Advection and Dispersion of Dissolved Species in Aquifers

2011 ◽  
pp. 3-76
Author(s):  
Vyacheslav G. Rumynin
Keyword(s):  
Dissolved Species

Mirsid volcanic tuff, alkaline activation, dissolved species, optimum activation time, optimum activating concentration

2020 ◽  
Vol 71 (2) ◽  
pp. 196-201
Author(s):  
Erika Reisz ◽  
Corneliu-Mircea Davidescu ◽  
Radu Ardelean ◽  
Liviu Costea
Keyword(s):  
Sudden Increase ◽  
Activation Time ◽  
Volcanic Tuff ◽  
X Ray ◽  
Second Stage ◽  
Dissolved Species ◽  
Species Optimum ◽  
Potassium Magnesium ◽  
Exchange Properties ◽  
Activating Solution

The purpose of this article is to study the activation of the Mir�id volcanic tuff with NaOH solutions at various concentrations. To be more specific, the work investigated the evolution of the concentrations of species that passed from the tuff into the activating solutions and the quantities of dissolved species from 100 g tuff. The species found in the activating solution were: potassium, magnesium, aluminium and silicon. The shape of the curves - a sudden increase followed by a plateau or a second stage of slower increase - allowed for setting up the optimal activation time at a half-hour. Another finding was the optimal concentration of 1 N for the activating solution. X-ray diffractograms showed the increase of clinoptilolite content in the tuff, thus improving the adsorbent as well as ion exchange properties by activation with NaOH solutions.

The Effect of Waste Package Components on Radionuclides Released from Spent Fuel Under Hydrothermal Conditions

1987 ◽  
Vol 112 ◽  
Author(s):  
Shirley A. Rawson ◽  
William L. Neal ◽  
James R. Burnell
Keyword(s):  
Low Carbon Steel ◽  
Fission Products ◽  
Nuclear Waste Repository ◽  
Low Carbon ◽  
Spent Fuel ◽  
Hydrothermal Conditions ◽  
Waste Package ◽  
Dissolved Species ◽  
Radionuclide Release ◽  
Time Invariant

AbstractThe Basalt Waste Isolation Project has conducted a series of hydrothermal experiments to characterize waste/barrier/rock interactions as a part of its study of the Columbia River basalts as a potential medium for a nuclear waste repository. Hydrothermal tests of 3–15 months duration were performed with light water reactor spent fuel and simulated groundwater, in combination with candidate container materials (low-carbon steel or copper) and/or basalt, in order to evaluate the effect of waste package materials on spent fuel radionuclide release behavior. Solutions were filtered through 400 and 1.8 nm filters to distinguish colloidal from dissolved species. In all experiments, 14C, 129I, and 137Cs occurred only as dissolved species, whereas the actinides occurred in 400 nm filtrates primarily as spent fuel particles. Actinide concentrations in 1.8 nm filtrates were below detection in steel-bearing experiments. In the system spent fuel + copper, apparent time-invariant concentrations of 14C and 137Cs were obtained, but in the spent fuel + steel system, the concentrations of 14C and 137Cs increased gradually throughout the experiments. In experiments containing basalt or steel + basalt, 137Cs concentrations decreased with time. In tests with copper + basalt, 14C and 129I concentrations attained time-invariant values and 137Cs concentrations decreased. Concentrations for the actinides and fission products measured in these experiments were below those calculated from Federal regulations governing radionuclide release.

