On-line solid phase selective separation and preconcentration of Cd(II) by solid-phase extraction using carbon active modified with methyl thymol blue

Energy Technology Data Exchange (ETDEWEB)

Ensafi, Ali A. [College of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)], E-mail: Ensafi@cc.iut.ac.ir; Ghaderi, Ali R. [College of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2007-09-05

An on-line flow system was used to develop a selective and efficient on-line sorbent extraction preconcentration system for cadmium. The method is based on adsorption of cadmium ions onto the activated carbon modified with methyl thymol blue. Then the adsorbed ions were washed using 0.5 M HNO{sub 3} and the eluent was used to determine the Cd(II) ions using flame atomic absorption spectrometry. The results obtained show that the modified activated carbon has the greatest adsorption capacity of 80 {mu}g of Cd(II) per 1.0 g of the solid phase. The optimal pH value for the quantitative preconcentration was 9.0 and full desorption is achieved by using 0.5 M HNO{sub 3} solution. It is established that the solid phase can be used repeatedly without a considerable adsorption capacity loss. The detection limit was less than 1 ng mL{sup -1} Cd(II), with an enrichment factor of 1000. The calibration graph was linear in the range of 1-2000 ng mL{sup -1} Cd(II). The developed method has been applied to the determination of trace cadmium (II) in water samples and in the following reference materials: sewage sludge (CRM144R), and sea water (CASS.4) with satisfactory results. The accuracy was assessed through recovery experiments.

On-line solid phase selective separation and preconcentration of Cd(II) by solid-phase extraction using carbon active modified with methyl thymol blue

International Nuclear Information System (INIS)

Ensafi, Ali A.; Ghaderi, Ali R.

2007-01-01

An on-line flow system was used to develop a selective and efficient on-line sorbent extraction preconcentration system for cadmium. The method is based on adsorption of cadmium ions onto the activated carbon modified with methyl thymol blue. Then the adsorbed ions were washed using 0.5 M HNO 3 and the eluent was used to determine the Cd(II) ions using flame atomic absorption spectrometry. The results obtained show that the modified activated carbon has the greatest adsorption capacity of 80 μg of Cd(II) per 1.0 g of the solid phase. The optimal pH value for the quantitative preconcentration was 9.0 and full desorption is achieved by using 0.5 M HNO 3 solution. It is established that the solid phase can be used repeatedly without a considerable adsorption capacity loss. The detection limit was less than 1 ng mL -1 Cd(II), with an enrichment factor of 1000. The calibration graph was linear in the range of 1-2000 ng mL -1 Cd(II). The developed method has been applied to the determination of trace cadmium (II) in water samples and in the following reference materials: sewage sludge (CRM144R), and sea water (CASS.4) with satisfactory results. The accuracy was assessed through recovery experiments

Molecular simulation of excess isotherm and excess enthalpy change in gas-phase adsorption.

Science.gov (United States)

Do, D D; Do, H D; Nicholson, D

2009-01-29

We present a new approach to calculating excess isotherm and differential enthalpy of adsorption on surfaces or in confined spaces by the Monte Carlo molecular simulation method. The approach is very general and, most importantly, is unambiguous in its application to any configuration of solid structure (crystalline, graphite layer or disordered porous glass), to any type of fluid (simple or complex molecule), and to any operating conditions (subcritical or supercritical). The behavior of the adsorbed phase is studied using the partial molar energy of the simulation box. However, to characterize adsorption for comparison with experimental data, the isotherm is best described by the excess amount, and the enthalpy of adsorption is defined as the change in the total enthalpy of the simulation box with the change in the excess amount, keeping the total number (gas + adsorbed phases) constant. The excess quantities (capacity and energy) require a choice of a reference gaseous phase, which is defined as the adsorptive gas phase occupying the accessible volume and having a density equal to the bulk gas density. The accessible volume is defined as the mean volume space accessible to the center of mass of the adsorbate under consideration. With this choice, the excess isotherm passes through a maximum but always remains positive. This is in stark contrast to the literature where helium void volume is used (which is always greater than the accessible volume) and the resulting excess can be negative. Our definition of enthalpy change is equivalent to the difference between the partial molar enthalpy of the gas phase and the partial molar enthalpy of the adsorbed phase. There is no need to assume ideal gas or negligible molar volume of the adsorbed phase as is traditionally done in the literature. We illustrate this new approach with adsorption of argon, nitrogen, and carbon dioxide under subcritical and supercritical conditions.

A solid-phase extraction method for rapidly determining the adsorption coefficient of pharmaceuticals in sewage sludge

Science.gov (United States)

Berthod, Laurence; Roberts, Gary; Whitley, David C.; Sharpe, Alan; Mills, Graham A.

2014-01-01

The partitioning of pharmaceuticals in the environment can be assessed by measuring their adsorption coefficients (Kd) between aqueous and solid phases. Measuring this coefficient in sewage sludge gives an indication of their partitioning behaviour in a wastewater treatment plant and hence contributes to an understanding of their subsequent fate. The regulatory approved method for measuring Kd in sewage sludge is the US Environmental Protection Agency's Office of Prevention, Pesticides and Toxic Substances (OPPTS) guideline 835.1110, which is labour intensive and time consuming. We describe an alternative method for measuring the Kd of pharmaceuticals in sewage sludge using a modified solid-phase extraction (SPE) technique. SPE cartridges were packed at different sludge/PTFE ratios (0.4, 6.0, 24.0 and 40.0% w/w sludge) and eluted with phosphate buffer at pH 7.4. The approach was tested initially using three pharmaceuticals (clofibric acid, diclofenac and oxytetracycline) that covered a range of Kd values. Subsequently, the sorption behaviour of ten further pharmaceuticals with varying physico-chemical properties was evaluated. Results from the SPE method were comparable to those of the OPPTS test, with a correlation coefficient of 0.93 between the two approaches. SPE cartridges packed with sludge and PTFE were stable for up to one year; use within one month reduced variability in measurements (to a maximum of 0.6 log units). The SPE method is low-cost, easy to use and enables the rapid measurement of Kd values for a large number of chemicals. It can be used as an alternative to the more laborious full OPPTS test in environmental fate studies and risk assessments. PMID:25299795

Modelling Gas Adsorption in Porous Solids: Roles of Surface ...

Indian Academy of Sciences (India)

Modelling the adsorption of small molecule gases such as N2, CH4 and CO2 in porous solids can ... fusive properties of CO2 adsorbed in the solids have been examined using ..... exhibit a wide range of physical behavior.78,79 The intro-.

Solid phase radioimmunoassays

International Nuclear Information System (INIS)

Wide, L.

1977-01-01

Solid phase coupled antibodies were introduced to facilitate the separation of bound and free labelled ligand in the competitive inhibition radioimmunoassay. Originally, the solid matrix used was in the form of small particles and since then a number of different matrices have been used such as very fine powder particles, gels, paper and plastic discs, magnetic particles and the inside surface of plastic tubes. The coupling of antibodies may be that of a covalent chemical binding, a strong physical adsorbtion, or an immunological binding to a solid phase coupled antigen. New principles of radioimmunoassay such as the solid phase sandwich techniques and the immunoradiometric assay were developped from the use of solid phase coupled antigens and antibodies. The solid phase sandwich techniques are reagent excess methods with a very wide applicability. Several of the different variants of solid phase techniques are suitable for automation. Advantages and disadvantages of solid phase radioimmunoassays when compared with those using soluble reagents are discussed. (orig.) [de

Non-equilibrium dynamics of single polymer adsorption to solid surfaces

International Nuclear Information System (INIS)

Panja, Debabrata; Barkema, Gerard T; Kolomeisky, Anatoly B

2009-01-01

The adsorption of polymers to surfaces is crucial for understanding many fundamental processes in nature. Recent experimental studies indicate that the adsorption dynamics is dominated by non-equilibrium effects. We investigate the adsorption of a single polymer of length N to a planar solid surface in the absence of hydrodynamic interactions. We find that for weak adsorption energies the adsorption timescales ∼N (1+2ν)/(1+ν) , where ν is the Flory exponent for the polymer. We argue that in this regime the single chain adsorption is closely related to a field-driven polymer translocation through narrow pores. Surprisingly, for high adsorption energies the adsorption time becomes longer, as it scales as ∼N 1+ν , which is explained by strong stretching of the unadsorbed part of the polymer close to the adsorbing surface. These two dynamic regimes are separated by an energy scale that is characterized by non-equilibrium contributions during the adsorption process. (fast track communication)

Solid phase extraction of uranium from phosphoric acid. Kinetic and thermodynamic study

Energy Technology Data Exchange (ETDEWEB)

Abdel-Magied, Ahmed Fawzy [Nuclear Materials Authority, Cairo (Egypt); Stockholm Univ. (Sweden). Dept. of Organic Chemistry

2017-07-01

There is a high interest to develop suitable solid phase extractants for uranium separation from aqueous solutions in order to reduce cost and enhance the efficiency. This paper describes solid phase extraction of uranium(VI) from aqueous phosphoric acid solution using MCM-41 based D2HEPA-TOPO organophosphorous extractants. The mixture of D2HEPA (di-2-ethyl-hexylphosphoric acid) and TOPO (tri-n-octylphosphine oxide) was impregnated into the pores of MCM-41 and the synthesized sorbent was fully characterized. The influences of different factors such as synergistic mixture ratio, phosphoric acid concentration, mixing time and temperature were investigated. The results showed that 90% of uranium(VI) extraction can be achieved within 5 min, using D2HEPA-TOPO rate at MCM-41 (mass ratio 2:1 w/w) from 1 M phosphoric acid containing 64 ppm of uranium at room temperature. High adsorption capacity of uranium(VI) have been achieved at the mentioned conditions. The rate constant for the chemical adsorption of uranium(VI) was 0.988 g mg{sup -1} min{sup -1} calculated by the pseudo-second order rate equation. The obtained thermodynamics parameters showed that uranium(VI) adsorption from H{sub 3}PO{sub 4} is an exothermic and spontaneous process.

Mechanics of adsorption-deformation coupling in porous media

Science.gov (United States)

Zhang, Yida

2018-05-01

This work extends Coussy's macroscale theory for porous materials interacting with adsorptive fluid mixtures. The solid-fluid interface is treated as an independent phase that obeys its own mass, momentum and energy balance laws. As a result, a surface strain energy term appears in the free energy balance equation of the solid phase, which further introduces the so-called adsorption stress in the constitutive equations of the porous skeleton. This establishes a fundamental link between the adsorption characteristics of the solid-fluid interface and the mechanical response of the porous media. The thermodynamic framework is quite general in that it recovers the coupled conduction laws, Gibbs isotherm and the Shuttleworth's equation for surface stress, and imposes no constraints on the magnitude of deformation and the functional form of the adsorption isotherms. A rich variety of coupling between adsorption and deformation is recovered as a result of combining different poroelastic models (isotropic vs. anisotropic, linear vs. nonlinear) and adsorption models (unary vs. mixture adsorption, uncoupled vs. stretch-dependent adsorption). These predictions are discussed against the backdrop of recent experimental data on coal swelling subjected to CO2 and CO2sbnd CH4 injections, showing the capability and versatility of the theory in capturing adsorption-induced deformation of porous materials.

Solid amine sorbents for CO2 capture by chemical adsorption: A review

Directory of Open Access Journals (Sweden)

Elif Erdal Ünveren

2017-03-01

Full Text Available Amines are well-known for their reversible reactions with CO2, which make them ideal for CO2 capture from several gas streams, including flue gas. In this respect, selective CO2 absorption by aqueous alkanolamines is the most mature technology but the process is energy intensive and has also corrosion problems. Both disadvantages can be diminished to a certain extent by chemical adsorption of CO2 selectively. The most important element of the chemical adsorption of CO2 involves the design and development of a suitable adsorbent which consist of a porous support onto which an amine is attached or immobilized. Such an adsorbent is often called as solid amine sorbent. This review covers solid amine-based studies which are developed and published in recent years. First, the review examines several different types of porous support materials, namely, three mesoporous silica (MCM-41, SBA-15 and KIT-6 and two polymeric supports (PMMA and PS for CO2 adsorption. Emphasis is given to the synthesis, modifications and characterizations -such as BET and PXRD data-of them. Amination of these supports to obtain a solid amine sorbent through impregnation or grafting is reviewed comparatively. Focus is given to the adsorption mechanisms, material characteristics, and synthesis methods which are discussed in detail. Significant amount of original data are also presented which makes this review unique. Finally, relevant CO2 adsorption (or equilibrium capacity data, and cyclic adsorption/desorption performance and stability of important classes of solid amine sorbents are critically reviewed. These include severa PEI or TEPA impregnated adsorbents and APTES-grafted systems.

Recent Application of Solid Phase Based Techniques for Extraction and Preconcentration of Cyanotoxins in Environmental Matrices.

Science.gov (United States)

Mashile, Geaneth Pertunia; Nomngongo, Philiswa N

2017-03-04

Cyanotoxins are toxic and are found in eutrophic, municipal, and residential water supplies. For this reason, their occurrence in drinking water systems has become a global concern. Therefore, monitoring, control, risk assessment, and prevention of these contaminants in the environmental bodies are important subjects associated with public health. Thus, rapid, sensitive, selective, simple, and accurate analytical methods for the identification and determination of cyanotoxins are required. In this paper, the sampling methodologies and applications of solid phase-based sample preparation methods for the determination of cyanotoxins in environmental matrices are reviewed. The sample preparation techniques mainly include solid phase micro-extraction (SPME), solid phase extraction (SPE), and solid phase adsorption toxin tracking technology (SPATT). In addition, advantages and disadvantages and future prospects of these methods have been discussed.

Two-dimensional solid-phase extraction strategy for the selective enrichment of aminoglycosides in milk.

Science.gov (United States)

Shen, Aijin; Wei, Jie; Yan, Jingyu; Jin, Gaowa; Ding, Junjie; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2017-03-01

An orthogonal two-dimensional solid-phase extraction strategy was established for the selective enrichment of three aminoglycosides including spectinomycin, streptomycin, and dihydrostreptomycin in milk. A reversed-phase liquid chromatography material (C 18 ) and a weak cation-exchange material (TGA) were integrated in a single solid-phase extraction cartridge. The feasibility of two-dimensional clean-up procedure that experienced two-step adsorption, two-step rinsing, and two-step elution was systematically investigated. Based on the orthogonality of reversed-phase and weak cation-exchange procedures, the two-dimensional solid-phase extraction strategy could minimize the interference from the hydrophobic matrix existing in traditional reversed-phase solid-phase extraction. In addition, high ionic strength in the extracts could be effectively removed before the second dimension of weak cation-exchange solid-phase extraction. Combined with liquid chromatography and tandem mass spectrometry, the optimized procedure was validated according to the European Union Commission directive 2002/657/EC. A good performance was achieved in terms of linearity, recovery, precision, decision limit, and detection capability in milk. Finally, the optimized two-dimensional clean-up procedure incorporated with liquid chromatography and tandem mass spectrometry was successfully applied to the rapid monitoring of aminoglycoside residues in milk. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon nanotubes as solid-phase extraction sorbents prior to atomic spectrometric determination of metal species: A review

International Nuclear Information System (INIS)

Herrero Latorre, C.; Álvarez Méndez, J.; Barciela García, J.; García Martín, S.; Peña Crecente, R.M.

2012-01-01

Highlights: ► The use of CNTs as sorbent for metal species in solid phase extraction has been described. ► Physical and chemical strategies for functionalization of carbon nanotubes have been discussed. ► Published analytical methods concerning solid phase extraction and atomic spectrometric determination have been reviewed. - Abstract: New materials have significant impact on the development of new methods and instrumentation for chemical analysis. From the discovery of carbon nanotubes in 1991, single and multi-walled carbon nanotubes – due to their high adsorption and desorption capacities – have been employed as sorption substrates in solid-phase extraction for the preconcentration of metal species from diverse matrices. Looking for successive improvements in sensitivity and selectivity, in the past few years, carbon nanotubes have been utilized as sorbents for solid phase extraction in three different ways: like as-grown, oxidized and functionalized nanotubes. In the present paper, an overview of the recent trends in the use of carbon nanotubes for solid phase extraction of metal species in environmental, biological and food samples is presented. The determination procedures involved the adsorption of metals on the nanotube surface, their quantitative desorption and subsequent measurement by means of atomic spectrometric techniques such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry/mass spectrometry, among others. Synthesis, purification and types of carbon nanotubes, as well as the diverse chemical and physical strategies for their functionalization are described. Based on 140 references, the performance and general properties of the applications of solid phase extraction based on carbon nanotubes for metal species atomic spectrometric determination are discussed.

Carbon nanotubes as solid-phase extraction sorbents prior to atomic spectrometric determination of metal species: A review

Energy Technology Data Exchange (ETDEWEB)

Herrero Latorre, C., E-mail: carlos.herrero@usc.es [Universidad de Santiago de Compostela, Dpto. Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Alfonso X el Sabio s/n, 27002 Lugo (Spain); Alvarez Mendez, J.; Barciela Garcia, J.; Garcia Martin, S.; Pena Crecente, R.M. [Universidad de Santiago de Compostela, Dpto. Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Alfonso X el Sabio s/n, 27002 Lugo (Spain)

2012-10-24

Highlights: Black-Right-Pointing-Pointer The use of CNTs as sorbent for metal species in solid phase extraction has been described. Black-Right-Pointing-Pointer Physical and chemical strategies for functionalization of carbon nanotubes have been discussed. Black-Right-Pointing-Pointer Published analytical methods concerning solid phase extraction and atomic spectrometric determination have been reviewed. - Abstract: New materials have significant impact on the development of new methods and instrumentation for chemical analysis. From the discovery of carbon nanotubes in 1991, single and multi-walled carbon nanotubes - due to their high adsorption and desorption capacities - have been employed as sorption substrates in solid-phase extraction for the preconcentration of metal species from diverse matrices. Looking for successive improvements in sensitivity and selectivity, in the past few years, carbon nanotubes have been utilized as sorbents for solid phase extraction in three different ways: like as-grown, oxidized and functionalized nanotubes. In the present paper, an overview of the recent trends in the use of carbon nanotubes for solid phase extraction of metal species in environmental, biological and food samples is presented. The determination procedures involved the adsorption of metals on the nanotube surface, their quantitative desorption and subsequent measurement by means of atomic spectrometric techniques such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry/mass spectrometry, among others. Synthesis, purification and types of carbon nanotubes, as well as the diverse chemical and physical strategies for their functionalization are described. Based on 140 references, the performance and general properties of the applications of solid phase extraction based on carbon nanotubes for metal species atomic spectrometric determination are discussed.

Effect of solid state fermentation of peanut shell on its dye adsorption performance.

Science.gov (United States)

Liu, Jiayang; Wang, Zhixin; Li, Hongyan; Hu, Changwei; Raymer, Paul; Huang, Qingguo

2018-02-01

The effect of solid state fermentation of peanut shell to produce beneficial laccase and on its dye adsorption performance was evaluated. The resulting residues from solid fermentation were tested as sorbents (designated as SFs) in comparison to the raw peanut shell (RPS) for their ability to remove crystal violet from water. The fermentation process reduced the adsorption capacity (q m ) of SF by about 50%, and changed the sorptive behavior when compared to the RPS. The Langmuir model was more suitable for fitting adsorption by SFs. q m was positively correlated with the surface area of peanut shell, but negatively correlated with acid detergent lignin content. For all the sorbents tested, the process was spontaneous and endothermic, and the adsorption followed both the pseudo 1st and 2nd order kinetic model and the film diffusion model. Dye adsorption efficiency was greater when SFs dispersed solution than when placed in filter packets. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solid-phase extraction and high-performance liquid chromatographic separation of pigments of red wines.

Science.gov (United States)

Csiktusnádi Kiss, G A; Forgács, E; Cserháti, T; Candeias, M; Vilas-Boas, L; Bronze, R; Spranger, I

2000-08-11

The adsorption and desorption capacities of 11 different solid-phase extraction sorbents were tested for the preconcenration of pigments of various Hungarian red wines. The concentrates were evaluated by multiwavelengh spectrophotometry combined with a spectral mapping technique (SPM) and by reversed-phase high-performance liquid chromatography. The highest (10-fold) concentration of pigments was achieved on octadecylsilica sorbent. It can be used five times without losing adsorption and desorption characteristics. SPM indicated that multiwavelength spectrophotometry can be employed for the differentiation of red wines. Comparison of the chromatograms of pigments with and without preconcentration showed that preconcentration makes possible the separation and detection of pigments present in low concentration in red wines.

transient effects on the performances of a solid adsorption solar

African Journals Online (AJOL)

generator/adsorber for use in solid adsorption refrigeration system is presented. The collector/generator/adsorber uses activated carbon as the adsorbent and methanol as the refrigerant. The study was undertaken using an earlier developed ...

Microwave assisted solid phase extraction for separation preconcentration sulfamethoxazole in wastewater using tyre based activated carbon as solid phase material prior to spectrophotometric determination

Science.gov (United States)

Mogolodi Dimpe, K.; Mpupa, Anele; Nomngongo, Philiswa N.

2018-01-01

This work was chiefly encouraged by the continuous consumption of antibiotics which eventually pose harmful effects on animals and human beings when present in water systems. In this study, the activated carbon (AC) was used as a solid phase material for the removal of sulfamethoxazole (SMX) in wastewater samples. The microwave assisted solid phase extraction (MASPE) as a sample extraction method was employed to better extract SMX in water samples and finally the analysis of SMX was done by the UV-Vis spectrophotometer. The microwave assisted solid phase extraction method was optimized using a two-level fractional factorial design by evaluating parameters such as pH, mass of adsorbent (MA), extraction time (ET), eluent ratio (ER) and microwave power (MP). Under optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.5 μg L- 1 and 1.7 μg L- 1, respectively, and intraday and interday precision expressed in terms of relative standard deviation were > 6%.The maximum adsorption capacity was 138 mg g- 1 for SMX and the adsorbent could be reused eight times. Lastly, the MASPE method was applied for the removal of SMX in wastewater samples collected from a domestic wastewater treatment plant (WWTP) and river water.

Simplified local density model for adsorption over large pressure ranges

International Nuclear Information System (INIS)

Rangarajan, B.; Lira, C.T.; Subramanian, R.

1995-01-01

Physical adsorption of high-pressure fluids onto solids is of interest in the transportation and storage of fuel and radioactive gases; the separation and purification of lower hydrocarbons; solid-phase extractions; adsorbent regenerations using supercritical fluids; supercritical fluid chromatography; and critical point drying. A mean-field model is developed that superimposes the fluid-solid potential on a fluid equation of state to predict adsorption on a flat wall from vapor, liquid, and supercritical phases. A van der Waals-type equation of state is used to represent the fluid phase, and is simplified with a local density approximation for calculating the configurational energy of the inhomogeneous fluid. The simplified local density approximation makes the model tractable for routine calculations over wide pressure ranges. The model is capable of prediction of Type 2 and 3 subcritical isotherms for adsorption on a flat wall, and shows the characteristic cusplike behavior and crossovers seen experimentally near the fluid critical point

Non-equilibrium Thermodynamic Dissolution Theory for Multi-Component Solid/Liquid Surfaces Involving Surface Adsorption and Radiolysis Kinetics

International Nuclear Information System (INIS)

Stout, R B

2001-01-01

A theoretical expression is developed for the dissolution rate response for multi-component radioactive materials that have surface adsorption kinetics and radiolysis kinetics when wetted by a multi-component aqueous solution. An application for this type of dissolution response is the performance evaluation of multi-component spent nuclear fuels (SNFs) for long term interim storage and for geological disposition. Typically, SNF compositions depend on initial composition, uranium oxide and metal alloys being most common, and on reactor burnup which results in a wide range of fission product and actinide concentrations that decay by alpha, beta, and gamma radiation. These compositional/burnup ranges of SNFs, whether placed in interim storage or emplaced in a geologic repository, will potentially be wetted by multi-component aqueous solutions, and these solutions may be further altered by radiolytic aqueous species due to three radiation fields. The solid states of the SNFs are not thermodynamically stable when wetted and will dissolve, with or without radiolysis. The following development of a dissolution theory is based on a non-equilibrium thermodynamic analysis of energy reactions and energy transport across a solid-liquid phase change discontinuity that propagates at a quasi-steady, dissolution velocity. The integral form of the energy balance equation is used for this spatial surface discontinuity analysis. The integral formulation contains internal energy functional of classical thermodynamics for both the SNFs' solid state and surface adsorption species, and the adjacent liquid state, which includes radiolytic chemical species. The steady-state concentrations of radiolytic chemical species are expressed by an approximate analysis of the decay radiation transport equation. For purposes of illustration a modified Temkin adsorption isotherm was assumed for the surface adsorption kinetics on an arbitrary, finite area of the solid-liquid dissolution interface. For

Adsorption by powders and porous solids principles, methodology and applications

CERN Document Server

Rouquerol, Jean; Llewellyn, Philip; Maurin, Guillaume; Sing, Kenneth SW

2013-01-01

The declared objective of this book is to provide an introductory review of the various theoretical and practical aspects of adsorption by powders and porous solids with particular reference to materials of technological importance. The primary aim is to meet the needs of students and non-specialists who are new to surface science or who wish to use the advanced techniques now available for the determination of surface area, pore size and surface characterization. In addition, a critical account is given of recent work on the adsorptive properties of activated carbons, oxides, clays and zeolit

Equilibrium, kinetics and thermodynamics studies of chitosan-based solid phase nanoparticles as sorbent for lead (II) cations from aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Shaker, Medhat A., E-mail: drmashaker@yahoo.com [Current address: Chemistry Department, Faculty of Science, University of Jeddah, Jeddah (Saudi Arabia); Permanent address: Chemistry Department, Faculty of Science, Damanhour University, Damanhour (Egypt)

2015-07-15

Ternary nanoparticles of chitosan, non-viable biomass (Pseudomonas sp.) and gelatin, CPG were synthesized by chemical crosslinking method and applied as a novel and cost-effective solid phase to adsorb Pb(II) cations from aqueous solution. Characterization of the fabricated CPG nanoparticles and their complexation behavior were extensively interrogated by dynamic light scattering (DLS), FTIR, TGA, XRD and SEM techniques. The extent of adsorption was found to be a function of medium pH, contact time, initial Pb(II) concentration and temperature. The Langmuir, Freundlich, Dubinin–Radushkevich and Redlich–Peterson models were used to illustrate the isotherms of the adsorption system. The adsorption of Pb(II) cations onto CPG best-fits the Langmuir isotherm model which predicts two stoichiometric temperature-independent adsorption sites, A and B with variable capacities, 35.4 and 91.1 mg g{sup −1}, respectively and removal capacity above 90%. Thermodynamic studies revealed that the adsorption process was physical, spontaneous, and endothermic. The adsorption rate is influenced by temperature and the adsorption kinetic is well confirmed with pseudo-second-order equation compared with three other investigated kinetic models. Present study indicated potential applications of CPG nanoparticles as excellent natural and promising solid phase for Pb(II) extraction in wastewater treatment. - Graphical abstract: Display Omitted - Highlights: • Kinetics and thermodynamics of Pb{sup 2+} biosorption onto CPG nanoparticles are studied. • Adsorption kinetic data are best modeled using second-order rate equations. • The Pb{sup 2}adsorption onto CPG was physical diffusion controlled reaction. • The experimental equilibrium results well fit the Langmuir model. • The thermodynamics show endothermic, favorable and spontaneous adsorption processes.

Anti-glomerular basement membrane autoantibodies in the Brown Norway rat: detection by a solid-phase radioimmunoassay

International Nuclear Information System (INIS)

Bowman, C.; Peters, D.K.; Lockwood, C.M.

1983-01-01

A solid-phase radioimmunoassay (RIA) is described for the detection of IgG autoantibodies to glomerular basement membrane (GBM) induced in the Brown Norway rat by mercuric chloride. The assay involves the adsorption of a collagenase digest of GBM to plastic microtitre plates and detection of bound antibody with affinity purified radiolabelled rabbit anti-rat IgG. Comparison with existing immunofluorescence methods for detection of anti-GBM antibody showed that the solid-phase RIA is highly sensitive, allowing detection of antibody in solutions with as low as 0.5 ng protein/ml. The assay is suitable for detection of anti-GBM antibody both in serum and in eluates from nephritic kidneys. The assay proved to be specific in competitive studies of inhibition brought about by GBM, keyhole limpet antigen and ovalbumin. This solid-phase RIA is reproducible, robust and easy to perform. (Auth.)

High Pressure Multicomponent Adsorption in Porous Media

DEFF Research Database (Denmark)

Shapiro, Alexander; Stenby, Erling Halfdan

1999-01-01

We analyse adsorption of a multicomponent mixture at high pressure on the basis of the potential theory of adsorption. The adsorbate is considered as a segregated mixture in the external field produced by a solid adsorbent. we derive an analytical equation for the thickness of a multicomponent fi...... close to a dew point. This equation (asymptotic adsorption equation, AAE) is a first order approximation with regard to the distance from a phase envelope....

Preconcentration of trace manganese from natural waters by complexation with dithiocarbamate and adsorption onto C18-solid phase extraction column for neutron activation analysis

International Nuclear Information System (INIS)

Sarmani, S.B.; Abdullah, M.P.; Bobaker, A.M.

2004-01-01

A method was developed for the preconcentration and separation of trace manganese from natural water samples by complexation with dithiocarbamate followed by adsorption onto C 18 -solid phase extraction column prior to irradiation. The Mn recovery was better than 99.8% without interference from iron(III) at 5 mg x l -1 , copper(II), zinc(II), aluminum(III) and cobalt(II) at 0.5 mg x l -1 and sodium(I), potassium(I), magnesium(II) and calcium(II) at 1 mg x l -1 . The separation factor was 100 and the detection limit was 0.01 μg x l -1 with good precision and accuracy with a relative error lower than 3%. The method was applied to the determination of Mn in tap, well, river and treated water samples. (author)

Role of particle size and composition in metal adsorption by solids deposited on urban road surfaces

International Nuclear Information System (INIS)

Gunawardana, Chandima; Egodawatta, Prasanna; Goonetilleke, Ashantha

2014-01-01

Despite common knowledge that the metal content adsorbed by fine particles is relatively higher compared to coarser particles, the reasons for this phenomenon have gained little research attention. The research study discussed in the paper investigated the variations in metal content for different particle sizes of solids associated with pollutant build-up on urban road surfaces. Data analysis confirmed that parameters favourable for metal adsorption to solids such as specific surface area, organic carbon content, effective cation exchange capacity and clay forming minerals content decrease with the increase in particle size. Furthermore, the mineralogical composition of solids was found to be the governing factor influencing the specific surface area and effective cation exchange capacity. There is high quartz content in particles >150 μm compared to particles <150 μm. As particle size reduces below 150 μm, the clay forming minerals content increases, providing favourable physical and chemical properties that influence adsorption. -- Highlights: • Physico-chemical parameters investigated in build-up samples from 32 road surfaces. • Mineralogical composition primarily governs the physico-chemical characteristics. • High clay forming mineral content in fine solids increases SSA and ECEC. • Characteristics influenced by quartz and amorphous content with particle size. • High quartz content in coarse particles contributes reduced metal adsorption. -- The mineralogical composition of solids is the governing factor influencing metal adsorption to solids in pollutant build-up on urban surfaces

The distribution and adsorption behavior of aliphatic amines in marine and lacustrine sediments

Science.gov (United States)

Wang, Xu-chen; Lee, Cindy

1990-10-01

The methylated amines—monomethyl-, dimethyl-, and trimethyl amine (MMA, DMA, TMA)—are commonly found in aquatic environments, apparently as a result of decomposition processes. Adsorption of these amines to clay minerals and organic matter significantly influences their distribution in sediments. Laboratory measurements using 14C-radiolabelled amines and application of a linear partitioning model resulted in calculated adsorption coefficients of 2.4-4.7 (MMA), 3.3 (DMA), and 3.3-4.1 (TMA). Further studies showed that adsorption of amines is influenced by salinity of the porewaters, and clay mineral and organic matter content of the sediment solid phase. Concentrations of monomethyl- and dimethyl amine were measured in the porewaters and the solid phase of sediment samples collected from Flax Pond and Lake Ronkonkoma (NY), Long Island Sound, and the coastal Peru upwelling area. These two amines were present in all sediments investigated. A clear seasonal increase in the solid-phase concentration of MMA and DMA in Flax Pond sediments was likely related to the annual senescence of salt marsh grasses, either directly as a source of these compounds or indirectly by providing additional exchange capacity to the sediments. The distribution of amines in the solid and dissolved phases observed in all sediments investigated suggests that the distribution of these compounds results from a balance among production, decomposition, and adsorption processes.

Carbon dioxide capture from exhaust gases by selective adsorption on porous solids

Energy Technology Data Exchange (ETDEWEB)

Schindler, M.; Ernst, S. [Technische Univ. Kaiserslautern (Germany). Dept. of Chemistry

2007-07-01

The metal-organic frameworks Cu{sub 3}(BTC){sub 2}, MIL-53 and MIL-96 were synthesized and characterized by powder X-ray diffraction, scanning electron microscopy and nitrogenphysisorption. The adsorption isotherms for carbon dioxide at temperatures of 20, 40 and 60 C and pressures up to 1000 mbar on this new type of microporous solids were measured by a static volumetric method. For comparison, experiments with zeolite NaX (13X) were also included. High adsorption capacities for carbon dioxide were found for the adsorbents investigated in this study. The breakthrough curves for the adsorption of a mixture of nitrogen and carbon dioxide on Cu{sub 3}(BTC){sub 2} reveal a high affinity of this material for the adsorption of carbon dioxide in the presence of nitrogen. (orig.)

Eriochrome Blue Black modified activated carbon as solid phase extractor for removal of Pb(II ions from water samples

Directory of Open Access Journals (Sweden)

Hassan M. Albishri

2017-05-01

Full Text Available In the current study, a sensitive and simple method for the removal of lead Pb(II, from water samples prior to its determination by inductively coupled plasma optical emission spectrometry (ICP-OES, was investigated. The method utilized activated carbon (AC physically modified with Eriochrome Blue Black (EBB as a solid-phase extractant. Surface properties of the AC-EBB phase were characterized by FT-IR and SEM. The separation parameters for effective adsorption of lead Pb(II, including effects of pH, initial concentration of Pb(II, coexisting ions and shaking time using batch method were studied. The optimum pH value for the separation of Pb(II on the new sorbent was 7.0, and the maximum static adsorption capacity of Pb(II onto the AC-EBB was 127.896 mg/g at this pH and after 1 h contact time. The Pb(II adsorption data were modeled using Langmuir adsorption isotherms. Results demonstrated that the adsorption of Pb(II onto activated carbon followed pseudo second-order kinetic model.

Characterization of van der Waals type bimodal,- lambda,- meta- and spinodal phase transitions in liquid mixtures, solid suspensions and thin films.

Science.gov (United States)

Rosenholm, Jarl B

2018-03-01

The perfect gas law is used as a reference when selecting state variables (P, V, T, n) needed to characterize ideal gases (vapors), liquids and solids. Van der Waals equation of state is used as a reference for models characterizing interactions in liquids, solids and their mixtures. Van der Waals loop introduces meta- and unstable states between the observed gas (vapor)-liquid P-V transitions at low T. These intermediate states are shown to appear also between liquid-liquid, liquid-solid and solid-solid phase transitions. First-order phase transitions are characterized by a sharp discontinuity of first-order partial derivatives (P, S, V) of Helmholtz and Gibbs free energies. Second-order partial derivatives (K T , B, C V , C P , E) consist of a static contribution relating to second-order phase transitions and a relaxation contribution representing the degree of first-order phase transitions. Bimodal (first-order) and spinodal (second-order) phase boundaries are used to separate stable phases from metastable and unstable phases. The boundaries are identified and quantified by partial derivatives of molar Gibbs free energy or chemical potentials with respect to P, S, V and composition (mole fractions). Molecules confined to spread Langmuir monolayers or adsorbed Gibbs monolayers are characterized by equation of state and adsorption isotherms relating to a two-dimensional van der Waals equation of state. The basic work of two-dimensional wetting (cohesion, adsorption, spreading, immersion), have to be adjusted by a horizontal surface pressure in the presence of adsorbed vapor layers. If the adsorption is extended to liquid films a vertical surface pressure (Π) may be added to account for the lateral interaction, thus restoring PV = ΠAh dependence of thin films. Van der Waals attraction, Coulomb repulsion and structural hydration forces contribute to the vertical surface pressure. A van der Waals type coexistence of ordered (dispersed) and disordered

Adsorption of Cationic Peptides to Solid Surfaces of Glass and Plastic

DEFF Research Database (Denmark)

Kristensen, Kasper; Henriksen, Jonas Rosager; Andresen, Thomas Lars

2015-01-01

, that the peptides adsorb to solid surfaces of glass and plastic. Specifically, we use analytical HPLC to systematically quantify the adsorption of the three cationic membraneactive peptides mastoparan X, melittin, and magainin 2 to the walls of commonly used glass and plastic sample containers. Our results show...

Effects of nonequilibrium adsorption on nuclide transport in a porous rock

International Nuclear Information System (INIS)

Shi-Ping Teng; Ching-Hor Lee

1994-01-01

An analytical solution covering the entire range of adsorption properties of rock has been derived for the migration of radionuclide in a porous rock matrix. The analysis takes into account the advective transport, hydrodynamic dispersion, adsorption between solid phase and liquid phase, and the radioactive decay. For adsorption of nuclide within the rock, the effects of no adsorption, linear nonequilibrium adsorption, and linear equilibrium adsorption are integrated into a generic transient analytical solution. The results indicate that the assumption of equilibrium adsorption can result in underestimation of the concentration profile in the early stages of migration. However, both the equilibrium and nonequilibrium profiles eventually approach the same value. It is also noted that for the case of nonequilibrium adsorption, plateaus appear in the concentration profile of the breakthrough curves. The effects of different adsorption rates are also analyzed

Lattice Boltzmann simulation of the gas-solid adsorption process in reconstructed random porous media

Science.gov (United States)

Zhou, L.; Qu, Z. G.; Ding, T.; Miao, J. Y.

2016-04-01

The gas-solid adsorption process in reconstructed random porous media is numerically studied with the lattice Boltzmann (LB) method at the pore scale with consideration of interparticle, interfacial, and intraparticle mass transfer performances. Adsorbent structures are reconstructed in two dimensions by employing the quartet structure generation set approach. To implement boundary conditions accurately, all the porous interfacial nodes are recognized and classified into 14 types using a proposed universal program called the boundary recognition and classification program. The multiple-relaxation-time LB model and single-relaxation-time LB model are adopted to simulate flow and mass transport, respectively. The interparticle, interfacial, and intraparticle mass transfer capacities are evaluated with the permeability factor and interparticle transfer coefficient, Langmuir adsorption kinetics, and the solid diffusion model, respectively. Adsorption processes are performed in two groups of adsorbent media with different porosities and particle sizes. External and internal mass transfer resistances govern the adsorption system. A large porosity leads to an early time for adsorption equilibrium because of the controlling factor of external resistance. External and internal resistances are dominant at small and large particle sizes, respectively. Particle size, under which the total resistance is minimum, ranges from 3 to 7 μm with the preset parameters. Pore-scale simulation clearly explains the effect of both external and internal mass transfer resistances. The present paper provides both theoretical and practical guidance for the design and optimization of adsorption systems.

Molecularly imprinted solid-phase extraction of glutathione from urine samples

International Nuclear Information System (INIS)

Song, Renyuan; Hu, Xiaoling; Guan, Ping; Li, Ji; Zhao, Na; Wang, Qiaoli

2014-01-01

Molecularly imprinted polymer (MIP) particles for glutathione were synthesized through iniferter-controlled living radical precipitation polymerization (IRPP) under ultraviolet radiation at ambient temperature. Static adsorption, solid-phase extraction, and high-performance liquid chromatography were carried out to evaluate the adsorption properties and selective recognition characteristics of the polymers for glutathione and its structural analogs. The obtained IRPP-MIP particles exhibited a regularly spherical shape, rapid binding kinetics, high imprinting factor, and high selectivity compared with the MIP particles prepared using traditional free-radical precipitation polymerization. The selective separation and enrichment of glutathione from the mixture of glycyl-glycine and glutathione disulfide could be achieved on the IRPP-MIP cartridge. The recoveries of glutathione, glycyl-glycine, and glutathione disulfide were 95.6% ± 3.65%, 29.5% ± 1.26%, and 49.9% ± 1.71%, respectively. The detection limit (S/N = 3) of glutathione was 0.5 mg·L −1 . The relative standard deviations (RSDs) for 10 replicate detections of 50 mg·L −1 of glutathione were 5.76%, and the linear range of the calibration curve was 0.5 mg·L −1 to 200 mg·L −1 under optimized conditions. The proposed approach was successfully applied to determine glutathione in spiked human urine samples with recoveries of 90.24% to 96.20% and RSDs of 0.48% to 5.67%. - Highlights: • Imprinted polymer particles were prepared by IRPP at ambient temperature. • High imprinting factor, high selectivity, and rapid binding kinetics were achieved. • Selective solid-phase extraction of glutathione from human urine samples

A microplate adaptation of the solid-phase C1q immune complex assay

International Nuclear Information System (INIS)

Hunt, J.S.; Kennedy, M.P.; Barber, K.E.; McGiven, A.R.

