Personal Research Database

Title: Vacuum

ISO Abbreviated Title: Vacuum

JCR Abbreviated Title: Vacuum

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: Impact Factor

? Rudzinski, W., Narkiewicz, J. and Patrykiejew, A. (1977), Theoretical origin of Haul and Gottwald empirical isotherm for ultrahigh-vacuum adsorption. Vacuum, 27 (9), 545-547.

Full Text: Vacuum27, 545

? Jaroniec, M. (1978), Kinetics of monolayer mixed-gas adsorption on heterogeneous surfaces. Vacuum, 28 (1), 17-19.

Full Text: Vacuum28, 17

Title: Vadose Zone Journal

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ISSN: 1539-1663

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: Impact Factor

? Goldberg, S. (2004), Modeling boron adsorption isotherms and envelopes using the constant capacitance model. Vadose Zone Journal, 3 (2), 676-680.

Full Text: 2004\Vad Zon J3, 676.pdf

Abstract: Boron adsorption on 23 soil samples belonging to six different soil orders was investigated both as a function of solution B concentration (0 - 23.1 mmol L-1) and as a function of solution pH (4 - 11). Boron exhibited maxima at high solution B concentration. Boron adsorption increased with increasing solution pH, reached a maximum around pH 9, and decreased with further increases in solution pH. The constant capacitance model was able to describe B adsorption the soil samples as a function of both solution B concentration and solution pH simultaneously by optimizing three surface complexation constants. The ability to describe B adsorption as a function of pH represents an advancement over the Langmuir and Freundlich adsorptration isotherm approaches. Incorporation of these constants into chemical speciation transport models will allow simulation of soil solution B concentrations under diverse environmental and agricultural conditions.

Keywords: Layer Silicates Sesquioxides, Soil Materials, Retention, Parameters, Sorption, Oxide

? Decker, D.L., Papelis, C., Tyler, S.W., Logsdon, M.J. and Simunek, J. (2006), Arsenate and arsenite sorption on carbonate hosted precious metals ore. Vadose Zone Journal, 5 (1), 419-429.

Full Text: 2006\Vad Zon J5, 419.pdf

Abstract: The societal impacts of As in water resources in the arid western USA are potentially acute as a consequence of the combined effects of limited water supplies and the pervasive occurrence of naturally occurring As in subsurface geologic formations, including the carbonate-hosted, disseminated gold-bearing formations of the Carlin Trend. The prevalence of As in secondary minerals in gold-bearing carbonate-hosted ores is of interest because of the potential for As release as a result of ore development. A key component to gold mining is the engineering and construction of large-scale heap-leach and waste-rock containment structures that are characterized by variably saturated hydrology. Estimating As release behavior from these structures with a variably saturated reactive flow and transport numerical model requires the quantification of the significant differences in the sorption behavior for the stable redox states for As. Therefore, the objective of this study was to quantify this sorption behavior and to represent the observed behavior with an isotherm formulation. The pH-dependent sorption behavior of arsenite, As(III), and arsenate, As(V), onto two carbonate-hosted gold ores is presented. The experimentally determined pH-dependent sorption behavior for both As(III) and As(V) is consistent with sorption on metal oxides as reported in studies on rock and soils with similar bulk mineralogical properties. The experimental sorption data are represented with two modified isotherm formulations. Modified formulations of the Langmuir isotherm and of the Sips isotherm are presented that include the pH of the sorbate solution as an additional model parameter. These formulations are applied to both As(III) and As(V) sorption data to generate an isotherm surface. The pH-dependent isotherm methodology can be incorporated readily into numerical models for the purposes of estimating As transport behavior in field-scale, variably saturated environments.

Keywords: Dependent Boron Adsorption, Nevada Test-Site, Surface Complexation, Competitive Adsorption, Zeolitized Tuffs, Water Interface, Ground-Water, Pit Lake, Arsenic(III), Soils

? Goldberg, S., Criscenti, L.J., Turner, D.R., Davis, J.A. and Cantrell, K.J. (2007), Adsorption - Desorption processes in subsurface reactive transport modeling. Vadose Zone Journal, 6 (3), 407-435.