Wormhole dynamics, competition for the flow and changes in transport behavior: an intermediate-scale experiment

2021 ◽  
Author(s):  
Michela Trabucchi ◽  
Daniel Fernàndez-Garcia ◽  
Jesús Carrera
Keyword(s):  
Tracer Tests ◽  
Dissolution Experiment ◽  
Intermediate Scale ◽  
Geochemical Conditions ◽  
Flow Parameters ◽  
Salt Flats ◽  
Dissolved Species ◽  
Formation And Evolution ◽  
Scale Experiment ◽  
The One

<p>Salt flats (Salares) are complex evaporitic systems of economic interest and environmental value. On the one hand, these aquifers are usually exploited for variety of minerals, including dissolved species (e.g. Lithium and Potassium) extracted from the brines. On the other hand, the genesys of salares favors that they are surrounded by uncommon ecosystems, which must be protected. In this context, it is fear that brine pumping might favor the development of dissolution channels (Wormholes) that could connect the Salar nucleus with the environmental sensitive surroundings. Thus, a full understanding of the conditions and processes involved in wormhole formation and evolution has to be achieved. The hydraulic and geochemical conditions for conduits growth have been widely discussed in carbonate environments, while little has been done in halitic and gypsum environments. But we unknowledge experimental works aimed at understanding wormhole dynamics and the mechanism of competition for the flow that influence dissolution pattern evolution.</p><p>In this study, we want to improve the understanding of multiple wormholes growth in the context of wormhole competition and consequent changes in transport behaviors. For that purpose, we designed and performed a laboratory intermediate-scale tank experiment under controlled conditions. Halite in the form of granular medium is used to reproduce the aquifer. Hydrodynamics and geochemical conditions are set as to reproduce a dominant wormhole dissolution regime. Several coloured tracer tests are carried out to characterize the medium before, during and after the dissolution experiment.  Tracer concentration, hydrogeochemical and flow parameters, as well as tank images are continuously recorded. In particular, the use of fluorescent tracer jointly with image processing analysis highlights wormholes growth, shape and propagation through the medium at different times. Experimental results allow visualizing and analyzing several features related to wormhole competition, e.g. wormhole growth rate and density evolution, as well the redistribution of the flow towards areas where dominant wormholes are developing. Results are compared to available numerical and analytical solutions. Lastly, the interpretation of BTCs allows to understand changes in flow and trasport behavior and related processes, given the developing dissolution pattern.</p>

Nanoplastic transport in aqueous environments: The role of chemo-electric properties and hydrodynamic forces for nanoplastic-mineral interaction.

2021 ◽  
Author(s):  
Sascha Müller ◽  
Jacek Fiutowski ◽  
Horst-Günter Rubahn ◽  
Nicole Rita Posth
Keyword(s):  
Specific Interaction ◽  
Chemical Processes ◽  
Flow Rates ◽  
Transport Studies ◽  
Subsurface Environments ◽  
Dissolved Species ◽  
Aqueous Environments ◽  
Interaction Scheme ◽  
Almost All ◽  
Mineral Interaction

The fate and transport characteristics of nanoplastic (NP) through different environmental systems is largely governed by physio-chemical processes and their specific interaction with environmental constituents (i.e., minerals, dissolved species, suspended particles). A hydrodynamic component present in almost all terrestrial and marine aqueous environments impact the physio-chemical processes micron-scale is largely overlooked in NP transport studies. Therefore, we tested the interaction behavior of nanosized plastic polystyrene particles of various coatings in the presence of minerals abundant in the Earth crust within a hydrodynamic continuum representing flow rates from groundwater to surface water systems. Our batch experiments show that particle-mineral adsorption is largely driven by the magnitude of opposite charge configurations, which is either produced by mineral type or specific nanoplastic surface coating. Zetapotential serves as a good predictor of adsorption between uncoated and carboxyl-coated polystyrene with minerals. It fails, however, to predict adsorption behavior between NH2 coated polystyrene and apatite or feldspars, due to the more complex and varying compositions of these minerals. Incorporating the hydrodynamic force component into the particle- mineral interaction scheme reproduces those adsorption trends at slow flowrates of 1e-04 m/d. However, increasing flow rates by a factor of 100 modifies charge-driven adsorption between minerals and plastics. This study highlights the unabating importance of hydrodynamic conditions when predicting nanoplastic transport in different subsurface environments, and has implications for nanoplastic behavior in both terrestrial and marine aqueous environments.