1980-01-01

A method has been developed for the detection of C1q binding immune complexes in serum in which microculture plates are used as the solid-phase matrix for adsorption of C1q. This micromethod used only one-tenth of the amount of both C1q and [ 125 I]antihuman immunoglobulin per test and enabled 7 times as many samples to be tested in triplicate in comparison with the number performed in duplicate by the standard tube assay. (Auth.)

Development of andrographolide molecularly imprinted polymer for solid-phase extraction

Science.gov (United States)

Yin, Xiaoying; Liu, Qingshan; Jiang, Yifan; Luo, Yongming

2011-06-01

A method employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE) to pretreat samples was developed. The polymers were prepared by precipitation polymerization with andrographolide as template molecule. The structure of MIP was characterized and its static adsorption capacity was measured by the Scatchard equation. In comparison with C 18-SPE and non-imprinted polymer (NIP) SPE column, MIP-SPE column displays high selectivity and good affinity for andrographolide and dehydroandrographolide for extract of herb Andrographis paniculata ( Burm.f.) Nees (APN). MIP-SPE column capacity was 11.9 ± 0.6 μmol/g and 12.1 ± 0.5 μmol/g for andrographolide and dehydroandrographolide, respectively and was 2-3 times higher than that of other two columns. The precision and accuracy of the method developed were satisfactory with recoveries between 96.4% and 103.8% (RSD 3.1-4.3%, n = 5) and 96.0% and 104.2% (RSD 2.9-3.7%, n = 5) for andrographolide and dehydroandrographolide, respectively. Various real samples were employed to confirm the feasibility of method. This developed method demonstrates the potential of molecularly imprinted solid phase extraction for rapid, selective, and effective sample pretreatment.

Solid phase extraction of copper(II) by fixed bed procedure on cation exchange complexing resins.

Science.gov (United States)

Pesavento, Maria; Sturini, Michela; D'Agostino, Girolamo; Biesuz, Raffaela

2010-02-19

The efficiency of the metal ion recovery by solid phase extraction (SPE) in complexing resins columns is predicted by a simple model based on two parameters reflecting the sorption equilibria and kinetics of the metal ion on the considered resin. The parameter related to the adsorption equilibria was evaluated by the Gibbs-Donnan model, and that related to the kinetics by assuming that the ion exchange is the adsorption rate determining step. The predicted parameters make it possible to evaluate the breakthrough volume of the considered metal ion, Cu(II), from different kinds of complexing resins, and at different conditions, such as acidity and ionic composition. Copyright 2009. Published by Elsevier B.V.

Neutron reflectivity as method to study in-situ adsorption of phospholipid layers to solid-liquid interfaces

DEFF Research Database (Denmark)

Gutberlet, Thomas; Klösgen, Beate Maria; Krastev, Rumen

2004-01-01

variation. It was observed that the method was capable of visualizing the adsorption of phospholipid layers to different solid-liquid interfaces and to resolve structural details at Angstroem resolution. The results depended strongly on a sufficiently good signal-to-noise ratio of the specific measurements......The use of neutron reflectivity as a method to study in-situ adsorption of phospholipid layers to solid-liquid interfaces was analyzed. The most important advantage of neutron reflectometry is the possibility to very the refractive index of the specific sample by isotope exchange, called contrast...

Thermodynamic and topochemical aspects of the adsorption of some gaseous fluorides and solid fluorides

International Nuclear Information System (INIS)

Le Gressus, Claude

1968-01-01

This research thesis addresses the study of chemical adsorption. Such an adsorption is limited to a mono-molecular layer. As the Order Disorder Theory (ODT) allows adsorption isotherms to be calculated while taking interaction between adsorbed molecules into account, this research reports a comparison between the shape of experimental isotherms and that of theoretical isotherms. The knowledge of the involved phenomena is completed by the measurement of adsorption differential heats. After some generalities and a brief presentation of the ODT, the author presents experimental installations and techniques (micro-calorimeter, Mac-Bain balance), describes the adsorbent pre-treatment, reports the analysis performed by micro-sublimation, reports the study of the adsorption of hydrofluoric acid on CaF 2 , highlights the existence of different cases of energies increasing with the overlay rate, reports the detailed study of adsorption isotherms of ClF 3 and UF 6 on various solid fluorides. Results are finally interpreted and discussed

Adsorption, aggregation and phase separation in colloidal systems

OpenAIRE

Dai, Jing

2017-01-01

The thesis presents work regarding amphiphilic molecules associated in aqueous solution or at the liquid/solid interface. Two main topics are included: the temperature-dependent behavior of micelles and the adsorption of dispersants on carbon nanotube (CNT) surfaces. Various NMR methods were used to analyze those systems, such as chemical shift detection, spectral intensity measurements, spin relaxation and, in particular, self-diffusion experiments. Besides this, small angle X-ray scattering...

Adsorption of fluids on solid surfaces: A route toward very dense layers

Energy Technology Data Exchange (ETDEWEB)

Sartarelli, S.A. [Instituto de Desarrollo Humano, Universidad Nacional de General Sarmiento, San Miguel (Argentina); Szybisz, L., E-mail: szybisz@tandar.cnea.gov.ar [Laboratorio TANDAR, Departamento de Fisica, Comision Nacional de Energia Atomica, RA-1429 Buenos Aires (Argentina); Departamento de Fiica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, RA-1033 Buenos Aires (Argentina)

2012-08-15

Adsorption of Xe on single planar walls is investigated in the frame of a density functional theory. The strength of the adsorbate-substrate attraction is changed by considering surfaces of Cs, Na, Li, and Mg. The behavior is analyzed by varying the temperature T (between the triple point T{sub t} and the critical T{sub c}) and the coverage {Gamma}{sub Script-Small-L }. The obtained adsorption isotherms exhibit a variety of wetting situations. Density profiles are reported. It is shown that for strongly attractive surfaces the adsorbed liquid becomes very dense reaching densities characteristic of solids.

Adsorption and Retardation of PFASs in Soil

Science.gov (United States)

Chen, W.; Yan, N.; Fu, X.; Carroll, K. C.; Holguin, F. O. O.; Brusseau, M. L.

2017-12-01

Per- and poly-fluorinated alkyl substances (PFASs) are emerging contaminants of concern that are present in the subsurface at numerous military and industrial facilities. Knowledge of the retention behavior of these compounds in the subsurface environment is critical for effective risk characterization and remediation. The objective of this research is to investigate the role of adsorption at the air-water interface on PFAS retention in vadose-zone systems. Surface tensions were measured for select PFAS to determine interfacial adsorption coefficients. Column experiments were conducted to characterize retardation and transport under saturated and unsaturated flow conditions. The impact of soil properties and groundwater constituents on surface tension, solid-phase adsorption, and interfacial adsorption was investigated.

Solid-solid phase transitions in Fe nanowires induced by axial strain

International Nuclear Information System (INIS)

Sandoval, Luis; Urbassek, Herbert M

2009-01-01

By means of classical molecular-dynamics simulations we investigate the solid-solid phase transition from a bcc to a close-packed crystal structure in cylindrical iron nanowires, induced by axial strain. The interatomic potential employed has been shown to be capable of describing the martensite-austenite phase transition in iron. We study the stress versus strain curves for different temperatures and show that for a range of temperatures it is possible to induce a solid-solid phase transition by axial strain before the elasticity is lost; these transition temperatures are below the bulk transition temperature. The two phases have different (non-linear) elastic behavior: the bcc phase softens, while the close-packed phase stiffens with temperature. We also consider the reversibility of the transformation in the elastic regimes, and the role of the strain rate on the critical strain necessary for phase transition.

Graphene oxide for solid-phase extraction of bioactive phenolic acids.

Science.gov (United States)

Hou, Xiudan; Wang, Xusheng; Sun, Yingxin; Wang, Licheng; Guo, Yong

2017-05-01

A solid-phase extraction (SPE) method for the efficient analysis of trace phenolic acids (PAs, caffeic acid, ferulic acid, protocatechuic acid, cinnamic acid) in urine was established. In this work, a graphene oxide (GO) coating was grafted onto pure silica to be investigated as SPE material. The prepared GO surface had a layered and wrinkled structure that was rough and well organized, which could provide more open adsorption sites. Owing to its hydrophilicity and polarity, GO showed higher extraction efficiency toward PAs than reduced GO did, in agreement with the theoretical calculation results performed by Gaussian 09 software. The adsorption mechanism of PAs on GO@Sil was also investigated through static state and kinetic state adsorption experiments, which showed a monolayer surface adsorption. Extraction capacity of the as-prepared material was optimized using the response surface methodology. Under the optimized conditions, the as-established method provided wide linearity range (2-50 μg L -1 for protocatechuic acid and 1-50 μg L -1 for caffeic acid, ferulic acid, and cinnamic acid) and low limits of detection (0.25-1 μg L -1 ). Finally, the established method was applied for the analysis of urine from two healthy volunteers. The results indicate that the prepared material is a practical, cost-effective medium for the extraction and determination of phenolic acids in complex matrices. Graphical Abstract A graphene oxide coating was grafted onto pure silica as the SPE material for the extraction of phenolic acids in urines and the extraction mechanism was also mainly investigated.

Adsorption process analysis at the solid-gas interface by the polarization phenomenon study

International Nuclear Information System (INIS)

Mouton-Chazel, V.

1994-01-01

In order to improve the safety of anti-gas filters users, the Cogema (Nuclear Materials General Company) has developed a gaseous pollutants saturation detection technology for respiratory protection masks. As a matter of fact, the problem consists in studying the surface properties of a solid. In this study the adsorption has been considered as a phenomenon which can be followed by a relatively simple electrical measure technology. A microscopic description of the adsorption phenomenon has been given at first and explained by the thermodynamics laws. Then a theoretical model has been elaborated. The developments which have been brought to this model in this work have allowed to give a satisfactory interpretation of the phenomena observed during the adsorption of a polar gas on a zeolite. (O.M.)

Adsorption process analysis at the solid-gas interface by the polarization phenomenon study; Analyse des processus d`adsorption a l`interface solide - gaz par l`etude du phenomene de polarisation

Energy Technology Data Exchange (ETDEWEB)

Mouton-Chazel, V

1994-10-05

In order to improve the safety of anti-gas filters users, the Cogema (Nuclear Materials General Company) has developed a gaseous pollutants saturation detection technology for respiratory protection masks. As a matter of fact, the problem consists in studying the surface properties of a solid. In this study the adsorption has been considered as a phenomenon which can be followed by a relatively simple electrical measure technology. A microscopic description of the adsorption phenomenon has been given at first and explained by the thermodynamics laws. Then a theoretical model has been elaborated. The developments which have been brought to this model in this work have allowed to give a satisfactory interpretation of the phenomena observed during the adsorption of a polar gas on a zeolite. (O.M.). 169 refs.

Employment of the generalized adsorption model for the prediction of the solid-water distribution of radiocesium in the river-estuary-ocean system

International Nuclear Information System (INIS)

Fan, Qiaohui; Takahashi, Yoshio

2017-01-01

Since last century, a large amount of radiocesium (RCs) released from atomic weapon tests and nuclear accidents, such as in Chernobyl and Fukushima, was directly introduced into the environment through atmospheric transportation and deposition on land surface soil, discharged into river systems by erosion effects during rainfall, and finally released into the ocean. In this study, a generalized adsorption model (GAM) for Cs + was employed to estimate the solid-water distribution of Cs + in the river-estuary-ocean system. The results confirmed that the capacity of each adsorption site of river sediments, i.e., interlayer site, type II site, and planar site, can be precisely optimized through the adsorption isotherm of Cs + on the river sediments combined with the radiocesium interception potential (RIP) and cation exchange capacity (CEC). According to the GAM, the main contributor for Cs + adsorption is the frayed edge site rather than others due to the very low concentration of Cs + in the river-estuary-ocean system. The different solid-water distribution of Cs + in the river-estuary-ocean system was dominantly controlled by the salinity in the aqueous phase. Therefore, Cs + should be highly reactive with strong adsorptive character to particulate matter in the river system, whereas a conservative distribution must be dominant in ocean with much weaker affinity to particulate matter because of the high salinity. - Highlights: • A new method to extend the utility range of GAM from illite to natural samples. • GAM was adapted to quantitatively explore the transportation of radiocesium in river in rive-estuary-ocean system. • High reactivity in river water and conservative behavior in seawater were clarified.

Gas-phase formaldehyde adsorption isotherm studies on activated carbon: correlations of adsorption capacity to surface functional group density.

Science.gov (United States)

Carter, Ellison M; Katz, Lynn E; Speitel, Gerald E; Ramirez, David

2011-08-01

Formaldehyde (HCHO) adsorption isotherms were developed for the first time on three activated carbons representing one activated carbon fiber (ACF) cloth, one all-purpose granular activated carbon (GAC), and one GAC commercially promoted for gas-phase HCHO removal. The three activated carbons were evaluated for HCHO removal in the low-ppm(v) range and for water vapor adsorption from relative pressures of 0.1-0.9 at 26 °C where, according to the IUPAC isotherm classification system, the adsorption isotherms observed exhibited Type V behavior. A Type V adsorption isotherm model recently proposed by Qi and LeVan (Q-L) was selected to model the observed adsorption behavior because it reduces to a finite, nonzero limit at low partial pressures and it describes the entire range of adsorption considered in this study. The Q-L model was applied to a polar organic adsorbate to fit HCHO adsorption isotherms for the three activated carbons. The physical and chemical characteristics of the activated carbon surfaces were characterized using nitrogen adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and Boehm titrations. At low concentrations, HCHO adsorption capacity was most strongly related to the density of basic surface functional groups (SFGs), while water vapor adsorption was most strongly influenced by the density of acidic SFGs.

Aflatoxin B1 adsorption by the natural aluminosilicates - concentrate of montmorillonite and zeolite

Directory of Open Access Journals (Sweden)

Marković Marija A.

2016-01-01

Full Text Available Aflatoxin B1 adsorption by the concentrate of bentonite clay - montmorillonite and the natural zeolite - clinoptilolite and was investigated at the initial toxin concentration 4 ppm, with different amonunts of solid phase in suspension (10, 5, 2 and 1 mg/10 mL and different pH values - 3, 7 and 9. Results indicated that for both minerals, decreasing the amount of solid phase in suspension, decrease the amount of active sites relevant for adsorption of aflatoxin B1. Thus, for concentrate of montnorillonite, at the lowest level of solid phase in suspension (1 mg/10 mL, aflatoxin B1 adsorption indexes were 97% at pH 3, 88% at pH 7 and 82% at pH 9, while for the natural zeolite, adsorption of toxin was 9% at pH 3 and 7% at pH 7 and 9. Since inorganic cations in minerals are mainly responsible for aflatoxin B1 adsorption, even the natural zeolite - clinoptilite has much higher cation exchange capacity (the content of inorganic exchangeable cations compared to the concentrate of montmorillonite, adsorption of aflatoxin B1 by this mineral is much lower. Comparing the molecular dimensions of aflatoxin B1 molecule with the dimension of channels of clinoptilolite and interlamellar space of montmorillonite it is obvious that this toxin is adsorbed only at the external surface of clinoptilolite while in the montmorillonite all active sites are equally available for its adsorption. Thus, the concentrate of montmorillonite posess by higher adsorption capacity for aflatoxin B1. Results presented in this paper confirmed the fact the differences in the structure of minerals led to their different efficiency for adsorption of aflatoxin B1. Mineralogical and chemical composition, determination of cation exchange capacity, etc., are very important parameters influencing the effectiveness of minerals as aflatoxin B1 adsorbents. [Projekat Ministarstva nauke Republike Srbije, br. 451-03-2802-IP Tip1/142, br. 172018 i br. 34013

KAJIAN ADSORPSI ION LOGAM Cr(VI OLEH ADSORBEN KOMBINASI ARANG AKTIF SEKAM PADI DAN ZEOLIT MENGGUNAKAN METODE SOLID-PHASE SPECTROPHOTOMETRY (SPS

Directory of Open Access Journals (Sweden)

Sulistyo Saputro

2016-10-01

  This study aims to study the use of activated rice husk charcoal and zeolite as combination adsorbents to adsorb Cr(VI metal ions; the effect of the combination adsorbents of activated rice husk charcoal and zeolite’s compositions to adsorb Cr(VI metal ions; and the sensitivity of solid-phase spectrophotometry (SPS as a method to determine the reduced levels of Cr(VI metal ions in the level of 15μ"> g/L. The activated rice husk charcoal used were obtained through the activation process by soaking in a solution of ZnCl2 10% while the zeolite with a solution of H2SO4 10%. The contacting process of the adsorbents with Cr(VI metal ions was done by varying the compositions of the activated rice husk charcoal and zeolite adsorbent, 1:1, 1:2, 1:3, and 2:1. The data analysis of the Cr(VI level used solid-phase spectrophotometry (SPS method. Characterization of activated rice husk charcoal and zeolite used FTIR. The results showed that: (1 a combination of activated rice husk charcoal and zeolite can be used as adsorbent to adsorb Cr(VI metal ions with the adsorption capacity was 0,28 15μ"> g/g; (2 the optimum composition of adsorbents was 1:2 with the percentage of absorption was 40,99%; (3 solid-phase spectrophotometry (SPS is a sensitive method to determine the reduced levels of Cr(VI in the level of 15μ"> g/L with the limit of detection (LOD was 0,021 15μ"> g/L.   Keywords: adsorption, Cr(VI,  activated  rice husk charcoal,  zeolite, solid-phase spectrophotometry

Thermodynamic Properties of Chromium Adsorption by Sediments ...

African Journals Online (AJOL)

MBI

2013-06-19

Jun 19, 2013 ... The adsorption of Chromium from aqueous solution using river Watari sediment as an adsorbent was modeled. The influence of initial ... number of metals, including chromium, copper, nickel and zinc. The ion ... through filter paper to determine the concentration ... liquid and solid phases were separated by.

Solid-phase peptide synthesis

DEFF Research Database (Denmark)

Jensen, Knud Jørgen

2013-01-01

This chapter provides an introduction to and overview of peptide chemistry with a focus on solid-phase peptide synthesis. The background, the most common reagents, and some mechanisms are presented. This chapter also points to the different chapters and puts them into perspective.......This chapter provides an introduction to and overview of peptide chemistry with a focus on solid-phase peptide synthesis. The background, the most common reagents, and some mechanisms are presented. This chapter also points to the different chapters and puts them into perspective....

Halogen bonding: A new retention mechanism for the solid phase extraction of perfluorinated iodoalkanes

International Nuclear Information System (INIS)

Yan Xiaoqing; Shen Qianjin; Zhao Xiaoran; Gao Haiyue; Pang Xue; Jin Weijun

2012-01-01

Highlights: ► Halogen bonding (XB) is firstly utilised in solid phase extraction. ► The perfluorinated iodine alkanes can be extracted by C-I⋯Cl − halogen bonding. ► The C-I⋯Cl − halogen bond is well characterised by spectroscopy methods. ► The analytes with strong halogen-bonding abilities can be selectively extracted. - Abstract: For the first time, halogen-bonding interaction is utilised in the solid phase extraction of perfluorinated iodoalkane (PFI). Nine PFIs, as model analytes, were tested, and analyses by UV, 19 F NMR and Raman spectroscopies demonstrate that the PFIs are extracted by a strong anion exchange (SAX) sorbent from n-hexane due to the C-I⋯Cl − halogen-bonding interactions. The results also show that the adsorptivities of SAX for the diiodoperfluoro-alkanes (diiodo-PFIs) were much stronger than those for the perfluoroalkyl iodides (monoiodo-PFIs). Specifically, the recoveries for 1,6-diiodoperfluorohexane and 1,8-diiodoperfluorooctane were higher than 80% when 100 mL of sample spiked with a 5 ng mL −1 analyte mixture was extracted. Interestingly, SAX had no adsorption for hexafluorobenzene at all, which is known to be unable to form a halogen bond with Cl − . The analytical performance of the halogen bond-based SPE-GC–MS method for the diiodo-PFIs was also examined in soil samples. The sorbent SAX enabled the selective extraction of four diiodo-PFIs successfully from soil samples. The recoveries of the diiodo-PFIs extracted from 5 g soil sample at the 100 ng g −1 spike level were in the range of 73.2–93.8% except 26.8% for 1,2-diiodoperfluoroethane. The limit of detection varied from 0.02 to 0.04 ng g −1 in soil samples. Overall, this work reveals the great application potential of halogen bonding in the field of solid phase extraction to selectively extract compounds with strong halogen-bonding abilities.

Preparation and characterization of a novel polymeric based solid-solid phase change heat storage material

International Nuclear Information System (INIS)

Xi Peng; Gu Xiaohua; Cheng Bowen; Wang Yufei

2009-01-01

Here we reported a two-step procedure for preparing a novel polymeric based solid-solid phase change heat storage material. Firstly, a copolymer monomer containing a polyethylene glycol monomethyl ether (MPEG) phase change unit and a vinyl unit was synthesized via the modification of hydrogen group of MPEG. Secondly, by copolymerization of the copolymer monomer and phenyl ethylene, a novel polymeric based solid-solid phase change heat storage material was prepared. The composition, structure and properties of the novel polymeric based solid-solid phase change material were characterized by IR, 1 H NMR, DSC, WAXD, and POM, respectively. The results show that the novel polymeric based solid-solid phase change material possesses of excellent crystal properties and high phase change enthalpy.

Liquid phase adsorption behavior of inulin-type fructan onto activated charcoal.

Science.gov (United States)

Li, Kecheng; Liu, Song; Xing, Ronge; Yu, Huahua; Qin, Yukun; Li, Pengcheng

2015-05-20

This study describes liquid phase adsorption characteristics of inulin-type fructan onto activated charcoal. Batch mode experiments were conducted to study the effects of pH, contact time, temperature and initial concentration of inulin. Nearly neutral solution (pH 6-8) was favorable to the adsorption and the equilibrium was attained after 40 min with the maximum adsorption Qmax 0.182 g/g (adsorbate/adsorbent) at 298 K. The experimental data analysis indicated that the adsorption process fitted well with the pseudo-second-order kinetic model (R(2) = 1) and Langmuir isotherms model (R(2) > 0.99). Thermodynamic parameters revealed that the adsorption process was spontaneous and exothermic with a physical nature. Inulin desorption could reach 95.9% using 50% ethanol solution and activated charcoal could be reused without significant losses in adsorption capacity. These results are of practical significance for the application of activated charcoal in the production and purification of inulin-type fructan. Copyright © 2015 Elsevier Ltd. All rights reserved.

Highly selective solid-phase extraction of trace Pd(II) by murexide functionalized halloysite nanotubes

Energy Technology Data Exchange (ETDEWEB)

Li Ruijun; He Qun; Hu Zheng; Zhang Shengrui [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou 730000 (China); Zhang Lijun [Faculty of Science and Engineer, Curtin University, Perth, WA 6845 (Australia); Chang Xijun, E-mail: lirj2010@lzu.edu.cn [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou 730000 (China)

2012-02-03

Graphical abstract: Murexide functionalized halloysite nanotubes have been developed to separate and concentrate trace Pd(II) from aqueous samples. Parameters that affected the sorption and elution efficiency were studied in column mode, and the new adsorbent presented high selectivity and adsorption capacity for the solid phase extraction of trace Pd(II). Highlights: Black-Right-Pointing-Pointer Murexide modified halloysite nanotubes as adsorbent has been reported originally. Black-Right-Pointing-Pointer This adsorbent has a unique selectivity for Pd(II) at pH 1.0. Black-Right-Pointing-Pointer This adsorbent had high adsorption capacity for Pd(II). Black-Right-Pointing-Pointer The precision and accuracy of the method are satisfactory. - Abstract: The originality on the high efficiency of murexide modified halloysite nanotubes as a new adsorbent of solid phase extraction has been reported to preconcentrate and separate Pd(II) in solution samples. The new adsorbent was confirmed by Fourier transformed infrared spectra, X-ray diffraction, scanning electron microscope, transmission electron microscope and N{sub 2} adsorption-desorption isotherms. Effective preconcentration conditions of analyte were examined using column procedures prior to detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of pH, the amount of adsorbent, the sample flow rate and volume, the elution condition and the interfering ions were optimized in detail. Under the optimized conditions, Pd(II) could be retained on the column at pH 1.0 and quantitatively eluted by 2.5 mL of 0.01 mol L{sup -1} HCl-3% thiourea solution at a flow rate of 2.0 mL min{sup -1}. The analysis time was 5 min. An enrichment factor of 120 was accomplished. Common interfering ions did not interfere in both separation and determination. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 42.86 mg g{sup -1} for Pd(II). The detection limit (3{sigma}) of

Graphene oxide decorated with silver nanoparticles as a coating on a stainless-steel fiber for solid-phase microextraction.

Science.gov (United States)

Wang, Licheng; Hou, Xiudan; Li, Jubai; Liu, Shujuan; Guo, Yong

2015-07-01

A novel graphene oxide decorated with silver nanoparticles coating on a stainless-steel fiber for solid-phase microextraction was prepared. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize the coating surface and showed that silver nanoparticles were dispersed on the wrinkled graphene oxide surface. Coupled to gas chromatography with flame ionization detection, the extraction abilities of the fiber for polycyclic aromatic hydrocarbons were examined in the headspace solid-phase microextraction mode. The extraction parameters including adsorption time, adsorption temperature, salt concentration, desorption time and desorption temperature were investigated. Under the optimized condition, wide linearity with low limits of detection from 2 to 10 ng/L was obtained. The relative standard deviations for single-fiber repeatability and fiber-to-fiber reproducibility were less than 10.6 and 17.5%, respectively. The enrichment factors were from 1712.5 to 4503.7, showing the fiber has good extraction abilities. Moreover, the fiber exhibited a good stability and could be reused for more than 120 times. The established method was also applied for determination of polycyclic aromatic hydrocarbons in two real water samples and the recoveries of analytes ranged from 84.4-116.3% with relative standard deviations less than 16.2%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption of Lead Content in Leachate of Sukawinatan Landfill Using Solid Waste of Tofu

Directory of Open Access Journals (Sweden)

Sri Hartati

2016-08-01

Full Text Available A study on the adsorption of lead content in the leachate from the landfill by using solid waste of tofu. This study assed the effects of weight of the solid waste of tofu and the contact time on the efficiency of the Pb adsorption. The sample used in this study was artificial sample of a solution of Pb metal ion and the sample of the leachate of the landfill waste. The study was carried out with a batch system, with the variables of weight of waste of tofu of 0.5; 1.0; 1.5 g. While the variables of the contact time were 0, 30, 60, 90, 120 and 150 minutes. To determine the optimum conditions, the waste of tofu was dissolved in 50 mL of Pb metal ion solution with a concentration of 20.27 mg/L and stirred with a shaker for 30 minutes at a speed of 180 rpm. The same thing was done by varying the contact time. When the optimum condition was obtained, it was applied with varying concentrations of Pb metal ion solution and garbage landfill leachate. The initial and the final levels of the Pb metal ion solution were analyzed by using the Atomic Adsorption Spectroscopy (AAS. The initial and the final results of the heavy metals were analyzed for disclosing the adsorption efficiency. To reveal the effects of the weight of the waste of tofu and the contact time, the data were analyzed with graphs. The waste of tofu with a weight of 1.5 g and a contact time of 90 minutes, had an adsorption efficiency of 97.68% at a concentration of 20.27 mg / L for Pb ion solution and 28.57% for the leachate from the landfill waste in 100 mL of leachate.

Imprinted magnetic graphene oxide for the mini-solid phase extraction of Eu (III) from coal mine area

Science.gov (United States)

Patra, Santanu; Roy, Ekta; Madhuri, Rashmi; Sharma, Prashant K.

2017-05-01

The present work represents the preparation of imprinted magnetic reduced graphene oxide and applied it for the selective removal of Eu (III) from local coal mines area. A simple solid phase extraction method was used for this purpose. The material shows a very high adsorption as well as removal efficiency towards Eu (III), which suggest that the material have potential to be used in future for their real time applications in removal of Eu (III) from complex matrices.

Multiplexed Colorimetric Solid-Phase Extraction

Science.gov (United States)

Gazda, Daniel B.; Fritz, James S.; Porter, Marc D.

2009-01-01

Multiplexed colorimetric solid-phase extraction (MC-SPE) is an extension of colorimetric solid-phase extraction (C-SPE) an analytical platform that combines colorimetric reagents, solid phase extraction, and diffuse reflectance spectroscopy to quantify trace analytes in water. In CSPE, analytes are extracted and complexed on the surface of an extraction membrane impregnated with a colorimetric reagent. The analytes are then quantified directly on the membrane surface using a handheld diffuse reflectance spectrophotometer. Importantly, the use of solid-phase extraction membranes as the matrix for impregnation of the colorimetric reagents creates a concentration factor that enables the detection of low concentrations of analytes in small sample volumes. In extending C-SPE to a multiplexed format, a filter holder that incorporates discrete analysis channels and a jig that facilitates the concurrent operation of multiple sample syringes have been designed, enabling the simultaneous determination of multiple analytes. Separate, single analyte membranes, placed in a readout cartridge create unique, analyte-specific addresses at the exit of each channel. Following sample exposure, the diffuse reflectance spectrum of each address is collected serially and the Kubelka-Munk function is used to quantify each water quality parameter via calibration curves. In a demonstration, MC-SPE was used to measure the pH of a sample and quantitate Ag(I) and Ni(II).

Solid-Phase Contact Assay That Uses a lux-Marked Nitrosomonas europaea Reporter Strain To Estimate Toxicity of Bioavailable Linear Alkylbenzene Sulfonate in Soil

OpenAIRE

Brandt, Kristian K.; Pedersen, Anders; Sørensen, Jan

2002-01-01

Information about in situ toxicity of the bioavailable pools of adsorptive soil pollutants is a prerequisite for proper ecological risk assessment in contaminated soils. Such toxicity data may be obtained by assays allowing for direct exposure of introduced test microorganisms to the toxicants, as they appear in solid solution equilibria in the natural soil. We describe a novel sensitive solid-phase contact assay for in situ toxicity testing of soil pollutants based on a recombinant biolumine...

Density-functional theory for fluid-solid and solid-solid phase transitions.

Science.gov (United States)

Bharadwaj, Atul S; Singh, Yashwant

2017-03-01

We develop a theory to describe solid-solid phase transitions. The density functional formalism of classical statistical mechanics is used to find an exact expression for the difference in the grand thermodynamic potentials of the two coexisting phases. The expression involves both the symmetry conserving and the symmetry broken parts of the direct pair correlation function. The theory is used to calculate phase diagram of systems of soft spheres interacting via inverse power potentials u(r)=ε(σ/r)^{n}, where parameter n measures softness of the potential. We find that for 1/nfcc) structure while for 1/n≥0.154 the body-centred-cubic (bcc) structure is preferred. The bcc structure transforms into the fcc structure upon increasing the density. The calculated phase diagram is in good agreement with the one found from molecular simulations.

Adsorption of marine phycotoxin okadaic acid on a covalent organic framework.

Science.gov (United States)

Salonen, Laura M; Pinela, Sara R; Fernandes, Soraia P S; Louçano, João; Carbó-Argibay, Enrique; Sarriá, Marisa P; Rodríguez-Abreu, Carlos; Peixoto, João; Espiña, Begoña

2017-11-24

Phycotoxins, compounds produced by some marine microalgal species, can reach high concentrations in the sea when a massive proliferation occurs, the so-called harmful algal bloom. These compounds are especially dangerous to human health when concentrated in the digestive glands of seafood. In order to generate an early warning system to alert for approaching toxic outbreaks, it is very important to improve monitoring methods of phycotoxins in aquatic ecosystems. Solid-phase adsorption toxin tracking devices reported thus far based on polymeric resins have not been able to provide an efficient harmful algal bloom prediction system due to their low adsorption capabilities. In this work, a water-stable covalent organic framework (COF) was evaluated as adsorbent for the hydrophobic toxin okadaic acid, one of the most relevant marine toxins and the parental compound of the most common group of toxins responsible for the diarrhetic shellfish poisoning. Adsorption kinetics of okadaic acid onto the COF in seawater showed that equilibrium concentration was reached in only 60min, with a maximum experimental adsorption of 61mgg -1 . Desorption of okadaic acid from the COF was successful with both 70% ethanol and acetonitrile as solvent, and the COF material could be reused with minor losses in adsorption capacity for three cycles. The results demonstrate that COF materials are promising candidates for solid-phase adsorption in water monitoring devices. Copyright © 2017 Elsevier B.V. All rights reserved.

A KINETIC MODEL FOR MONO-LAYER GLOBULAR PROTEIN ADSORPTION ON SOLID/LIQUID INTERFACES

Directory of Open Access Journals (Sweden)

Kamal I. M. Al-Malah

2012-12-01

Full Text Available A kinetic model was derived for globular protein adsorption. The model takes into account the three possible scenarios of a protein molecule in solution, being exposed to an interface: adsorption step from the solution to the interface; the possible desorption back into the solution; and the surface-induced unfolding or spreading of the protein unto the substrate surface. A globular protein molecule is visualized as a sphere with radius D. In addition to the general case of protein adsorption, which portrays either the surface coverage (Theta or surface concentration (� as a function of the adsorption time, special cases, like equilibrium condition, lowsurface coverage, irreversible, and Langmuirian were also presented and treated in light of the derived model. The general model was simplified for each of the subset cases. The irreversibility versus reversibility of protein adsorption was discussed. The substrate surface energetics or effects are accounted for via the proposition of the percent relative change in D/V ratio for the adsorbing protein, called (D/VPRC parameter. (D/VPRC is calculated with respect to the monolayer surface concentration of protein, where the latter is given by D/Vratio. This can be used as a landmark to protein adsorption isotherms or even kinetics. This is visualized as an indicator for solid substrate effects on the adsorbing proteins. (D/VPRC can be zero (fresh monolayer, negative (aged monolayer, or positive (multi-layer. The reference surface concentration is reported for some selected proteins.

Chemically-modified activated carbon with ethylenediamine for selective solid-phase extraction and preconcentration of metal ions.

Science.gov (United States)

Li, Zhenhua; Chang, Xijun; Zou, Xiaojun; Zhu, Xiangbing; Nie, Rong; Hu, Zheng; Li, Ruijun

2009-01-26

A new method that utilizes ethylenediamine-modified activated carbon (AC-EDA) as a solid-phase extractant has been developed for simultaneous preconcentration of trace Cr(III), Fe(III), Hg(II) and Pb(II) prior to the measurement by inductively coupled plasma optical emission spectrometry (ICP-OES). The new sorbent was prepared by oxidative surface modification. Experimental conditions for effective adsorption of trace levels of Cr(III), Fe(III), Hg(II) and Pb(II) were optimized with respect to different experimental parameters using batch and column procedures in detail. The optimum pH value for the separation of metal ions simultaneously on the new sorbent was 4.0. Complete elution of absorbed metal ions from the sorbent surface was carried out using 3.0 mL of 2% (%w/w) thiourea and 0.5 mol L(-1) HCl solution. Common coexisting ions did not interfere with the separation and determination of target metal ions. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 39.4, 28.9, 60.5 and 49.9 mg g(-1) for Cr(III), Fe(III), Hg(II) and Pb(II), respectively. The time for 94% adsorption of target metal ions was less than 2 min. The detection limits of the method was found to be 0.28, 0.22, 0.09 and 0.17 ng mL(-1) for Cr(III), Fe(III), Hg(II) and Pb(II), respectively. The precision (R.S.D.) of the method was lower 4.0% (n=8). The prepared sorbent as solid-phase extractant was successfully applied for the preconcentration of trace Cr(III), Fe(III), Hg(II) and Pb(II) in natural and certified samples with satisfactory results.

Hexagonal boron nitride nanosheets as adsorbents for solid-phase extraction of polychlorinated biphenyls from water samples

Energy Technology Data Exchange (ETDEWEB)

Jia, Shiliang; Wang, Zhenhua; Ding, Ning [Key Laboratory for Applied Technology of Sophisticated Analytical Instruments, Shandong Academy of Sciences, Jinan, Shandong (China); Elaine Wong, Y.-L. [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Chen, Xiangfeng, E-mail: xiangfchensdas@163.com [Key Laboratory for Applied Technology of Sophisticated Analytical Instruments, Shandong Academy of Sciences, Jinan, Shandong (China); Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Qiu, Guangyu [Department of Physics and Materials Science, City University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Dominic Chan, T.-W., E-mail: twdchan@cuhk.edu.hk [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong)

2016-09-14

The adsorptive potential of hexagonal boron nitride nanosheets (h-BNNSs) for solid-phase extraction (SPE) of pollutants was investigated for the first time. Seven indicators of polychlorinated biphenyls (PCBs) were selected as target analytes. The adsorption of PCBs on the surface of the h-BNNSs in water was simulated by the density functional theory and molecular dynamics. The simulation results indicated that the PCBs are adsorbed on the surface by π–π, hydrophobic, and electrostatic interactions. The PCBs were extracted with an h-BNNS-packed SPE cartridge, and eluted by dichloromethane. Gas chromatography–tandem mass spectrometry working in the multiple reaction monitor mode was used for the sample quantification. The effect of extraction parameters, including the flow rate, pH value, breakthrough volume, and the ionic strength, were investigated. Under the optimal working conditions, the developed method showed low limits of detection (0.24–0.50 ng L{sup −1}; signal-to-noise ratio = 3:1), low limits of quantification (0.79–1.56 ng L{sup −1}; signal-to-noise ratio = 10:1), satisfactory linearity (r > 0.99) within the concentration range of 2–1000 ng L{sup −1}, and good precision (relative standard deviation < 12%). The PCBs concentration in environmental water samples was determined by the developed method. This results demonstrate that h-BNNSs have high analytical potential in the enrichment of pollutants. - Highlights: • The hexagonal boron nitride nanosheets were synthesized. • The nanosheets were used as adsorbent for solid-phase extraction. • The h-BN demonstrates remarkable adsorption of PCBs from water samples. • The method was successfully applied in determination of PCBs in water samples.

Influence of alumina phases on the molybdenum adsorption capacity and chemical stability for {sup 99}Mo/{sup 99m}Tc generators columns

Energy Technology Data Exchange (ETDEWEB)

Guedes-Silva, Cecilia C.; Ferreira, Thiago dos Santos; Paula, Carolina M. de; Otubo, Larissa, E-mail: cecilia.guedes@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Carvalho, Flavio M.S. [Universidade de Sao Paulo (IGC/USP), SP (Brazil). Instituto de Geociencias

2016-07-15

Technetium-{sup 99m} is the clinically most used radionuclide worldwide. Although many techniques can be applied to separate {sup 99}Mo and {sup 99m}Tc, the most commonly used method is the column chromatography with alumina as stationary phase. However, the alumina nowadays used has limited adsorption capacity of molybdate ions which implies the need to develop or improve materials to produce high specific activity generators. In this paper, alumina was obtained by a solid state method and heat treatments at different conditions. The powders had a microstructure with porous particles of γ, δ, θ and α-Al{sub 2}O{sub 3} phases as well as specific surface area between 36 and 312 m{sup 2} g{sup -1}. Most interesting results were reached by powders calcined at 900 deg C for 5 hours which had high chemical stability and a molybdenum adsorption capacity of 92.45 mg Mo per g alumina. (author)

Solid-solid phase change thermal storage application to space-suit battery pack

Science.gov (United States)

Son, Chang H.; Morehouse, Jeffrey H.

1989-01-01

High cell temperatures are seen as the primary safety problem in the Li-BCX space battery. The exothermic heat from the chemical reactions could raise the temperature of the lithium electrode above the melting temperature. Also, high temperature causes the cell efficiency to decrease. Solid-solid phase-change materials were used as a thermal storage medium to lower this battery cell temperature by utilizing their phase-change (latent heat storage) characteristics. Solid-solid phase-change materials focused on in this study are neopentyl glycol and pentaglycerine. Because of their favorable phase-change characteristics, these materials appear appropriate for space-suit battery pack use. The results of testing various materials are reported as thermophysical property values, and the space-suit battery operating temperature is discussed in terms of these property results.

Solid phase assays

International Nuclear Information System (INIS)

Reese, M.G.; Johnson, L.R.; Ransom, D.K.

1980-01-01

In a solid phase assay for quantitative determination of biological and other analytes, a sample such as serum is contacted with a receptor for the analyte being assayed, the receptor being supported on a solid support. No tracer for the analyte is added to the sample before contacting with the receptor; instead the tracer is contacted with the receptor after unbound analyte has been removed from the receptor. The assay can be otherwise performed in a conventional manner but can give greater sensitivity. (author)

Metal-organic framework based in-syringe solid-phase extraction for the on-site sampling of polycyclic aromatic hydrocarbons from environmental water samples.

