosation to gjve a diazonium salt followed by coupling with an appropriate reagent to form a dye. This colorimetric method continues to be applied in the laboratory and the field for …

Zinc Speculation And Ligand Fluxes In Chesapeake Bay And Elizabeth River Pore Waters, Duncan Glover Byers

Chemistry & Biochemistry Theses & Dissertations

Presented here are the first data on the vertical concentrations, complexation, speciation, and fluxes of total dissolved zinc and zinc complexing ligands, and zinc speciation in sediment pore waters in the Chesapeake Bay and Elizabeth River, Virginia.

Sediment pore waters were collected in mid and southern Chesapeake Bay in November 1997 and in the Elizabeth River (Pinner's Point) in March, April, and July 1998. Flux experiments were conducted in Elizabeth River sediment cores in April and July 1998. [TDZn] and zinc complexation were determined using differential pulse anodic stripping voltammetry at a hanging mercury drop electrode (DPASV-HMDE).

[TDZn] in the …

Councilmanic Perceptions Of Water Policy For The Lake Gaston Water Supply Project In Virginia And North Carolina, Beverly Mcafee Hedberg

Theses and Dissertations in Urban Services - Urban Management

The purpose of this case study is to analyze the perceptions of city council members in formulating and implementing policy on the Lake Gaston Water Supply Project in Virginia and North Carolina. A comparison of the perceptions of twenty-three members of three city councils: Henderson, North Carolina; Roanoke Rapids, North Carolina; and Virginia Beach, Virginia serves as the basis for analysis. Their perceptions of the issues and how they view other actors in the intergovernmental arena, within the context of the Lake Gaston Water Supply Project.

Specifically, the research examines how city council members view (1) water-policy issues, (2) the …

Relation Of Groundwater Fluoride Concentrations To Sediment Mineralogy, Potomac Formation (Cretaceous), Southeastern Virginia, Paul Anthony Maciuika

OES Theses and Dissertations

Thirty-seven Early cretaceous sediment samples of the Potomac Formation were obtained from four cores to determine if fluoride bearing minerals are responsible for elevated fluoride concentrations in Potomac Formation groundwaters of southeastern Virginia. Investigative methods included total sediment fluoride and particle size analysis, semiquantitative mineralogical analysis (achieved by X-Ray Diffraction) and statistical methods (cluster, canonical and regression analysis). The sediments showed wide variation in textures, ranging from clean sands and gravels to silty clays. Sediment mineralogies were dependent on the prevailing size fraction, with quartz and feldspar dominating the sand and silt fractions, muscovite primarily being found in the silt …

Reactions Of Organic N-Chloramines In The Gastric Fluid Of The Rat, Kathryn E. Mazina

Chemistry & Biochemistry Theses & Dissertations

Using chlorine as a drinking water disinfectant may have potential health effects due to its reactivity with organic amino nitrogen compounds found in the stomach. Organic N-chloramines have been shown to form in the stomachs of laboratory rats. The possible reactions of N-chloramines in the stomach fluid were examined in this study using a model radiolabeled N-chloramine. ³⁶Cl-N-Chloropiperidine, was synthesized and purified to remove ³⁶Cl-chloride. Stomach fluid was obtained from Sprague-Dawley rats which had been first fasted for 24 or 48 hours and then administered 3 mL of deionized water. Different concentrations of radiolabeled chloramine were reacted with …

Chemistry Of Organic N-Chloramines, Formation Of Arenesulfonamides By Derivatization Of Organic N-Chloramine With Sodium Arenesulfinate, Katherine F. Bowdring

Chemistry & Biochemistry Theses & Dissertations

Organic N-chloramines are recognized by-products of chlorinated water systems. Because of their chemistry, none have been isolated or identified.

This paper discusses a method for the derivatization of the organic N-chloramines based on a nucleophillic substitution mechanism. N-Chloro derivatives of amines of various structures were studied including primary and secondary aliphatic amines, as well as amino acids. The effect of the presence of other functional groups including aromatic and unsaturated systems was investigated.

Derivatization was done by three different methods, one involving derivatization of the pure N-chloramine, and two involving derivatizations of the N-chloramine generated in situ. Seventeen arenesulfonamides have …

A Technique For The Isolation And Identification Of Aliphatic Amines In Water, Peter Alan Drew

Chemistry & Biochemistry Theses & Dissertations

Small, aliphatic amines added to a basic, aqueous solution (16.2 L) at a concentration of 100 parts per billion were isolated by sorption on a small column of macroreticular resin. The amines were eluted with diethyl ether; the eluate concentrated, and the compounds separated and identified by gas chromatography. The efficiency of the recovery of a-nines ranged from 5 to 28%.

A protocol for derivatizing pyrrolidine and n-pentylamine in ether with fluorinated acylating agents was developed. The method was found to be adequate for the detection of approximately 13 micrograms of &-nines in concentrated ether extract.

Environmental water samples …