DETERMINATION OF THE CONSTANTS OF THE HENDERSON-HASSELBALCH EQUATION, (alpha)CO2 AND pKa, IN SEA TURTLE PLASMA

1993 ◽  
Vol 180 (1) ◽  
pp. 311-314 ◽  
Author(s):  
E. K. Stabenau ◽  
T. A. Heming
Keyword(s):  
Ionic Strength ◽  
Vapor Pressure ◽  
Blood Plasma ◽  
Water Content ◽  
Protein Concentration ◽  
Acid Base ◽  
Constant Weight ◽  
Blood Samples ◽  
Dissolved Species ◽  
Hasselbalch Equation

Hydration of CO2 yields HCO3- via the reaction: CO2 + H2O = H2CO3 = HCO3- + H+ = CO32- + 2H+. (1) Acid-base physiologists traditionally simplify the reaction by omitting the H2CO3 term and lumping all ionic CO2 species into the HCO3- term. The simplified reaction forms the basis for the familiar Henderson-Hasselbalch equation of the CO2-HCO3- buffer system: pH = pKa + log([HCO3-]/(alpha)CO2PCO2), (2) where (alpha)CO2 is the solubility coefficient relating [CO2] and PCO2 (Henry's Law). The apparent pK (pKa) in this equation lacks a rigorous thermodynamic definition. Instead, it is an empirical factor relating pH, the product of (alpha)CO2 and PCO2, and the apparent [HCO3-] (i.e. the sum of all ionic CO2 species). (alpha)CO2 and pKa are sensitive to the temperature, pH and/or the ionic strength of the reaction medium. (alpha)CO2 and pKa of normal mammalian blood plasma have been well defined over a range of temperatures and pH values (e.g. Severinghaus, 1965; Siggaard-Andersen, 1974; Reeves, 1976). These mammalian values are commonly used in analyses of the acid-base status of non- mammalian species, despite evidence that such practices can produce misleading results (Nicol et al. 1983). As an alternative, Heisler (1984; erratum in Heisler, 1986) developed complex equations for (alpha)CO2 (mmol l-1 mmHg-1) (1 mmHg=133.22 Pa) and pKa that are purported to be generally applicable to aqueous solutions (including body fluids) between 0 and 40 °C and incorporate the molarity of dissolved species (Md), solution pH, temperature (T, °C), sodium concentration ([Na+], mol l-1), ionic strength of nonprotein ions (I, mol l-1) and protein concentration ([Pr], g l-1): (alpha)CO2 = 0.1008 - 2.980 × 10–2Md + (1.218 × 10-3Md - 3.639 × 10-3)T - (1.957 × 10-5Md - 6.959 × 10-5)T2 + (7.171 × 10-8Md - 5.596 × 10-7)T3. (3) pKa = 6.583 - 1.341 × 10-2T + 2.282 × 10-4T2 - 1.516 × 10-6T3 - 0.341I0.323 - log{1 + 3.9 × 10-4[Pr] + 10A(1 + 10B)}, (4) where A = pH - 10.64 + 0.011T + 0.737I0.323 and B = 1.92 - 0.01T - 0.737I0.323 + log[Na+] + (0.651 - 0.494I)(1 + 0.0065[Pr]). Experimental validation of these equations has not appeared in the literature to date. We determined the (alpha)CO2 and pKa of blood plasma from Kemp's ridley sea turtles (Lepidochelys kempi Garman) and compared the values with those predicted from Heisler's equations. Blood samples were collected into heparinized syringes from the dorsal cervical sinus of 1- to 2-year- old animals at the National Marine Fisheries Service, Galveston Laboratory, Texas. Separated plasma was obtained by centrifugation of the whole blood samples. (alpha)CO2 was determined gasometrically by equilibrating 2 ml samples of acidified plasma (titrated to pH 2.5 with 1 mol l-1 HCl) in a tonometer with 99.9 % CO2 at 20, 25, 30 or 35 °C. Fresh samples of plasma were used at each temperature. The total CO2 content (CCO2) of plasma was measured in duplicate after 15 min of equilibration, using the methods described by Cameron (1971). The CO2 electrode (Radiometer, type E5036) was calibrated at each temperature using known [HCO3-]. Plasma PCO2 was calculated from the known fractional CO2 content of the equilibration gas, corrected for temperature, barometric pressure and water vapor pressure. Plasma water content was measured by weighing samples of plasma before and after they had been dried at 60 °C to constant weight. (alpha)CO2 was calculated as The quotient of CCO2 and PCO2, taking into account the plasma water content (mean +/− s.e.= 96+/−0.03 %). pKa was determined gasometrically by equilibrating 2 ml samples of plasma in a tonometer with 4.78 or 10.2 % CO2 (balance N2) at 20 or 30 °C. Fresh samples of plasma were used at each temperature and gas concentration. Plasma CCO2 and pH were measured in duplicate. The pH electrode (Radiometer, type G297/G2) was calibrated at each temperature using precision Radiometer pH buffers (S1500 and S1510). Plasma PCO2 was determined as above. pKa was calculated from a rearrangement of the Henderson-Hasselbalch equation (equation 2), assuming CCO2 to be the sum of [HCO3-] and [CO2] (i.e. (alpha)CO2PCO2). Heisler's equations were adapted for use with L. kempi plasma using measured values of the molarity of dissolved species (Md), [Na+] and protein concentration ([Pr]). These parameters were quantified as follows: Md with a vapor pressure osmometer (Precision Systems, model 5004), [Na+] by flame photometry (Jenway, model PFP7) and [Pr] by a standard spectrophotometric method (Sigma kit 541). The average values were Md=0.304+/−0.003 mol l-1, [Na+]=0.141+/−0.004 mol l-1 and [Pr]=28+/−3 g l- 1. The ionic strength of nonprotein ions (I) was assigned a value of 0.150 mol l-1. Computed (alpha)CO2 and pKa values were generated for a wider range of temperature and pH conditions than were used experimentally in order to emphasize the pattern and range of effects of temperature and/or pH.