Science.gov (United States)

Zhang, Xiaoqiong; Wang, Peiyi; Han, Qiang; Li, Hengzhen; Wang, Tong; Ding, Mingyu

2018-04-01

In-syringe solid-phase extraction is a promising sample pretreatment method for the on-site sampling of water samples because of its outstanding advantages of portability, simple operation, short extraction time, and low cost. In this work, a novel in-syringe solid-phase extraction device using metal-organic frameworks as the adsorbent was fabricated for the on-site sampling of polycyclic aromatic hydrocarbons from environmental waters. Trace polycyclic aromatic hydrocarbons were effectively extracted through the self-made device followed by gas chromatography with mass spectrometry analysis. Owing to the excellent adsorption performance of metal-organic frameworks, the analytes could be completely adsorbed during one adsorption cycle, thus effectively shortening the extraction time. Moreover, the adsorbed analytes could remain stable on the device for at least 7 days, revealing the potential of the self-made device for on-site sampling of degradable compounds in remote regions. The limit of detection ranged from 0.20 to 1.9 ng/L under the optimum conditions. Satisfactory recoveries varying from 84.4 to 104.5% and relative standard deviations below 9.7% were obtained in real samples analysis. The results of this study promote the application of metal-organic frameworks in sample preparation and demonstrate the great potential of in-syringe solid-phase extraction for the on-site sampling of trace contaminants in environmental waters. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of Magnetic Molecularly Imprinted Polymer for Chlorpyrifos Adsorption and Enrichment

Science.gov (United States)

Chen, M.; Ma, X.; Sheng, J.

2017-11-01

Magnetic molecularly imprinted polymer (MMIP) for chlorpyrifos was prepared and characterized. The adsorption performance of MMIP for chlorpyrifos was evaluated under various conditions. The results showed that the adsorption equilibrium was achieved within 1 h, the adsorption capacity was 16.8 mg/g, and the adsorption process could be well described by Langmuir isotherm model and pseudo-second-order kinetic model. The MMIP was used as the selective sorbent for solid-phase extraction of chlorpyrifos from environmental water and vegetable samples. Combined with gas chromatography-mass spectrometry, a LOD of 30 ng/L, spiked recovery of 89.6%-107.3% and RSD of 1.9%-3.8% for chlorpyrifos were obtained.

Solid-phase single molecule biosensing using dual-color colocalization of fluorescent quantum dot nanoprobes

Science.gov (United States)

Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Liu, Wei; Wang, Dong

2013-10-01

The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to the QD560-TBA I substrate. Thus, the presence of the target thrombin can be determined based on fluorescent colocalization measurements of the nanoassemblies, without target amplification or probe separation. The detection limit of this assay reached 0.8 pM. This fluorescent colocalization assay has enabled single molecule recognition in a separation-free detection format, and can serve as a sensitive biosensing platform that greatly suppresses the nonspecific adsorption false-positive signal. This method can be extended to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies.The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to

Adsorption factor effect on dispersive ability of polymethylmethylmethacrylate

International Nuclear Information System (INIS)

Gorokhovskij, G.A.; Samsonov, G.V.; Gorshunov, V.P.

1977-01-01

A relationhsip between the rate of polymer macromolecules absorption on some refractory compounds and the dispersion ability of polymer-abrasive compositions was investigated at various contents of the polymethacrylate polymer in an abrasive composition. The solid phase used was powders of Al 2 O 3 , WC, W 2 B 5 , TiB 2 . It was established that the dispersion ability of the polymer-abrasive compositions was a function not only of the cutting properties of the abrasives and the dispersion ability of the polymers, but also of the adsorption properties of the solid phase and of its capacity to transport macromolecules to the surface being worked

Combinatorial Solid-Phase Synthesis of Balanol Analogues

DEFF Research Database (Denmark)

Nielsen, John; Lyngsø, Lars Ole

1996-01-01

The natural product balanol has served as a template for the design and synthesis of a combinatorial library using solid-phase chemistry. Using a retrosynthetic analysis, the structural analogues have been assembled from three relatively accessible building blocks. The solid-phase chemistry inclu...

Comparison of the solid-phase extraction efficiency of a bounded and an included cyclodextrin-silica microporous composite for polycyclic aromatic hydrocarbons determination in water samples.

Science.gov (United States)

Mauri-Aucejo, Adela; Amorós, Pedro; Moragues, Alaina; Guillem, Carmen; Belenguer-Sapiña, Carolina

2016-08-15

Solid-phase extraction is one of the most important techniques for sample purification and concentration. A wide variety of solid phases have been used for sample preparation over time. In this work, the efficiency of a new kind of solid-phase extraction adsorbent, which is a microporous material made from modified cyclodextrin bounded to a silica network, is evaluated through an analytical method which combines solid-phase extraction with high-performance liquid chromatography to determine polycyclic aromatic hydrocarbons in water samples. Several parameters that affected the analytes recovery, such as the amount of solid phase, the nature and volume of the eluent or the sample volume and concentration influence have been evaluated. The experimental results indicate that the material possesses adsorption ability to the tested polycyclic aromatic hydrocarbons. Under the optimum conditions, the quantification limits of the method were in the range of 0.09-2.4μgL(-1) and fine linear correlations between peak height and concentration were found around 1.3-70μgL(-1). The method has good repeatability and reproducibility, with coefficients of variation under 8%. Due to the concentration results, this material may represent an alternative for trace analysis of polycyclic aromatic hydrocarbons in water trough solid-phase extraction. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface phase transitions in cu-based solid solutions

Science.gov (United States)

Zhevnenko, S. N.; Chernyshikhin, S. V.

2017-11-01

We have measured surface energy in two-component Cu-based systems in H2 + Ar gas atmosphere. The experiments on solid Cu [Ag] and Cu [Co] solutions show presence of phase transitions on the surfaces. Isotherms of the surface energy have singularities (the minimum in the case of copper solid solutions with silver and the maximum in the case of solid solutions with cobalt). In both cases, the surface phase transitions cause deficiency of surface miscibility: formation of a monolayer (multilayer) (Cu-Ag) or of nanoscale particles (Cu-Co). At the same time, according to the volume phase diagrams, the concentration and temperature of the surface phase transitions correspond to the solid solution within the volume. The method permits determining the rate of diffusional creep in addition to the surface energy. The temperature and concentration dependence of the solid solutions' viscosity coefficient supports the fact of the surface phase transitions and provides insights into the diffusion properties of the transforming surfaces.

Combining Pickering Emulsion Polymerization with Molecular Imprinting to Prepare Polymer Microspheres for Selective Solid-Phase Extraction of Malachite Green

Directory of Open Access Journals (Sweden)

Weixin Liang

2017-08-01

Full Text Available Malachite green (MG is currently posing a carcinogenic threat to the safety of human lives; therefore, it is highly desirable to develop an effective method for fast trace detection of MG. Herein, for the first time, this paper presents a systematic study on polymer microspheres, being prepared by combined Pickering emulsion polymerization and molecular imprinting, to detect and purify MG. The microspheres, molecularly imprinted with MG, show enhanced adsorption selectivity to MG, despite a somewhat lowered adsorption capacity, as compared to the counterpart without molecular imprinting. Structural features and adsorption performance of these microspheres are elucidated by different characterizations and kinetic and thermodynamic analyses. The surface of the molecularly imprinted polymer microspheres (M-PMs exhibits regular pores of uniform pore size distribution, endowing M-PMs with impressive adsorption selectivity to MG. In contrast, the microspheres without molecular imprinting show a larger average particle diameter and an uneven porous surface (with roughness and a large pore size, causing a lower adsorption selectivity to MG despite a higher adsorption capacity. Various adsorption conditions are investigated, such as pH and initial concentration of the solution with MG, for optimizing the adsorption performance of M-PMs in selectively tackling MG. The adsorption kinetics and thermodynamics are deeply discussed and analyzed, so as to provide a full picture of the adsorption behaviors of the polymer microspheres with and without the molecular imprinting. Significantly, M-PMs show promising solid-phase extraction column applications for recovering MG in a continuous extraction manner.

Molecular simulation of adsorption and transport in hierarchical porous materials.

Science.gov (United States)

Coasne, Benoit; Galarneau, Anne; Gerardin, Corine; Fajula, François; Villemot, François

2013-06-25

Adsorption and transport in hierarchical porous solids with micro- (~1 nm) and mesoporosities (>2 nm) are investigated by molecular simulation. Two models of hierarchical solids are considered: microporous materials in which mesopores are carved out (model A) and mesoporous materials in which microporous nanoparticles are inserted (model B). Adsorption isotherms for model A can be described as a linear combination of the adsorption isotherms for pure mesoporous and microporous solids. In contrast, adsorption in model B departs from adsorption in pure microporous and mesoporous solids; the inserted microporous particles act as defects, which help nucleate the liquid phase within the mesopore and shift capillary condensation toward lower pressures. As far as transport under a pressure gradient is concerned, the flux in hierarchical materials consisting of microporous solids in which mesopores are carved out obeys the Navier-Stokes equation so that Darcy's law is verified within the mesopore. Moreover, the flow in such materials is larger than in a single mesopore, due to the transfer between micropores and mesopores. This nonzero velocity at the mesopore surface implies that transport in such hierarchical materials involves slippage at the mesopore surface, although the adsorbate has a strong affinity for the surface. In contrast to model A, flux in model B is smaller than in a single mesopore, as the nanoparticles act as constrictions that hinder transport. By a subtle effect arising from fast transport in the mesopores, the presence of mesopores increases the number of molecules in the microporosity in hierarchical materials and, hence, decreases the flow in the micropores (due to mass conservation). As a result, we do not observe faster diffusion in the micropores of hierarchical materials upon flow but slower diffusion, which increases the contact time between the adsorbate and the surface of the microporosity.

Fabrication of a novel hydrophobic/ion-exchange mixed-mode adsorbent for the dispersive solid-phase extraction of chlorophenols from environmental water samples.

Science.gov (United States)

Gao, Li; Wei, Yinmao

2016-08-01

A novel mixed-mode adsorbent was prepared by functionalizing silica with tris(2-aminoethyl)amine and 3-phenoxybenzaldehyde as the main mixed-mode scaffold due to the presence of the plentiful amino groups and benzene rings in their molecules. The adsorption mechanism was probed with acidic, natural and basic compounds, and the mixed hydrophobic and ion-exchange interactions were found to be responsible for the adsorption of analytes. The suitability of dispersive solid-phase extraction was demonstrated in the determination of chlorophenols in environmental water. Several parameters, including sample pH, desorption solvent, ionic strength, adsorbent dose, and extraction time were optimized. Under the optimal extraction conditions, the proposed dispersive solid-phase extraction coupled with high-performance liquid chromatography showed good linearity range and acceptable limits of detection (0.22∽0.54 ng/mL) for five chlorophenols. Notably, the higher extraction recoveries (88.7∽109.7%) for five chlorophenols were obtained with smaller adsorbent dose (10 mg) and shorter extraction time (15 min) compared with the reported methods. The proposed method might be potentially applied in the determination of trace chlorophenols in real water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption mechanism of acids and bases in reversed-phase liquid chromatography in weak buffered mobile phases designed for liquid chromatography/mass spectrometry.

Science.gov (United States)

Gritti, Fabrice; Guiochon, Georges

2009-03-06

The overloaded band profiles of five acido-basic compounds were measured, using weakly buffered mobile phases. Low buffer concentrations were selected to provide a better understanding of the band profiles recorded in LC/MS analyses, which are often carried out at low buffer concentrations. In this work, 10 microL samples of a 50 mM probe solution were injected into C(18)-bonded columns using a series of five buffered mobile phases at (SW)pH between 2 and 12. The retention times and the shapes of the bands were analyzed based on thermodynamic arguments. A new adsorption model that takes into account the simultaneous adsorption of the acidic and the basic species onto the endcapped adsorbent, predicts accurately the complex experimental profiles recorded. The adsorption mechanism of acido-basic compounds onto RPLC phases seems to be consistent with the following microscopic model. No matter whether the acid or the base is the neutral or the basic species, the neutral species adsorbs onto a large number of weak adsorption sites (their saturation capacity is several tens g/L and their equilibrium constant of the order of 0.1 L/g). In contrast, the ionic species adsorbs strongly onto fewer active sites (their saturation capacity is about 1g/L and their equilibrium constant of the order of a few L/g). From a microscopic point of view and in agreement with the adsorption isotherm of the compound measured by frontal analysis (FA) and with the results of Monte-Carlo calculations performed by Schure et al., the first type of adsorption sites are most likely located in between C(18)-bonded chains and the second type of adsorption sites are located deeper in contact with the silica surface. The injected concentration (50 mM) was too low to probe the weakest adsorption sites (saturation capacity of a few hundreds g/L with an equilibrium constant of one hundredth of L/g) that are located at the very interface between the C(18)-bonded layer and the bulk phase.

Study of high-pressure adsorption from supercritical fluids by the potential theory

DEFF Research Database (Denmark)

Monsalvo, Matias Alfonso; Shapiro, Alexander

2009-01-01

The multicomponent potential theory of adsorption (MPTA), which has been previously used to study low-pressure adsorption of subcritical fluids, is extended to adsorption equilibria from supercritical fluids up to high pressures. The MPTA describes an adsorbed phase as an inhomogeneous fluid...... the adsorbed and the gas phases. We have also evaluated the performance of the classical Soave-Redlich-Kwong (SRK) EoS. The fluid-solid interactions are described by simple Dubinin-Radushkevich-Astakhov (DRA) potentials. In addition, we test the performance of the 10-4-3 Steele potential. It is shown...... that application of sPC-SAFT slightly improves the performance of the MPTA and that in spite of its simplicity, the DRA model can be considered as an accurate potential, especially, for mixture adsorption. We show that, for the sets of experimental data considered in this work, the MPTA is capable of predicting...

Adsorption of short-chain fluids at solid substrates from density functional theory

International Nuclear Information System (INIS)

Bryk, P.; Bucior, K.; Sokolowski, S.; Zukocinski, G.

2005-01-01

We use microscopic density functional theory to investigate the adsorption of short-chains at solid surfaces. The fluid is modeled as freely-jointed tangent spheres that interact via a short-ranged attractive potential. Within the framework of fundamental measure theory we study how the structure and surface phase behaviour of adsorbed fluid changes when the chain length is increased. We observe that the wetting temperature rescaled by the bulk critical temperature decreases with an increase of the chain length. For longer chains this temperature reaches a plateau. For the surface critical temperature an inverse effect is observed, i.e. the surface critical temperature increases with the chain length and then attains a plateau. Furthermore, we analyze how the layering transitions change with the change of the chain length and with relative strength of the fluid-solid interaction. The critical temperature of the first layering transition, rescaled by the bulk critical temperature increases slightly with an increase of the chain length. We have found that for longer chains the layering transitions within consecutive layers are shifted towards very low temperatures and that their sequence is finally replaced by a single transition. Finally we investigate capillary condensation of chain fluid in slit-like pores. We find that for a fluid of chains consisting of a larger number of segments we observe an inversion effect. Namely, the critical temperature of capillary condensation decreases with increasing pore width for a certain interval of values of the pore width. This anomalous behavior is also influenced by the interaction between molecules and pore walls. (author)

Solid phase transformations

CERN Document Server

Čermák, J

2008-01-01

This special-topic book, devoted to ""Solid Phase Transformations"" , covers a broad range of phenomena which are of importance in a number of technological processes. Most commercial alloys undergo thermal treatment after casting, with the aim of imparting desired compositions and/or optimal morphologies to the component phases. In spite of the fact that the topic has lain at the center of physical metallurgy for a long time, there are numerous aspects which are wide open to potential investigative breakthroughs. Materials with new structures also stimulate research in the field, as well as n

Solid diffusion control of the adsorption of basic dyes onto granular activated carbon and natural zeolite in fixed bed columns

Directory of Open Access Journals (Sweden)

M. MARINKOVSKI

2001-07-01

Full Text Available The adsorption of basic dyes from aqueous solutions onto granular activated carbon and natural zeolite was studied using a fixed bed column. The design procedures for fixed bed adsorption columns were investigated for two basic dyes Maxilon Goldgelb GL EC 400 % (MG-400 and Maxilon Schwarz FBL-01 300 % (MS-300. A computer program based on the solid diffusion control model has been developed. The model parameters: solid diffusion coefficient, DS, axial dispersion coefficient, DL and external mass transfer coefficient, kf for all the investigated systems were estimated by means of a best fit approach.

Modeling adsorption of binary and ternary mixtures on microporous media

DEFF Research Database (Denmark)

Monsalvo, Matias Alfonso; Shapiro, Alexander

2007-01-01

it possible using the same equation of state to describe the thermodynamic properties of the segregated and the bulk phases. For comparison, we also used the ideal adsorbed solution theory (IAST) to describe adsorption equilibria. The main advantage of these two models is their capabilities to predict......The goal of this work is to analyze the adsorption of binary and ternary mixtures on the basis of the multicomponent potential theory of adsorption (MPTA). In the MPTA, the adsorbate is considered as a segregated mixture in the external potential field emitted by the solid adsorbent. This makes...... multicomponent adsorption equilibria on the basis of single-component adsorption data. We compare the MPTA and IAST models to a large set of experimental data, obtaining reasonable good agreement with experimental data and high degree of predictability. Some limitations of both models are also discussed....

Effect on Cs removal of solid-phase metal oxidation in metal ferrocyanides

Energy Technology Data Exchange (ETDEWEB)

Lee, Keun-Young; Kim, Jimin; Oh, Maengkyo; Lee, Eil-Hee; Kim, Kwang-Wook; Chung, Dong-Yong; Moon, Jei-Kwon [Korea Atomic Energy Research Institute (KAERI), Daejeon (Korea, Republic of).

2017-07-01

Metal ferrocyanides (MFCs) have been studied for many years and are regarded as efficient adsorbents for the selective removal of radioactive cesium (Cs) from contaminated aqueous solutions. Although their efficiency has been demonstrated, various investigations on the physicochemical, thermal, and radiological stability of the solids of MFCs are required to enhance the applicability of MFCs in the treatment process. We observed that the Cs adsorption efficiencies of cobalt and nickel ferrocyanides decreased as their aging period increased, while the Cs adsorption efficiencies of copper and zinc ferrocyanides did not decrease. The tendencies of these ferrocyanides were accelerated by exposure of the solids at a higher temperature for a longer time. Our comprehensive analyses demonstrated that only the oxidizable metals in the MFCs can be oxidized by aging time and increasing temperature; also, this affects the Cs removal efficiency by decreasing the exchangeable sites in the solids. The chemical stability of MFCs is very important for the optimization of the synthesis and storage conditions.

Solid-Solid Vacuum Regolith Heat-Exchanger for Oxygen Production, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This SBIR Phase-1 project will demonstrate the feasibility of using a novel coaxial counterflow solid-solid heat exchanger to recover heat energy from spent regolith...

Solid-phase spectrophotometry

International Nuclear Information System (INIS)

Brykina, G.D.; Marchenko, D.Yu.; Shpigun, O.A.

1995-01-01

Solid-phase spectrophotometry (SPS), which is based on the direct measurement of light absorption of an ion exchanger containing a substance of interest, was reviewed. Since 1976, it has been known that aborbance of an ion exchanger is directly proportional to the concentration of a particular ion in solution. A similar dependence can also be followed for other sorbents, as well as for foams, membranes, films, etc., which do not exhibit ion exchange properties. One can use absorption, diffuse reflection, and luminescence spectra parameters as an analytical signal. Thus, SPS of ion exchangers is among the analytical techniques that combine the sorption concentration and surface determination of the substance of interest. This review summarizes the advancements in SPS over the last six years and demonstrates the prospects for its development. Special attention is paid to experimental methods for measuring solid-phase absorption and to the basic procedures of sample preparation, including new ones. These two facets are of great importance for obtaining precise results and extending the capabilities of SPS

Adsorption mechanisms of removing heavy metals and dyes from aqueous solution using date pits solid adsorbent

International Nuclear Information System (INIS)

Al-Ghouti, Mohammad A.; Li, Juiki; Salamh, Yousef; Al-Laqtah, Nasir; Walker, Gavin; Ahmad, Mohammad N.M.

2010-01-01

A potential usefulness of raw date pits as an inexpensive solid adsorbent for methylene blue (MB), copper ion (Cu 2+ ), and cadmium ion (Cd 2+ ) has been demonstrated in this work. This work was conducted to provide fundamental information from the study of equilibrium adsorption isotherms and to investigate the adsorption mechanisms in the adsorption of MB, Cu 2+ , and Cd 2+ onto raw date pits. The fit of two models, namely Langmuir and Freundlich models, to experimental data obtained from the adsorption isotherms was checked. The adsorption capacities of the raw date pits towards MB and both Cu 2+ and Cd 2+ ions obtained from Langmuir and Freundlich models were found to be 277.8, 35.9, and 39.5 mg g -1 , respectively. Surface functional groups on the raw date pits surface substantially influence the adsorption characteristics of MB, Cu 2+ , and Cd 2+ onto the raw date pits. The Fourier transform infrared spectroscopy (FTIR) studies show clear differences in both absorbances and shapes of the bands and in their locations before and after solute adsorption. Two mechanisms were observed for MB adsorption, hydrogen bonding and electrostatic attraction, while other mechanisms were observed for Cu 2+ and Cd 2+ . For Cu 2+ , binding two cellulose/lignin units together is the predominant mechanism. For Cd 2+ , the predominant mechanism is by binding itself using two hydroxyl groups in the cellulose/lignin unit.

Modeling of Shale Gas Adsorption and its Influence on Phase Equilibrium

DEFF Research Database (Denmark)

Sandoval Lemus, Diego Rolando; Yan, Wei; Michelsen, Michael Locht

2018-01-01

provides a comparison of several engineering models for gas adsorption in shale based on the recent literature data for pure and binary gases. For pure components, Langmuir, the modied Toth-Langmuir, and the Multicomponent Potential Theory of Adsorption using Dubinin-Radushkevich potential (MPTA-DRA) were...... compared. The three models show similar deviations lower than 10%. For binary gases, Multicomponent Langmuir (ML), Ideal Adsorbed Solution Theory (IAST) and MPTA were evaluated, where MPTA shows the lowest deviation with 17.9%. Additionally, we presented an analysis of the phase envelope shift under...

Advanced functional materials in solid phase extraction for ICP-MS determination of trace elements and their species - A review.

Science.gov (United States)

He, Man; Huang, Lijin; Zhao, Bingshan; Chen, Beibei; Hu, Bin

2017-06-22

For the determination of trace elements and their species in various real samples by inductively coupled plasma mass spectrometry (ICP-MS), solid phase extraction (SPE) is a commonly used sample pretreatment technique to remove complex matrix, pre-concentrate target analytes and make the samples suitable for subsequent sample introduction and measurements. The sensitivity, selectivity/anti-interference ability, sample throughput and application potential of the methodology of SPE-ICP-MS are greatly dependent on SPE adsorbents. This article presents a general overview of the use of advanced functional materials (AFMs) in SPE for ICP-MS determination of trace elements and their species in the past decade. Herein the AFMs refer to the materials featuring with high adsorption capacity, good selectivity, fast adsorption/desorption dynamics and satisfying special requirements in real sample analysis, including nanometer-sized materials, porous materials, ion imprinting polymers, restricted access materials and magnetic materials. Carbon/silica/metal/metal oxide nanometer-sized adsorbents with high surface area and plenty of adsorption sites exhibit high adsorption capacity, and porous adsorbents would provide more adsorption sites and faster adsorption dynamics. The selectivity of the materials for target elements/species can be improved by using physical/chemical modification, ion imprinting and restricted accessed technique. Magnetic adsorbents in conventional batch operation offer unique magnetic response and high surface area-volume ratio which provide a very easy phase separation, greater extraction capacity and efficiency over conventional adsorbents, and chip-based magnetic SPE provides a versatile platform for special requirement (e.g. cell analysis). The performance of these adsorbents for the determination of trace elements and their species in different matrices by ICP-MS is discussed in detail, along with perspectives and possible challenges in the future

Highly selective solid-phase extraction of trace Pd(II) by murexide functionalized halloysite nanotubes

International Nuclear Information System (INIS)

Li Ruijun; He Qun; Hu Zheng; Zhang Shengrui; Zhang Lijun; Chang Xijun

2012-01-01

Graphical abstract: Murexide functionalized halloysite nanotubes have been developed to separate and concentrate trace Pd(II) from aqueous samples. Parameters that affected the sorption and elution efficiency were studied in column mode, and the new adsorbent presented high selectivity and adsorption capacity for the solid phase extraction of trace Pd(II). Highlights: ► Murexide modified halloysite nanotubes as adsorbent has been reported originally. ► This adsorbent has a unique selectivity for Pd(II) at pH 1.0. ► This adsorbent had high adsorption capacity for Pd(II). ► The precision and accuracy of the method are satisfactory. - Abstract: The originality on the high efficiency of murexide modified halloysite nanotubes as a new adsorbent of solid phase extraction has been reported to preconcentrate and separate Pd(II) in solution samples. The new adsorbent was confirmed by Fourier transformed infrared spectra, X-ray diffraction, scanning electron microscope, transmission electron microscope and N 2 adsorption–desorption isotherms. Effective preconcentration conditions of analyte were examined using column procedures prior to detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of pH, the amount of adsorbent, the sample flow rate and volume, the elution condition and the interfering ions were optimized in detail. Under the optimized conditions, Pd(II) could be retained on the column at pH 1.0 and quantitatively eluted by 2.5 mL of 0.01 mol L −1 HCl–3% thiourea solution at a flow rate of 2.0 mL min −1 . The analysis time was 5 min. An enrichment factor of 120 was accomplished. Common interfering ions did not interfere in both separation and determination. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 42.86 mg g −1 for Pd(II). The detection limit (3σ) of the method was 0.29 ng mL −1 , and the relative standard deviation (RSD) was 3.1% (n = 11). The method was

Molecularly imprinted layer-coated silica nanoparticles for selective solid-phase extraction of bisphenol A from chemical cleansing and cosmetics samples

International Nuclear Information System (INIS)

Zhu Rong; Zhao Wenhui; Zhai Meijuan; Wei Fangdi; Cai Zheng; Sheng Na; Hu Qin

2010-01-01

Highly selective molecularly imprinted layer-coated silica nanoparticles for bisphenol A (BPA) were synthesized by molecular imprinting technique with a sol-gel process on the supporter of silica nanoparticles. The BPA-imprinted silica nanoparticles were characterized by fourier transform infrared spectrometer, transmission electron microscope, dynamic adsorption and static adsorption tests. The equilibrium association constant, K a , and the apparent maximum number of binding sites, Q max , were estimated to be 1.25 x 10 5 mL μmol -1 and 16.4 μmol g -1 , respectively. The BPA-imprinted silica nanoparticles solid-phase extraction (SPE) column had higher selectivity for BPA than the commercial C18-SPE column. The results of the study indicated that the prepared BPA-imprinted silica nanoparticles exhibited high adsorption capacity and selectivity, and offered a fast kinetics for the rebinding of BPA. The BPA-imprinted silica nanoparticles were successfully used in SPE to selectively enrich and determine BPA from shampoo, bath lotion and cosmetic cream samples.

Application of solid-phase microextraction in analytical toxicology.

Science.gov (United States)

Pragst, Fritz

2007-08-01

Solid-phase microextraction (SPME) is a miniaturized and solvent-free sample preparation technique for chromatographic-spectrometric analysis by which the analytes are extracted from a gaseous or liquid sample by absorption in, or adsorption on, a thin polymer coating fixed to the solid surface of a fiber, inside an injection needle or inside a capillary. In this paper, the present state of practical performance and of applications of SPME to the analysis of blood, urine, oral fluid and hair in clinical and forensic toxicology is reviewed. The commercial coatings for fibers or needles have not essentially changed for many years, but there are interesting laboratory developments, such as conductive polypyrrole coatings for electrochemically controlled SPME of anions or cations and coatings with restricted-access properties for direct extraction from whole blood or immunoaffinity SPME. In-tube SPME uses segments of commercial gas chromatography (GC) capillaries for highly efficient extraction by repeated aspiration-ejection cycles of the liquid sample. It can be easily automated in combination with liquid chromatography but, as it is very sensitive to capillary plugging, it requires completely homogeneous liquid samples. In contrast, fiber-based SPME has not yet been performed automatically in combination with high-performance liquid chromatography. The headspace extractions on fibers or needles (solid-phase dynamic extraction) combined with GC methods are the most advantageous versions of SPME because of very pure extracts and the availability of automatic samplers. Surprisingly, substances with quite high boiling points, such as tricyclic antidepressants or phenothiazines, can be measured by headspace SPME from aqueous samples. The applicability and sensitivity of SPME was essentially extended by in-sample or on-fiber derivatization. The different modes of SPME were applied to analysis of solvents and inhalation narcotics, amphetamines, cocaine and metabolites

Wax Precipitation Modeled with Many Mixed Solid Phases

DEFF Research Database (Denmark)

Heidemann, Robert A.; Madsen, Jesper; Stenby, Erling Halfdan

2005-01-01

The behavior of the Coutinho UNIQUAC model for solid wax phases has been examined. The model can produce as many mixed solid phases as the number of waxy components. In binary mixtures, the solid rich in the lighter component contains little of the heavier component but the second phase shows sub......-temperature and low-temperature forms, are pure. Model calculations compare well with the data of Pauly et al. for C18 to C30 waxes precipitating from n-decane solutions. (C) 2004 American Institute of Chemical Engineers....

Solid - solid and solid - liquid phase transitions of iron and iron alloys under laser shock compression

Science.gov (United States)

Harmand, M.; Krygier, A.; Appel, K.; Galtier, E.; Hartley, N.; Konopkova, Z.; Lee, H. J.; McBride, E. E.; Miyanishi, K.; Nagler, B.; Nemausat, R.; Vinci, T.; Zhu, D.; Ozaki, N.; Fiquet, G.

2017-12-01

An accurate knowledge of the properties of iron and iron alloys at high pressures and temperatures is crucial for understanding and modelling planetary interiors. While Earth-size and Super-Earth Exoplanets are being discovered in increasingly large numbers, access to detailed information on liquid properties, melting curves and even solid phases of iron and iron at the pressures and temperatures of their interiors is still strongly limited. In this context, XFEL sources coupled with high-energy lasers afford unique opportunities to measure microscopic structural properties at far extreme conditions. Also the achievable time resolution allows the shock history and phase transition mechanisms to be followed during laser compression, improving our understanding of the high pressure and high strain experiments. Here we present recent studies devoted to investigate the solid-solid and solid-liquid transition in laser-shocked iron and iron alloys (Fe-Si, Fe-C and Fe-O alloys) using X-ray diffraction and X-ray diffuse scattering. Experiment were performed at the MEC end-station of the LCLS facility at SLAC (USA). Detection of the diffuse scattering allowed the identification of the first liquid peak position along the Hugoniot, up to 4 Mbar. The time resolution shows ultrafast (between several tens and several hundreds of picoseconds) solid-solid and solid-liquid phase transitions. Future developments at XFEL facilities will enable detailed studies of the solid and liquid structures of iron and iron alloys as well as out-of-Hugoniot studies.

Preparation and Evaluation of Core–Shell Magnetic Molecularly Imprinted Polymers for Solid-Phase Extraction and Determination of Sterigmatocystin in Food

Directory of Open Access Journals (Sweden)

Jing-Min Liu

2017-10-01

Full Text Available Magnetic molecularly imprinted polymers (MMIPs, combination of outstanding magnetism with specific selective binding capability for target molecules, have proven to be attractive in separation science and bio-applications. Herein, we proposed the core–shell magnetic molecularly imprinted polymers for food analysis, employing the Fe3O4 particles prepared by co-precipitation protocol as the magnetic core and MMIP film onto the silica layer as the recognition and adsorption of target analytes. The obtained MMIPs materials have been fully characterized by scanning electron microscope (SEM, Fourier transform infrared spectrometer (FT-IR, vibrating sample magnetometer (VSM, and re-binding experiments. Under the optimal conditions, the fabricated Fe3O4@MIPs demonstrated fast adsorption equilibrium, a highly improved imprinting capacity, and excellent specificity to target sterigmatocystin (ST, which have been successfully applied as highly efficient solid-phase extraction materials followed by high-performance liquid chromatography (HPLC analysis. The MMIP-based solid phase extraction (SPE method gave linear response in the range of 0.05–5.0 mg·L−1 with a detection limit of 9.1 µg·L−1. Finally, the proposed method was used for the selective isolation and enrichment of ST in food samples with recoveries in the range 80.6–88.7% and the relative standard deviation (RSD <5.6%.

Multiple solid-phase microextraction

NARCIS (Netherlands)

Koster, EHM; de Jong, GJ

2000-01-01

Theoretical aspects of multiple solid-phase microextraction are described and the principle is illustrated with the extraction of lidocaine from aqueous solutions. With multiple extraction under non-equilibrium conditions considerably less time is required in order to obtain an extraction yield that

Influence of organobentonite structure on toluene adsorption from water solution

Directory of Open Access Journals (Sweden)

Nuria Vidal

2012-12-01

Full Text Available Due to increase water pollution by organic compound derived from hydrocarbons such as toluene, several alternative technologies for remediation of polluted water have been originated. In this work natural bentonites were modified with cetyltrimethylammonium (CTMA+ for obtaining organophilic bentonites. The obtained CTMA-bentonites would be suitable for use as adsorbents of toluene present in water. The influence of structural characteristics of CTMA-bentonites on their adsorption capacity was studied. It was shown that adsorption of toluene depended on homogeneous interlayer space associated with arrangements of CTMA+ paraffin-monolayer and bilayer models, accompanied by a high degree ordering of the carbon chain of organic cation in both arrangements. However, packing density would not have an evident influence on the retention capacity of these materials. The solids obtained were characterized by chemical analysis, X-ray diffractions and infrared spectroscopy. Toluene adsorption was measured by UV-visible spectrophotometer. Adsorption capacity was studied by determining adsorption isotherms and adsorption coefficient calculation. The adsorption isotherms were straight-line indicating a partition phenomenon of toluene between the aqueous and organic phase present in organophilic bentonites.

The preparation of solid acid and acid water reducing agent for slag is prepared by adsorption method

Science.gov (United States)

Zhao, Su; Wang, Jinpeng; Zhu, Xitong

2018-03-01

Solid polycarboxylate superplasticizer can not only solve the problems caused by water reducing agent in storage and transportation, but also meet the needs of some special projects. We can choose to use the mineral slag, which is larger than surface area and has stronger adsorption, as adsorbent to absorb liquid polycarboxylate superplasticizer and absorb its moisture, and then makes solid polycarboxylate superplasticizer after drying. It determines the solid-liquid ratio to prepare the solid polycarboxylate superplasticizer to be 3:1. The temperature change within 100°C will not cause changes in the functional group and structure of the water reducing agent molecule. The application of the solid polycarboxylate superplasticizer was basically unchanged compared with its liquid water reducing agent.

New method for evaluating irreversible adsorption and stationary phase bleed in gas chromatographic capillary columns.

Science.gov (United States)

Wright, Bob W; Wright, Cherylyn W

2012-10-26

A novel method is described for the evaluation of irreversible adsorption and column bleed in gas chromatographic (GC) columns using a tandem GC approach. This work specifically determined the degree of irreversible adsorption behavior of specific sulfur and phosphorous containing test probe compounds at levels ranging from approximately 50 picograms (pg) to 1 nanogram (ng) on selected gas chromatographic columns. This method does not replace existing evaluation methods that characterize reversible adsorption but provides an additional tool. The test compounds were selected due to their ease of adsorption and their importance in the specific trace analytical detection methodology being developed. Replicate chromatographic columns with 5% phenylmethylpolysiloxane (PMS), polyethylene glycol (wax), trifluoropropylpolysiloxane (TFP), or 78% cyanopropylpolysiloxane stationary phases from a variety of vendors were evaluated. As expected, the results demonstrate that the different chromatographic phases exhibit differing degrees of irreversible adsorption behavior. The results also indicate that all manufacturers do not produce equally inert columns nor are columns from a given manufacturer identical. The wax-coated columns for the test probes used were more inert as a group than 5% PMS coated columns, and they were more reproducibly manufactured. Both TFP and 78% cyanopropylpolysiloxane columns displayed superior inertness to the test compounds compared to either 5% PMS- or wax-coated columns. Irreversible adsorption behavior was characterized for a limited range of stationary phase film thicknesses. In addition, the method was shown effective for characterizing column bleed and methods to remove bleed components. This method is useful in screening columns for demanding applications and to obtain diagnostic information related to improved preparation methods. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of solids, caloric content on dual-phase gastric emptying

Energy Technology Data Exchange (ETDEWEB)

Van Den Maegdenbergh, V.; Urbain, J.L.; Siegel, J.A.; Mortelmans, L.; De Roo, M. (Univ. Hospital Gasthuisberg, Leuven (Belgium) Temple Univ. Hospital, Philadelphia, PA (USA))

1990-03-01

The dual-phase gastric emptying technique is routinely employed to determine the differential emptying of solids and liquids in a wide spectrum of gastrointestinal diseases. Composition, acidity, volume, caloric density, physical form and viscosity of the test means have been shown to be important determinants for the quantitative evaluation of gastric emptying. In this study, the authors have evaluated the effect of increasing the caloric content of the solid portion of a physiologic test mean on both solid and liquid emptying kinetics in health male volunteers. They observed that increasing solid caloric content delayed emptying of both solids and liquids. For the solid phase, the delay was accounted for by a longer lag phase and decrease in emptying rate; for liquids a longer emptying rate was also obtained. They conclude that modification of the caloric content of the solid portion of a meal not only affects the emptying of the solid phase but also alters the emptying of the liquid component of the meal.

Phase stability in wear-induced supersaturated Al-Ti solid solution

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Y.; Yokoyama, K. [Dept. of Functional Machinery Mechanics Shinshu Univ., Ueda (Japan); Hosoda, H. [Precision and Intelligence Lab., Tokyo Inst. of Tech., Nagatsuta, Midori-ku, Yokohama (Japan)

2002-07-01

Al-Ti supersaturated solid solutions were introduced by wear testing and the rapid quenching of an Al/Al{sub 3}Ti composite (part of an Al/Al{sub 3}Ti functionally graded material) that was fabricated using the centrifugal method. The phase stability of the supersaturated solid solution was studied through systematic annealing of the supersaturated solid solution. It was found that the Al-Ti supersaturated solid solution decomposed into Al and Al{sub 3}Ti intermetallic compound phases during the heat treatment. The Al-Ti supersaturated solid solutions fabricated were, therefore, not an equilibrium phase, and thus decomposed into the equilibrium phases during heat treatment. It was also found that heat treatment leads to a significant hardness increase for the Al-Ti supersaturated solid solution. Finally, it was concluded that formation of the wear-induced supersaturated solid solution layer was a result of severe plastic deformation. (orig.)

Assessment of possible solid-phase phosphate sorbents to mitigate eutrophication: Influence of pH and anoxia.

Science.gov (United States)

Mucci, Maíra; Maliaka, Valentini; Noyma, Natalia Pessoa; Marinho, Marcelo Manzi; Lürling, Miquel

2018-04-01

Managing eutrophication remains a challenge to water managers. Currently, the manipulation of biogeochemical processes (i.e., geo-engineering) by using phosphorus-adsorptive techniques has been recognized as an appropriate tool to manage the problem. The first step in finding potential mitigating materials is conducting a sequence of upscaling studies that commence with controlled laboratory experiments. Here, the abilities of 10 possible solid-phase-sorbents (SPS) to adsorb P were examined. Four materials adsorbed P, and two of these materials were modified, i.e., a lanthanum-modified-bentonite (LMB) and an aluminum-modified-zeolite (AMZ), and had the highest adsorption capacities of 11.4 and 8.9mgPg -1 , respectively. Two natural materials, a red soil (RS) and a bauxite (BAU), were less efficient with adsorption capacities of 2.9 and 3.4mgPg -1 , respectively. Elemental composition was not related to P adsorption. Since SPS might be affected by pH and redox status, we also tested these materials at pH values of 6, 7, 8 and 9 and under anoxic condition. All tested materials experienced decreased adsorption capacities under anoxic condition, with maximum adsorptions of 5.3mgPg -1 for LMB, 5.9mgPg -1 for AMZ, 0.2mgPg -1 for RS and 0.2mgPg -1 for BAU. All materials were able to adsorb P across the range of pH values that were tested. The maximum adsorption capacities of LMB and RS were highest at pH6, AMZ was higher at a pH of 9 and BAU at a pH of 8. Thus, pH influenced P adsorption differently. Given the effects of pH and anoxia, other abiotic variables should also be considered. Considering the criteria that classify a useful SPS (i.e., effective, easy to produce, cheap and safe), only the two modified materials that were tested seem to be suitable for upscaling to enclosure studies with anoxic sediments. Copyright © 2017 Elsevier B.V. All rights reserved.

Adsorption of hyaluronic acid on solid supports: role of pH and surface chemistry in thin film self-assembly.