Full Text: 2007\Vad Zon J6, 407.pdf

Abstract: Adsorption-desorption reactions are important processes that affect the transport of contaminants in the environment. Various empirical approaches, such as the distribution coefficient and Freundlich and Langmuir isotherm equations, have been used to represent adsorption. The empirical approaches are not capable of accounting for the effects of variable chemical conditions, such as pH, on adsorption reactions. This can be done using chemical models such as surface complexation models. These models define specific surface species, chemical reactions, equilibrium constants, mass balances, and charge balances, and their molecular features can be given thermodynamic significance. Ion adsorption mechanisms and surface configurations for the surface complexation models can be established from independent experimental observations. These include both indirect measurements, such as point of zero charge shifts, ionic strength effects, and calorimetry, and direct spectroscopic techniques, including vibrational spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and X-ray absorption spectroscopy. Surface complexation models were developed for single mineral phases but have now been applied to natural mineral assemblages using both component additivity (CA) and generalized composite (GC) approaches. Surface complexation models have been incorporated into subsurface transport models at several field sites, although simplifying assumptions are needed to deal with heterogeneous materials. Surface complexation models for contaminant adsorption have the potential to increase the confidence and scientific credibility of transport modeling by reducing the uncertainty in quantifying retardation and providing a means of quantifying that uncertainty.

Keywords: X-Ray-Absorption, Constant Capacitance Model, Oxide-Water Interface, Surface-Complexation Models, Electrical Double-Layer, Bond-Valence Determination, Hydrolyzable Metal-Ions, Density-Functional Calculations, Chromate Retention Mechanisms, Alumina Electrolyte Interface

? Flury, M. and Qiu, H.X. (2008), Modeling colloid-facilitated contaminant transport in the vadose zone. Vadose Zone Journal, 7 (2), 682-697.

Full Text: 2008\Vad Zon J7, 682.pdf

Abstract: Subsurface colloids can enhance the movement of strongly sorbing contaminants’ a phenomenon called colloid-facilitated contaminant transport. In the presence of mobile subsurface colloids, contaminants may move faster and farther than in the absence of colloids, thereby bypassing the filter and buffer capacity of soils and sediments. Fate and transport models neglecting colloid-facilitated transport therefore often underpredict contaminant movement. Long-term predictions of contaminant fate and transport as well as risk assessment rely on an accurate representation of subsurface processes, and in the case of strongly sorbing contaminants, need to consider mobile colloids as potential contaminant carriers. The purpose of this review is to discuss the current knowledge and recent developments of modeling colloid-facilitated contaminant transport in the vadose zone. The main part of this review is devoted to the discussion of conceptual models used to describe colloid-facilitated contaminant transport in the vadose zone and their mathematical implementation. Modeling of colloid-facilitated contaminant transport involves various interactions, including colloid attachment to and detachment from the solid matrix and the air-water interface, contaminant adsorption to and desorption from colloids and transport with mobile colloids, and contaminant adsorption to and desorption from the solid matrix. Most of these processes in colloid-facilitated contaminant transport models have been described by first- or second-order kinetics. The unique feature of the vadose zone is the presence of an air phase, which affects colloid and contaminant transport in several ways. Colloids can be trapped in immobile water, strained in thin water films and in the smallest regions of the pore space, or attached to the air-water interface itself. The modeling of colloid-facilitated contaminant transport in the vadose zone has mostly been theoretical, and tested only with column experiments; field applications are still lacking.

Keywords: Adsorption, Air-Water Interfaces, Assessment, Capacity, Cation-Exchange, Colloid, Colloids, Column Experiments, Contaminant Transport, Desorption, Experiments, Feature, First, Hanford Sediments, Kinetics, Knowledge, Laboratory Column, Modeling, Models, Potential, Reactive Transport, Representation, Review, Risk, Risk Assessment, Second-Order Kinetics, Solute Transport, Subsurface Colloids, Transient-Flow Conditions, Transport, Unsaturated Porous-Media, Vadose Zone, Water