Solvated Ions in Water

2016 ◽  
Author(s):  
Bruce C. Bunker ◽  
William H. Casey
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecules ◽  
Halide Ions ◽  
Bulk Fluid ◽  
Undergraduate Chemistry ◽  
Dissolved Species ◽  
Solvated Ions ◽  
Oxygen Anions ◽  
Chemical Attributes ◽  
Ionic Clathrate Hydrates

In most undergraduate chemistry classes, students are taught to consider reactions in which cations and anions dissolved in water are depicted as isolated ions. For example, the magnesium ion is depicted as Mg2+, or at best Mg2+(aq). For anions, these descriptions may be adequate (if not accurate). However, for cations, these abbreviations almost always fail to describe the critical chemical attributes of the dissolved species. A much more meaningful description of Mg2+ dissolved in water is [Mg(H2O)6]2+, because Mg2+ in water does not behave like a bare Mg2+ ion, nor do the waters coordinated to the Mg2+ behave anything like water molecules in the bulk fluid. In many respects, the [Mg(H2O)6]2+ ion acts like a dissolved molecular species. In this chapter, we discuss the simple solvation of anions and cations as a prelude to exploring more complex reactions of soluble oxide precursors called hydrolysis products. The two key classes of water–oxide reactions introduced here are acid–base and ligand exchange. First, consider how simple anions modify the structure and properties of water. As discussed in Chapter 3, water is a dynamic and highly fluxional “oxide” containing transient rings and clusters based on tetrahedral oxygen anions held together by linear hydrogen bonds. Simple halide ions can insert into this structure by occupying sites that would normally be occupied by other water molecules because they have radii (ranging from 0.13 to 0.22 nm in the series from F− to I−) that are comparable to that of the O2− ion (0.14 nm). Such substitution is clearly seen in the structures of ionic clathrate hydrates, where the anion can replace one and sometimes even two water molecules. Larger anions can also replace water molecules within clathrate hydrate cages. For example, carboxylate hydrate structures incorporate the carboxylate group within the water framework whereas the hydrophobic hydrocarbon “tails” occupy a cavity within the water framework, as in methane hydrate (see Chapter 3). Water molecules form hydrogen bonds to dissolved halide ions just as they can to other water molecules, as designated by OH−Y−.