Science.gov (United States)

Choi, Jae-Hyeok; Kim, Seong-Oh; Linardy, Eric; Dreaden, Erik C; Zhdanov, Vladimir P; Hammond, Paula T; Cho, Nam-Joon

2015-06-15

Owing to its biocompatibility, resistance to biofouling, and desirable physicochemical and biological properties, hyaluronic acid (HA) has been widely used to modify the surface of various materials. The role of various physicochemical factors in HA adsorption remains, however, to be clarified. Herein, we employed quartz crystal microbalance with dissipation (QCM-D) in order to investigate HA adsorption at different pH conditions onto three substrates-silicon oxide, amine-terminated self-assembled monolayer (SAM) on gold, and carboxylic acid-terminated SAM on gold. The QCM-D experiments indicated specific pH conditions where either strong or weak HA adsorption occurs. The morphology of the adsorbed HA layers was investigated by atomic force microscopy (AFM), and we identified that strong HA adsorption produced a complete, homogenous and smooth HA layer, while weak HA adsorption resulted in rough and inhomogeneous HA layers. The observed specifics of the kinetics of HA adsorption, including a short initial linear phase and subsequent long non-linear phase, were described by using a mean-field kinetic model taking HA diffusion limitations and reconfiguration in the adsorbed state into account. The findings extend the physicochemical background of design strategies for improving the use of passive HA adsorption for surface modification applications. Copyright © 2015 Elsevier Inc. All rights reserved.

Determination of diethylstilbestrol in seawater by molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography.

Science.gov (United States)

He, Xiuping; Mei, Xiaoqi; Wang, Jiangtao; Lian, Ziru; Tan, Liju; Wu, Wei

2016-01-15

An effective and highly selective molecularly imprinted material was prepared by suspension polymerization for the isolation and pre-concentration of synthetic estrogen diethylstilbestrol (DES) in seawater. The obtained MIPMs were proved to have more uniform size and porous structure, with maximum adsorption capacity of 8.43 mg g(-1) almost two times more than NIPMs (4.43 mg g(-1)). The MIPMs showed no significant deterioration of the adsorption capacity after five rounds of regeneration. An off-line molecularly imprinted solid phase extraction (MISPE) method followed by HPLC-DAD was proposed for the detection of DES in seawater, and recoveries were satisfactorily higher than 77%. Four seawater samples in aquaculture area were analyzed and 0.61 ng mL(-1) DES was detected in one sample. The result demonstrated that this method can be used for the rapid separation and clean up of trace residual of DES in seawater. Copyright © 2015 Elsevier Ltd. All rights reserved.

Adsorption on metal surfaces: Final report

International Nuclear Information System (INIS)

Einstein, T.L.; Glover, R.E. III; Park, R.L.

1987-01-01

This report discusses the progress at the University of Maryland Department of Physics on the adsorption of atoms or molecules on the surfaces of metals. Also discussed are: Phase transformation studies; the use of transfer matrices to study the 2-d, 3-state chiral Potts model; electron-induced ionization of core electrons of atoms; the reflected electron energy loss fine structure above the M/sub 2,3/ core excitation edge of Cu; and other research in atomic and solid state physics

The development of a general solid-phase radioimmunoassay method. Application to follicle stimulating hormone and to luteinizing hormone radioimmunoassays

International Nuclear Information System (INIS)

Fleury, B.

1981-10-01

A solid phase method of radioimmunoassay utilizing a second antibody adsorbed onto tubes was developed. Polyethylene tubes were selected for their adsorption capacity. The following topics were emphasized: the rate of labelled antigen uptake on the second antibody adsorbed on the tubes through the medium of the first antibody; the influence of the second antibody on the antigen-first antibody reaction and comparison with the immunoprecipiting technique; the various factors able to influence the calibration curve and applications to assay optimization; the performances of hFSH AND hLH assays [fr

Novel materials and methods for solid-phase extraction and liquid chromatography

Energy Technology Data Exchange (ETDEWEB)

Ambrose, Diana [Iowa State Univ., Ames, IA (United States)

1997-06-24

This report contains a general introduction which discusses solid-phase extraction and solid-phase micro-extraction as sample preparation techniques for high-performance liquid chromatography, which is also evaluated in the study. This report also contains the Conclusions section. Four sections have been removed and processed separately: silicalite as a sorbent for solid-phase extraction; a new, high-capacity carboxylic acid functionalized resin for solid-phase extraction; semi-micro solid-phase extraction of organic compounds from aqueous and biological samples; and the high-performance liquid chromatographic determination of drugs and metabolites in human serum and urine using direct injection and a unique molecular sieve.

Axial dispersion of gas and solid phases in a gas—solid packed column at trickle flow

NARCIS (Netherlands)

Roes, A.W.M.; van Swaaij, Willibrordus Petrus Maria

1979-01-01

Axial dispersion of gas and solid phases in a gas—solid packed column at trickle flow, a promising new countercurrent operation, was evaluated using residence time distribution (RTD) experiments. The column was packed with dumped Pall rings, the gas phase was air at ambient conditions and the solid

Solid-phase extraction versus matrix solid-phase dispersion: Application to white grapes.

Science.gov (United States)

Dopico-García, M S; Valentão, P; Jagodziñska, A; Klepczyñska, J; Guerra, L; Andrade, P B; Seabra, R M

2007-11-15

The use of matrix solid-phase dispersion (MSPD) was tested to, separately, extract phenolic compounds and organic acids from white grapes. This method was compared with a more conventional analytical method previously developed that combines solid liquid extraction (SL) to simultaneously extract phenolic compounds and organic acids followed by a solid-phase extraction (SPE) to separate the two types of compounds. Although the results were qualitatively similar for both techniques, the levels of extracted compounds were in general quite lower on using MSPD, especially for organic acids. Therefore, SL-SPE method was preferred to analyse white "Vinho Verde" grapes. Twenty samples of 10 different varieties (Alvarinho, Avesso, Asal-Branco, Batoca, Douradinha, Esganoso de Castelo Paiva, Loureiro, Pedernã, Rabigato and Trajadura) from four different locations in Minho (Portugal) were analysed in order to study the effects of variety and origin on the profile of the above mentioned compounds. Principal component analysis (PCA) was applied separately to establish the main sources of variability present in the data sets for phenolic compounds, organic acids and for the global data. PCA of phenolic compounds accounted for the highest variability (77.9%) with two PCs, enabling characterization of the varieties of samples according to their higher content in flavonol derivatives or epicatechin. Additionally, a strong effect of sample origin was observed. Stepwise linear discriminant analysis (SLDA) was used for differentiation of grapes according to the origin and variety, resulting in a correct classification of 100 and 70%, respectively.

Adsorptive removal of phthalate ester (Di-ethyl phthalate) from aqueous phase by activated carbon: a kinetic study.

Science.gov (United States)

Venkata Mohan, S; Shailaja, S; Rama Krishna, M; Sarma, P N

2007-07-19

Adsorptive studies were carried out on Di-ethyl phthalate (DEP) removal from aqueous phase onto activated carbon. Batch sorption studies were performed and the results revealed that activated carbon demonstrated ability to adsorb DEP. Influence of varying experimental conditions such as DEP concentration, pH of aqueous solution, and dosage of adsorbent were investigated on the adsorption process. Sorption interaction of DEP onto activated carbon obeyed the pseudo second order rate equation. Experimental data showed good fit with both the Langmuir and Freundlich adsorption isotherm models. DEP sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be greater at acidic pH.

Phase coexistence in ferroelectric solid solutions: Formation of monoclinic phase with enhanced piezoelectricity

Directory of Open Access Journals (Sweden)

Xiaoyan Lu

2016-10-01

Full Text Available Phase morphology and corresponding piezoelectricity in ferroelectric solid solutions were studied by using a phenomenological theory with the consideration of phase coexistence. Results have shown that phases with similar energy potentials can coexist, thus induce interfacial stresses which lead to the formation of adaptive monoclinic phases. A new tetragonal-like monoclinic to rhombohedral-like monoclinic phase transition was predicted in a shear stress state. Enhanced piezoelectricity can be achieved by manipulating the stress state close to a critical stress field. Phase coexistence is universal in ferroelectric solid solutions and may provide a way to optimize ultra-fine structures and proper stress states to achieve ultrahigh piezoelectricity.

Sulfonated poly(styrene-divinylbenzene) modified with amines and the application for pipette-tip solid-phase extraction of carbendazim in apples.

Science.gov (United States)

Ma, Yuxin; Liu, Lingling; Tang, Weiyang; Zhu, Tao

2017-10-01

Sulfonated poly(styrene-divinylbenzene) modified with five kinds of amine functional groups was applied to the determination of carbendazim in apple samples with a pipette-tip solid-phase extraction method. The structures of the polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Five different modifications of the solid-phase extraction sorbent based on sulfonated poly(styrene-divinylbenzene) were tested under static and pipette-tip solid-phase extraction conditions. The polymer modified with p-methoxyaniline showed the best recognition capacity and adsorption amount for carbendazim. Under the optimum conditions, 3.00 mg of the adsorbent, 1.00 mL of ethyl acetate as washing solvent, and 1.00 mL of ammonia/acetonitrile (5:95, v/v) as elution solvent were used in the pretreatment procedure of apple samples. The calibration graphs of carbendazim in methanol were linear over 5.00-200.00 μg/mL, and the limits of detection and quantification were 0.01 and 0.03 μg/mL, respectively. The method recoveries of carbendazim were in the range of 91.31-98.13% with associated intraday relative standard deviations of 0.76-2.13% and interday relative standard deviations of 1.10-1.85%. Sulfonated poly(styrene-divinylbenzene) modified with p-methoxyaniline showed satisfactory results (recovery: 97.96%) and potential for the rapid purification of carbendazim in apple samples combined with the pipette-tip solid-phase extraction. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption of gases on heterogeneous surfaces

CERN Document Server

Rudzinski, W

1991-01-01

All real solid surfaces are heterogeneous to a greater or lesser extent and this book provides a broad yet detailed survey of the present state of gas adsorption. Coverage is comprehensive and extends from basic principles to computer simulation of adsorption. Underlying concepts are clarified and the strengths and weaknesses of the various methods described are discussed.Key Features* Adsorption isotherm equations for various types of heterogeneous solid surfaces* Methods of determining the nature of surface heterogeneity and porosity from experimental data* Studies of pha

Mass transfer between gas and particles in a gas-solid trickle flow reactor

NARCIS (Netherlands)

Kiel, J.H.A.; Kiel, J.H.A.; Prins, W.; van Swaaij, Willibrordus Petrus Maria

1992-01-01

Gas-solids mass transfer was studied for counter-current flow of gas and millimetre-sized solid particles over an inert packing at dilute phase or trickle flow conditions. Experimental data were obtained from the adsorption of water vapour on 640 and 2200 ¿m diameter molecular sieve spheres at

Using reweighting and free energy surface interpolation to predict solid-solid phase diagrams

Science.gov (United States)

Schieber, Natalie P.; Dybeck, Eric C.; Shirts, Michael R.

2018-04-01

Many physical properties of small organic molecules are dependent on the current crystal packing, or polymorph, of the material, including bioavailability of pharmaceuticals, optical properties of dyes, and charge transport properties of semiconductors. Predicting the most stable crystalline form at a given temperature and pressure requires determining the crystalline form with the lowest relative Gibbs free energy. Effective computational prediction of the most stable polymorph could save significant time and effort in the design of novel molecular crystalline solids or predict their behavior under new conditions. In this study, we introduce a new approach using multistate reweighting to address the problem of determining solid-solid phase diagrams and apply this approach to the phase diagram of solid benzene. For this approach, we perform sampling at a selection of temperature and pressure states in the region of interest. We use multistate reweighting methods to determine the reduced free energy differences between T and P states within a given polymorph and validate this phase diagram using several measures. The relative stability of the polymorphs at the sampled states can be successively interpolated from these points to create the phase diagram by combining these reduced free energy differences with a reference Gibbs free energy difference between polymorphs. The method also allows for straightforward estimation of uncertainties in the phase boundary. We also find that when properly implemented, multistate reweighting for phase diagram determination scales better with the size of the system than previously estimated.

Heterogeneous Ferroelectric Solid Solutions Phases and Domain States

CERN Document Server

Topolov, Vitaly

2012-01-01

The book deals with perovskite-type ferroelectric solid solutions for modern materials science and applications, solving problems of complicated heterophase/domain structures near the morphotropic phase boundary and applications to various systems with morphotropic phases. In this book domain state–interface diagrams are presented for the interpretation of heterophase states in perovskite-type ferroelectric solid solutions. It allows to describe the stress relief in the presence of polydomain phases, the behavior of unit-cell parameters of coexisting phases and the effect of external electric fields. The novelty of the book consists in (i) the first systematization of data about heterophase states and their evolution in ferroelectric solid solutions (ii) the general interpretation of heterophase and domain structures at changing temperature, composition or electric field (iii) the complete analysis of interconnection domain structures, unit-cell parameters changes, heterophase structures and stress relief.

Molecularly imprinted layer-coated silica nanoparticles for selective solid-phase extraction of bisphenol A from chemical cleansing and cosmetics samples

Energy Technology Data Exchange (ETDEWEB)

Zhu Rong; Zhao Wenhui; Zhai Meijuan; Wei Fangdi; Cai Zheng; Sheng Na [School of Pharmacy, Nanjing Medical University, Hanzhong Road 140, Nanjing, Jiangsu 210029 (China); Hu Qin, E-mail: huqin@njmu.edu.cn [School of Pharmacy, Nanjing Medical University, Hanzhong Road 140, Nanjing, Jiangsu 210029 (China)

2010-01-25

Highly selective molecularly imprinted layer-coated silica nanoparticles for bisphenol A (BPA) were synthesized by molecular imprinting technique with a sol-gel process on the supporter of silica nanoparticles. The BPA-imprinted silica nanoparticles were characterized by fourier transform infrared spectrometer, transmission electron microscope, dynamic adsorption and static adsorption tests. The equilibrium association constant, K{sub a}, and the apparent maximum number of binding sites, Q{sub max}, were estimated to be 1.25 x 10{sup 5} mL {mu}mol{sup -1} and 16.4 {mu}mol g{sup -1}, respectively. The BPA-imprinted silica nanoparticles solid-phase extraction (SPE) column had higher selectivity for BPA than the commercial C18-SPE column. The results of the study indicated that the prepared BPA-imprinted silica nanoparticles exhibited high adsorption capacity and selectivity, and offered a fast kinetics for the rebinding of BPA. The BPA-imprinted silica nanoparticles were successfully used in SPE to selectively enrich and determine BPA from shampoo, bath lotion and cosmetic cream samples.

Adsorption of amphipathic dendrons on polystyrene nanoparticles.

Science.gov (United States)

Sakthivel, T; Florence, A T

2003-03-18

Adsorption of dendrons onto nanoparticles may provide new model structures which may be useful in drug and gene delivery. Tritiated amphipathic dendrons having three lipidic (C(14)) chains coupled to branched (dendritic) lysine head groups with 8, 16 or 32 free terminal amino groups have been synthesised by solid phase peptide techniques. The interaction between these tritiated dendrons and 200 nm polystyrene latex nanoparticles was investigated in phosphate buffered saline. The amount of dendron adsorbed increased with increasing concentration of dendrons and then decreased. Maximum adsorption of dendrons per gram of nanoparticles was found to be between 8.2 and 84 x 10(-6)M, the amounts adsorbed being inversely proportional to the number of amino groups present in the molecule. The number of dendron molecules adsorbed per nanoparticle was found to be between 430 and 4421. The degree of adsorption was found to be slightly altered by the temperature. Copyright 2002 Elsevier Science B.V.

Pyrolytic in situ magnetization of metal-organic framework MIL-100 for magnetic solid-phase extraction.

Science.gov (United States)

Huo, Shu-Hui; An, Hai-Yan; Yu, Jing; Mao, Xue-Feng; Zhang, Zhe; Bai, Lei; Huang, Yan-Feng; Zhou, Peng-Xin

2017-09-29

In this study, we report a facile, environmental friendly fabrication of a type of magnetic metal-organic framework (MOF) MIL-100 that can be used for magnetic solid-phase extraction (MSPE). The magnetic MOF composites were fabricated using in situ calcination method. The as-synthesized materials exhibited both high porosity and magnetic characteristics. They used for the MSPE of polycyclic aromatic hydrocarbons (PAHs) from water samples. Such MOF-based magnetic solid-phase extraction in combination with gas chromatography equipped with a flame ionization detector (GC-FID), exhibited wide linearity (0.02-250μgL -1 ), low detection limits (4.6-8.9ngL -1 ), and high enrichment factors (452-907) for PAHs. The relative standard deviations (RSDs) for intra- and inter-day extractions of PAHs were ranging from 1.7% to 9.8% and 3.8% to 9.2%, respectively. The recoveries for spiked PAHs (1μgL -1 ) in water samples were in the range of 88.5% to 106.6%. The results showed that the special anion-π orbital (electron donor-acceptor) interaction and π-π stacking between magnetic MIL-100 and PAHs play an important role in the adsorption of PAHs. Copyright © 2017. Published by Elsevier B.V.

Properties and reactivity of Fe-organic matter associations formed by coprecipitation versus adsorption: Clues from arsenate batch adsorption

Science.gov (United States)

Mikutta, Robert; Lorenz, Dennis; Guggenberger, Georg; Haumaier, Ludwig; Freund, Anja

2014-11-01

Ferric oxyhydroxides play an important role in controlling the bioavailability of oxyanions such as arsenate and phosphate in soil. Despite this, little is known about the properties and reactivity of Fe(III)-organic matter phases derived from adsorption (reaction of organic matter (OM) to post-synthesis Fe oxide) versus coprecipitation (formation of Fe oxides in presence of OM). Coprecipitates and adsorption complexes were synthesized at pH 4 using two natural organic matter (NOM) types extracted from forest floor layers (Oi and Oa horizon) of a Haplic Podzol. Iron(III) coprecipitates were formed at initial molar metal-to-carbon (M/C) ratios of 1.0 and 0.1 and an aluminum (Al)-to-Fe(III) ratio of 0.2. Sample properties were studied by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), N2 gas adsorption, dynamic light scattering, and electrophoretic mobility measurements. Arsenic [As(V)] adsorption to Fe-OM phases was studied in batch experiments (168 h, pH 4, 100 μM As). The organic carbon (OC) contents of the coprecipitates (82-339 mg g-1) were higher than those of adsorption complexes (31 and 36 mg g-1), leading to pronounced variations in specific surface area (9-300 m2 g-1), average pore radii (1-9 nm), and total pore volumes (11-374 mm3 g-1) but being independent of the NOM type or the presence of Al. The occlusion of Fe solids by OM (XPS surface concentrations: 60-82 atom% C) caused comparable pHPZC (1.5-2) of adsorption complexes and coprecipitates. The synthesis conditions resulted in different Fe-OM association modes: Fe oxide particles in 'M/C 0.1' coprecipitates covered to a larger extent the outermost aggregate surfaces, for some 'M/C 1.0' coprecipitates OM effectively enveloped the Fe oxides, while OM in the adsorption complexes primarily covered the outer aggregate surfaces. Despite of their larger OC contents, adsorption of As(V) was fastest to coprecipitates formed at low Fe availability (M/C 0.1) and facilitated by desorption of weakly

Determination of ciprofloxacin in Jiaozhou Bay using molecularly imprinted solid-phase extraction followed by high-performance liquid chromatography with fluorescence detection

International Nuclear Information System (INIS)

Lian, Ziru; Wang, Jiangtao

2016-01-01

A high selective pre-treatment method for the cleanup and preconcentration of ciprofloxacin in natural seawater samples was developed based on molecularly imprinted solid-phase extraction (MISPE). The ciprofloxacin imprinted polymers were synthesized and the characteristics of obtained polymers were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy and binding experiments. The imprinted materials showed high adsorption ability for ciprofloxacin and were applied as special solid-phase extraction sorbents for selective separation of ciprofloxacin. An off-line MISPE procedure was optimized and the developed MISPE method allowed direct purification and enrichment of the ciprofloxacin from the aqueous samples prior to high-performance liquid chromatography analysis. The recoveries of spiked seawater on the MISPE cartridges ranged from 75.2 to 112.4% and the relative standard deviations were less than 4.46%. Five seawater samples from Jiaozhou Bay were analyzed and ciprofloxacin was detected in two samples with the concentrations of 0.24 and 0.38 μg L −1 , respectively. - Highlights: • Ciprofloxacin molecularly imprinted polymers (Cip-MIPs) were prepared. • The characteristics and recognition efficiency of MIPs were studied. • An off-line method for Cip was developed using MIPs as solid-phase extraction. • Cip in five seawater samples from Jiaozhou Bay of China was determined.

Matrix molecularly imprinted mesoporous sol–gel sorbent for efficient solid-phase extraction of chloramphenicol from milk

International Nuclear Information System (INIS)

Samanidou, Victoria; Kehagia, Maria; Kabir, Abuzar; Furton, Kenneth G.

2016-01-01

Highly selective and efficient chloramphenicol imprinted sol–gel silica based inorganic polymeric sorbent (sol–gel MIP) was synthesized via matrix imprinting approach for the extraction of chloramphenicol in milk. Chloramphenicol was used as the template molecule, 3-aminopropyltriethoxysilane (3-APTES) and triethoxyphenylsilane (TEPS) as the functional precursors, tetramethyl orthosilicate (TMOS) as the cross-linker, isopropanol as the solvent/porogen, and HCl as the sol–gel catalyst. Non-imprinted sol–gel polymer (sol–gel NIP) was synthesized under identical conditions in absence of template molecules for comparison purpose. Both synthesized materials were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and nitrogen adsorption porosimetry, which unambiguously confirmed their significant structural and morphological differences. The synthesized MIP and NIP materials were evaluated as sorbents for molecularly imprinted solid phase extraction (MISPE) of chloramphenicol in milk. The effect of critical extraction parameters (flow rate, elution solvent, sample and eluent volume, selectivity coefficient, retention capacity) was studied in terms of retention and desorption of chloramphenicol. Competition and cross reactivity tests have proved that sol–gel MIP sorbent possesses significantly higher specific retention and enrichment capacity for chloramphenicol compared to its non-imprinted analogue. The maximum imprinting factor (IF) was found as 9.7, whereas the highest adsorption capacity of chloramphenicol by sol–gel MIP was 23 mg/g. The sol–gel MIP was found to be adequately selective towards chloramphenicol to provide the necessary minimum required performance limit (MRPL) of 0.3 μg/kg set forth by European Commission after analysis by LC-MS even without requiring time consuming solvent evaporation and sample reconstitution step, often considered as an integral part in solid phase extraction work

Matrix molecularly imprinted mesoporous sol–gel sorbent for efficient solid-phase extraction of chloramphenicol from milk

Energy Technology Data Exchange (ETDEWEB)

Samanidou, Victoria, E-mail: samanidu@chem.auth.gr [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki (Greece); Kehagia, Maria [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki (Greece); Kabir, Abuzar, E-mail: akabir@fiu.edu [International Forensic Research Institute, Department of Chemistry and Biochemistry, Florida International University, Miami, FL (United States); Furton, Kenneth G. [International Forensic Research Institute, Department of Chemistry and Biochemistry, Florida International University, Miami, FL (United States)

2016-03-31

Highly selective and efficient chloramphenicol imprinted sol–gel silica based inorganic polymeric sorbent (sol–gel MIP) was synthesized via matrix imprinting approach for the extraction of chloramphenicol in milk. Chloramphenicol was used as the template molecule, 3-aminopropyltriethoxysilane (3-APTES) and triethoxyphenylsilane (TEPS) as the functional precursors, tetramethyl orthosilicate (TMOS) as the cross-linker, isopropanol as the solvent/porogen, and HCl as the sol–gel catalyst. Non-imprinted sol–gel polymer (sol–gel NIP) was synthesized under identical conditions in absence of template molecules for comparison purpose. Both synthesized materials were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and nitrogen adsorption porosimetry, which unambiguously confirmed their significant structural and morphological differences. The synthesized MIP and NIP materials were evaluated as sorbents for molecularly imprinted solid phase extraction (MISPE) of chloramphenicol in milk. The effect of critical extraction parameters (flow rate, elution solvent, sample and eluent volume, selectivity coefficient, retention capacity) was studied in terms of retention and desorption of chloramphenicol. Competition and cross reactivity tests have proved that sol–gel MIP sorbent possesses significantly higher specific retention and enrichment capacity for chloramphenicol compared to its non-imprinted analogue. The maximum imprinting factor (IF) was found as 9.7, whereas the highest adsorption capacity of chloramphenicol by sol–gel MIP was 23 mg/g. The sol–gel MIP was found to be adequately selective towards chloramphenicol to provide the necessary minimum required performance limit (MRPL) of 0.3 μg/kg set forth by European Commission after analysis by LC-MS even without requiring time consuming solvent evaporation and sample reconstitution step, often considered as an integral part in solid phase extraction work

Matrix molecularly imprinted mesoporous sol-gel sorbent for efficient solid-phase extraction of chloramphenicol from milk.

Science.gov (United States)

Samanidou, Victoria; Kehagia, Maria; Kabir, Abuzar; Furton, Kenneth G

2016-03-31

Highly selective and efficient chloramphenicol imprinted sol-gel silica based inorganic polymeric sorbent (sol-gel MIP) was synthesized via matrix imprinting approach for the extraction of chloramphenicol in milk. Chloramphenicol was used as the template molecule, 3-aminopropyltriethoxysilane (3-APTES) and triethoxyphenylsilane (TEPS) as the functional precursors, tetramethyl orthosilicate (TMOS) as the cross-linker, isopropanol as the solvent/porogen, and HCl as the sol-gel catalyst. Non-imprinted sol-gel polymer (sol-gel NIP) was synthesized under identical conditions in absence of template molecules for comparison purpose. Both synthesized materials were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and nitrogen adsorption porosimetry, which unambiguously confirmed their significant structural and morphological differences. The synthesized MIP and NIP materials were evaluated as sorbents for molecularly imprinted solid phase extraction (MISPE) of chloramphenicol in milk. The effect of critical extraction parameters (flow rate, elution solvent, sample and eluent volume, selectivity coefficient, retention capacity) was studied in terms of retention and desorption of chloramphenicol. Competition and cross reactivity tests have proved that sol-gel MIP sorbent possesses significantly higher specific retention and enrichment capacity for chloramphenicol compared to its non-imprinted analogue. The maximum imprinting factor (IF) was found as 9.7, whereas the highest adsorption capacity of chloramphenicol by sol-gel MIP was 23 mg/g. The sol-gel MIP was found to be adequately selective towards chloramphenicol to provide the necessary minimum required performance limit (MRPL) of 0.3 μg/kg set forth by European Commission after analysis by LC-MS even without requiring time consuming solvent evaporation and sample reconstitution step, often considered as an integral part in solid phase extraction work-flow. Intra and

Co-pyrolysis of coal with organic solids

Energy Technology Data Exchange (ETDEWEB)

Straka, P.; Buchtele, J. [Inst. of Rock Structure and Mechanics, Prague (Czechoslovakia)

1995-12-01

The co-pyrolysis of high volatile A bituminous coal with solid organic materials (proteins, cellulose, polyisoprene, polystyrene, polyethylene-glycolterephtalate-PEGT) at a high temperature conditions was investigated. Aim of the work was to evaluate, firstly, the changes of the texture and of the porous system of solid phase after high temperature treatment in presence of different types of macromolecular solids, secondly, properties and composition of the tar and gas. Considered organic solids are important waste components. During their co-pyrolysis the high volatile bituminous coal acts as a hydrogen donor in the temperature rank 220-480{degrees}C. In the rank 500- 1000{degrees}C the solid phase is formed. The co-pyrolysis was carried out at heating rate 3 K/min. It was found that an amount of organic solid (5-10%) affects important changes in the optical texture forms of solid phase, in the pore distribution and in the internal surface area. Transport large pores volume decreases in presence of PEGT, polystyrene and cellulose and increases in presence of proteins and polyisoprene. (image analysis measurements show that the tendency of coal to create coarse pores during co-pyrolysis is very strong and increases with increasing amount of organic solid in blend). An addition of considered materials changes the sorption ability (methylene blue test, iodine adsorption test), moreover, the reactivity of the solid phase.

The effect of lithium adsorption on the formation of 1T-MoS2 phase based on first-principles calculation

International Nuclear Information System (INIS)

Zheng, Yuanliao; Huang, Yan; Shu, Haibo; Zhou, Xiaohao; Ding, Jiayi; Chen, Xiaoshuang; Lu, Wei

2016-01-01

The effect of lithium adsorption on the phase transition from 1H-MoS 2 to 1T-MoS 2 is studied by first-principles computations. The results indicate the possibilities of the phase transition for the lithium adsorption. Based on the results of charge density difference and charge-transfer of molybdenum disulfide with lithium adsorption, we elucidated that the mechanism of the changes of electronic property accompanying the phase transition is attributed to the electron transfer of different atoms. According to the result of transition state, it can be found that the phase-transition barrier is related to the coverage of lithium atoms on MoS 2 surface. It may be helpful to obtaining experimentally the stable 1T-MoS 2 structure. - Highlights: • The transformation of MoS 2 from semiconducting to metallic phases is elucidated on the essence of the electron transfer. • The relationship between Li coverage and phase transition barrier is obtained. • The decomposing of Lithiated 1T-MoS 2 at a high concentration of Li adsorption is explained. • The results can be helpful to obtaining experimentally the stable 1T-MoS 2 structure.

The Gaseous Phase as a Probe of the Astrophysical Solid Phase Chemistry

Energy Technology Data Exchange (ETDEWEB)

Abou Mrad, Ninette; Duvernay, Fabrice; Isnard, Robin; Chiavassa, Thierry; Danger, Grégoire, E-mail: gregoire.danger@univ-amu.fr [Aix-Marseille Université, PIIM UMR-CNRS 7345, F-13397 Marseille (France)

2017-09-10

In support of space missions and spectroscopic observations, laboratory experiments on ice analogs enable a better understanding of organic matter formation and evolution in astrophysical environments. Herein, we report the monitoring of the gaseous phase of processed astrophysical ice analogs to determine if the gaseous phase can elucidate the chemical mechanisms and dominant reaction pathways occurring in the solid ice subjected to vacuum ultra-violet (VUV) irradiation at low temperature and subsequently warmed. Simple (CH{sub 3}OH), binary (H{sub 2}O:CH{sub 3}OH, CH{sub 3}OH:NH{sub 3}), and ternary ice analogs (H{sub 2}O:CH{sub 3}OH:NH{sub 3}) were VUV-processed and warmed. The evolution of volatile organic compounds in the gaseous phase shows a direct link between their relative abundances in the gaseous phase, and the radical and thermal chemistries modifying the initial ice composition. The correlation between the gaseous and solid phases may play a crucial role in deciphering the organic composition of astrophysical objects. As an example, possible solid compositions of the comet Lovejoy are suggested using the abundances of organics in its comae.

Study of distribution coefficient of some radionuclides in liquid-solid systems

International Nuclear Information System (INIS)

Ghafar, M.; Abdul-Hadi, A.; Al-Hassanieh, O.

2001-10-01

The distribution of the elements U, Th, Am, Eu, Cs, Sr and Ra in a solid-aqueous system. Natural phosphate in contact with groundwater, was investigated usingγ and α spectroscopy. The effect of various factors such as phase contact time, Ph, particle size of the solid phase, and the concentration of a element Ca, were studied. The obtained results show that, more than 98% of the actinide elements and europium are adsorbed by the solid phase under all conditions. The fission products Cs and Sr have different behaviours, depending on experiment conditions. The behaviour of Ra is closer to the actinides than to the fission products. There are small differences between the behaviour of the actinide elements, which can be interpreted by migration mechanism from the aqueous to the solid phase i.e. adsorption or precipitation. (author)

Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation

Directory of Open Access Journals (Sweden)

Qing Chen

2017-01-01

Full Text Available Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indicates that nitrogen adsorption on shale includes monolayer adsorption, multilayer adsorption, and capillary condensation. Usually, Langmuir isotherm is a monolayer adsorption model for ideal interfaces; BET (Brunauer, Emmett, Teller adsorption isotherm is a multilayer adsorption model based on specific assumptions; Freundlich isotherm is an empirical equation widely applied in liquid phase adsorption. In this study, a new nitrogen adsorption isotherm is applied to simultaneously depict monolayer adsorption, multilayer adsorption, and capillary condensation, which provides more real and accurate representation of nitrogen adsorption on shale. In addition, parameters are discussed in relation to heat of adsorption which is relevant to the shape of the adsorption isotherm curve. The curve fitting results indicate that our new nitrogen adsorption isotherm can appropriately describe the whole process of nitrogen adsorption on shale.

Influence of Adsorption and Capillary Pressure on Phase Equilibria Inside Shale Reservoirs

DEFF Research Database (Denmark)

Sandoval, Diego R.; Yan, Wei; Michelsen, Michael L.

2018-01-01

is moderate in comparison to the that at low pressure and high temperature. The adsorption effects are stronger for the gas bulk phase region, leading to bigger changes in the gas phase composition and the shift of the dew point curve. PVT simulations of two model reservoir fluid systems show significant...... envelope is different. In general, a much shrunk phase envelope with a shifted critical point is observed. The heavier components are preferentially adsorbed in the whole pressure and temperature range studied here. At high pressure and low temperature, the selectivity towards heavier components...

Comparative solution and solid-phase glycosylations toward a disaccharide library

DEFF Research Database (Denmark)

Agoston, K.; Kröger, Lars; Agoston, Agnes

2009-01-01

A comparative study on solution-phase and solid-phase oligosaccharide synthesis was performed. A 16-member library containing all regioisomers of Glc-Glc, Glc-Gal, Gal-Glc, and Gal-Gal disaccharides was synthesized both in solution and on solid phase. The various reaction conditions for different...

Role of nanoparticles in analytical solid phase microextraction (SPME)

NARCIS (Netherlands)

Zielinska, K.; Leeuwen, van H.P.

2013-01-01

Solid phase microextraction (SPME) is commonly used to measure the free concentration of fairly hydrophobic substances in aqueous media on the basis of their partitioning between sample solution and a solid phase. Here we study the role of nanoparticles that may sorb the analyte in the sample

Radiation-induced reactions of amino acids adsorbed on solid surfaces

Energy Technology Data Exchange (ETDEWEB)

Lopez-Esquivel Kranksith, L.; Negron-Mendoza, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, UNAM. Cd. Universitaria, A.P. 70-543, 04510 Mexico D.F. (Mexico); Mosqueira, F.G. [Direcion General de Divulgacion de la Ciencia, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, AP. 70-487 Mexico D.F. (Mexico); Ramos-Bernal, Sergio, E-mail: ramos@nucleares.unam.m [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, UNAM. Cd. Universitaria, A.P. 70-543, 04510 Mexico D.F. (Mexico)

2010-07-21

The purpose of this work is to study the adsorption of compounds such as amino acids on clays and carbon nanotubes (CNTs) as a possible phase in the chemical evolution that may have occurred on the primitive Earth or in extraterrestrial environments. We further study the behavior of amino acids adsorbed on these solid surfaces at different conditions of pH and levels of irradiation, simulating a high-radiation field at early Earth conditions. The relevance of this work is to explain the possible contribution of solids (clays and CNTs) as promoters of polymerization and as shields for the adsorbed organic compounds against external sources of energy. To this end, tryptophan, aspartic acid, and glutamic acid were adsorbed on fixed amounts of solid surfaces and were irradiated by a {sup 60}Co source for different periods of time at fixed dose rates. After irradiation, the amino acids were extracted from the solid and analyzed with UV and IR spectroscopes and high-performance liquid chromatography. The most efficient surface for adsorption of amino acids was clay, followed by CNTs. Studies of the gamma irradiation of amino acids adsorbed on clay (in the solid phase) show a low yield of recovery of the amino acid.

Analytical study of solids-gas two phase flow

International Nuclear Information System (INIS)

Hosaka, Minoru

1977-01-01

Fundamental studies were made on the hydrodynamics of solids-gas two-phase suspension flow, in which very small solid particles are mixed in a gas flow to enhance the heat transfer characteristics of gas cooled high temperature reactors. Especially, the pressure drop due to friction and the density distribution of solid particles are theoretically analyzed. The friction pressure drop of two-phase flow was analyzed based on the analytical result of the single-phase friction pressure drop. The calculated values of solid/gas friction factor as a function of solid/gas mass loading are compared with experimental results. Comparisons are made for Various combinations of Reynolds number and particle size. As for the particle density distribution, some factors affecting the non-uniformity of distribution were considered. The minimum of energy dispersion was obtained with the variational principle. The suspension density of particles was obtained as a function of relative distance from wall and was compared with experimental results. It is concluded that the distribution is much affected by the particle size and that the smaller particles are apt to gather near the wall. (Aoki, K.)

Adsorptive removal of phenol from aqueous phase by using a porous acrylic ester polymer

International Nuclear Information System (INIS)

Pan Bingjun; Pan Bingcai; Zhang Weiming; Zhang Qingrui; Zhang Quanxing; Zheng Shourong

2008-01-01

The removal of phenol from aqueous solution was examined by using a porous acrylic ester polymer (Amberlite XAD-7) as an adsorbent. Favorable phenol adsorption was observed at acidic solution pH and further increase of solution pH results in a marked decrease of adsorption capacity, and the coexisting inorganic salt NaCl exerts positive effect on the adsorption process. Adsorption isotherms of phenol were linearly correlated and found to be well represented by either the Langmuir or Freundlich isotherm model. Thermodynamic parameters such as changes in the enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) indicate that phenol adsorption onto XAD-7 is an exothermic and spontaneous process in nature, and lower ambient temperature results in more favorable adsorption. Kinetic experiments at different initial solute concentrations were investigated and the pseudo-second-order kinetic model was successfully represented the kinetic data. Additionally, the column adsorption result showed that a complete removal of phenol from aqueous phase can be achieved by XAD-7 beads and the exhausted adsorbent was amenable to an entire regeneration by using ethanol as the regenerant. More interestingly, relatively more volume of hot water in place of ethanol can also achieve a similar result for repeated use of the adsorbent

Materials research for passive solar systems: Solid-state phase-change materials

Science.gov (United States)

Benson, D. K.; Webb, J. D.; Burrows, R. W.; McFadden, J. D. O.; Christensen, C.

1985-03-01

A set of solid-state phase-change materials is being evaluated for possible use in passive solar thermal energy storage systems. The most promising materials are organic solid solutions of pentaerythritol (C5H12O4), pentaglycerinve (C5H12O3), and neopentyl glycol (C5H12O2). Solid solution mixtures of these compounds can be tailored so that they exhibit solid-to-solid phase transformations at any desired temperature between 25 C and 188 C, and have latent heats of transformation etween 20 and 70 cal/g. Transformation temperatures, specific heats, and latent heats of transformation have been measured for a number of these materials. Limited cyclic experiments suggest that the solid solutions are stable. These phase-change materials exhibit large amounts of undercooling; however, the addition of certain nucleating agents as particulate dispersions in the solid phase-change material greatly reduces this effect. Computer simulations suggest that the use of an optimized solid-state phase-change material in a Trombe wall could provide better performance than a concrete Trombe wall four times thicker and nine times heavier.

Adsorption behaviors of thiophene, benzene, and cyclohexene on FAU zeolites: Comparison of CeY obtained by liquid-, and solid-state ion exchange

Energy Technology Data Exchange (ETDEWEB)

Qin, Yucai [College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266555, Shandong (China); Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Province, Liaoning Shihua University, Fushun 113001, Liaoning (China); Mo, Zhousheng; Yu, Wenguang; Dong, Shiwei; Duan, Linhai [College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266555, Shandong (China); Gao, Xionghou, E-mail: gaoxionghou@petrochina.com.cn [Petrochemical Research Institute, PetroChina Company Limited, 9 Dongzhimen North Street, Dongcheng District, Beijing 100007 (China); Song, Lijuan, E-mail: lsong56@263.net [College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266555, Shandong (China); Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Province, Liaoning Shihua University, Fushun 113001, Liaoning (China)

2014-02-15

Cerium containing Y zeolites were prepared by liquid- (L-CeY) and solid- (S-CeY) state ion exchange from NaY and HY, respectively. The structural and textural properties were characterized by XRD and N{sub 2} adsorption, and acidity properties were characterized by NH{sub 3} temperature-programmed desorption (NH{sub 3}-TPD) and in situ FTIR spectrum of chemisorbed pyridine (in situ Py-FTIR). Furthermore, the single component adsorption and multi-component competitive adsorption behavior of thiophene, benzene and cyclohexene on those zeolites have also been studied by using vapor adsorption isotherms, solution adsorption breakthrough curves, thermogravimetry and derivative thermogravimetry (TG/DTG), frequency response (FR) and in situ FTIR techniques. The results indicate that the primary adsorption mode of benzene is simply micropore filling process, but the nature of effect of aromatics on selective adsorption of thiophene is competitive adsorption. The strong chemical adsorptions and protonization reactions of thiophene and cyclohexene occur upon the Brönsted acid sites of the HY and L-CeY zeolites, and the preferable acid catalytic protonization reactions of olefins hinder the further adsorption of sulfur compounds.

Application of novel activated carbon fiber solid-phase, microextraction to the analysis of chlorinated hydrocarbons in water by gas chromatography-mass spectrometry

International Nuclear Information System (INIS)

Sun Tonghua; Jia Jinping; Fang Nenghu; Wang Yalin

2005-01-01

This paper presents a study on the performance of activated carbon fiber (ACF) used as extraction fiber for solid-phase microextraction (SPME) and its application for analysis of chlorinated hydrocarbons in water. By means of evaluating scanning electron microscope (SEM) images, specific surface area, pore volume, pore distribution, and properties of adsorption and desorption, the optimal active concentration of phosphoric acid has been determined. Coupled with gas chromatograph-mass spectrometry (GC-MS), ACF-SPME is suitable for determination chlorinated hydrocarbons in water with headspace. Experimental parameters such as adsorption and desorption conditions were studied. The optimized method has an acceptable linearity, good precision, with R.S.D. values <10% for each compound. Compared with commercial fibers, ACF has many advantages such as better resistance to organic solvents, better endurance to high temperature and longer lifetime

Solid-phase reductive amination for glycomic analysis.

Science.gov (United States)

Jiang, Kuan; Zhu, He; Xiao, Cong; Liu, Ding; Edmunds, Garrett; Wen, Liuqing; Ma, Cheng; Li, Jing; Wang, Peng George

2017-04-15

Reductive amination is an indispensable method for glycomic analysis, as it tremendously facilitates glycan characterization and quantification by coupling functional tags at the reducing ends of glycans. However, traditional in-solution derivatization based approach for the preparation of reductively aminated glycans is quite tedious and time-consuming. Here, a simpler and more efficient strategy termed solid-phase reductive amination was investigated. The general concept underlying this new approach is to streamline glycan extraction, derivatization, and purification on non-porous graphitized carbon sorbents. Neutral and sialylated standard glycans were utilized to test the feasibility of the solid-phase method. As results, almost complete labeling of those glycans with four common labels of aniline, 2-aminobenzamide (2-AB), 2-aminobenzoic acid (2-AA) and 2-amino-N-(2-aminoethyl)-benzamide (AEAB) was obtained, and negligible desialylation occurred during sample preparation. The labeled glycans derived from glycoproteins showed excellent reproducibility in high performance liquid chromatography (HPLC) and matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. Direct comparisons based on fluorescent absorbance and relative quantification using isotopic labeling demonstrated that the solid-phase strategy enabled 20-30% increase in sample recovery. In short, the solid-phase strategy is simple, reproducible, efficient, and sensitive for glycan analysis. This method was also successfully applied for N-glycan profiling of HEK 293 cells with MALDI-TOF MS, showing its attractive application in the high-throughput analysis of mammalian glycome. Published by Elsevier B.V.

Humic acid-bonded silica as a novel sorbent for solid-phase extraction of benzo[a]pyrene in edible oils

International Nuclear Information System (INIS)

Luo Dan; Yu Qiongwei; Yin Hongrui; Feng Yuqi

2007-01-01

A novel solid-phase extraction (SPE) sorbent, humic acid-bonded silica (HAS), was prepared. Humic acids (HAs) were grafted onto silica matrices via an amide linkage between humyl chloride and the amido terminus of 3-aminopropyltrimethoxysilane (APTS)-silica gel. The resulting material was characterized by Fourier transform infrared spectrometer, elemental analysis, and nitrogen adsorption analysis. This sorbent exhibits an excellent adsorption capacity for some electron-abundant analytes owing to its peculiar structure. In this paper, we choose benzo[a]pyrene (BaP) in oil as a probe to validate the adsorption capacity of the material. Thus a fast, cheap and simple SPE method with humic acid-bonded silica cartridge for edible oil clean-up, followed by high-performance liquid chromatography (HPLC) with fluorescence detection was established. The effects of experimental variables, such as washing and elution solvents, and the amount of sorbents have been studied. The recoveries of BaP in edible oils spiked at 0.2-100 μg kg -1 were in the range of 78.8-102.7% with relative standard deviations ranging between 1.3 and 9.3%; the limit of detection was -0.06 μg kg -1

Innovative separation and preconcentration technique of coagulating homogenous dispersive micro solid phase extraction exploiting graphene oxide nanosheets

Energy Technology Data Exchange (ETDEWEB)

Ghazaghi, Mehri [Department of Chemistry, College of Science, Semnan University, P.O. Box: 35131-19111, Semnan (Iran, Islamic Republic of); Mousavi, Hassan Zavvar, E-mail: hzmousavi@semnan.ac.ir [Department of Chemistry, College of Science, Semnan University, P.O. Box: 35131-19111, Semnan (Iran, Islamic Republic of); Rashidi, Ali Morad [Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Entrance Blvd., Olympic Village, P.O. Box: 14857-33111, Tehran (Iran, Islamic Republic of); Shirkhanloo, Hamid [Occupational and Environmental Health Research Center (OEHRC), Iranian Petroleum Industry Health Research Institute (IPIHRI), Tehran (Iran, Islamic Republic of); Rahighi, Reza [Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Entrance Blvd., Olympic Village, P.O. Box: 14857-33111, Tehran (Iran, Islamic Republic of); Department of Research and Development, Sharif Ultrahigh Nanotechnologists (SUN) Company, P.O. Box: 13488-96394, Tehran (Iran, Islamic Republic of)

2016-01-01

A uniquely novel, fast, and facile technique is introduced for the first time in which a scant amount of graphene oxide (GO), without modification, has been utilized in dispersive mode of solid phase extraction (SPE) for an efficient yet simple separation. The proposed method of coagulating homogenous dispersive micro solid phase extraction (CHD-µSPE) is based on coagulation of homogeneous GO solution with the aid of polyetheneimine (PEI). CHD-µSPE use full adsorption capacity of GO because in this method was used GO solution obtained from synthesis process without drying step and stacking nanosheets. In optimized condition, 30 µL GO solution (7 mg mL{sup −1}), obtained in synthesis process, was injected into 1.5 mL the sample solution followed by immediate injection of 53 µL PEI solution (1 mg mL{sup −1}). After inserting PEI, GO sheets aggregate and can be readily separated by centrifugation. PEI not only cause aggregation of GO, but also form three-dimensional network of GO with easy handling in following separation steps. Lead, cadmium, and chromium were selected as model analytes and the effecting parameters including the amount of GO, concentration of PEI, sample pH, extraction time, and type of desorption solvent were investigated and optimized. The results indicate that the proposed CHD-µSPE method can be successfully applied GO in dispersive mode of SPE without effecting on good capability adsorption of GO. The novel method was applied in determination of lead, cadmium, and chromium in water, human saliva, and urine samples by electrothermal atomic absorption spectrometry. The detection limits are as low as 0.035, 0.005, and 0.012 µg L{sup −1} for Pb, Cd, and Cr respectively. The intra-day precisions (RSDs) were lower than 3.8%. CHD-µSPE method showed a good linear ranges of 0.24–15.6, 0.015–0.95 and 0.039–2.33 µg L{sup −1} for Pb, Cd and Cr respectively. Method performance was investigated by determination of mentioned

Study on confirmation of Solid-Meal Lag Phase of Gastric Emptying

International Nuclear Information System (INIS)

Lee, Ji Young; Lee, Kyoung Soo; Kim, Chang Guhn; Juhng, Seon Kwan; Won, Jong Jin; Nah, Yong Ho

1991-01-01

The purpose of this study was to examine the existence of a lag phase of gastric emptying of solid meals. We studied solid phase gastric emptying in 26 normal subject using continuous data acquisition for 30 minutes. Each ingested a 300 g meal containing 99m Tc-labeled scrambled egg (solid 150 g, milk 150 ml). Lag phase was determined by 1) inspection of the gastric emptying curve 2) time to a 2% decrease in stomach activity 3) the time of visual appearance of duodenal activity on computer image. We concluded that solid meal lag phase exist.

Study on confirmation of Solid-Meal Lag Phase of Gastric Emptying

Energy Technology Data Exchange (ETDEWEB)

Lee, Ji Young; Lee, Kyoung Soo; Kim, Chang Guhn; Juhng, Seon Kwan; Won, Jong Jin; Nah, Yong Ho [Wonkwang University School of Medicine, Iksan (Korea, Republic of)

1991-07-15

The purpose of this study was to examine the existence of a lag phase of gastric emptying of solid meals. We studied solid phase gastric emptying in 26 normal subject using continuous data acquisition for 30 minutes. Each ingested a 300 g meal containing {sup 99m}Tc-labeled scrambled egg (solid 150 g, milk 150 ml). Lag phase was determined by 1) inspection of the gastric emptying curve 2) time to a 2% decrease in stomach activity 3) the time of visual appearance of duodenal activity on computer image. We concluded that solid meal lag phase exist.

Core-shell Fe3O4 polydopamine nanoparticles as sorbent for magnetic dispersive solid-phase extraction of copper from food samples.

Science.gov (United States)

Yavuz, Emre; Tokalıoğlu, Şerife; Patat, Şaban

2018-10-15

In the present study, core-shell Fe 3 O 4 polydopamine nanoparticles were synthesized and used for the first time as an adsorbent for the vortex assisted magnetic dispersive solid phase extraction of copper from food samples. After elution, copper in the solutions was determined by FAAS. The adsorbent was characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area, and zeta potential measurements. Various parameters affecting the magnetic dispersive solid-phase extraction were evaluated. The optimum pH and magnetic adsorbent amount were found to be 5 and 40 mg, respectively. Elution was made by 3 mL of 2 mol L -1 HNO 3 .The major advantage of the method is the fast equilibration during adsorption without the need for vortexing or shaking. The preconcentration factor and detection limit of the method were found to be 150 and 0.22 mg L -1 , respectively. The precision (as RSD%) and adsorption capacity of the method were 3.7% and 28 mg g -1 , respectively. The method was successfully verified by analyzing four certified reference materials (SPS-WW1 Batch 114 Wastewater, TMDA-53.3 Lake water, BCR-482 Lichen and 1573a Tomato Leaves) and by addition/recovery tests of copper standard solution in organic baby food, muesli, macaroni, honey, and milk samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

An adsorption of carbon dioxide on activated carbon controlled by temperature swing adsorption

Science.gov (United States)

Tomas, Korinek; Karel, Frana

2017-09-01

This work deals with a method of capturing carbon dioxide (CO2) in indoor air. Temperature Swing Adsorption (TSA) on solid adsorbent was chosen for CO2 capture. Commercial activated carbon (AC) in form of extruded pellets was used as a solid adsorbent. There was constructed a simple device to testing effectiveness of CO2 capture in a fixed bed with AC. The TSA cycle was also simulated using the open-source software OpenFOAM. There was a good agreement between results obtained from numerical simulations and experimental data for adsorption process.

Novel solid – solid phase change material based on polyethylene glycol and cellulose used for temperature stabilisation

Directory of Open Access Journals (Sweden)

Wojda Marta

2014-01-01

Full Text Available Thermal management is one of crucial issues in the development of modern electronic devices. In the recent years interest in phase change materials (PCMs as alternative cooling possibility has increased significantly. Preliminary results concerning the research into possibility of the use of solid-solid phase change materials (S-S PCMs for stabilisation temperature of electronic devices has been presented in the paper. Novel solid-solid phase change material based on polyethylene glycol and cellulose has been synthesized. Attempt to improve its thermal conductivity has been taken. Material has been synthesized for the purpose of stabilisation of temperature of electronic devices.

Adsorption of radon and water vapor on commercial activated carbons

International Nuclear Information System (INIS)

Hassan, N.M.; Ghosh, T.K.; Hines, A.L.; Loyalka, S.K.

1995-01-01

Equilibrium adsorption isotherms are reported for radon and water vapor on two commercial activated carbons: coconut shell Type PCB and hardwood Type BD. The isotherms of the water vapor were measured gravimetrically at 298 K. The isotherms of radon from dry nitrogen were obtained at 293, 298, and 308 K while the data for the mixture of radon and water vapor were measured at 298 K. The concentrations of radon in the gas and solid phases were measured simultaneously, once the adsorption equilibrium and the radioactive equilibrium between the radon and its daughter products were established. The shape of the isotherms was of Type III for the radon and Type V for the water vapor, according to Brunauer's classification. The adsorption mechanism was similar for both the radon and the water vapor, being physical adsorption on the macropore surface area in the low pressure region and micropore filling near saturation pressure. The uptake capacity of radon decreased both with increasing temperature and relative humidity. The heat of adsorption data indicated that the PCB- and the BD-activated carbons provided a heterogeneous surface for radon adsorption. The equilibrium data for radon were correlated with a modified Freundlich equation

Selective solid-phase extraction based on molecularly imprinted technology for the simultaneous determination of 20 triazole pesticides in cucumber samples using high-performance liquid chromatography-tandem mass spectrometry.

Science.gov (United States)

Zhao, Fengnian; She, Yongxin; Zhang, Chao; Cao, Xiaolin; Wang, Shanshan; Zheng, Lufei; Jin, Maojun; Shao, Hua; Jin, Fen; Wang, Jing

2017-10-01

A selective analytical method for the simultaneous determination of 20 triazole fungicides and plant growth regulators in cucumber samples was developed using solid-phase extraction with specific molecularly imprinted polymers (MIPs) as adsorbents. The MIPs were successfully prepared by precipitation polymerization using triadimefon as the template molecule, methacrylic acid as the functional monomer, trimethylolpropane trimethacrylate as the crosslinker, and acetonitrile as the porogen. The performance and recognition mechanism for both the MIPs and non-molecularly imprinted polymers were evaluated using adsorption isotherms and adsorption kinetics. Liquid chromatography-tandem quadrupole mass spectrometry was used to identify and quantify the target analytes. The solid-phase extraction using the MIPs was rapid, convenient, and efficient for extraction and enrichment of the 20 triazole pesticides from cucumber samples. The recoveries obtained at three concentration levels (1, 2, and 10μgL -1 ) ranged from 82.3% to 117.6% with relative standard deviations of less than 11.8% (n=5) for all analytes. The limits of detection for the 20 triazole pesticides were all less than 0.4μgL -1 , and were sufficient to meet international standards. Copyright © 2017 Elsevier B.V. All rights reserved.

Volatile organic compound adsorption in a gas-solid fluidized bed.

Science.gov (United States)

Ng, Y L; Yan, R; Tsen, L T S; Yong, L C; Liu, M; Liang, D T

2004-01-01

Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas

Determination of solid-liquid partition coefficients (Kd) for the herbicides inspiration and trifluralin in five UK agricultural soils

International Nuclear Information System (INIS)

Cooke, Cindy M.; Shaw, George; Collins, Chris D.

2004-01-01

Isoproturon and trifluralin are herbicides of contrasting chemical characters and modes of action. Standard batch sorption procedures were carried out to investigate the individual sorption behaviour of 14 C-isoproturon and 14 C-trifluralin in five agricultural soils (1.8-4.2% OC), and the soil solid-liquid partition coefficients (K d values) were determined. Trifluralin exhibited strong partitioning to the soil solid phase (K d range 106-294) and low desorption potential, thus should not pose a threat to sensitive waters via leaching, although particle erosion and preferential flow pathways may facilitate transport. For isoproturon, soil adsorption was low (K d range 1.96-5.75) and desorption was high, suggesting a high leaching potential, consistent with isoproturon being the most frequently found pesticide in UK surface waters. Soil partitioning was directly related to soil organic carbon (OC) content. Accumulation isotherms were modelled using a dual-phase adsorption model to estimate adsorption and desorption rate coefficients. Associations between herbicides and soil humic substances were also shown using gel filtration chromatography. - Capsule: Herbicide soil sorption described by a dual-phase adsorption model reflected soil partitioning, as influenced by soil OC and humic substances

N-Acyliminium Intermediates in Solid-Phase Synthesis

DEFF Research Database (Denmark)

Quement, Sebastian Thordal le; Petersen, Rico; Meldal, M.

2010-01-01

N-Acyliminium ions are powerful intermediates in synthetic organic chemistry. Examples of their use are numerous in solution-phase synthesis, but there are unmerited few reports on these highly reactive electrophiles in solid-phase synthesis. The present review covers the literature to date and i...

Solid-phase synthesis of molecularly imprinted nanoparticles.

Science.gov (United States)

Canfarotta, Francesco; Poma, Alessandro; Guerreiro, Antonio; Piletsky, Sergey

2016-03-01

Molecularly imprinted polymers (MIPs) are synthetic materials, generally based on acrylic or methacrylic monomers, that are polymerized in the presence of a specific target molecule called the 'template' and capable of rebinding selectively to this target molecule. They have the potential to be low-cost and robust alternatives to biomolecules such as antibodies and receptors. When prepared by traditional synthetic methods (i.e., with free template in solution), their usefulness has been limited by high binding site heterogeneity, the presence of residual template and the fact that the production methods are complex and difficult to standardize. To overcome some of these limitations, we developed a method for the synthesis of MIP nanoparticles (nanoMIPs) using an innovative solid-phase approach, which relies on the covalent immobilization of the template molecules onto the surface of a solid support (glass beads). The obtained nanoMIPs are virtually free of template and demonstrate high affinity for the target molecule (e.g., melamine and trypsin in our published work). Because of an affinity separation step performed on the solid phase after polymerization, poor binders and unproductive polymer are removed, so the final product has more uniform binding characteristics. The overall protocol, starting from the immobilization of the template onto the solid phase and including the purification and characterization of the nanoparticles, takes up to 1 week.

Magnetic nanoparticles modified with polydimethylsiloxane and multi-walled carbon nanotubes for solid-phase extraction of fluoroquinolones

International Nuclear Information System (INIS)

Xu, S.; Jiang, C.; Lin, Y.; Jia, L.

2012-01-01

We have surface-functionalized magnetic particles (MPs) with polydimethylsiloxane and multi-walled carbon nanotubes in a two-step reaction. The MPs were applied to solid-phase extraction of the fluoroquinolones ofloxacin, norfloxacin, ciprofloxacin, enrofloxacin prior to their determination by capillary liquid chromatography. The effects of sample pH, adsorption time, type of eluent, desorption time and desorption temperature were investigated. Under the optimum conditions, the extraction efficiencies are in the range from 81.5 % to 94.1 %, with relative standard deviations (RSDs) of -1 . The method was applied to the analysis of spiked mineral water and honey. The recoveries for the fluoroquinolones in the real samples range from 84.0 % to 112 %, with RSDs ranging from 2.9 % to 7.8 %. (author)

Determination of Differential Enthalpy and Isotherm by Adsorption Calorimetry

Directory of Open Access Journals (Sweden)

V. Garcia-Cuello

2008-01-01

Full Text Available An adsorption microcalorimeter for the simultaneous determination of the differential heat of adsorption and the adsorption isotherm for gas-solid systems are designed, built, and tested. For this purpose, a Calvet heat-conducting microcalorimeter is developed and is connected to a gas volumetric unit built in stainless steel to record adsorption isotherms. The microcalorimeter is electrically calibrated to establish its sensitivity and reproducibility, obtaining K=154.34±0.23 WV−1. The adsorption microcalorimeter is used to obtain adsorption isotherms and the corresponding differential heats for the adsorption of CO2 on a reference solid, such as a NaZSM-5 type zeolite. Results for the behavior of this system are compared with those obtained with commercial equipment and with other studies in the literature.

Synthesis of g-C3N4/Fe3O4 nanocomposites and application as a new sorbent for solid phase extraction of polycyclic aromatic hydrocarbons in water samples.

Science.gov (United States)

Wang, Man; Cui, Shihai; Yang, Xiaodi; Bi, Wentao

2015-01-01

An easy preparation of g-C3N4/Fe3O4 nanocomposites by chemical co-precipitation has been demonstrated. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The high affinity of g-C3N4 toward polycyclic aromatic hydrocarbons and the magnetic behavior of Fe3O4 were combined to provide an efficient and simple magnetic solid phase extraction (MSPE). The adsorption and desorption of polycyclic aromatic hydrocarbons on g-C3N4/Fe3O4 were examined. Different factors affecting the magnetic solid phase extraction of polycyclic aromatic hydrocarbons were assessed in terms of adsorption, desorption, and recovery. Under the optimized conditions, the proposed method showed good limits of detection (LOD, S/N=3) in the range of 0.05-0.1 ng mL(-1) and precision in the range of 1.8-5.3% (RSDs, n=3). This method was also successfully applied to the analysis of real water samples; good spiked recoveries over the range of 80.0-99.8% were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

An initial research on solute migration model coupled with adsorption of surface complexation in groundwater

International Nuclear Information System (INIS)

Qian Tianwei; Chen Fanrong

2003-01-01

The influence of solution chemical action in groundwater on solute migration has attracted increasing public attention, especially adsorption action occurring on surface of solid phase and liquid phase, which has play a great role in solute migration. There are various interpretations on adsorption mechanism, in which surface complexion is one of successful hypothesis. This paper first establishes a geochemical model based on surface complexion and then coupled it with traditional advection-dispersion model to constitute a solute migration model, which can deal with surface complexion action. The simulated results fit very well with those obtained by the precursors, as compared with a published famous example, which indicates that the model set up by this paper is successful. (authors)

Solid phase extraction membrane

Science.gov (United States)

Carlson, Kurt C [Nashville, TN; Langer, Roger L [Hudson, WI

2002-11-05

A wet-laid, porous solid phase extraction sheet material that contains both active particles and binder and that possesses excellent wet strength is described. The binder is present in a relatively small amount while the particles are present in a relatively large amount. The sheet material is sufficiently strong and flexible so as to be pleatable so that, for example, it can be used in a cartridge device.

Selective solid-phase extraction using oxidized activated carbon modified with triethylenetetramine for preconcentration of metal ions

Science.gov (United States)

Zhang, Li; Chang, Xijun; Li, Zhenhua; He, Qun

2010-02-01

A new selective solid-phase extractant using activated carbon as matrix which was purified, oxidized and modified by triethylenetetramine (AC-TETA) was prepared and characterized by FT-IR spectroscopy. At pH 4, quantitative extraction of trace Cr(III), Fe(III) and Pb(II) was obtained and determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Complete elution of the adsorbed metal ions from the sorbent surface was carried out using 0.5 mol L -1 HCl. The maximum static adsorption capacity of sorbent for Cr(III), Fe(III) and Pb(II) was 34.6, 36.5 and 51.9 mg g -1, respectively. The time of quantitative adsorption was less than 2 min. The detection limits of the method was found to be 0.71, 0.35 and 0.45 ng mL -1 for Cr(III), Fe(III) and Pb(II), and the relative standard deviation (RSD) was 3.7%, 2.2% and 2.5%, respectively. Moreover, the method was free from interference with common coexiting ions. The method was also successfully applied to the preconcentration of trace Cr(III), Fe(III) and Pb(II) in synthetic samples and a real sample with satisfactory results.

Gas Phase Transport, Adsorption and Surface Diffusion in Porous Glass Membrane

Czech Academy of Sciences Publication Activity Database

Yang, J.; Čermáková, Jiřina; Uchytil, Petr; Hamel, Ch.; Seidel-Morgenstern, A.

2005-01-01

Roč. 104, 2-4 (2005), s. 344-351 ISSN 0920-5861. [International Conference on Catalysis in Membrane Reactors /6./. Lahnstein, 06.07.2004-09.07.2004] R&D Projects: GA AV ČR(CZ) IAA4072402 Institutional research plan: CEZ:AV0Z40720504 Keywords : gas phase transport * vycor glass * adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.365, year: 2005

Solid phase syntheses of oligoureas

Energy Technology Data Exchange (ETDEWEB)

Burgess, K.; Linthicum, D.S.; Russell, D.H.; Shin, H.; Shitangkoon, A.; Totani, R.; Zhang, A.J.; Ibarzo, J. [Texas A& M Univ., College Station, TX (United States)

1997-02-19

Isocyanates 7 were formed from monoprotected diamines 3 or 6, which in turn can be easily prepared from commercially available N-BOC- or N-FMOC-protected amino acid derivatives. Isocyanates 7, formed in situ, could be coupled directly to a solid support functionalized with amine groups or to amino acids anchored on resins using CH{sub 2}Cl{sub 2} as solvent and an 11 h coupling time at 25 {degree}C. Such couplings afforded peptidomimetics with an N-phthaloyl group at the N-terminus. The optimal conditions identified for removal of the N-phthaloyl group were to use 60% hydrazine in DMF for 1-3 h. Several sequences of amino acids coupled to ureas (`peptidic ureas`) and of sequential urea units (`oligoureas`) were prepared via solid phase syntheses and isolated by HPLC. Partition coefficients were measured for two of these peptidomimetics, and their water solubilities were found to be similar to the corresponding peptides. A small library of 160 analogues of the YGGFL-amide sequence was prepared via Houghten`s tea bag methodology. This library was tested for binding to the anti-{beta}-endorphin monoclonal antibody. Overall, this paper describes methodology for solid phase syntheses of oligourea derivatives with side chains corresponding to some of the protein amino acids. The chemistry involved is ideal for high-throughput syntheses and screening operations. 51 refs., 3 figs., 2 tabs.

All solid-state SBS phase conjugate mirror

Science.gov (United States)

Dane, C.B.; Hackel, L.A.

1999-03-09

A stimulated Brillouin scattering (SBS) phase conjugate laser mirror uses a solid-state nonlinear gain medium instead of the conventional liquid or high pressure gas medium. The concept has been effectively demonstrated using common optical-grade fused silica. An energy threshold of 2.5 mJ and a slope efficiency of over 90% were achieved, resulting in an overall energy reflectivity of >80% for 15 ns, 1 um laser pulses. The use of solid-state materials is enabled by a multi-pass resonant architecture which suppresses transient fluctuations that would otherwise result in damage to the SBS medium. This all solid state phase conjugator is safer, more reliable, and more easily manufactured than prior art designs. It allows nonlinear wavefront correction to be implemented in industrial and defense laser systems whose operating environments would preclude the introduction of potentially hazardous liquids or high pressure gases. 8 figs.

Solid-Phase S-Alkylation Promoted by Molecular Sieves.

Science.gov (United States)

Calce, Enrica; Leone, Marilisa; Mercurio, Flavia Anna; Monfregola, Luca; De Luca, Stefania

2015-11-20

A solid-phase S-alkylation procedure to introduce chemical modification on the cysteine sulfhydryl group of a peptidyl resin is reported. The reaction is promoted by activated molecular sieves and consists of a solid-solid process, since both the catalyst and the substrate are in a solid state. The procedure was revealed to be efficient and versatile, particularly when used in combination with the solution S-alkylation approach, allowing for the introduction of different molecular diversities on the same peptide molecule.

Linkage of biomolecules to solid phases for immunoassay

International Nuclear Information System (INIS)

Chapman, R.S.

1998-01-01

Topics covered by this lecture include a brief review of the principal methods of linkage of biomolecules to solid phase matrices. Copies of the key self explanatory slides are presented as figures together with reprints of two publications by the author dealing with a preferred chemistry for the covalent linkage of antibodies to hydroxyl and amino functional groups and the effects of changes in solid phase matrix and antibody coupling chemistry on the performance of a typical excess reagent immunoassay for thyroid stimulating hormone

Modeling adsorption: Investigating adsorbate and adsorbent properties

Science.gov (United States)

Webster, Charles Edwin

1999-12-01

Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

A batch adsorption study on bentonite clay Pertinence to transport modeling?

Science.gov (United States)

BOURG, I.; BOURG, A. C.; SPOSITO, G.

2001-12-01

Bentonite clay is often used as a component of engineered barriers for the isolation of high-level toxic wastes. This swelling clay is used for its physical (impermeability, self-healing) but also for its chemical properties, mostly a high cation exchange capacity (CEC). The adsorbed cations being temporarily immobilized, this should slow down the release of cations from the waste to the surrounding environment. In order to assess the performance of the engineered barrier, the partitioning of solutes between the liquid and solid phases needs to be quantified for use in transport models. The usual method for characterizing the adsorption is through batch adsorption experiments on dispersed suspensions of the solid, yielding an adsorption isotherm (adsorbed concentration vs. dissolved concentration). This isotherm however should be a function of various environmental variables (e.g., pH, ionic strength, concentrations of various ligands and competing adsorbents), so that extrapolation of lab data to performance assessment in the field is problematic. We present results from a study of the adsorption of cesium, strontium, cadmium and lead on dispersed suspensions of the standard BX-80 bentonite. Through a wide range of experimental parameters (pH, ionic strength, reaction time, reactor open or closed to the atmosphere, study of a range of cations of differing properties), we seek a mechanistic interpretation of the results instead of an empirical determination of adsorption parameters. Depending on the mechanisms that control the adsorption in different experimental ranges, we discuss the degree to which the partitioning coefficient (Kd) obtained in the lab can be extrapolated to a transport model through compacted bentonite in a natural environment.

Environmental mobility of cobalt-Influence of solid phase characteristics and groundwater chemistry

International Nuclear Information System (INIS)

Payne, T.E.; Itakura, T.; Comarmond, M.J.; Harrison, J.J.

2009-01-01

The adsorption of cobalt on samples from a potential waste repository site in an arid region was investigated in batch experiments, as a function of various solution phase parameters including the pH and ionic strength. The samples were characterized using a range of techniques, including BET surface area measurements, total clay content and quantitative X-ray diffraction. The statistical relationships between the measured cobalt distribution coefficients (K d values) and the solid and liquid phase characteristics were assessed. The sorption of cobalt increased with the pH of the aqueous phase. In experiments with a fixed pH value, the measured K d values were strongly correlated to the BET surface area, but not to the amount of individual clay minerals (illite, kaolinite or smectite). A further set of sorption experiments was undertaken with two samples of distinctive mineralogy and surface area, and consequently different sorption properties. A simple surface complexation model (SCM) that conceptualized the surface sites as having equivalent sorption properties to amorphous Fe-oxide was moderately successful in explaining the pH dependence of the sorption data on these samples. Two different methods of quantifying the input parameters for the SCM were assessed. While a full SCM for cobalt sorption on these complex environmental substrates is not yet possible, the basic applicability and predictive capability of this type of modeling is demonstrated. A principal requirement to further develop the modeling approach is adequate models for cobalt sorption on component mineral phases of complex environmental sorbents.

Phase diagram of a Lennard-Jones solid

International Nuclear Information System (INIS)

Choi, Y.; Ree, T.; Ree, F.H.

1993-01-01

A phase diagram of a Lennard-Jones solid at kT/ε≥0.8 is constructed by our recent perturbation theory. It shows the stability of the face-centered-cubic phase except within a small pressure and temperature domain, where the hexagonal-close packed phase may occur. The theory predicts anharmonic contributions to the Helmholtz free energy (important to the crystal stability) in good agreement with Monte Carlo data

Biological treatment of soils contaminated with hydrophobic organics using slurry and solid phase techniques

International Nuclear Information System (INIS)

Cassidy, D.P.; Irvine, R.L.

1995-01-01

Both slurry-phase and solid-phase bioremediation are effective ex situ soil decontamination methods. Slurry is energy intensive relative to solid-phase treatment, but provides homogenization and uniform nutrient distribution. Limited contaminant bioavailability at concentrations above the required cleanup level reduces biodegradation rates and renders solid phase bioremediation more cost effective than complete treatment in a bioslurry reactor. Slurrying followed by solid-phase bioremediation combines the advantages and minimizes the weaknesses of each treatment method when used alone. A biological treatment system consisting of slurrying followed by aeration in solid phase bioreactors was developed and tested in the laboratory using a silty clay load contaminated with diesel fuel. The first set of experiments was designed to determine the impact of the water content and mixing time during slurrying on the ate and extent of contaminant removal in continuously aerated solid phase bioreactors. The second set of experiments compared the volatile and total diesel fuel removal in solid phase bioreactors using periodic and continuous aeration strategies

MOLECULARLY IMPRINTED SOLID PHASE EXTRACTION FOR TRACE ANALYSIS OF DIAZINON IN DRINKING WATER

Directory of Open Access Journals (Sweden)

M. Rahiminejad ، S. J. Shahtaheri ، M. R. Ganjali ، A. Rahimi Forushani ، F. Golbabaei

2009-04-01

Full Text Available Amongst organophosphate pesticides, the one most widely used and common environmental contaminant is diazinon; thus methods for its trace analysis in environmental samples must be developed. Use of diazinon imprinted polymers such as sorbents in solid phase extraction, is a prominent and novel application area of molecular imprinted polymers. For diazinon extraction, high performance liquid chromatography analysis was demonstrated in this study. During optimization of the molecular imprinted solid phase extraction procedure for efficient solid phase extraction of diazinon, Plackett-Burman design was conducted. Eight experimental factors with critical influence on molecular imprinted solid phase extraction performance were selected, and 12 different experimental runs based on Plackett-Burman design were carried out. The applicability of diazinon imprinted polymers as the sorbent in solid phase extraction, presented obtained good recoveries of diazinon from LC-grade water. An increase in pH caused an increase in the recovery on molecular imprinted solid phase extraction. From these results, the optimal molecular imprinted solid phase extraction procedure was as follows: solid phase extraction packing with 100 mg diazinon imprinted polymers; conditioning with 5 mL of methanol and 6 mL of LC-grade water; sample loading containing diazinon (pH=10; washing with 1 mL of LC-grade water, 1 mL LC- grade water containing 30% acetonitrile and 0.5 mL of acetonitrile, respectively; eluting with 1 mL of methanol containing 2% acetic acid. The percentage recoveries obtained by the optimized molecular imprinted solid phase extraction were more than 90% with drinking water spiked at different trace levels of diazinon. Generally speaking, the molecular imprinted solid phase extraction procedure and subsequent high performance liquid chromatography analysis can be a relatively fast and proper approach for qualitative and quantitative analysis of diazinon in

Determination of solid-liquid partition coefficients (K{sub d}) for the herbicides inspiration and trifluralin in five UK agricultural soils

Energy Technology Data Exchange (ETDEWEB)

Cooke, Cindy M. [Department of Environmental Science and Technology, Faculty of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY (United Kingdom)]. E-mail: cindy.cooke@imperial.ac.uk; Shaw, George [Department of Environmental Science and Technology, Faculty of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY (United Kingdom); Collins, Chris D. [Department of Environmental Science and Technology, Faculty of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY (United Kingdom)

2004-12-01

Isoproturon and trifluralin are herbicides of contrasting chemical characters and modes of action. Standard batch sorption procedures were carried out to investigate the individual sorption behaviour of {sup 14}C-isoproturon and {sup 14}C-trifluralin in five agricultural soils (1.8-4.2% OC), and the soil solid-liquid partition coefficients (K{sub d} values) were determined. Trifluralin exhibited strong partitioning to the soil solid phase (K{sub d} range 106-294) and low desorption potential, thus should not pose a threat to sensitive waters via leaching, although particle erosion and preferential flow pathways may facilitate transport. For isoproturon, soil adsorption was low (K{sub d} range 1.96-5.75) and desorption was high, suggesting a high leaching potential, consistent with isoproturon being the most frequently found pesticide in UK surface waters. Soil partitioning was directly related to soil organic carbon (OC) content. Accumulation isotherms were modelled using a dual-phase adsorption model to estimate adsorption and desorption rate coefficients. Associations between herbicides and soil humic substances were also shown using gel filtration chromatography. - Capsule: Herbicide soil sorption described by a dual-phase adsorption model reflected soil partitioning, as influenced by soil OC and humic substances.

Phase-field model of vapor-liquid-solid nanowire growth

Science.gov (United States)

Wang, Nan; Upmanyu, Moneesh; Karma, Alain

2018-03-01

We present a multiphase-field model to describe quantitatively nanowire growth by the vapor-liquid-solid (VLS) process. The free-energy functional of this model depends on three nonconserved order parameters that distinguish the vapor, liquid, and solid phases and describe the energetic properties of various interfaces, including arbitrary forms of anisotropic γ plots for the solid-vapor and solid-liquid interfaces. The evolution equations for those order parameters describe basic kinetic processes including the rapid (quasi-instantaneous) equilibration of the liquid catalyst to a droplet shape with constant mean curvature, the slow incorporation of growth atoms at the droplet surface, and crystallization within the droplet. The standard constraint that the sum of the phase fields equals unity and the conservation of the number of catalyst atoms, which relates the catalyst volume to the concentration of growth atoms inside the droplet, are handled via separate Lagrange multipliers. An analysis of the model is presented that rigorously maps the phase-field equations to a desired set of sharp-interface equations for the evolution of the phase boundaries under the constraint of force balance at three-phase junctions (triple points) given by the Young-Herring relation that includes torque term related to the anisotropy of the solid-liquid and solid-vapor interface excess free energies. Numerical examples of growth in two dimensions are presented for the simplest case of vanishing crystalline anisotropy and the more realistic case of a solid-liquid γ plot with cusped minima corresponding to two sets of (10 ) and (11 ) facets. The simulations reproduce many of the salient features of nanowire growth observed experimentally, including growth normal to the substrate with tapering of the side walls, transitions between different growth orientations, and crawling growth along the substrate. They also reproduce different observed relationships between the nanowire growth

Solid phase selective separation and preconcentration of Cu(II) by Cu(II)-imprinted polymethacrylic microbeads.

Science.gov (United States)

Dakova, Ivanka; Karadjova, Irina; Ivanov, Ivo; Georgieva, Ventsislava; Evtimova, Bisera; Georgiev, George

2007-02-12

Ion-imprinted polymer (IIP) particles are prepared by copolymerization of methacrylic acid as monomer, trimethylolpropane trimethacrylate as crosslinking agent and 2,2'-azo-bis-isobutyronitrile as initiator in the presence of Cu(II), a Cu(II)-4-(2-pyridylazo)resorcinol (Cu(II)-PAR) complex, and PAR only. A batch procedure is used for the determination of the characteristics of the Cu(II) solid phase extraction from the IIP produced. The results obtained show that the Cu(II)-PAR IIP has the greatest adsorption capacity (37.4 micromol g(-1) of dry copolymer) among the IIPs investigated. The optimal pH value for the quantitative preconcentration is 7, and full desorption is achieved by 1 M HNO(3). The selectivity coefficients (S(Cu/Me)) for Me=Ni(II), Co(II) are 45.0 and 38.5, respectively. It is established that Cu(II)-PAR IIPs can be used repeatedly without a considerable adsorption capacity loss. The determination of Cu(II) ions in seawater shows that the interfering matrix does not influence the preconcentration and selectivity values of the Cu(II)-PAR IIPs. The detection and quantification limits are 0.001 micromol L(-1) (3sigma) and 0.003 micromol L(-1) (6sigma), respectively.

Breakthrough Adsorption Study of Crude Oil Removal Using Buffing Dust

Science.gov (United States)

Setyaningsih, L. W. N.; Yuliansyah, A. T.; Prasetyo, A.; Arimanintan, S. K.; Putri, D. R.

2018-05-01

The utilization of leather industry solid waste as adsorbent to separate oil from water emulsions of surfactant flooding process is a solution that is relatively inexpensive. This study was conducted aiming to obtain a mathematical model that is appropriate for the adsorption process of crude oil by buffing dust in emulsion phase with a continuous adsorption method. Variations in the column adsorption experiments were carried out, such as: flow rate of feed of water-crude oil-surfactant, the concentration of crude oil in the feed, and mass of adsorbent used. Data were evaluated using three models: Adams Bohart, Thomas and Yan. Best results are obtained on the following conditions, the feed flow rate of 60 mL/minute, the crude oil concentration in feed is 1.5% volume and the mass of adsorbent used was 10 g. The values of kinetic constant and adsorption capacity obtained from Yan Model was 21.7774 mL/mg/minute and 220.9581 mg/g with the relative error obtained is 5.4424%.

Solid phase microextraction.

Science.gov (United States)

Pawliszyn, J

2001-01-01

Solid Phase Microextraction (SPME) uses a small volume of sorbent dispersed typically on the surface of small fibres, to isolate and concentrate analytes from sample matrix. After contact with sample, analytes are absorbed or adsorbed by the fibre phase (depending on the nature of the coating) until an equilibrium is reached in the system. The amount of an analyte extracted by the coating at equilibrium is determined by the magnitude of the partition coefficient of the analyte between the sample matrix and the coating material. After the extraction step, the fibres are transferred, with the help of a syringe-like handling device, to analytical instrument, for separation and quantitation of target analytes. This technique integrates sampling, extraction and sample introduction and is a simple way of facilitating on-site monitoring. Applications of this technique include environmental monitoring, industrial hygiene, process monitoring, clinical, forensic, food, flavour, fragrance and drug analyses, in laboratory and on-site analysis.

Solid-phase extraction based on a molecularly imprinted polymer nanoshell at the surface of silica nanospheres for the specific enrichment and identification of alkaloids from Crinum asiaticum L. var. sinicum.