Basin-Scale Transport of Dissolved Species in Groundwater

1988 ◽  
pp. 75-93 ◽  
Author(s):  
Andrea Rinaldo ◽  
Giuseppe Gambolati
Keyword(s):  
Dissolved Species ◽  
Basin Scale

scholarly journals Pluvial percolation in pyrite-bearing coal stockpiles

2009 ◽  
Vol 62 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Danielle Andrade Pimentel ◽  
José Aurélio Medeiros da Luz
Keyword(s):  
Heavy Metal ◽  
Acid Mine Drainage ◽  
Metal Content ◽  
Environmental Problem ◽  
Mine Drainage ◽  
Leaching Process ◽  
Polymeric Reagents ◽  
Dissolved Species ◽  
Sulfide Ore ◽  
Pyrite Content

Acid mine drainage is a main environmental problem linked to coal and sulfide ore mining. Its treatment usually involves alkalinization and subsequent precipitation and immobilization of the dissolved species. Rainfalls over stockpiles can cause a very similar phenomenon. This work aimed to study the effluents from such a leaching process in steam-coal stockpiles Brazilian coal with a high pyrite content was used. The effluents have been chemically characterized. Effluent clarification by aggregation and settling in an attempt to simultaneously deplete heavy metal content was studied. Settling experiments were carried out with coal suspensions, in order to evaluate the efficiency of inorganic and polymeric reagents in the process.

scholarly journals Numerical simulation of modification of non-metallic inclusions by calcium treatment in the argon-stirred ladle

2019 ◽  
Vol 116 (5) ◽  
pp. 515
Author(s):  
Edgar Ivan Castro-Cedeno ◽  
Alain Jardy ◽  
Benjamin Boissiere ◽  
Jean Lehmann ◽  
Pascal Gardin ◽  
...  
Keyword(s):  
Flow Model ◽  
Fluid Dynamic ◽  
Steel Ladle ◽  
Local Concentration ◽  
Two Phase ◽  
Euler Flow ◽  
Metallic Inclusions ◽  
Dissolved Species ◽  
Secondary Steelmaking ◽  
Technological Challenge

Nowadays, depending on the steel grade, Ca treatment with the aim of modifying the morphology and melting temperature of non-metallic inclusions is performed in the secondary steelmaking process. The addition of calcium to steel melts rises a technological challenge because at steelmaking temperatures Ca has the tendency to vaporize from the ladle. Efforts are actively pursued in developing solutions that increase Ca yield and improve repeatability of results from treatment to treatment. This work presents a two-phase Euler-Euler flow model of a steel ladle with gas stirring through bottom porous plugs. The model considers that before gas exits through the ladle top, some Ca is transferred from the gas to the liquid steel. The yield is thus defined as the ratio between the Ca transferred to the steel and the total calcium injected into the ladle. The fluid-dynamic calculations are coupled with ArcelorMittal thermodynamic software CEQCSI to get the evolution of the local concentration of dissolved species and non-metallic inclusions assuming local thermodynamic equilibrium. Industrial trials have been performed at one of ArcelorMittal’s facilities with the aim of obtaining data to validate the model. Samples of steel were taken before, during, and after the Ca injection treatment. The total Ca content and the inclusion populations in the steel samples can be compared against the results given by the model, as well as the measured and calculated Ca yield.

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