Science.gov (United States)

Yang, Ruixiang; Zhu, Dong; Wen, Hongmei; Fu, Anchen; Zhao, Zihan; Dai, Guoying; Miao, Zhaoyi; Hu, Yue

2017-03-01

A molecularly imprinted nanoshell on the surface of silica nanospheres was prepared for specific enrichment and identification of alkaloids from Crinum asiaticum L. var. sinicum. The nanoshell was synthesized by surface polymerization using lycorine as the template, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, 2',2-azobisisobutyronitrile as the initiator and acetonitrile as the pore-forming agent. The core-shell nanospheres were characterized by transmission electron microscopy and infrared spectroscopy, and the results show that the nanoshell layer was homogeneously attached to the surface of vinyl-modified SiO 2 nanospheres. The adsorption capacity of the nanospheres was estimated by binding equilibrium and adsorption kinetics experiments. The maximum adsorption amount of lycorine on the nanospheres was 6.68 μmol/g and the imprinting factor was nearly 2.5, indicating a good imprinting effect. The nanospheres were successfully applied in solid-phase extraction for lycorine from Crinum asaticum L. var. sinicum and detection of target molecule in rat metabolites. The average recoveries of lycorine in Crinum asaticum L. var. sinicum extraction and rat metabolites were 93.5 ± 0.6% (n = 3) and 91.6 ± 1.9% (n = 3), respectively. This work provides a simple approach for the fabrication of a molecularly imprinted nanoshell at the surface of silica nanospheres-based solid-phase extraction for drug analysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Real time, high resolution studies of protein adsorption and structure at the solid-liquid interface using dual polarization interferometry

International Nuclear Information System (INIS)

Freeman, Neville J; Peel, Louise L; Swann, Marcus J; Cross, Graham H; Reeves, Andrew; Brand, Stuart; Lu, Jian R

2004-01-01

A novel method for the analysis of thin biological films, called dual polarization interferometry (DPI), is described. This high resolution (<1 A), laboratory-based technique allows the thickness and refractive index (density) of biological molecules adsorbing or reacting at the solid-liquid interface to be measured in real time (up to 10 measurements per second). Results from the adsorption of bovine serum albumin (BSA) on to a silicon oxynitride chip surface are presented to demonstrate how time dependent molecular behaviour can be examined using DPI. Mechanistic and structural information relating to the adsorption process is obtained as a function of the solution pH

Solid state phase change materials for thermal energy storage in passive solar heated buildings

Science.gov (United States)

Benson, D. K.; Christensen, C.

1983-11-01

A set of solid state phase change materials was evaluated for possible use in passive solar thermal energy storage systems. The most promising materials are organic solid solutions of pentaerythritol, pentaglycerine and neopentyl glycol. Solid solution mixtures of these compounds can be tailored so that they exhibit solid-to-solid phase transformations at any desired temperature within the range from less than 25 deg to 188 deg. Thermophysical properties such as thermal conductivity, density and volumetric expansion were measured. Computer simulations were used to predict the performance of various Trombe wall designs incorporating solid state phase change materials. Optimum performance was found to be sensitive to the choice of phase change temperatures and to the thermal conductivity of the phase change material. A molecular mechanism of the solid state phase transition is proposed and supported by infrared spectroscopic evidence.

The adsorption of argon on ZnO at 77K

Science.gov (United States)

Marinelli, Francis; Grillet, Yves; Pellenq, Roland J.-M.

We have studied the adsorption of argon onto ZnO surfaces at 77K by means of quasiequilibrium adsorption volumetry coupled with high resolution microcalorimetry and Grand Canonical Monte-Carlo (GCMC) simulations. The adsorbate/surface adsorption potential function (PN type) used in the simulations, was determined on the basis of ab initio calculations (corrected for dispersion interactions). The first aspect of this work was to test the ability of a standard solid-state Hartree-Fock technique coupled with a perturbative semiempirical approach in deriving a reliable adsorption potential function. The dispersion part of the adsorbate/surface interatomic potential was derived by using perturbation theory-based equations while the repulsive and induction interactions were derived from periodic HartreeFock (CRYSTAL92) calculations. GCMC simulations based on this adsorption potential allow one to calculate adsorption isotherms and isosteric heat versus loading curves as well as singlet distribution functions at 77K for each type of ZnO (neutral and polar) faces. The combined analysis of the simulation data for all surfaces gives a good insight of the adsorption mechanism of argon onto ZnO surfaces at 77K in agreement with experiment. As far as neutral surfaces are concerned, it is shown that adsorption first takes place within the 'troughs' which cover ZnO neutral surfaces. At low chemical potentials, these semi-channels are preferential adsorption sites in which we could detect a nearly one-dimensional adsorbate freezing in a commensurate phase at 77K. The polar O faces are the most favourable surfaces for adsorption at higher chemical potentials.

A study on the adsorption of heavy metals by using raw wheat bran bioadsorbent in aqueous solution phase.

Science.gov (United States)

Ogata, Fumihiko; Kangawa, Moe; Iwata, Yuka; Ueda, Ayaka; Tanaka, Yuko; Kawasaki, Naohito

2014-01-01

Raw wheat bran (R-WB) was used as a biomass adsorbent. The properties of R-WB were investigated. Moreover, the adsorption of cadmium and lead ions onto R-WB was evaluated. Adsorption equilibrium of cadmium and lead ions onto R-WB was achieved within 10 h, indicating that the adsorption followed a pseudo-second-order model rather than a pseudo-first-order kinetic model. The adsorption amount increased with increasing temperature. Correlation coefficient of the Langmuir equation is 0.999 for cadmium and 0.996 for lead ions, and that of the Freundlich equation is 0.994 for cadmium and 0.993 for lead ions. The negative ΔG value implied that the adsorption of cadmium and lead ions onto R-WB is a spontaneous process. The positive ΔS value indicated an increase in randomness at the solid-liquid interface. The optimal conditions for the adsorption column experiment were investigated (space velocity (SV) 2.2 1/h, linear velocity (LV) 0.1 m/h for cadmium; SV 6.51 1/h, LV 0.23 m/h for lead ions). Further, repeated adsorption-desorption of the cadmium and lead ions could be effected by using 0.01 mol/L HCl or 0.01 mol/L HNO3 solution. Consequently, polluted water could be successfully purified by using a column filled with this bioadsorbent.

Utilization of modified corn silk as a biosorbent for solid-phase extraction of Cr(III) and chromium speciation.

Science.gov (United States)

Yu, Hongmei; Pang, Jing; Wu, Mei; Wu, Qiaoli; Huo, Cuixiu

2014-01-01

The ues of corn silk modified with diluted nitric acid (HNO3-MCS) as a novel biosorbent has been established for solid-phase extraction of Cr(III) and chromium speciation in water samples. The functional groups of the HNO3-MCS surface are favorable for the adsorption of Cr(III). Effective extraction conditions were optimized in both batch and column methods. At pH 3.0 - 6.0, a discrimination of Cr(III) and Cr(VI) is achieved on the HNO3-MCS surface. Cr(III) ions are retained onto the HNO3-MCS surface, however, the adsorption of Cr(VI) is negligible under the same conditions. The adsorption isotherm of HNO3-MCS for Cr(III) has been demonstrated in accordance with a linear form of the Langmuir equation, and the maximum adsorption capacity is 35.21 mg g(-1). The well fitted linear regression of the pseudo-second order model showed the indication of a chemisorption mechanism for the entire concentration range. Thermodynamic studies have shown that the adsorption process is spontaneous and endothermic. The adsorbed Cr(III) was quantitatively eluted by a nitric acid solution with detection by flame atomic absorption spectrometry (FAAS). With a sample volume of 30 mL, a detection limit (3σ) of 0.85 μg L(-1) and a precision of 2.0% RSD at the 40 μg L(-1) level were achieved. The concentration of Cr(III) could be accurately quantified within a linear range of 3 - 200 μg L(-1). After Cr(VI) has been reduced to Cr(III) with hydroxylamine hydrochloride, the total amount of chromium was obtained, and the content of Cr(VI) was given by subtraction. The procedure was validated by analyzing chromium in a certified reference material (GBW (E) 080039). It was also successfully applied for the speciation of chromium in wastewater samples.

Theoretical insight of adsorption cooling

KAUST Repository

Chakraborty, Anutosh

2011-06-03

This letter proposes and presents a thermodynamic formulation to calculate the energetic performances of an adsorption cooler as a function of pore widths and volumes of solid adsorbents. The simulated results in terms of the coefficient of performance are validated with experimental data. It is found from the present analysis that the performance of an adsorption cooling device is influenced mainly by the physical characteristics of solid adsorbents, and the characteristics energy between the adsorbent-adsorbate systems. The present study confirms that there exists a special type of silicagel having optimal physical characteristics that allows us to obtain the best performance.

Theoretical insight of adsorption cooling

KAUST Repository

Chakraborty, Anutosh; Leong, Kai Choong; Thu, Kyaw; Saha, Bidyut Baran; Ng, Kim Choon

2011-01-01

This letter proposes and presents a thermodynamic formulation to calculate the energetic performances of an adsorption cooler as a function of pore widths and volumes of solid adsorbents. The simulated results in terms of the coefficient of performance are validated with experimental data. It is found from the present analysis that the performance of an adsorption cooling device is influenced mainly by the physical characteristics of solid adsorbents, and the characteristics energy between the adsorbent-adsorbate systems. The present study confirms that there exists a special type of silicagel having optimal physical characteristics that allows us to obtain the best performance.

Adsorption of surfactants and polymers at interfaces

Science.gov (United States)

Rojas, Orlando Jose

Surface tension and high-resolution laser light scattering experiments were used to investigate the adsorption of isomeric sugar-based surfactants at the air/liquid interface in terms of surfactant surface packing and rheology. Soluble monolayers of submicellar surfactant solutions exhibited a relatively viscous behavior. It was also proved that light scattering of high-frequency thermally-induced capillary waves can be utilized to study surfactant exchange between the surface and the bulk solution. Such analysis revealed the existence of a diffusional relaxation mechanism. A procedure based on XPS was developed for quantification, on an absolute basis, of polymer adsorption on mica and Langmuir-Blodgett cellulose films. The adsorption of cationic polyelectrolytes on negatively-charged solid surfaces was highly dependent on the polymer ionicity. It was found that the adsorption process is driven by electrostatic mechanisms. Charge overcompensation (or charge reversal) of mica occurred after adsorption of polyelectrolytes of ca. 50% charge density, or higher. It was demonstrated that low-charge-density polyelectrolytes adsorb on solid surfaces with an extended configuration dominated by loops and tails. In this case the extent of adsorption is limited by steric constraints. The conformation of the polyelectrolyte in the adsorbed layer is dramatically affected by the presence of salts or surfactants in aqueous solution. The phenomena which occur upon increasing the ionic strength are consistent with the screening of the electrostatic attraction between polyelectrolyte segments and solid surface. This situation leads to polyelectrolyte desorption accompanied by both an increase in the layer thickness and the range of the steric force. Adsorbed polyelectrolytes and oppositely charged surfactants readily associate at the solid/liquid interface. Such association induces polyelectrolyte desorption at a surfactant concentration which depends on the polyelectrolyte charge

Finite-deformation phase-field chemomechanics for multiphase, multicomponent solids

Science.gov (United States)

Svendsen, Bob; Shanthraj, Pratheek; Raabe, Dierk

2018-03-01

The purpose of this work is the development of a framework for the formulation of geometrically non-linear inelastic chemomechanical models for a mixture of multiple chemical components diffusing among multiple transforming solid phases. The focus here is on general model formulation. No specific model or application is pursued in this work. To this end, basic balance and constitutive relations from non-equilibrium thermodynamics and continuum mixture theory are combined with a phase-field-based description of multicomponent solid phases and their interfaces. Solid phase modeling is based in particular on a chemomechanical free energy and stress relaxation via the evolution of phase-specific concentration fields, order-parameter fields (e.g., related to chemical ordering, structural ordering, or defects), and local internal variables. At the mixture level, differences or contrasts in phase composition and phase local deformation in phase interface regions are treated as mixture internal variables. In this context, various phase interface models are considered. In the equilibrium limit, phase contrasts in composition and local deformation in the phase interface region are determined via bulk energy minimization. On the chemical side, the equilibrium limit of the current model formulation reduces to a multicomponent, multiphase, generalization of existing two-phase binary alloy interface equilibrium conditions (e.g., KKS). On the mechanical side, the equilibrium limit of one interface model considered represents a multiphase generalization of Reuss-Sachs conditions from mechanical homogenization theory. Analogously, other interface models considered represent generalizations of interface equilibrium conditions consistent with laminate and sharp-interface theory. In the last part of the work, selected existing models are formulated within the current framework as special cases and discussed in detail.

Biogasification of solid wastes by two-phase anaerobic fermentation

International Nuclear Information System (INIS)

Ghosh, S.; Vieitez, E.R.; Liu, T.; Kato, Y.

1997-01-01

Municipal, industrial and agricultural solid wastes, and biomass deposits, cause large-scale pollution of land and water. Gaseous products of waste decomposition pollute the air and contribute to global warming. This paper describes the development of a two-phase fermentation system that alleviates methanogenic inhibition encountered with high-solids feed, accelerates methane fermentation of the solid bed, and captures methane (renewable energy) for captive use to reduce global warming. The innovative system consisted of a solid bed reactor packed with simulated solid waste at a density of 160 kg/m 3 and operated with recirculation of the percolated culture (bioleachate) through the bed. A rapid onset of solids hydrolysis, acidification, denitrification and hydrogen gas formation was observed under these operating conditions. However, these fermentative reactions stopped at a total fatty acids concentration of 13,000 mg/l (as acetic) at pH 5, with a reactor head-gas composition of 75 percent carbon dioxide, 20 percent nitrogen, 2 percent hydrogen and 3 percent methane. Fermentation inhibition was alleviated by moving the bioleachate to a separate methane-phase fermenter, and recycling methanogenic effluents at pH 7 to the solid bed. Coupled operation of the two reactors promoted methanogenic conversion of the high-solids feed. (author)

solid phase extraction method for selective determination

African Journals Online (AJOL)

FATOKI

determination of phthalate ester plasticizers in rivers and marine water samples. Of the ... samples that receive effluent from industries that use phthalate esters. ... Keywords Phthalates, Plasticizers, Solid Phase Gas Chromatography.

Liquid-phase and solid-phase radioimmunoassay with herpes simplex virus type 1 nucleocapsids

International Nuclear Information System (INIS)

Bystricka, M.; Rajcani, J.; Libikova, H.; Sabo, A.; Foeldes, O.; Sadlon, J.

1985-01-01

Liquid-phase radioimmunoassay and solid-phase radioimmunoassay are described using 125 I-labelled or immobilized nucleocapsids (NC) of herpes simplex virus (HSV) type1. These techniques appeared sensitive and specific for quantitation of HSV-NC antigens and corresponding antibodies. (author)

Adsorption of nicotine on different zeolite types, from aqueous solutions

Directory of Open Access Journals (Sweden)

Stošić Dušan K.

2007-01-01

Full Text Available The plant alkaloid, nicotine, is a strongly toxic heterocyclic compound: the lethal dose for an adult human being (40-60 mg is importantly lower in comparison with the other known poisons such as arsenic or strychni­ne. Cigarettes represent "the most toxic and addictive form of nicotine". Besides the negative effects of nicotine on public health produced by self-administration, recently another potentially very dangerous effect has been recognized: because of its miscibility with water, nicotine can be found in industrial wastewaters, and consequently, in groundwater. Therefore, the problem of nicotine removal from aqueous solutions has became an interesting topic. In this work, the removal of nicotine has been probed by adsorption on solid materials. Adsorption of nicotine on different zeolites (clinoptilolite, ZSM-5 and β zeolite and on activated carbon was investigated from aqueous solutions, at 298 K. The obtained results are presented as adsorption isotherms: the amount of adsorbed nicotine as a function of equilibrium concentration. These data were obtained from the residual amount of nicotine in the aqueous phase, by the use of UV spectroscopy. The highest amounts of adsorbed nicotine was found for activated carbon and p zeolite (~ mmol·g-1. The attempt to modify the adsorption properties of ZSM-5 zeolite has been also done: ZSM-5 was modified by ion-exchange with VIII group metal (Cu2+ and Fe3+. In addition, the adsorption of nicotine on ZSM-5 zeolite with different Si/Al ratios has been done. It has been noticed that ion-exchange did not improve the adsorption possibilities, while the adsorption was importantly lower in the case of higher silicon content in ZMS-5 structure. 13C NMR spectra were collected for suspensions formed of solid adsorbent and aqueous solution of nicotine; in this way, the part of nicotine molecule which is most probably connected with the adsorbent was recognized.

Biological treatment of soils contaminated with hydrophobic organics using slurry- and solid-phase techniques

Science.gov (United States)

Cassidy, Daniel H.; Irvine, Robert L.

1995-10-01

Both slurry-phase and solid-phase bioremediation are effective ex situ soil decontamination methods. Slurrying is energy intensive relative to solid-phase treatment, but provides homogenization and uniform nutrient distribution. Limited contaminant bioavailability at concentrations above the required cleanup level reduces biodegradation rates and renders solid phase bioremediation more cost effective than complete treatment in a bio-slurry reactor. Slurrying followed by solid-phase bioremediation combines the advantages and minimizes the weaknesses of each treatment method when used alone. A biological treatment system consisting of slurrying followed by aeration in solid phase bioreactors was developed and tested in the laboratory using a silty clay loam contaminated with diesel fuel. The first set of experiments was designed to determine the impact of the water content and mixing time during slurrying on the rate an extent of contaminant removal in continuously aerated solid phase bioreactors. The second set of experiments compared the volatile and total diesel fuel removal in solid phase bioreactors using periodic and continuous aeration strategies. Results showed that slurrying for 1.5 hours at a water content less than saturation markedly increased the rate and extent of contaminant biodegradation in the solid phase bioreactors compared with soil having no slurry pretreatment. Slurrying the soil at or above its saturation moisture content resulted in lengthy dewatering times which prohibited aeration, thereby delaying the onset of biological treatment in the solid phase bioreactors. Results also showed that properly operated periodic aeration can provide less volatile contaminant removal and a grater fraction of biological contaminant removal than continuous aeration.

Adsorption of hydrocarbons in chalk reservoirs

Energy Technology Data Exchange (ETDEWEB)

Madsen, L.

1996-12-31

The present work is a study on the wettability of hydrocarbon bearing chalk reservoirs. Wettability is a major factor that influences flow, location and distribution of oil and water in the reservoir. The wettability of the hydrocarbon reservoirs depends on how and to what extent the organic compounds are adsorbed onto the surfaces of calcite, quartz and clay. Organic compounds such as carboxylic acids are found in formation waters from various hydrocarbon reservoirs and in crude oils. In the present investigation the wetting behaviour of chalk is studied by the adsorption of the carboxylic acids onto synthetic calcite, kaolinite, quartz, {alpha}-alumina, and chalk dispersed in an aqueous phase and an organic phase. In the aqueous phase the results clearly demonstrate the differences between the adsorption behaviour of benzoic acid and hexanoic acid onto the surfaces of oxide minerals and carbonates. With NaCl concentration of 0.1 M and with pH {approx_equal} 6 the maximum adsorption of benzoic acid decreases in the order: quartz, {alpha}-alumina, kaolinite. For synthetic calcite and chalk no detectable adsorption was obtaind. In the organic phase the order is reversed. The maximum adsorption of benzoic acid onto the different surfaces decreases in the order: synthetic calcite, chalk, kaolinite and quartz. Also a marked difference in adsorption behaviour between probes with different functional groups onto synthetic calcite from organic phase is observed. The maximum adsorption decreases in the order: benzoic acid, benzyl alcohol and benzylamine. (au) 54 refs.

The Pictet-Spengler reaction in solid-phase combinatorial chemistry

DEFF Research Database (Denmark)

Nielsen, Thomas E; Diness, Frederik; Meldal, Morten

2003-01-01

The Pictet-Spengler reaction is an important reaction for the generation of tetrahydro-beta-carbolines and tetrahydroisoquinoline ring systems, which exhibit a range of biological and pharmacological properties. This review covers the solid-phase Pictet-Spengler reaction, as employed in solid...

Experimental study and computerized simulation of the elements fixation in trace on mineral oxides. Contribution to the study of natural solids adsorption properties

International Nuclear Information System (INIS)

Marmier, N.

1994-12-01

The aim of this work is to identify some natural or synthetical materials allowing the nuclear wastes confinement in underground geological sites by adsorption of radioelements. The materials composition variety which can be used is very large it is then necessary to make use of models able to predict solid complexes behaviour towards the adsorption from known properties of parent constituents. This type of model still does not exist and its focusing requires the demonstration of mineral complexes parent constituents intrinsic properties additivity. The oxides as aluminium or silicon oxides being parent constituents, the author has demonstrated their properties additivity in an aluminium-silicon oxides physical mixture and in an aluminium silicate : the kaolinite. These surface properties have been determined for different quantities of aluminium and silicon oxides in a 0,1 M sodium nitrate. This study has been realized following the steps below : choice of a theoretical concept describing the adsorption adapted to the studied solid-solution system : the surface complexation model at constant capacitance; the focusing of a surface chemical and physical parameters determination method; the verification of these properties additivity on the aluminium-silicon oxides mixture and on the kaolinite. The studied cation for the adsorption on these materials is the ytterbium trivalent ion because the behaviour of the trivalent ions towards the adsorption is not very well known and because the lanthanides are considered as compounds similar to some fission products present in radioactive wastes. The method used for this work is applicable to all the other ions. (O.L.). 73 refs., 91 figs., 14 tabs

Phase 2, Solid waste retrieval strategy

International Nuclear Information System (INIS)

Johnson, D.M.

1994-01-01

Solid TRU retrieval, Phase 1 is scheduled to commence operation in 1998 at 218W-4C-T01 and complete recovery of the waste containers in 2001. Phase 2 Retrieval will recover the remaining buried TRU waste to be retrieved and provide the preliminary characterization by non-destructive means to allow interim storage until processing for disposal. This document reports on researching the characterization documents to determine the types of wastes to be retrieved and where located, waste configurations, conditions, and required methods for retrieval. Also included are discussions of wastes encompassed by Phase 2 for which there are valid reasons to not retrieve

Phase 2, Solid waste retrieval strategy

Energy Technology Data Exchange (ETDEWEB)

Johnson, D.M.

1994-09-29

Solid TRU retrieval, Phase 1 is scheduled to commence operation in 1998 at 218W-4C-T01 and complete recovery of the waste containers in 2001. Phase 2 Retrieval will recover the remaining buried TRU waste to be retrieved and provide the preliminary characterization by non-destructive means to allow interim storage until processing for disposal. This document reports on researching the characterization documents to determine the types of wastes to be retrieved and where located, waste configurations, conditions, and required methods for retrieval. Also included are discussions of wastes encompassed by Phase 2 for which there are valid reasons to not retrieve.

The role of solid-solid phase transitions in mantle convection

Science.gov (United States)

Faccenda, Manuele; Dal Zilio, Luca

2017-01-01

With changing pressure and temperature conditions, downwelling and upwelling crustal and mantle rocks experience several solid-solid phase transitions that affect the mineral physical properties owing to structural changes in the crystal lattice and to the absorption or release of latent heat. Variations in density, together with phase boundary deflections related to the non-null reaction slope, generate important buoyancy forces that add to those induced by thermal perturbations. These buoyancy forces are proportional to the density contrast between reactant and product phases, their volume fraction, the slope and the sharpness of the reaction, and affect the style of mantle convection depending on the system composition. In a homogeneous pyrolitic mantle there is little tendency for layered convection, with slabs that may stagnate in the transition zone because of the positive buoyancy caused by post-spinel and post-ilmenite reactions, and hot plumes that are accelerated by phase transformations in the 600-800 km depth range. By adding chemical and mineralogical heterogeneities as on Earth, phase transitions introduce bulk rock and volatiles filtering effects that generate a compositional gradient throughout the entire mantle, with levels that are enriched or depleted in one or more of these components. Phase transitions often lead to mechanical softening or hardening that can be related to a different intrinsic mechanical behaviour and volatile solubility of the product phases, the heating or cooling associated with latent heat, and the transient grain size reduction in downwelling cold material. Strong variations in viscosity would enhance layered mantle convection, causing slab stagnation and plume ponding. At low temperatures and relatively dry conditions, reactions are delayed due to the sluggish kinetics, so that non-equilibrium phase aggregates can persist metastably beyond the equilibrium phase boundary. Survival of low-density metastable olivine

STUDY OF GAS SEPARATION PROCESS BY DYNAMIC ADSORPTION IN FIXED BED

Directory of Open Access Journals (Sweden)

Ioan Solomon

2010-10-01

Full Text Available An experimental study of mass transfer at gas separation by dynamic adsorption in fixed bed of impregnated silica gel is presented in this work. By means of a mathematical model based on constants and coefficient easy to evaluate, the distributions of adsorbate concentration in gas and solid phases were determined as a function of time and throughout the height of the fixed bed, under isothermal conditions.With this aim, water vapors from air were adsorbed in a fixed bed of impregnated silica gel. The values of the volumetric mass transfer coefficient, Kv, were determined experimentally at several values of air superficial velocity, an air relative humidity of 69�20at 38 °C. The influence of the gas flow velocity and initial water concentration in adsorbent on the distribution of water concentration in both phases was established as a function of time and throughout the height of the fixed bed. The results obtained allow one to determination of the local adsorption rate.

Phase transitions in solids under high pressure

CERN Document Server

Blank, Vladimir Davydovich

2013-01-01

Phase equilibria and kinetics of phase transformations under high pressureEquipment and methods for the study of phase transformations in solids at high pressuresPhase transformations of carbon and boron nitride at high pressure and deformation under pressurePhase transitions in Si and Ge at high pressure and deformation under pressurePolymorphic α-ω transformation in titanium, zirconium and zirconium-titanium alloys Phase transformations in iron and its alloys at high pressure Phase transformations in gallium and ceriumOn the possible polymorphic transformations in transition metals under pressurePressure-induced polymorphic transformations in АIBVII compoundsPhase transformations in AIIBVI and AIIIBV semiconductor compoundsEffect of pressure on the kinetics of phase transformations in iron alloysTransformations during deformation at high pressure Effects due to phase transformations at high pressureKinetics and hysteresis in high-temperature polymorphic transformations under pressureHysteresis and kineti...

Cadmium adsorption by coal combustion ashes-based sorbents-Relationship between sorbent properties and adsorption capacity

Energy Technology Data Exchange (ETDEWEB)

Balsamo, Marco; Di Natale, Francesco; Erto, Alessandro; Lancia, Amedeo [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Montagnaro, Fabio, E-mail: fabio.montagnaro@unina.it [Dipartimento di Chimica, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant' Angelo, 80126 Napoli (Italy); Santoro, Luciano [Dipartimento di Chimica, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant' Angelo, 80126 Napoli (Italy)

2011-03-15

A very interesting possibility of coal combustion ashes reutilization is their use as adsorbent materials, that can also take advantage from proper beneficiation techniques. In this work, adsorption of cadmium from aqueous solutions was taken into consideration, with the emphasis on the intertwining among waste properties, beneficiation treatments, properties of the beneficiated materials and adsorption capacity. The characterization of three solid materials used as cadmium sorbents (as-received ash, ash sieved through a 25 {mu}m-size sieve and demineralized ash) was carried out by chemical analysis, infrared spectroscopy, laser granulometry and mercury porosimetry. Cadmium adsorption thermodynamic and kinetic tests were conducted at room temperature, and test solutions were analyzed by atomic absorption spectrophotometry. Maximum specific adsorption capacities resulted in the range 0.5-4.3 mg g{sup -1}. Different existing models were critically considered to find out an interpretation of the controlling mechanism for adsorption kinetics. In particular, it was observed that for lower surface coverage the adsorption rate is governed by a linear driving force while, once surface coverage becomes significant, mechanisms such as the intraparticle micropore diffusion may come into play. Moreover, it was shown that both external fluid-to-particle mass transfer and macropore diffusion hardly affect the adsorption process, which was instead regulated by intraparticle micropore diffusion: characteristic times for this process ranged from 4.1 to 6.1 d, and were fully consistent with the experimentally observed equilibrium times. Results were discussed in terms of the relationship among properties of beneficiated materials and cadmium adsorption capacity. Results shed light on interesting correlations among solid properties, cadmium capture rate and maximum cadmium uptake.

Trace and ultratrace determination of heavy metal ions by energy-dispersive X-ray fluorescence spectrometry using graphene as solid sorbent in dispersive micro solid-phase extraction

Energy Technology Data Exchange (ETDEWEB)

Kocot, Karina; Sitko, Rafal, E-mail: rafal.sitko@us.edu.pl

2014-04-01

In this paper, the adsorptive properties of graphene nanosheets were used for simultaneous preconcentration of cobalt, nickel, copper and lead ions from water samples. The developed methodology is based on dispersive micro-solid phase extraction (DMSPE) which is miniaturized and a simplified version of classical solid phase extraction technique. In proposed procedure only 200 μL of suspension containing graphene (0.2 mg), ammonium pyrrolidine dithiocarbamate (APDC) (0.8 mg) and Triton-X-100 (0.1 mg) is rapidly injected to 50 mL of water sample. Then, graphene nanosheets with adsorbed metal-APDC chelates are collected on membrane filter and measured using energy-dispersive X-ray fluorescence (EDXRF) spectrometry. The various parameters including pH, amount of APDC, sample volume, amount of Triton-X-100 and sorption time were optimized in order to obtain the best recoveries. The experiment shows that Co, Ni, Cu and Pb can be simultaneously preconcentrated at pH of 5 with high recoveries (97%, 96%, 99% and 96% for Co, Ni, Cu and Pb, respectively) and very good precision (RSDs within 2.6–3.4%). Due to the excellent enrichment factors ranging from 400 to 2500 the proposed DMSPE–EDXRF procedure offers low detection limits. For optimized measurement conditions (voltage and current of X-ray tube, primary beam filter) the detection limits are even 0.08, 0.07, 0.08 and 0.20 ng mL{sup −1} for Co, Ni, Cu and Pb, respectively. - Highlights: • Excellent detection limits using EDXRF • A new preconcentration procedure combining DMSPE and EDXRF measurement • Graphene as a promising and efficient solid sorbent in DMSPE • Simple, fast, inexpensive and environmental friendly method.

Experimental study and modelling of competitive adsorption equilibria of aromatics in liquid phase on X and Y faujasites; Etude experimentale et modelisation des equilibres d'adsorption competitive d'aromatiques en phase liquide sur des faujasites X et Y

Energy Technology Data Exchange (ETDEWEB)

Tournier, H.

2000-10-13

The separation of p-xylene from C{sub 8} aromatics is performed industrially by selective adsorption on zeolitic molecular sieves. The aim of this work is to study and model adsorption equilibria of C{sub 8} and C{sub 10} aromatics on X and Y zeolites. The experimental data are obtained by an entirely automated equipment allowing to work in a large range of temperature (50 deg. C - 250 deg. C). With this equipment, we can follow the evolution of the composition of the liquid phase and determine the composition of the adsorbed phase at equilibrium by a mass balance calculation and with an inert component. Two analytical techniques are used to determine the composition of the liquid phase: (1) a classical method using a gas chromatograph (GC) allowed to measure selectivities in the concentration range (3%-97%) in a component; (2) an original method based on the use and on the measure of {sup 13}C labelled xylenes was developed to investigate the ranges of strongly contrasting concentrations [0-3%] and [97%-100%] in a component, which are representative of high purity domains. Lastly, three thermodynamic models are used to describe the adsorption equilibria: the Langmuir-Freundlich model, the quasi-chemical model and the statistical model. The last model is the more interesting, because it is based on physical considerations. A new statistical model has been developed with taking into account some observations coming from adsorption phenomenon in zeolites. (author)

Solid Phase Extraction and Spectrophotometric Determination of ...

African Journals Online (AJOL)

NJD

2005-04-15

Apr 15, 2005 ... to the economy and has significant industrial applications. The development of a ... Waters Solid Phase Extraction (SPE) device (the device can carry out twenty ... HPLC grade dimethyl formamide (DMF) (Fisher. Corporation ...

Magnetic Solid Phase Extraction and Removal of Five Cationic Dyes from Aqueous Solution Using Magnetite Nanoparticle Loaded Platanusorientalis Waste Leaves

Directory of Open Access Journals (Sweden)

Elaheh Madrakian

2016-12-01

Full Text Available This paper reports on synthesis of a magnetic adsorbent for wastewater treatment purposes. In this regard, platanus orientalis waste leaves were chosen as a cheap material for preparing the magnetic adsorbent by loading magnetite nanoparticles on it. The synthesized adsorbent was characterized using scanning electron microscope and X-ray diffractometer. Then, it was used for magnetic solid phase extraction and removal of five cationic dyes including methyl violet (MV, methylene blue (MB, malachite green (MG, crystal violet (CV, and neutral red (NR from aqueous solution as a model application. Different important factors affecting the adsorption process were optimized, and the results showed that under the optimized conditions (pH 10 for CV, MV, MB, and MG; pH 6 for NR; adsorbent dosage, 20 mg; agitation time, 25 min efficient removal of the investigated dyes (adsorption capacities between of 89-133 mg g-1 is achievable using the synthesized adsorbent. Furthermore, the reusability experiments showed that the adsorbent could be reused at least ten cycles without any significant loss in its sorption behavior.

Pressure Effects on Solid State Phase Transformation of Aluminium Bronze in Cooling Process

International Nuclear Information System (INIS)

Hai-Yan, Wang; Jian-Hua, Liu; Gui-Rong, Peng; Yan, Chen; Yu-Wen, Liu; Fei, Li; Wen-Kui, Wang

2009-01-01

Effects of high pressure (6 GPa) on the solid state phase transformation kinetic parameters of aluminum bronze during the cooling process are investigated, based on the measurement and calculation of its solid state phase transformation temperature, duration and activation energy and the observation of its microstructures. The results show that high pressure treatment can reduce the solid phase transformation temperature and activation energy in the cooling process and can shorten the phase transformation duration, which is favorable when forming fine-grained aluminum bronze

Communication: Thermodynamic analysis of critical conditions of polymer adsorption

International Nuclear Information System (INIS)

Cimino, R.; Neimark, A. V.; Rasmussen, C. J.

2013-01-01

Polymer adsorption to solid surfaces is a ubiquitous phenomenon, which has attracted long-lasting attention. Dependent on the competition between the polymer-solid adsorption and polymer-solvent solvation interactions, a chain may assume either 3d solvated conformation when adsorption is weak or 2d adsorbed conformation when adsorption is strong. The transition between these conformations occurring upon variation of adsorption strength is quite sharp, and in the limit of “infinite” chain length, can be treated as a critical phenomenon. We suggest a novel thermodynamic definition of the critical conditions of polymer adsorption from the equality of incremental chemical potentials of adsorbed and free chains. We show with the example of freely jointed Lennard-Jones chains tethered to an adsorbing surface that this new definition provides a link between thermodynamic and geometrical features of adsorbed chains and is in line with classical scaling relationships for the fraction of adsorbed monomers, chain radii of gyration, and free energy

Communication: Thermodynamic analysis of critical conditions of polymer adsorption

Energy Technology Data Exchange (ETDEWEB)

Cimino, R.; Neimark, A. V., E-mail: aneimark@rutgers.edu [Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854 (United States); Rasmussen, C. J. [DuPont Central Research and Development, Corporate Center for Analytical Sciences, Macromolecular Characterization, Route 141 and Henry Clay, Wilmington, Delaware 19803 (United States)

2013-11-28

Polymer adsorption to solid surfaces is a ubiquitous phenomenon, which has attracted long-lasting attention. Dependent on the competition between the polymer-solid adsorption and polymer-solvent solvation interactions, a chain may assume either 3d solvated conformation when adsorption is weak or 2d adsorbed conformation when adsorption is strong. The transition between these conformations occurring upon variation of adsorption strength is quite sharp, and in the limit of “infinite” chain length, can be treated as a critical phenomenon. We suggest a novel thermodynamic definition of the critical conditions of polymer adsorption from the equality of incremental chemical potentials of adsorbed and free chains. We show with the example of freely jointed Lennard-Jones chains tethered to an adsorbing surface that this new definition provides a link between thermodynamic and geometrical features of adsorbed chains and is in line with classical scaling relationships for the fraction of adsorbed monomers, chain radii of gyration, and free energy.

Solid phase extraction method for determination of mitragynine in ...

African Journals Online (AJOL)

All rights reserved. ... 1Department of Pharmacology, 2Department of Applied Science, 3Police Forensic Science Center 10, Yala 95000, 4Natural ... Purpose: To develop a solid phase extraction (SPE) method that utilizes reverse-phase high.

A multi-phase equation of state for solid and liquid lead

International Nuclear Information System (INIS)

Robinson, C.M.

2004-01-01

This paper considers a multi-phase equation of state for solid and liquid lead. The thermodynamically consistent equation of state is constructed by calculating separate equations of state for the solid and liquid phases. The melt curve is the curve in the pressure, temperature plane where the Gibb's free energy of the solid and liquid phases are equal. In each phase a complete equation of state is obtained using the assumptions that the specific heat capacity is constant and that the Grueneisen parameter is proportional to the specific volume. The parameters for the equation of state are obtained from experimental data. In particular they are chosen to match melt curve and principal Hugoniot data. Predictions are made for the shock pressure required for melt to occur on shock and release

Solid-phase equilibria on Pluto's surface

Science.gov (United States)

Tan, Sugata P.; Kargel, Jeffrey S.

2018-03-01

Pluto's surface is covered by volatile ices that are in equilibrium with the atmosphere. Multicomponent phase equilibria may be calculated using a thermodynamic equation of state and, without additional assumptions, result in methane-rich and nitrogen-rich solid phases. The former is formed at temperature range between the atmospheric pressure-dependent sublimation and condensation points, while the latter is formed at temperatures lower than the sublimation point. The results, calculated for the observed 11 μbar atmospheric pressure and composition, are consistent with recent work derived from observations by New Horizons.

Synthesis and application of surface-imprinted activated carbon sorbent for solid-phase extraction and determination of copper (II)

Science.gov (United States)

Li, Zhenhua; Li, Jingwen; Wang, Yanbin; Wei, Yajun

2014-01-01

A new Cu(II)-imprinted amino-functionalized activated carbon sorbent was prepared by a surface imprinting technique for selective solid-phase extraction (SPE) of Cu(II) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of Cu(II) were optimized with respect to different experimental parameters using static and dynamic procedures in detail. Compared with non-imprinted sorbent, the ion-imprinted sorbent had higher selectivity and adsorption capacity for Cu(II). The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Cu(II) was 26.71 and 6.86 mg g-1, respectively. The relatively selectivity factor values (αr) of Cu(II)/Zn(II), Cu(II)/Ni(II), Cu(II)/Co(II) and Cu(II)/Pb(II) were 166.16, 50.77, 72.26 and 175.77, respectively, which were greater than 1. Complete elution of the adsorbed Cu(II) from Cu(II)-imprinted sorbent was carried out using 2 mL of 0.1 mol L-1 EDTA solution. The relative standard deviation of the method was 2.4% for eleven replicate determinations. The method was validated for the analysis by two certified reference materials (GBW 08301, GBW 08303), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace copper in natural water samples with satisfactory results.

Mechanism and microstructures in Ga2O3 pseudomartensitic solid phase transition.

Science.gov (United States)

Zhu, Sheng-Cai; Guan, Shu-Hui; Liu, Zhi-Pan

2016-07-21

Solid-to-solid phase transition, although widely exploited in making new materials, challenges persistently our current theory for predicting its complex kinetics and rich microstructures in transition. The Ga2O3α-β phase transformation represents such a common but complex reaction with marked change in cation coordination and crystal density, which was known to yield either amorphous or crystalline products under different synthetic conditions. Here we, via recently developed stochastic surface walking (SSW) method, resolve for the first time the atomistic mechanism of Ga2O3α-β phase transformation, the pathway of which turns out to be the first reaction pathway ever determined for a new type of diffusionless solid phase transition, namely, pseudomartensitic phase transition. We demonstrate that the sensitivity of product crystallinity is caused by its multi-step, multi-type reaction pathway, which bypasses seven intermediate phases and involves all types of elementary solid phase transition steps, i.e. the shearing of O layers (martensitic type), the local diffusion of Ga atoms (reconstructive type) and the significant lattice dilation (dilation type). While the migration of Ga atoms across the close-packed O layers is the rate-determining step and yields "amorphous-like" high energy intermediates, the shearing of O layers contributes to the formation of coherent biphase junctions and the presence of a crystallographic orientation relation, (001)α//(201[combining macron])β + [120]α//[13[combining macron]2]β. Our experiment using high-resolution transmission electron microscopy further confirms the theoretical predictions on the atomic structure of biphase junction and the formation of (201[combining macron])β twin, and also discovers the late occurrence of lattice expansion in the nascent β phase that grows out from the parent α phase. By distinguishing pseudomartensitic transition from other types of mechanisms, we propose general rules to predict the

Direct formation of new, phase-stable, and photoactive anatase-type Ti1-2XNbXScXO2 solid solution nanoparticles by hydrothermal method

International Nuclear Information System (INIS)

Hirano, Masanori; Ito, Takaharu

2008-01-01

A new anatase phase of photoactive Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) solid solutions was directly formed as nanoparticles from precursor solutions of TiOSO 4 , NbCl 5 , and Sc(NO 3 ) 3 under mild hydrothermal conditions at 180 deg. C for 5 h using the hydrolysis of urea. With the increase of the content of niobium and scandium from X = 0 to 0.2, the lattice parameters a 0 and c 0 , the crystallite size, and the optical band gap of anatase gradually increased. Their photocatalytic activity and adsorptivity were evaluated separately by the measurement of the concentration of methylene blue (MB) remained in the solution in the dark or under UV-light irradiation. The anatase-type Ti 1-2X Nb X Sc X O 2 (X = 0.05) showed approximately two times and three times as high photocatalytic activity as those of the hydrothermal anatase-type pure TiO 2 and commercially available reference pure TiO 2 (ST-01), respectively. The anatase phase of Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) existed stably up to 900 deg. C during heat treatment in air. New rutile-type Ti 1-2X Nb X Sc X O 2 solid solutions are formed through the phase transformation. The starting temperature of anatase-to-rutile phase transformation for Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) solid solutions was delayed but its completing temperature was accelerated

Solid-phase synthesis of complex and pharmacologically interesting heterocycles

DEFF Research Database (Denmark)

Nielsen, Thomas Eiland

2009-01-01

Efficient routes for the creation of heterocycles continue to be one of the primary goals for solid-phase synthesis. Recent advances in this field rely most notably on transition-metal-catalysis and N-acyliminium chemistry to mediate a range of cyclization processes for the generation of compounds...... with significant structural complexity and diversity. This review describes some of the most systematic solid-phase approaches that are potentially suited for pharmaceutical applications, that is, the methods described are useful for the synthesis of compound collections, and exhibit tunable stereochemistry...

Indigenous microbial capability in solid manure residues to start-up solid-phase anaerobic digesters.

Science.gov (United States)

Yap, S D; Astals, S; Jensen, P D; Batstone, D J; Tait, S

2017-06-01

Batch solid-phase anaerobic digestion is a technology for sustainable on-farm treatment of solid residues, but is an emerging technology that is yet to be optimised with respect to start-up and inoculation. In the present study, spent bedding from two piggeries (site A and B) were batch digested at total solids (TS) concentration of 5, 10 and 20% at mesophilic (37°C) and thermophilic (55°C) temperatures, without adding an external inoculum. The results showed that the indigenous microbial community present in spent bedding was able to recover the full methane potential of the bedding (140±5 and 227±6L CH 4 kgVS fed -1 for site A and B, respectively), but longer treatment times were required than for digestion with an added external inoculum. Nonetheless, at high solid loadings (i.e. TS level>10%), the digestion performance was affected by chemical inhibition due to ammonia and/or humic acid. Thermophilic temperatures did not influence digestion performance but did increase start-up failure risk. Further, inoculation of residues from the batch digestion to subsequent batch enhanced start-up and achieved full methane potential recovery of the bedding. Inoculation with liquid residue (leachate) was preferred over a solid residue, to preserve treatment capacity for fresh substrate. Overall, the study highlighted that indigenous microbial community in the solid manure residue was capable of recovering full methane potential and that solid-phase digestion was ultimately limited by chemical inhibition rather than lack of suitable microbial community. Copyright © 2017 Elsevier Ltd. All rights reserved.

Core-Shell Diamond as a Support for Solid-Phase Extraction and High-Performance Liquid Chromatography

Energy Technology Data Exchange (ETDEWEB)

Saini, Gaurav; Jensen, David S.; Wiest, Landon A.; Vail, Michael A.; Dadson, Andrew; Lee, Milton L.; Shutthanandan, V.; Linford, Matthew R.

2010-06-01

We report the formation of core-shell diamond particles for solid phase extraction (SPE) and high performance liquid chromatography (HPLC) made by layer-by-layer (LbL) deposition. Their synthesis begins with the amine functionalization of microdiamond by its immersion in an aqueous solution of a primary amine-containing polymer (polyallylamine (PAAm)). The amine-terminated microdiamond is then immersed in an aqueous suspension of nanodiamond, which leads to adsorption of the nanodiamond. Alternating (self-limiting) immersions in the solutions of the amine-containing polymer and the suspension of nanodiamond are continued until the desired number of nanodiamond layers is formed around the microdiamond. Finally, the core-shell particles are cross-linked with 1,2,5,6-diepoxycyclooctane or reacted with 1,2-epoxyoctadecane. Layer-by-layer deposition of PAAm and nanodiamond is also studied on planar Si/SiO2 surfaces, which were characterized by SEM, Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Core-shell particles are characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), environmental scanning electron microscopy (ESEM), and Brunauer Emmett Teller (BET) surface area and pore size measurements. Larger (ca. 50 μm) core-shell diamond particles have much higher surface areas, and analyte loading capacities in SPE than nonporous solid diamond particles. Smaller (ca. 3 μm), normal and reversed phase, core-shell diamond particles have been used for HPLC, with 36,300 plates per meter for mesitylene in a separation of benzene and alkyl benzenes on a C18 adsorbent, and 54,800 plates per meter for diazinon in a similar separation of two pesticides.

Core-shell diamond as a support for solid-phase extraction and high-performance liquid chromatography.

Science.gov (United States)

Saini, Gaurav; Jensen, David S; Wiest, Landon A; Vail, Michael A; Dadson, Andrew; Lee, Milton L; Shutthanandan, V; Linford, Matthew R

2010-06-01

We report the formation of core-shell diamond particles for solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) made by layer-by-layer (LbL) deposition. Their synthesis begins with the amine functionalization of microdiamond by its immersion in an aqueous solution of a primary amine-containing polymer (polyallylamine (PAAm)). The amine-terminated microdiamond is then immersed in an aqueous suspension of nanodiamond, which leads to adsorption of the nanodiamond. Alternating (self-limiting) immersions in the solutions of the amine-containing polymer and the suspension of nanodiamond are continued until the desired number of nanodiamond layers is formed around the microdiamond. Finally, the core-shell particles are cross-linked with 1,2,5,6-diepoxycyclooctane or reacted with 1,2-epoxyoctadecane. Layer-by-layer deposition of PAAm and nanodiamond is also studied on planar Si/SiO(2) surfaces, which were characterized by scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA). Core-shell particles are characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), environmental scanning electron microscopy (ESEM), and Brunauer-Emmett-Teller (BET) surface area and pore size measurements. Larger (ca. 50 microm) core-shell diamond particles have much higher surface areas and analyte loading capacities in SPE than nonporous solid diamond particles. Smaller (ca. 3 microm), normal and reversed-phase, core-shell diamond particles have been used for HPLC, with 36,300 plates/m for mesitylene in a separation of benzene and alkyl benzenes and 54,800 plates/m for diazinon in a similar separation of two pesticides on a C(18) adsorbent.

Core-Shell Diamond as a Support for Solid-Phase Extraction and High-Performance Liquid Chromatography

International Nuclear Information System (INIS)

Saini, Gaurav; Jensen, David S.; Wiest, Landon A.; Vail, Michael A.; Dadson, Andrew; Lee, Milton L.; Shutthanandan, V.; Linford, Matthew R.

2010-01-01

We report the formation of core-shell diamond particles for solid phase extraction (SPE) and high performance liquid chromatography (HPLC) made by layer-by-layer (LbL) deposition. Their synthesis begins with the amine functionalization of microdiamond by its immersion in an aqueous solution of a primary amine-containing polymer (polyallylamine (PAAm)). The amine-terminated microdiamond is then immersed in an aqueous suspension of nanodiamond, which leads to adsorption of the nanodiamond. Alternating (self-limiting) immersions in the solutions of the amine-containing polymer and the suspension of nanodiamond are continued until the desired number of nanodiamond layers is formed around the microdiamond. Finally, the core-shell particles are cross-linked with 1,2,5,6-diepoxycyclooctane or reacted with 1,2-epoxyoctadecane. Layer-by-layer deposition of PAAm and nanodiamond is also studied on planar Si/SiO2 surfaces, which were characterized by SEM, Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Core-shell particles are characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), environmental scanning electron microscopy (ESEM), and Brunauer Emmett Teller (BET) surface area and pore size measurements. Larger (ca. 50 ?m) core-shell diamond particles have much higher surface areas, and analyte loading capacities in SPE than nonporous solid diamond particles. Smaller (ca. 3 ?m), normal and reversed phase, core-shell diamond particles have been used for HPLC, with 36,300 plates per meter for mesitylene in a separation of benzene and alkyl benzenes on a C18 adsorbent, and 54,800 plates per meter for diazinon in a similar separation of two pesticides.

A coordination chemistry approach for modeling trace element adsorption

International Nuclear Information System (INIS)

Bourg, A.C.M.

1986-01-01

The traditional distribution coefficient, Kd, is highly dependent on the water chemistry and the surface properties of the geological system being studied and is therefore quite inappropriate for use in predictive models. Adsorption, one of the many processes included in Kd values, is described here using a coordination chemistry approach. The concept of adsorption of cationic trace elements by solid hydrous oxides can be applied to natural solids. The adsorption process is thus understood in terms of a classical complexation leading to the formation of surface (heterogeneous) ligands. Applications of this concept to some freshwater, estuarine and marine environments are discussed. (author)

On the study of the solid-solid phase transformation of TlBiTe2

International Nuclear Information System (INIS)

Chrissafis, K.; Vinga, E.S.; Paraskevopoulos, K.M.; Polychroniadis, E.K.

2003-01-01

The narrow gap semiconductor TlBiTe 2 undergoes a solid-solid phase transformation from the rhombohedral (D 3d ) to the cubic (O h ) phase. The present paper deals with the study of this phase transformation combining the results of Differential Scanning Calorimetry (DSC) and Transmission Electron Microscopy (TEM). It has been found that during heating the transformation is an athermal activated process, which can be described only by a combination of more than one processes while during cooling it exhibits an expectable thermal hysteresis due to the volume difference. The results of the kinetic analysis combined with the electron microscopy findings, supported also by the Fourier Transform Infrared (FTIR) spectroscopy ones, lead to the conclusion that TlBiTe 2 undergoes a multiple-step, displacive, martensitic type transformation. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Effect of organic matter and pH on the adsorption of metalaxyl and penconazole by soils

Energy Technology Data Exchange (ETDEWEB)

Gondar, Dora; López, Rocío [Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Antelo, Juan [Departamento de Edafología y Química Agrícola, Facultad de Biología, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Fiol, Sarah, E-mail: sarah.fiol@usc.es [Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Arce, Florencio [Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

2013-09-15

Highlights: • The adsorption of non-ionic pesticides on soils is affected by pH. • At pH < 5, the C{sub s}{sup OC}/C{sub e} ratio increased as the pH of the medium decreased. • The effect of pH on adsorption is related to the ionization of carboxylic groups. • SOM charge had similar effect on C{sub s}{sup OC}/C{sub e} in the four soils under study. -- Abstract: Soil organic matter (SOM) is considered to be the primary adsorbent of non-ionic pesticides, and it is therefore thought to determine the concentration of such pesticides in the soil solution and how they are transported throughout the medium. It is generally assumed that the sorption capacity of different soils is the same per unit mass of SOM; however, the reactivity also depends on the SOM composition and the pH of the medium. We carried out experiments to study the effects of pH and ionic strength on the adsorption of the non-ionic fungicides metalaxyl and penconazole on four soils containing different amounts of organic carbon. The adsorption isotherms fitted a Freundlich equation. For pH > 5, partitioning of the fungicides between the solid phase and the soil solution did not vary with the pH, while at lower pH, the fraction adsorbed on the solid phase increased as the pH decreased. The response was related to the effect of pH on the ionization of the carboxylic groups of the SOM and therefore to the hydrophilic nature of the SOM. Analysis of the charge effect on the partitioning of both fungicides revealed a common response in all four soils. Adsorption appears to be related to the magnitude of the charge developed at the SOM due to ionization of the carboxylic acid groups.

Texture study of divided solids by gas adsorption: application to beryllia, alumina and to gels and oxides

International Nuclear Information System (INIS)

Rouquerol, F.

1965-12-01

A certain number of porous materials have been studied in an adsorption apparatus developed by us and leading to a measurement of the surface area with a reproducibility as good as 1/1 000. We have shown that this is only obtained at the cost of a number necessary precautions in the measurement of the gaseous volume adsorbed in a monomolecular layer (especially in the case of microporous solids). It also appears convenient to substitute argon to nitrogen, the latter being sensitive to chemical or electrical interactions with the adsorbent. Calculation methods of the pore size distribution are analyzed and discussed. The experimental data shows that the thickness of the multi-molecular layer must be estimated from the number of layers given by Shull using a layer thickness of 3.6 angstrom. A new method of analysis of the desorption curve is also given. We have also shown that a certain number of lamellar, non porous, systems, such as Be(OH) 2 present a hysteresis branch on the adsorption isotherm of type I or II. Using the numerical data obtained by our method together with the information provided by the electronic microscope, we have been able to conclude that this hysteresis can be ascribed to the lack of rigidity of the solid. On the contrary, samples of microporous texture (r [fr

Flame atomic absorption spectrometric determination of zinc, nickel, iron and lead in different matrixes after solid phase extraction on sodium dodecyl sulfate (SDS)-coated alumina as their bis (2-hydroxyacetophenone)-1, 3-propanediimine chelates

International Nuclear Information System (INIS)

Ghaedi, M.; Tavallali, H.; Shokrollahi, A.; Zahedi, M.; Montazerozohori, M.; Soylak, M.

2009-01-01

A sensitive and simple solid phase extraction method for the simultaneous determination of trace and toxic metals in food samples has been reported. The method is based on the adsorption of zinc, nickel, iron and lead on sodium dodecyl sulfate (SDS)-coated alumina, which is also chelated with bis (2-hydroxyacetophenone)-1, 3-propanediimine (BHAPN). The retained analyte ions on modified solid phase were eluted using 8 mL of 4 mol L -1 HNO 3 . The analyte determinations were carried out by flame atomic absorption spectrometry. The influences of some metal ions and anions on the recoveries of understudy analyte ions were investigated. The proposed method has been successfully applied for the evaluation of these trace and toxic metals in some traditional food samples from Iran.

Solid phase radioimmunoassays for human C-reactive protein

International Nuclear Information System (INIS)

Shine, B.; Beer, F.C. de; Pepys, M.B.

1981-01-01

Two new, rapid and sensitive radioimmunoassays for human C-reactive protein (CRP) have been established using antiserum coupled to magnetizable cellulose particles, which facilitate phase separation. A single antibody method, using solid phase anti-CRP, provides a sensitivity of 50 μg/l with a 1-h incubation time and intra- and inter-assay coefficients of variation of 10%. A double antibody method, using fluid phase rabbit anti-CRP serum and solid phase sheep anti-rabbit IgG serum, provides a sensitivity of 3 μg/l with an overnight incubation and intra- and inter-assay coefficients of variation of 10%. Among 468 sera from normal adult volunteer blood donors the median CRP concentration was 800 μg/l, interquartile range 340-1700 μg/l and range 70-29,000 μg/l. Ninety percent of samples contained less than 3 mg/l and 99% less than 10 mg/l. Low levels (14-650 μg/l) of CRP were detected both in amniotic fluids and in cerebrospinal fluids. (Auth.)

SOLID-PHASE PEPTIDE SYNTHESIS OF ISOTOCIN WITH AMIDE ...

African Journals Online (AJOL)

SOLID-PHASE PEPTIDE SYNTHESIS OF ISOTOCIN WITH AMIDE OF ASPARAGINE PROTECTED WITH 1-TETRALINYL. TRIFLUOROMETHANESULPHONIC ACID (TFMSA) DEPROTECTION, CLEAVAGE AND AIR OXIDATION OF MERCAPTO GROUPS TO DISULPHIDE.

Solid-State NMR Investigation of Drug-Excipient Interactions and Phase Behavior in Indomethacin-Eudragit E Amorphous Solid Dispersions.

Science.gov (United States)

Lubach, Joseph W; Hau, Jonathan

2018-02-20

To investigate the nature of drug-excipient interactions between indomethacin (IMC) and methacrylate copolymer Eudragit® E (EE) in the amorphous state, and evaluate the effects on formulation and stability of these amorphous systems. Amorphous solid dispersions containing IMC and EE were spray dried with drug loadings from 20% to 90%. PXRD was used to confirm the amorphous nature of the dispersions, and DSC was used to measure glass transition temperatures (T g ). 13 C and 15 N solid-state NMR was utilized to investigate changes in local structure and protonation state, while 1 H T 1 and T 1ρ relaxation measurements were used to probe miscibility and phase behavior of the dispersions. T g values for IMC-EE solid dispersions showed significant positive deviations from predicted values in the drug loading range of 40-90%, indicating a relatively strong drug-excipient interaction. 15 N solid-state NMR exhibited a change in protonation state of the EE basic amine, with two distinct populations for the EE amine at -360.7 ppm (unprotonated) and -344.4 ppm (protonated). Additionally, 1 H relaxation measurements showed phase separation at high drug load, indicating an amorphous ionic complex and free IMC-rich phase. PXRD data showed all ASDs up to 90% drug load remained physically stable after 2 years. 15 N solid-state NMR experiments show a change in protonation state of EE, indicating that an ionic complex indeed forms between IMC and EE in amorphous solid dispersions. Phase behavior was determined to exhibit nanoscale phase separation at high drug load between the amorphous ionic complex and excess free IMC.

Bioinspired magnetite synthesis via solid precursor phases

NARCIS (Netherlands)

Lenders, J.J.M.; Mirabello, G.; Sommerdijk, N.A.J.M.

2016-01-01

Living organisms often exploit solid but poorly ordered mineral phases as precursors in the biomineralization of their inorganic body parts. Generally speaking, such precursor-based approaches allow the organisms-without the need of high supersaturation levels-to accumulate significant quantities of

Texture study of divided solids by gas adsorption: application to beryllia, alumina and to gels and oxides; Contribution a l'etude, par adsorption gazeuse, de la texture des solides divises. Application a l'alumine, a la glucine et a differents gels et oxydes

Energy Technology Data Exchange (ETDEWEB)

Rouquerol, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-12-01

A certain number of porous materials have been studied in an adsorption apparatus developed by us and leading to a measurement of the surface area with a reproducibility as good as 1/1 000. We have shown that this is only obtained at the cost of a number necessary precautions in the measurement of the gaseous volume adsorbed in a monomolecular layer (especially in the case of microporous solids). It also appears convenient to substitute argon to nitrogen, the latter being sensitive to chemical or electrical interactions with the adsorbent. Calculation methods of the pore size distribution are analyzed and discussed. The experimental data shows that the thickness of the multi-molecular layer must be estimated from the number of layers given by Shull using a layer thickness of 3.6 angstrom. A new method of analysis of the desorption curve is also given. We have also shown that a certain number of lamellar, non porous, systems, such as Be(OH){sub 2} present a hysteresis branch on the adsorption isotherm of type I or II. Using the numerical data obtained by our method together with the information provided by the electronic microscope, we have been able to conclude that this hysteresis can be ascribed to the lack of rigidity of the solid. On the contrary, samples of microporous texture (r < 20 A) of the type of beryllia, provide the case, which we have been able to characterize, of porous materials which do not exhibit a hysteresis phenomenon. The above conclusions have allowed us to describe the evolution of the texture during their progressive dehydration (thermal treatment from 150 to 1100 C) of two series of samples, namely beryllia and alumina. (author) [French] A l'aide d'un appareil d'adsorption que nous avons mis au point, et qui permet d'atteindre Une reproductibilite de 1/1000 dans la mesure des surfaces specifiques, nous avons etudie de nombreux solides divises. Nous montrons qu'il est indispensable, de prendre des precautions (en particulier dans le cas des

Magnetic metal-organic frameworks for fast and efficient solid-phase extraction of six Sudan dyes in tomato sauce.

Science.gov (United States)

Shi, Xin-Ran; Chen, Xue-Lei; Hao, Yu-Lan; Li, Li; Xu, Hou-Jun; Wang, Man-Man

2018-06-01

Magnetic solid-phase extraction is an effective and useful technique to preconcentrate trace analytes from food samples. In this study, a magnetic trimeric chromium octahedral metal-organic framework (Fe 3 O 4 -NH 2 @MIL-101) was fabricated and characterized. Fe 3 O 4 -NH 2 @MIL-101 was applied as an adsorbent of magnetic solid-phase extraction combined with high performance liquid chromatography to effectively isolate and simultaneously determine six Sudan dyes (Para Red, Sudan I-IV, and Sudan Red 7B) from tomato sauce. Potential factors affecting the MSPE were investigated in detail, and adsorption efficiency of Fe 3 O 4 -NH 2 @MIL-101 was compared with those of conventional adsorbents, such as neutral alumina, HLB, and C 18 . The developed method facilitated the extraction with using only 3 mg of adsorbent in 2 min. In addition, enhancement factors of 50, linear range of 0.01-25 μg/mL, and detection limit (S/N = 3) of 0.5-2.5 μg/kg were obtained. The intra-day and inter-day recoveries for spiked Sudan dyes were in the range of 72.6%-92.9% and 69.6%-91.6%, respectively, with relative standard deviations of ≤9.2%. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of Secondary Equilibria on the Adsorption of Ibuprofen Enantiomers on a Chiral Stationary Phase with a Grafted Antibiotic Eremomycin

Science.gov (United States)

Reshetova, E. N.; Asnin, L. D.; Kachmarsky, K.

2018-02-01

The chromatographic separation of ibuprofen enantiomers on a Nautilus-E chiral stationary phase with a grafted eremomycin antibiotic at high column loading is accompanied by distortion of the shape of chromatographic peaks. A model is proposed to explain this phenomenon. A number of factors are considered in the model: the ionization of ibuprofen in the mobile phase, the pH change in the mass transfer zone caused by ionization, and competitive adsorption involving buffer components. Simulations performed using this model within the theory of nonequilibrium chromatography allow the shape of chromatograms for large amounts of S- and R-ibuprofen samples to be predicted. The adsorption mechanism is found to be mainly ion-exchange. The contribution from the molecular adsorption of ibuprofen to the total retention is shown to be several percent.

Determination of solid-liquid partition coefficients (Kd) for the herbicides isoproturon and trifluralin in five UK agricultural soils.

Science.gov (United States)

Cooke, Cindy M; Shaw, George; Collins, Chris D

2004-12-01

Isoproturon and trifluralin are herbicides of contrasting chemical characters and modes of action. Standard batch sorption procedures were carried out to investigate the individual sorption behaviour of 14C-isoproturon and 14C-trifluralin in five agricultural soils (1.8-4.2% OC), and the soil solid-liquid partition coefficients (Kd values) were determined. Trifluralin exhibited strong partitioning to the soil solid phase (Kd range 106-294) and low desorption potential, thus should not pose a threat to sensitive waters via leaching, although particle erosion and preferential flow pathways may facilitate transport. For isoproturon, soil adsorption was low (Kd range 1.96-5.75) and desorption was high, suggesting a high leaching potential, consistent with isoproturon being the most frequently found pesticide in UK surface waters. Soil partitioning was directly related to soil organic carbon (OC) content. Accumulation isotherms were modelled using a dual-phase adsorption model to estimate adsorption and desorption rate coefficients. Associations between herbicides and soil humic substances were also shown using gel filtration chromatography.

Design, construction and test run of a solid adsorption solar refrigerator using activated carbon/methanol, as adsorbent/adsorbate pair

International Nuclear Information System (INIS)

Anyanwu, E.E.; Ezekwe, C.I.

2003-01-01

The design, construction and test run of a solid adsorption solar refrigerator are presented. It used activated carbon/methanol as the adsorbent/adsorbate pair. The refrigerator has three major components: collector/generator/adsorber, condenser and evaporator. Its flat plate type collector/generator/adsorber used clear plane glass sheet of effective exposed area of 1.2 m 2 . The steel condenser tube with a square plan view was immersed in pool of stagnant water contained in a reinforced sandcrete tank. The evaporator is a spirally coiled copper tube immersed in stagnant water. Adsorbent cooling during the adsorption process is both by natural convection of air over the collector plate and tubes and night sky radiation facilitated by removing the collector box end cover plates. Ambient temperatures during the adsorbate generation and adsorption process varied over 18.5-34 deg. C. The refrigerator yielded evaporator temperatures ranging over 1.0-8.5 deg. C from water initially in the temperature range 24-28 deg. C. Accordingly, the maximum daily useful cooling produced was 266.8 kJ/m 2 of collector area

Investigation of binary solid phases by calorimetry and kinetic modelling

OpenAIRE

Matovic, M.

2007-01-01

The traditional methods for the determination of liquid-solid phase diagrams are based on the assumption that the overall equilibrium is established between the phases. However, the result of the crystallization of a liquid mixture will typically be a non-equilibrium or metastable state of the solid. For a proper description of the crystallization process the equilibrium approach is insufficient and a kinetic approach is actually required. In this work, we show that during slow crystallizatio...

Adsorption and diffusion of plutonium in soil

International Nuclear Information System (INIS)

Relyea, J.F.; Brown, D.A.

1978-01-01

The behavior of plutonium in soil--water systems was studied by measuring its apparent diffusion coefficient in the aqueous and solid phases and by finding the adsorption--desorption relationships between soil and solution. Apparent diffusion coefficients of plutonium in soil were measured using a quick-freeze method. Aqueous diffusion was studied in a capillary-tube diffusion cell. Adsorption studies were done by equilibrating a tagged soil--water mixture on a rotary shaker before centrifuging and sampling. As expected from high adsorption coefficients (Kd) (300--10,000), the apparent diffusion coefficients were low compared with normal soil cations (1.4 x 10 -8 cm 2 /sec in a sandy soil to less than 2.4 x 10 -11 cm 2 /sec in a silt loam). The Kd of plutonium in aqueous solution containing the chelate ethylenediaminetetraacetic acid (EDTA) was reduced compared with the Kd in dilute HNO 3 . As the EDTA concentration was increased, the Kd was decreased. The chelate diethylenetriaminepentaacetic acid (DTPA) reduced the Kd more than EDTA at comparable concentrations. The aqueous diffusion coefficients varied from 3.1 x 10 -7 cm 2 /sec in a solution extracted from the silt loam up to 2.7 x 10 -5 cm 2 /sec in a solution extracted from the sandy soil

Solid-phase route to Fmoc-protected cationic amino acid building blocks

DEFF Research Database (Denmark)

Clausen, Jacob Dahlqvist; Linderoth, Lars; Nielsen, Hanne Mørck

2012-01-01

Diamino acids are commonly found in bioactive compounds, yet only few are commercially available as building blocks for solid-phase peptide synthesis. In the present work a convenient, inexpensive route to multiple-charged amino acid building blocks with varying degree of hydrophobicity...... was developed. A versatile solid-phase protocol leading to selectively protected amino alcohol intermediates was followed by oxidation to yield the desired di- or polycationic amino acid building blocks in gram-scale amounts. The synthetic sequence comprises loading of (S)-1-(p-nosyl)aziridine-2-methanol onto...... of simple neutral amino acids as well as analogs displaying high bulkiness or polycationic side chains was prepared. Two building blocks were incorporated into peptide sequences using microwave-assisted solid-phase peptide synthesis confirming their general utility....

Micro solid-phase radioimmunoassay for detection of herpesvirus type-specific antibody: parameters involved in standardization

Energy Technology Data Exchange (ETDEWEB)

Matson, D.O.; Adler-Storthz, K.; Adam, E.; Dreesman, G.R. (Baylor Univ., Houston, TX (USA). Coll. of Medicine)

1983-02-01

A micro solid-phase radioimmunoassay (micro-SPRIA) was developed to demonstrate type-specific antibodies to herpes simplex virus types 1 and 2 (HSV1 and HSV2). Glycoproteins from the 123,000 dalton region of HSV1 (VP123) and the 119,000 dalton region of HSV2 (VP119) were isolated on preparative polyacrylamide gels for use as antigens in the micro-SPRIA. Human sera selected from clinical samples by virological history and appropriate microneutralization data were used to standardize the micro-SPRIA. Optimization of the assay required the use of siliconized microtiter wells for adsorption of antigen. Maximized results were highly dependent on the concentrations of antigen, primary antibody, and secondary antibody as well as the diluents used for these principal test reagents. Incorporation of HSV glycoproteins of each respective type with the optimal condition established in this study facilitates the direct detection of type-specific antibody in human sera.

Unitized solid phase immunoassay kit and method

International Nuclear Information System (INIS)

1975-01-01

A unitized solid phase kit for radioimmunoassay is disclosed. All of the necessary assay reagents are incorporated into a single tube wherein all phases of the assay procedure are performed, requiring only the addition of the patient's sample. Antibody is bound to the tube surface while labelled antigen is also present but unbound. Storage in the absence of air and water results in the stabilization of the reagents such that the system can be stored for long periods

Surface complexation models for uranium adsorption in the sub-surface environment

International Nuclear Information System (INIS)

Payne, T.E.

2007-01-01

Adsorption experiments with soil component minerals under a range of conditions are being used to develop models of uranium(VI) uptake in the sub-surface environment. The results show that adsorption of U on iron oxides and clay minerals is influenced by chemical factors including the pH, partial pressure of CO 2 , and the presence of ligands such as phosphate. Surface complexation models (SCMs) can be used to simulate U adsorption on these minerals. The SCMs are based on plausible mechanistic assumptions and describe the experimental data more adequately than Kd values or sorption isotherms. It is conceptually possible to simulate U sorption data on complex natural samples by combining SCMs for individual component minerals. This approach was used to develop a SCM for U adsorption to mineral assemblages from Koongarra (Australia), and produced a reasonable description of U uptake. In order to assess the applicability of experimental data to the field situation, in-situ measurements of U distributions between solid and liquid phases were undertaken at the Koongarra U deposit. This field partitioning data showed a satisfactory agreement with laboratory sorption data obtained under comparable conditions. (author)

The design of a two-phase radiolabelled meal for gastric emptying studies

International Nuclear Information System (INIS)

Mather, S.J.; Ellison, D.; Nightingale, J.; Kamm, M.; Britton, K.E.

1991-01-01

A meal intended for use in gastric emptying studies must be highly reproducible, must provide a normal physiological stimulus in terms of bulk, calorie content and composition and must employ stable radiotracers which accurately reflect in their biodistribution, the fate of the two-phases. This is particularly important in a field, such as gastric emptying, where so many variables may influence the results. A conventional pancake and orange juice were chosen as suitable vehicles for the solid and liquid phases. 111 In-labelled resin beads were used as the solid-phase marker and a variety of 99 Tc m -labelled radiopharmaceuticals including pertechnetate, DTPA and colloid forms were investigated as liquid-phase markers. Prior to administration to patients, the stability of the phases and their interactions in vitro were investigated. The use of 99 Tc m -DTPA resulted in a loss of 111 In from solid to liquid phase. All non-colloidal markers exhibited a tendency for adsorption onto solid phase. Colloidal markers including rhenium and antimony sulphide colloids showed the truest delineation of the liquid phase. (author)

Solid-phase microextraction

DEFF Research Database (Denmark)

Nilsson, Torben

The objective of this study has been to develop new analytical methods using the rapid, simple and solvent-free extraction technique solid-phase microextraction (SPME) for the quantitative analysis of organic pollutants at trace level in drinking water and environmental samples. The dynamics...... of SPME were examined for halogenated and non-halogenated volatile hydrocarbons, and a standard method for their quantitative analysis in aqueous samples was developed and validated in inter-laboratory studies on the basis of reference material and in comparison with the traditional methods....... The influences of some possible interferences on the SPME process were examined, and new SPME probes were tested for the in situ monitoring of groundwater pollutants. Inter-laboratory studies were carried out also for the validation of SPME for the quantitative analysis of organochlorine, organonitrogen...

Phase segregation in cerium-lanthanum solid solutions

NARCIS (Netherlands)

Belliere, V.; Joorst, G; Stephan, O; de Groot, FMF; Weckhuysen, BM

2006-01-01

Electron energy-loss spectroscopy (EELS) in combination with scanning transmission electron microscopy ( STEM) reveals that the La enrichment at the surface of cerium-lanthanum solid solutions is an averaged effect and that segregation occurs in a mixed oxide phase. This separation occurs within a

Complement fixation by solid phase immune complexes. Reduced capacity in SLE sera

DEFF Research Database (Denmark)

Baatrup, G; Jonsson, H; Sjöholm, A

1988-01-01

We describe an ELISA for assessment of complement function based on the capacity of serum to support fixation of complement components to solid phase immune complexes (IC). Microplates were coated with aggregated bovine serum albumin (BSA) followed by rabbit anti-BSA IgG. The solid phase IC were...

Interactions in the aqueous phase and adsorption at the air-water interface of caseinoglycomacropeptide (GMP) and beta-lactoglobulin mixed systems.

Science.gov (United States)

Martinez, María J; Sánchez, Cecilio Carrera; Patino, Juan M Rodríguez; Pilosof, Ana M R

2009-01-01

The aim of this work was to study the interactions and adsorption of caseinoglycomacropeptide (GMP) and GMP:beta-lactoglobulin (beta-lg) mixed system in the aqueous phase and at the air-water interface. The existence of associative interactions between GMP and beta-lg in the aqueous phase was investigated by dynamic light scattering, differential scanning calorimetry (DSC), fluorometry and native PAGE-electrophoresis. The surface pressure isotherm and the static and dynamic surface pressure were determined by tensiometry and surface dilatational properties. The results showed that GMP presented higher surface activity than beta-lg at a concentration of 4%wt but beta-lg showed higher film forming ability. In the mixed systems beta-lg dominated the static and dynamic surface pressure and the rheological properties of interfacial films suggesting that beta-lg hinders GMP adsorption because, in simple competition, GMP should dominate because of its higher surface activity. The surface predominance of beta-lg can be attributed to binding of GMP to beta-lg in the aqueous phase that prevents GMP adsorption on its own.

Biological nitrate removal from water and wastewater by solid-phase denitrification process.

Science.gov (United States)

Wang, Jianlong; Chu, Libing

2016-11-01

Nitrate pollution in receiving waters has become a serious issue worldwide. Solid-phase denitrification process is an emerging technology, which has received increasing attention in recent years. It uses biodegradable polymers as both the carbon source and biofilm carrier for denitrifying microorganisms. A vast array of natural and synthetic biopolymers, including woodchips, sawdust, straw, cotton, maize cobs, seaweed, bark, polyhydroxyalkanoate (PHA), polycaprolactone (PCL), polybutylene succinate (PBS) and polylactic acid (PLA), have been widely used for denitrification due to their good performance, low cost and large available quantities. This paper presents an overview on the application of solid-phase denitrification in nitrate removal from drinking water, groundwater, aquaculture wastewater, the secondary effluent and wastewater with low C/N ratio. The types of solid carbon source, the influencing factors, the microbial community of biofilm attached on the biodegradable carriers, the potential adverse effect, and the cost of denitrification process are introduced and evaluated. Woodchips and polycaprolactone are the popular and competitive natural plant-like and synthetic biodegradable polymers used for denitrification, respectively. Most of the denitrifiers reported in solid-phase denitrification affiliated to the family Comamonadaceae in the class Betaproteobacteria. The members of genera Diaphorobacter, Acidovorax and Simplicispira were mostly reported. In future study, more attention should be paid to the simultaneous removal of nitrate and toxic organic contaminants such as pesticide and PPCPs by solid-phase denitrification, to the elucidation of the metabolic and regulatory relationship between decomposition of solid carbon source and denitrification, and to the post-treatment of the municipal secondary effluent. Solid-phase denitrification process is a promising technology for the removal of nitrate from water and wastewater. Copyright © 2016

Solid-solid synthesis and structural phase transition process of SmF3

Science.gov (United States)

Yan, Qi-Cao; Guo, Xing-Min

2018-04-01

Mazes of contradictory conclusions have been obtained by previous researches about structural phase transition process of SmF3. In this paper, the single crystals of SmF3 (hexagonal and orthorhombic) were prepared by solid-solid synthesis, which have shown gradual changes in crystal growth modes with the increase temperature and holding time. Furthermore, we propose the phase transition process of in SmF3. Hexagonal symmetry of SmF3 (space group Pnma) was prepared firstly by heating Sm2O3 and NH4HF2 over 40 min at 270 °C. And then orthorhombic symmetry of SmF3 (space group P63mc) was obtained by heating hexagonal symmetry over 10 h at 650 °C. The reaction of SmF3 (hexagonal) = SmF3 (orthorhombic) is extremely sluggish at a low temperature (less than 650 °C), which was seen as a Mixed Grown Region.

Thermodynamic phase behavior of API/polymer solid dispersions.

Science.gov (United States)

Prudic, Anke; Ji, Yuanhui; Sadowski, Gabriele

2014-07-07

To improve the bioavailability of poorly soluble active pharmaceutical ingredients (APIs), these materials are often integrated into a polymer matrix that acts as a carrier. The resulting mixture is called a solid dispersion. In this work, the phase behaviors of solid dispersions were investigated as a function of the API as well as of the type and molecular weight of the carrier polymer. Specifically, the solubility of artemisinin and indomethacin was measured in different poly(ethylene glycol)s (PEG 400, PEG 6000, and PEG 35000). The measured solubility data and the solubility of sulfonamides in poly(vinylpyrrolidone) (PVP) K10 and PEG 35000 were modeled using the perturbed-chain statistical associating fluid theory (PC-SAFT). The results show that PC-SAFT predictions are in a good accordance with the experimental data, and PC-SAFT can be used to predict the whole phase diagram of an API/polymer solid dispersion as a function of the kind of API and polymer and of the polymer's molecular weight. This remarkably simplifies the screening process for suitable API/polymer combinations.

Solid phase extraction of uranium(VI) onto benzoylthiourea-anchored activated carbon

International Nuclear Information System (INIS)

Zhao Yongsheng; Liu Chunxia; Feng Miao; Chen Zhen; Li Shuqiong; Tian Gan; Wang Li; Huang Jingbo; Li Shoujian

2010-01-01

A new solid phase extractant selective for uranium(VI) based on benzoylthiourea anchored to activated carbon was developed via hydroxylation, amidation and reaction with benzoyl isothiocyanate in sequence. Fourier transform infrared spectroscopy and total element analysis proved that benzoylthiourea had been successfully grafted to the surface of the activated carbon, with a loading capacity of 1.2 mmol benzoylthiourea per gram of activated carbon. The parameters that affect the uranium(VI) sorption, such as contact time, solution pH, initial uranium(VI) concentration, adsorbent dose and temperature, have been investigated. Results have been analyzed by Langmuir and Freundlich isotherm; the former was more suitable to describe the sorption process. The maximum sorption capacity (82 mg/g) for uranium(VI) was obtained at experimental conditions. The rate constant for the uranium sorption by the as-synthesized extractant was 0.441 min -1 from the first order rate equation. Thermodynamic parameters (ΔH 0 = -46.2 kJ/mol; ΔS 0 = -98.0 J/mol K; ΔG 0 = -17.5 kJ/mol) showed the adsorption of an exothermic process and spontaneous nature, respectively. Additional studies indicated that the benzoylthiourea-anchored activated carbon (BT-AC) selectively sorbed uranyl ions in the presence of competing ions, Na + , Co 2+ , Sr 2+ , Cs + and La 3+ .

Quasi-Phase Diagrams at Air/Oil Interfaces and Bulk Oil Phases for Crystallization of Small-Molecular Semiconductors by Adjusting Gibbs Adsorption.

Science.gov (United States)

Watanabe, Satoshi; Ohta, Takahisa; Urata, Ryota; Sato, Tetsuya; Takaishi, Kazuto; Uchiyama, Masanobu; Aoyama, Tetsuya; Kunitake, Masashi

2017-09-12

The temperature and concentration dependencies of the crystallization of two small-molecular semiconductors were clarified by constructing quasi-phase diagrams at air/oil interfaces and in bulk oil phases. A quinoidal quaterthiophene derivative with four alkyl chains (QQT(CN)4) in 1,1,2,2-tetrachroloethane (TCE) and a thienoacene derivative with two alkyl chains (C8-BTBT) in o-dichlorobenzene were used. The apparent crystal nucleation temperature (T n ) and dissolution temperature (T d ) of the molecules were determined based on optical microscopy examination in closed glass capillaries and open dishes during slow cooling and heating processes, respectively. T n and T d were considered estimates of the critical temperatures for nuclear formation and crystal growth, respectively. The T n values of QQT(CN)4 and C8-BTBT at the air/oil interfaces were higher than those in the bulk oil phases, whereas the T d values at the air/oil interfaces were almost the same as those in the bulk oil phases. These Gibbs adsorption phenomena were attributed to the solvophobic effect of the alkyl chain moieties. The temperature range between T n and T d corresponds to suitable supercooling conditions for ideal crystal growth based on the suppression of nucleation. The T n values at the water/oil and oil/glass interfaces did not shift compared with those of the bulk phases, indicating that adsorption did not occur at the hydrophilic interfaces. Promotion and inhibition of nuclear formation for crystal growth of the semiconductors were achieved at the air/oil and hydrophilic interfaces, respectively.

Direct Adsorption and Molecular Self-Assembly of Octylthioacetates on Au(111) in the Vapor Phase

International Nuclear Information System (INIS)

Park, Tae Sung; Kang, Hun Gu; Kim, You Young; Lee, Seong Keun; Noh, Jae Geun

2011-01-01

We demonstrate that the direct adsorption of OTA on Au(111) in ethanol solution led to the formation of a disordered phase, whereas OTA SAMs grown from the vapor phase have an ordered 5 Χ √3 striped phase. Thus, vapor deposition was found to be a more effective technique, as compared to solution deposition, for improving the structural order of SAMs by direct adsorption of thioacetates on gold. Organic thiols are prone to easily oxidize to disulfides or other oxidized species that can affect the formation and structure of SAMs. The presence of disulfides or oxidized compounds in thiol samples often yields poorly ordered SAMs containing a high defect density and disordered phases. An approach that minimizes undesirable thiol oxidation is the use of a protected thiol that is deprotected in situ before or during SAM formation. The protection of thiol groups can be readily accomplished by acetylation. SAMs derived from acetyl protected thiols (thioacetates) on gold have usually been formed via an in situ deprotection process of the acetyl group in strong acidic or basic solutions. Other deprotection techniques have also been developed that use organic compounds such as triethylamine, tetrabutylammonium cyanide, and 1,8-diazabicyclo[5.4.0]undec-7-ene, and organic SAMs with a high degree of structural order have been successfully constructed in solutions containing these deprotection reagents

Solid-phase microextraction for bioconcentration studies according to OECD TG 305

Energy Technology Data Exchange (ETDEWEB)

Duering, Rolf-Alexander; Boehm, Leonard [Land Use and Nutrition (IFZ) Justus Liebig University Giessen, Institute of Soil Science and Soil Conservation, Research Centre for BioSystems, Giessen (Germany); Schlechtriem, Christian [Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Schmallenberg (Germany)

2012-12-15

An important aim of the European Community Regulation on chemicals and their safe use is the identification of (very) persistent, (very) bioaccumulative, and toxic substances. In other regulatory chemical safety assessments (pharmaceuticals, biocides, pesticides), the identification of such (very) persistent, (very) bioaccumulative, and toxic substances is of increasing importance. Solid-phase microextraction is especially capable of extracting total water concentrations as well as the freely dissolved fraction of analytes in the water phase, which is available for bioconcentration in fish. However, although already well established in environmental analyses to determine and quantify analytes mainly in aqueous matrices, solid-phase microextraction is still a rather unusual method in regulatory ecotoxicological research. Here, the potential benefits and drawbacks of solid-phase microextraction are discussed as an analytical routine approach for aquatic bioconcentration studies according to OECD TG 305, with a special focus on the testing of hydrophobic organic compounds characterized by log K{sub OW}> 5. (orig.)

Gas phase adsorption technology for nitrogen isotope separation and its feasibility for highly enriched nitrogen gas production

International Nuclear Information System (INIS)

Inoue, Masaki; Asaga, Takeo

2000-04-01

Highly enriched nitrogen-15 gas is favorable to reduce radioactive carbon-14 production in reactor. The cost of highly enriched nitrogen-15 gas in mass production is one of the most important subject in nitride fuel option in 'Feasibility Study for FBR and Related Fuel Cycle'. In this work gas phase adsorption technology was verified to be applicable for nitrogen isotope separation and feasible to produce highly enriched nitrogen-15 gas in commercial. Nitrogen isotopes were separated while ammonia gas flows through sodium-A type zeolite column using pressure swing adsorption process. The isotopic ratio of eight samples were measured by high resolution mass spectrometry and Fourier transform microwave spectroscopy. Gas phase adsorption technology was verified to be applicable for nitrogen isotope separation, since the isotopic ratio of nitrogen-15 and nitrogen-14 in samples were more than six times as high as in natural. The cost of highly enriched nitrogen-15 gas in mass production were estimated by the factor method. It revealed that highly enriched nitrogen-15 gas could be supplied in a few hundred yen per gram in mass production. (author)

Simulating Solid-Solid Phase Transition in Shape-Memory Alloy Microstructure by Face-Offsetting Method

International Nuclear Information System (INIS)

Bellur Ramaswamy, Ravi S.; Tortorelli, Daniel A.; Fried, Eliot; Jiao Xiangmin

2008-01-01

Advances in the understanding of martensitic transformations (diffusionless, solid-solid phase transformations) have been instrumental to the recent discovery of new low hysteresis alloys. However, some key fundamental issues must be better understood to design still better alloys. Restricting attention to antiplane shear, we use finite element analysis to model the shape-memory alloy microstructure within the Abeyaratne-Knowles continuum thermomechanical framework and use an interface kinetic relation of the kind proposed by Rosakis and Tsai. Geometric singularities and topological changes associated with microstructural evolution pose significant numerical challenges. We address such challenges with a recently developed front-tracking scheme called the face-offsetting method (FOM) to explicitly model phase interfaces. Initial results demonstrate the effectiveness of FOM in resolving needle-like twinned microstructures

Kinetics of a gas adsorption compressor

International Nuclear Information System (INIS)

Chan, C.K.; Elleman, D.D.; Tward, E.

1984-01-01

This chapter uses a two-phase model to analyze the transients of a gas adsorption compressor. The modeling of the adsorption process is based on complete thermal and mechanical equilibrium between the gaseous phase and the adsorbed gas phase. The theories and techniques that have been developed for a two-phase system are used to predict the pressure, the temperature and the mass flow transients in a gas sorption compressor. The analytical solutions are then compared with the performance of a laboratory gas adsorption compressor. A computer code was written to solve the governing equations, using a standard forward marching predictor-corrector method. It is found that while the analytical model overpredicts the pressure and the temperature transient, it predicts the general trend of the transient profile and the existence of the turning point

Preparation of molecularly imprinted adsorptive resin for trapping of ligustrazine from the traditional Chinese herb Ligusticum chuanxiong Hort

International Nuclear Information System (INIS)

Guo Zhifeng; Guo Tingting; Guo Mufan

2008-01-01

A highly selective molecularly imprinted adsorptive resin for ligustrazine was prepared by melamine-urea-formaldehyde (MUF) gel. In the experiments, two pieces of MUF gel were synthesized firstly; one was added ligustrazine hydrochloride as the template molecule in it to prepare the imprinted adsorptive resin, and the other was not. Scanning electron microscopy (SEM) revealed that both resins were the porous with a network structure whether or not it was added template molecule. The imprinted adsorptive resin had an absorbability of 85.22% measured by a 200 mg L -1 solution of ligustrazine hydrochloride at room temperature. The resin of MUF without template, on the other hand, displayed an adsorption capacity of almost zero. It illuminated the imprinted adsorptive resin formed ligustrazine recognition sites when the template molecule had been eluted. In the present paper, ligustrazine was effectively separated and enriched from herbs by using a solid-phase adsorptive column filled with the imprinted adsorptive resin. Its eluate, obtained from three kinds of solvents, was analyzed by GC-MS, and the results indicated that the imprinted adsorptive resin showed a high selectivity for ligustrazine. This is believed to be beneficial for extracting natural and highly purified ligustrazine

Toward a solid-phase nucleic acid hybridization assay within microfluidic channels using immobilized quantum dots as donors in fluorescence resonance energy transfer.

Science.gov (United States)

Chen, Lu; Algar, W Russ; Tavares, Anthony J; Krull, Ulrich J

2011-01-01

The optical properties and surface area of quantum dots (QDs) have made them an attractive platform for the development of nucleic acid biosensors based on fluorescence resonance energy transfer (FRET). Solid-phase assays based on FRET using mixtures of immobilized QD-oligonucleotide conjugates (QD biosensors) have been developed. The typical challenges associated with solid-phase detection strategies include non-specific adsorption, slow kinetics of hybridization, and sample manipulation. The new work herein has considered the immobilization of QD biosensors onto the surfaces of microfluidic channels in order to address these challenges. Microfluidic flow can be used to dynamically control stringency by adjustment of the potential in an electrokinetic-based microfluidics environment. The shearing force, Joule heating, and the competition between electroosmotic and electrophoretic mobilities allow the optimization of hybridization conditions, convective delivery of target to the channel surface to speed hybridization, amelioration of adsorption, and regeneration of the sensing surface. Microfluidic flow can also be used to deliver (for immobilization) and remove QD biosensors. QDs that were conjugated with two different oligonucleotide sequences were used to demonstrate feasibility. One oligonucleotide sequence on the QD was available as a linker for immobilization via hybridization with complementary oligonucleotides located on a glass surface within a microfluidic channel. A second oligonucleotide sequence on the QD served as a probe to transduce hybridization with target nucleic acid in a sample solution. A Cy3 label on the target was excited by FRET using green-emitting CdSe/ZnS QD donors and provided an analytical signal to explore this detection strategy. The immobilized QDs could be removed under denaturing conditions by disrupting the duplex that was used as the surface linker and thus allowed a new layer of QD biosensors to be re-coated within the channel

Texture study of divided solids by gas adsorption: application to beryllia, alumina and to gels and oxides; Contribution a l'etude, par adsorption gazeuse, de la texture des solides divises. Application a l'alumine, a la glucine et a differents gels et oxydes

Energy Technology Data Exchange (ETDEWEB)

Rouquerol, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-12-01

A certain number of porous materials have been studied in an adsorption apparatus developed by us and leading to a measurement of the surface area with a reproducibility as good as 1/1 000. We have shown that this is only obtained at the cost of a number necessary precautions in the measurement of the gaseous volume adsorbed in a monomolecular layer (especially in the case of microporous solids). It also appears convenient to substitute argon to nitrogen, the latter being sensitive to chemical or electrical interactions with the adsorbent. Calculation methods of the pore size distribution are analyzed and discussed. The experimental data shows that the thickness of the multi-molecular layer must be estimated from the number of layers given by Shull using a layer thickness of 3.6 angstrom. A new method of analysis of the desorption curve is also given. We have also shown that a certain number of lamellar, non porous, systems, such as Be(OH){sub 2} present a hysteresis branch on the adsorption isotherm of type I or II. Using the numerical data obtained by our method together with the information provided by the electronic microscope, we have been able to conclude that this hysteresis can be ascribed to the lack of rigidity of the solid. On the contrary, samples of microporous texture (r < 20 A) of the type of beryllia, provide the case, which we have been able to characterize, of porous materials which do not exhibit a hysteresis phenomenon. The above conclusions have allowed us to describe the evolution of the texture during their progressive dehydration (thermal treatment from 150 to 1100 C) of two series of samples, namely beryllia and alumina. (author) [French] A l'aide d'un appareil d'adsorption que nous avons mis au point, et qui permet d'atteindre Une reproductibilite de 1/1000 dans la mesure des surfaces specifiques, nous avons etudie de nombreux solides divises. Nous montrons qu'il est indispensable, de prendre des precautions (en

Understanding the solid phase chemical fractionation of uranium in soil and effect of ageing

Energy Technology Data Exchange (ETDEWEB)

Rout, Sabyasachi, E-mail: srout.barc@gmail.com [Health Physics Division, Bhabha Atomic Research Centre, Mumbai (India); Kumar, Ajay [Health Physics Division, Bhabha Atomic Research Centre, Mumbai (India); Ravi, P.M.; Tripathi, R.M. [Homi Bhabha National Institute Anushaktinagar, Mumbai (India)

2016-11-05

Highlights: • Apart of U(VI) converted to U(IV) during adsorption to soil. • Ageing leads to rearrangement of chemical fractionation of U in soil. • Organic matter and carbonate minerals responsible for Surface enrichment of U. • There occurs Occlusion of U-Fe-Oxides (Hydroxide) in to silica. - Abstract: The aim of the present work is to understand the solid phase chemical fractionation of Uranium (U) in soil and the mechanism involved. This study integrated batch experiments of U(VI) adsorption to soil, study of U in different soil fractions, ageing impact on fractionation of U and spectroscopic investigation of adsorbed U(VI) using X-ray Photoelectron Spectroscopy (XPS). For the study three soils, pedogenically different (S1: Igneous, S2: Sedimentary and S3: Metamorphic) were amended with U(VI) and chemical fractionation of U was studied by sequential extraction after an interval of one month and 12 months. It was found that there occurs a significant rearrangement of U in different fractions with ageing and no correlation was observed between the U content in different fractions and the adsorbents of respective fractions such as soil organic matter (SOM), Fe/Mn oxides (hydroxides) carbonates, soil cation exchange capacity (CEC). XPS study revealed that surface enrichment of U mainly governed by the carbonate minerals and SOM, whereas bulk concentration was controlled by the oxides (hydroxides) of Si and Al. Occlusion of U-Fe-oxides (hydroxides) on silica was identified as an important mechanism for bulk enrichment (Increase in residual fraction) and depletion of U concentration in reducible fraction.

Understanding the solid phase chemical fractionation of uranium in soil and effect of ageing

International Nuclear Information System (INIS)

Rout, Sabyasachi; Kumar, Ajay; Ravi, P.M.; Tripathi, R.M.

2016-01-01

Highlights: • Apart of U(VI) converted to U(IV) during adsorption to soil. • Ageing leads to rearrangement of chemical fractionation of U in soil. • Organic matter and carbonate minerals responsible for Surface enrichment of U. • There occurs Occlusion of U-Fe-Oxides (Hydroxide) in to silica. - Abstract: The aim of the present work is to understand the solid phase chemical fractionation of Uranium (U) in soil and the mechanism involved. This study integrated batch experiments of U(VI) adsorption to soil, study of U in different soil fractions, ageing impact on fractionation of U and spectroscopic investigation of adsorbed U(VI) using X-ray Photoelectron Spectroscopy (XPS). For the study three soils, pedogenically different (S1: Igneous, S2: Sedimentary and S3: Metamorphic) were amended with U(VI) and chemical fractionation of U was studied by sequential extraction after an interval of one month and 12 months. It was found that there occurs a significant rearrangement of U in different fractions with ageing and no correlation was observed between the U content in different fractions and the adsorbents of respective fractions such as soil organic matter (SOM), Fe/Mn oxides (hydroxides) carbonates, soil cation exchange capacity (CEC). XPS study revealed that surface enrichment of U mainly governed by the carbonate minerals and SOM, whereas bulk concentration was controlled by the oxides (hydroxides) of Si and Al. Occlusion of U-Fe-oxides (hydroxides) on silica was identified as an important mechanism for bulk enrichment (Increase in residual fraction) and depletion of U concentration in reducible fraction.

Evaluation of a solid-phase RIA technique and a solid-phase ELISA technique for demonstrating hepatitis-B surface antigen

International Nuclear Information System (INIS)

Vranckx, R.; Cole, J.; Peetermans, M.

1978-01-01

The sensitivities of a solid-phase radioimmunoassay (RIA), a solid-phase enzyme immunoassay (ELISA) and a haemagglutination test (RPHA) for the detection of the hepatitis-B surface antigen (HBsAg) were compared (1) by screening a panel of 300 sera (97 positives and 203 negatives), and (2) by titrating serial dilutions of 10 positive sera. Ninety-seven sera were positive by RIA, 95% were detected by ELISA and 81% were detected by RPHA. In the serial dilutions, the average end-points of the titrations were 0.005ng/ml for RIA, 0.01ng/ml for ELISA and 0.04 ng/ml for RPHA. It can be concluded that the sensitivity of the ELISA test is intermediate between that of the RIA and the RPHA. The ELISA and the RPHA tests seem to be a little more sensitive for the detection of subtype ay than for the detection of subtype ad. (author)

C18, C8, and perfluoro reversed phases on diamond for solid-phase extraction.

Science.gov (United States)

Saini, Gaurav; Wiest, Landon A; Herbert, David; Biggs, Katherine N; Dadson, Andrew; Vail, Michael A; Linford, Matthew R

2009-04-17

In spite of advances in solid-phase extraction (SPE) technology there are certain disadvantages to current SPE silica-based, column packings. The pH range over which extraction can occur is limited and each column is generally only used once. New diamond-based reversed SPE phases (C(18), C(8), and perfluorinated) were developed in our laboratories. Studies were done which show that these phases do not have the same limitations as traditional silica-based stationary phases. The synthesis and properties of these diamond-based phases are presented, and the stability, percent recovery, and column capacity are given for the C(18) phase.

Heavy metals in municipal solid waste deposits

Energy Technology Data Exchange (ETDEWEB)

Flyhammar, P.

1997-12-01

Extensive use of heavy metals in modern society influences routes followed by fluxes on the surface of the Earth. The changed flow paths may be harmful for the balance of biological systems at different levels, micro-organisms, human beings and whole ecosystems, since the toxicity of heavy metals is determined by their concentrations and chemical forms. Despite the low mobility of heavy metals (Zn, Cu, Pb, Cr, Ni and Cd) in municipal landfills, it was found that extensive transformations of the binding forms of heavy metal take place within the waste mass during the degradation of the waste. These changes appear to be closely related to the development of early diagenetic solid phases, i.e. new secondary solid phases formed in the waste. The heavy metals often constitute a minor part of these phases and the bindings include several forms such as adsorption, complexation, coprecipitation, precipitation, etc. It was also found that the associations between heavy metals and solid phases are dominated by several binding forms to one specific substrate rather than bindings to various solid phases. The mobility of iron and manganese seems to increase during the processes involved in waste degradation due to the solution of oxide/hydroxide phases, while the heavy metals appear to become less mobile due to their binding to organic compounds and sulphides. However, one exception in this case may be nickel. Another aspect of the transformation of heavy metals is the accumulation of pools of heavy metals which can become susceptible to environmental changes, such as oxidation or acidification. However, the risk of increased mobilization caused by lower pH values seem to be limited since municipal solid waste has a large buffer capacity. 66 refs, 9 figs, 3 tabs 66 refs, 9 figs, 3 tabs

Influence of Calcium on Microbial Reduction of Solid Phase Uranium (VI)

International Nuclear Information System (INIS)

Liu, Chongxuan; Jeon, Byong-Hun; Zachara, John M.; Wang, Zheming

2007-01-01

The effect of calcium on microbial reduction of a solid phase U(VI), sodium boltwoodite (NaUO2SiO3OH · 1.5H2O), was evaluated in a culture of a dissimilatory metal-reducing bacterium (DMRB), Shewanella oneidensis strain MR-1. Batch experiments were performed in a non-growth bicarbonate medium with lactate as electron donor at pH 7 buffered with PIPES. Calcium increased both the rate and extent of Na-boltwoodite dissolution by increasing its solubility through the formation of a ternary aqueous calcium-uranyl-carbonate species. The ternary species, however, decreased the rates of microbial reduction of aqueous U(VI). Laser-induced fluorescence spectroscopy (LIFS) and transmission electron microscopy (TEM) revealed that microbial reduction of solid phase U(VI) is a sequentially coupled process of Na-boltwoodite dissolution, U(VI) aqueous speciation, and microbial reduction of dissolved U(VI) to U(IV) that accumulated on bacterial surfaces/periplasm. The overall rates of microbial reduction of solid phase U(VI) can be described by the coupled rates of dissolution and microbial reduction that were both influenced by calcium. The results demonstrated that dissolved U(VI) concentration during microbial reduction was a complex function of solid phase U(VI) dissolution kinetics, aqueous U(VI) speciation, and microbial activity

Solution of adsorption problems involving steep moving profiles

DEFF Research Database (Denmark)

Kiil, Søren; Bhatia, Suresh K.

1998-01-01

The moving finite element collocation method proposed by Kiil et al. (1995) for solution of problems with steep gradients is further developed to solve transient problems arising in the field of adsorption. The technique is applied to a model of adsorption in solids with bidisperse pore structures....... Numerical solutions were found to match the analytical solution when it exists (i.e. when the adsorption isotherm is linear). Results of this application study show that the method is simple yet sufficiently accurate for use in adsorption problems with steep moving gradients, where global collocation...

Solid phase tube radioimmunoassay for digoxin detection

International Nuclear Information System (INIS)

Stellner, K.; Glatz, C.; Linke, R.

1975-01-01

A solid phase radioimmunoassay with 125 I is described for cardiac patients. The test for the digoxin determination and the poisoning due to cardiac glycosides can be measured very accurately and carried out easily. In addition, the test determination can be automatically performed in connection with other tests. (GSE/LH) [de

Experimental (solid + liquid) or (liquid + liquid) phase equilibria of (amine + nitrile) binary mixtures

International Nuclear Information System (INIS)

Domanska, Urszula; Marciniak, Malgorzata

2007-01-01

(Solid + liquid) phase diagrams have been determined for (hexylamine, or octylamine, or 1,3-diaminopropane + acetonitrile) mixtures. Simple eutectic systems have been observed in these mixtures. (Liquid + liquid) phase diagrams have been determined for (octylamine, or decylamine + propanenitrile, or + butanenitrile) mixtures. Mixtures with propanenitrile and butanenitrile show immiscibility in the liquid phase with an upper critical solution temperature, UCST. (Solid + liquid) phase diagrams have been correlated using NRTL, NRTL 1, Wilson and UNIQUAC equations. (Liquid + liquid) phase diagrams have been correlated using NRTL equation

Characterization of rhamnolipids by liquid chromatography/mass spectrometry after solid-phase extraction.

Science.gov (United States)

Behrens, Beate; Engelen, Jeannine; Tiso, Till; Blank, Lars Mathias; Hayen, Heiko

2016-04-01

Rhamnolipids are surface-active agents with a broad application potential that are produced in complex mixtures by bacteria of the genus Pseudomonas. Analysis from fermentation broth is often characterized by laborious sample preparation and requires hyphenated analytical techniques like liquid chromatography coupled to mass spectrometry (LC-MS) to obtain detailed information about sample composition. In this study, an analytical procedure based on chromatographic method development and characterization of rhamnolipid sample material by LC-MS as well as a comparison of two sample preparation methods, i.e., liquid-liquid extraction and solid-phase extraction, is presented. Efficient separation was achieved under reversed-phase conditions using a mixed propylphenyl and octadecylsilyl-modified silica gel stationary phase. LC-MS/MS analysis of a supernatant from Pseudomonas putida strain KT2440 pVLT33_rhlABC grown on glucose as sole carbon source and purified by solid-phase extraction revealed a total of 20 congeners of di-rhamnolipids, mono-rhamnolipids, and their biosynthetic precursors 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) with different carbon chain lengths from C8 to C14, including three rhamnolipids with uncommon C9 and C11 fatty acid residues. LC-MS and the orcinol assay were used to evaluate the developed solid-phase extraction method in comparison with the established liquid-liquid extraction. Solid-phase extraction exhibited higher yields and reproducibility as well as lower experimental effort.

Unusual seeding mechanism for enhanced performance in solid-phase magnetic extraction of Rare Earth Elements

Science.gov (United States)

Polido Legaria, Elizabeth; Rocha, Joao; Tai, Cheuk-Wai; Kessler, Vadim G.; Seisenbaeva, Gulaim A.

2017-03-01

Due to the increasing demand of Rare Earth Elements (REE or RE), new and more efficient techniques for their extraction are necessary, suitable for both mining and recycling processes. Current techniques such as solvent extraction or solid adsorbents entail drawbacks such as using big volumes of harmful solvents or limited capacity. Hybrid nanoadsorbents based on SiO2 and highly stable γ-Fe2O3-SiO2 nanoparticles, proved recently to be very attractive for adsorption of REE, yet not being the absolute key to solve the problem. In the present work, we introduce a highly appealing new approach in which the nanoparticles, rather than behaving as adsorbent materials, perform as inducers of crystallization for the REE in the form of hydroxides, allowing their facile and practically total removal from solution. This induced crystallization is achieved by tuning the pH, offering an uptake efficiency more than 20 times higher than previously reported (up to 900 mg RE3+/g vs. 40 mg RE3+/g). The obtained phases were characterized by SEM-EDS, TEM, STEM and EFTEM and 13C and 29Si solid state NMR. Magnetic studies showed that the materials possessed enough magnetic properties to be easily removed by a magnet, opening ways for an efficient and industrially applicable separation technique.

Krypton retention on solid adsorbents

International Nuclear Information System (INIS)

Monson, P.R. Jr.

1980-01-01

Radioactive krypton-85 is released to the atmosphere in the off-gas from nuclear reprocessing plants. Three main methods have been suggested for removal of krypton from off-gas streams: cryogenic distillation; fluorocarbon absorption; and adsorption on solid sorbents. Use of solid adsorbents is the least developed of these methods, but offers the potential advantages of enhanced safety and lower operating costs. An experimental laboratory program was developed that will be used to investigate systematically many solid adsorbents (such as zeolites, i.e., mordenites) for trapping krypton in air. The objective of this investigation is to find an adsorbent that is more economical than silver-exchanged mordenite. Various physical and chemical characteristics such as adsorption isotherms, decontamination factors, co-adsorption, regeneration, and the mechanism and kinetics of noble gas adsorption were used to characterize the adsorbents. In the experimental program, a gas chromatograph using a helium ionization detector was used to measure the krypton in air before and after the adsorbent bed. This method can determine directly decontamination factors greater than 100

Improved detection limits for phthalates by selective solid-phase micro-extraction

KAUST Repository

Zia, Asif I.; Afsarimanesh, Nasrin; Xie, Li; Nag, Anindya; Al-Bahadly, I. H.; Yu, P. L.; Kosel, Jü rgen

2016-01-01

Presented research reports on an improved method and enhanced limits of detection for phthalates; a hazardous additive used in the production of plastics by solid-phase micro-extraction (SPME) polymer in comparison to molecularly imprinted solid

Elementary excitations and phase transformations in solids

International Nuclear Information System (INIS)

Cowley, R.A.

1985-01-01

Neutron scattering is and will continue to be a uniquely powerful tool for the study of elementary excitations and phase transformations in solids. The paper examines a few recent experiments on molecular crystals, superionic materials, paramagnetic scattering and phase transitions to see what experimental features made these experiments possible, and hence to make suggestions about future needs. It is concluded that new instruments will extend the scope of neutron scattering studies to new excitations, that there is a need for higher resolution, particularly for phase transition studies, and that it will be important to use intensity information, discrimination against unwanted inelastic processes and polarization analysis to reliably measure the excitations in new materials. (author)

Adsorption of a small protein to a methyl-terminated hydrophobic surfaces

DEFF Research Database (Denmark)

Otzen, Daniel; Oliveberg, M.; Höök, F.

2003-01-01

We have studied the adsorption kinetics of a small monomeric protein S6 using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique. Competitive adsorption from various proportions of native (Nat) and denatured (Den) protein in the bulk phase was carried out using a range...... of chemical denaturant concentrations. The ratio between Nat and Den in bulk has a profound affect on the adsorption behavior, most obvious from a significant (one order of magnitude) increase in the rate of a lag– and consolidation–adsorption phase when Nat is the major species present in bulk, signaling...... that these adsorption phases originates from the Den fraction of proteins in the bulk. To determine whether the kinetics of protein unfolding in the bulk phase are rate-limiting for adsorption of Nat, the adsorption kinetics of wildtype S6 with the mutant VA85 (whose unfolding kinetics are around 30 times more rapid...

Simulating multi-component liquid phase adsorption systems: ethanol and residual sugar

Energy Technology Data Exchange (ETDEWEB)

Jones, R.; Tezel, F.H.; Thibault, J. [Department of Chemical and Biological Engineering, University of Ottawa (Canada)], email: Jules.Thibault@uottawa.ca

2011-07-01

A series of multi-component adsorption studies was performed to determine the relative advantages of producing ethanol which is to be blended with gasoline. These studies developed a model to describe the competition for adsorption sites between ethanol and sugar molecules on the surface of the adsorbent. Three competitive adsorption models established by batch systems were examined to evaluate the suitability of the experiment data across different ethanol and sugar concentrations and determine their isotherm parameters. Multi-component packed bed adsorption experiments were then performed. The results show that ethanol capacity was decreased only slightly from that obtained in single component adsorption studies. There is significant evidence to indicate that sugar displacement from adsorption sites occurs because adsorption of ethanol is preferred. So the capacity of sugars will be greatly reduced if there are appreciable ethanol concentrations.

Semi-automated microwave assisted solid-phase peptide synthesis

DEFF Research Database (Denmark)

Pedersen, Søren Ljungberg

with microwaves for SPPS has gained in popularity as it for many syntheses has provided significant improvement in terms of speed, purity, and yields, maybe especially in the synthesis of long and "difficult" peptides. Thus, precise microwave heating has emerged as one new parameter for SPPS, in addition...... to coupling reagents, resins, solvents etc. We have previously reported on microwave heating to promote a range of solid-phase reactions in SPPS. Here we present a new, flexible semi-automated instrument for the application of precise microwave heating in solid-phase synthesis. It combines a slightly modified...... Biotage Initiator microwave instrument, which is available in many laboratories, with a modified semi-automated peptide synthesizer from MultiSynTech. A custom-made reaction vessel is placed permanently in the microwave oven, thus the reactor does not have to be moved between steps. Mixing is achieved...

Investigation of solid-phase hydrogenation of amino acids and peptides

International Nuclear Information System (INIS)

Zolotarev, Yu.A.; Myasoedov, N.F.; Zajtsev, D.A.; Lubnin, M.Yu.; Tatur, V.Yu.; Kozik, V.S.; Dorokhova, E.M.; Rozenberg, S.N.

1990-01-01

The possibility of synthesizing amino acids and peptides multiply labelled with tritium or deuterium by the method of solid-phase isotopic exchange with gaseous hydrogen isotopes was verified. Establishment of the isotopic hydrogen equilibrium between the gaseous phase and the solid phase formed by the amino acid molecules was found experimentally. The activation energy of the isotopic exchange is 13 kcal/mol. A mathematical model was set up for the isotopic exchange with a probable substitution of hydrogen atoms. Uniformly labelled amino acids were obtained in a high optical purity and with 80 to 90% hydrogen substitution by deuterium and tritium. Tritiated peptides were prepared in high yields at molar activities of 1.5 to 3.7 TBq/mmol. (author). 4 tabs

The use of solid sorbents for direct accumulation of organic compounds from water matrices : a review of solid-phase extraction techniques

NARCIS (Netherlands)

Liska, I.; Krupcik, J.; Leclercq, P.A.

1989-01-01

The main principles of solid-phase extraction techniques are reviewed in this paper. Various solid sorbents can be used as a suitable trap for direct accumulation of organic compounds from aqueous solutions. The trapped analytes can be desorbed by elution with suitably chosen liquid phases. These

The growth and tensile deformation behavior of the silver solid solution phase with zinc

International Nuclear Information System (INIS)

Wu, Jiaqi; Lee, Chin C.

2016-01-01

The growth of homogeneous silver solid solution phase with zinc are conducted at two different compositions. X-ray diffraction (XRD) and Scanning electron microscope/Energy dispersive X-ray spectroscopy (SEM/EDX) are carried out for phase identification and chemical composition verification. The mechanical properties of silver solid solution phase with zinc are evaluated by tensile test. The engineering and true stress vs. strain curves are presented and analyzed, with those of pure silver in comparison. According to the experimental results, silver solid solution phase with zinc at both compositions show tempered yield strength, high tensile strength and large uniform strain compared to those of pure silver. Fractography further confirmed the superior ductility of silver solid solution phase with zinc at both compositions. Our preliminary but encouraging results may pave the way for the silver based alloys to be applied in industries such as electronic packaging and structure engineering.

Three-phase boundary length in solid-oxide fuel cells: A mathematical model

Energy Technology Data Exchange (ETDEWEB)

Janardhanan, Vinod M. [Institutefor Chemical Technology and Polymer Chemistry, University of Karlsruhe (TH), Kaiserstr. 12, D-76128 Karlsruhe (Germany); Heuveline, Vincent; Deutschmann, Olaf [Institute for Applied and Numerical Mathematics, University of Karlsruhe (TH), Kaiserstr. 12, D-76128 Karlsruhe (Germany)

2008-03-15

A mathematical model to calculate the volume specific three-phase boundary length in the porous composite electrodes of solid-oxide fuel cell is presented. The model is exclusively based on geometrical considerations accounting for porosity, particle diameter, particle size distribution, and solids phase distribution. Results are presented for uniform particle size distribution as well as for non-uniform particle size distribution. (author)

Three-phase boundary length in solid-oxide fuel cells: A mathematical model

Science.gov (United States)

Janardhanan, Vinod M.; Heuveline, Vincent; Deutschmann, Olaf

A mathematical model to calculate the volume specific three-phase boundary length in the porous composite electrodes of solid-oxide fuel cell is presented. The model is exclusively based on geometrical considerations accounting for porosity, particle diameter, particle size distribution, and solids phase distribution. Results are presented for uniform particle size distribution as well as for non-uniform particle size distribution.

Solid-Phase Extraction of Sulfur Mustard Metabolites Using an Activated Carbon Fiber Sorbent.

Science.gov (United States)

Lee, Jin Young; Lee, Yong Han

2016-01-01

A novel solid-phase extraction method using activated carbon fiber (ACF) was developed and validated. ACF has a vast network of pores of varying sizes and microporous structures that result in rapid adsorption and selective extraction of sulfur mustard metabolites according to the pH of eluting solvents. ACF could not only selectively extract thiodiglycol and 1-methylsulfinyl-2-[2-(methylthio)-ethylsulfonyl]ethane eluting a 9:1 ratio of dichloromethane to acetone, and 1,1'-sulfonylbis[2-(methylsulfinyl)ethane] and 1,1'-sulfonylbis- [2-S-(N-acetylcysteinyl)ethane] eluting 3% hydrogen chloride in methanol, but could also eliminate most interference without loss of analytes during the loading and washing steps. A sample preparation method has been optimized for the extraction of sulfur mustard metabolites from human urine using an ACF sorbent. The newly developed extraction method was applied to the trace analysis of metabolites of sulfur mustard in human urine matrices in a confidence-building exercise for the analysis of biomedical samples provided by the Organisation for the Prohibition of Chemical Weapons. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A reactor/separator device for use in automated solid phase immunoassay

International Nuclear Information System (INIS)

Farina, P.R.; Ordonez, K.P.; Siewers, I.J.

1979-01-01

A reactor/separator device is described for use in automated solid phase immunoassay, including radioimmunoassays. The device is a column fitted at the bottom portion with a water impermeable disc which can hold, for example, immunoabsorbents, immobilized antisera or ion exchange resins. When the contents of the column supported by the disc are brought into contact with an aqueous phase containing reagents or reactants, a chemical reaction is initiated. After the reaction, centrifugally applied pressure forces the aqueous phase through the filter disc making it water permeable and separating a desired component for subsequent analysis. The reactor/separator device of the present invention permits kinetic solid phase assays (non-equilibrium conditions) to be carried out which would be difficult to perform by other conventional methods. (author)

Prediction of overpotential and effective thickness of Ni/YSZ anode for solid oxide fuel cell by improved species territory adsorption model

Science.gov (United States)

Nagasawa, Tsuyoshi; Hanamura, Katsunori

2017-06-01

The reliability of analytical model for hydrogen oxidation at Ni/YSZ anode in solid oxide fuel cell named as species territory adsorption model has been improved by introducing referenced thermodynamic and kinetic parameters predicted by density function theory calculations. The model can explicitly predict anode overpotential using unknown values of quantities of state for oxygen migration process in YSZ near a triple phase boundary (TPB), frequency factor for hydrogen oxidation, and effective anode thickness. The former two are determined through careful fitting process between the predicted and experimental results of Ni/YSZ cermet and Ni-patterned anodes. This makes it possible to estimate effective anode thickness, which tends to increase with temperature in six kinds of Ni/YSZ anodes in references. In addition, the comparison between the proposed model and a published numerical simulation indicates that the model can predict more precise dependence of anode overpotential on steam partial pressure than that by Butler-Volmer equation with empirical exchange current density. The introduction of present model into numerical simulation instead of Butler-Volmer equation can give more accurate prediction of anode polarization.

Faults of solid-phase welding in titanium joints and their effect on strength

International Nuclear Information System (INIS)

Matyushkin, B.A.; Redchits, V.V.

1982-01-01

A possibility of the usage of thermal arc energy for the determination of the kinetics of solid-phase joint formation of the VT20 titanium alloy is found out experimentally. Positive action of diffusion annealing upon mechanical properties. of solid-phase joints is explained by the defect elimination

Molecular Simulation of Adsorption in Microporous Materials

OpenAIRE

Yiannourakou M.; Ungerer P.; Leblanc B.; Rozanska X.; Saxe P.; Vidal-Gilbert S.; Gouth F.; Montel F.

2013-01-01

The development of industrial software, the decreasing cost of computing time, and the availability of well-tested forcefields make molecular simulation increasingly attractive for chemical engineers. We present here several applications of Monte-Carlo simulation techniques, applied to the adsorption of fluids in microporous solids such as zeolites and model carbons (pores < 2 nm). Adsorption was computed in the Grand Canonical ensemble ...

Method for calculating solid-solid phase transitions at high temperature: An application to N2O

International Nuclear Information System (INIS)

Kuchta, B.; Etters, R.D.

1992-01-01

Two similar techniques for calculating solid-solid phase transitions at high temperatures are developed, where the contribution of the entropy may be a decisive factor. They utilize an artificial reversible path from one phase to another by application of a control parameter. Thermodynamic averages are calculated using constant-volume and constant-pressure Monte Carlo techniques. An application to N 2 O at room temperature shows that the cubic Pa3 to orthorhombic Cmca transition occurs near 4.9-GPa pressure, very close to the value calculated at very low temperatures. These results support experimental evidence that the transition pressure is virtually independent of temperature

The design of a two-phase radiolabelled meal for gastric emptying studies

Energy Technology Data Exchange (ETDEWEB)

Mather, S.J.; Ellison, D.; Nightingale, J.; Kamm, M.; Britton, K.E. (Saint Bartholomew' s Hospital, London (UK) St. Marks Hospital, London (UK))

1991-05-01

A meal intended for use in gastric emptying studies must be highly reproducible, must provide a normal physiological stimulus in terms of bulk, calorie content and composition and must employ stable radiotracers which accurately reflect in their biodistribution, the fate of the two-phases. This is particularly important in a field, such as gastric emptying, where so many variables may influence the results. A conventional pancake and orange juice were chosen as suitable vehicles for the solid and liquid phases. {sup 111}In-labelled resin beads were used as the solid-phase marker and a variety of {sup 99}Tc{sup m}-labelled radiopharmaceuticals including pertechnetate, DTPA and colloid forms were investigated as liquid-phase markers. Prior to administration to patients, the stability of the phases and their interactions in vitro were investigated. The use of {sup 99}Tc{sup m}-DTPA resulted in a loss of {sup 111}In from solid to liquid phase. All non-colloidal markers exhibited a tendency for adsorption onto solid phase. Colloidal markers including rhenium and antimony sulphide colloids showed the truest delineation of the liquid phase. (author).

Comparison of different types of coatings in headspace solid phase micro extraction for the analysis of pesticide residues in vegetables and fruits

International Nuclear Information System (INIS)

Chai, Mee Kin; Tan, Guan Huat

2008-01-01

Despite the continuing development of solid-phase micro extraction (SPME) fiber coatings, their selection presents some difficulties for analytes in choosing the appropriate fiber for a particular application. There are many types of SPME coatings available commercially. The most widely used for determination of pesticide residues in vegetable and fruits are polydimethylsiloxane (PDMS) and polyacrylate (PA). A headspace solid phase micro extraction (HS-SPME) procedure using these two commercialized fibers (PDMS and PA) is presented for the determination of selected groups of organo chlorine and organophosphorus pesticides. The extraction performances of these compounds were compared using these two fibers. The optimal experimental procedures for the adsorption and desorption of pesticides were determined. An explanation for the extraction differences is suggested based on the different thickness, polarity of the polymeric film of fibers and the different extracting matrices. In addition, the higher detector response of the pesticides after addition of aliquots of water and an organic solvent to the vegetable and fruit samples are also discussed. The SPME fibers were reusable until a maximum of 120 extractions. Finally, the optimized procedures were applied successfully for the determination of these compounds in vegetable and fruits samples. Mean recoveries for all pesticides were between 75.0-97 % with RSD below 7 %. (author)

A review of solid-fluid selection options for optical-based measurements in single-phase liquid, two-phase liquid-liquid and multiphase solid-liquid flows

Science.gov (United States)

Wright, Stuart F.; Zadrazil, Ivan; Markides, Christos N.

2017-09-01

Experimental techniques based on optical measurement principles have experienced significant growth in recent decades. They are able to provide detailed information with high-spatiotemporal resolution on important scalar (e.g., temperature, concentration, and phase) and vector (e.g., velocity) fields in single-phase or multiphase flows, as well as interfacial characteristics in the latter, which has been instrumental to step-changes in our fundamental understanding of these flows, and the development and validation of advanced models with ever-improving predictive accuracy and reliability. Relevant techniques rely upon well-established optical methods such as direct photography, laser-induced fluorescence, laser Doppler velocimetry/phase Doppler anemometry, particle image/tracking velocimetry, and variants thereof. The accuracy of the resulting data depends on numerous factors including, importantly, the refractive indices of the solids and liquids used. The best results are obtained when the observational materials have closely matched refractive indices, including test-section walls, liquid phases, and any suspended particles. This paper reviews solid-liquid and solid-liquid-liquid refractive-index-matched systems employed in different fields, e.g., multiphase flows, turbomachinery, bio-fluid flows, with an emphasis on liquid-liquid systems. The refractive indices of various aqueous and organic phases found in the literature span the range 1.330-1.620 and 1.251-1.637, respectively, allowing the identification of appropriate combinations to match selected transparent or translucent plastics/polymers, glasses, or custom materials in single-phase liquid or multiphase liquid-liquid flow systems. In addition, the refractive indices of fluids can be further tuned with the use of additives, which also allows for the matching of important flow similarity parameters such as density and viscosity.

Preparation by low-temperature nonthermal plasma of graphite fiber and its characteristics for solid-phase microextraction

International Nuclear Information System (INIS)

Luo Fan; Wu Zucheng; Tao Ping; Cong Yanqing

2009-01-01

Low-temperature nonthermal plasma has been used to prepare solid-phase microextraction (SPME) fibers with high adsorbability, long-term serviceability, and high reproducibility. Graphite rods serving as fiber precursors were treated by an air plasma discharged at 15.2-15.5 kV for a duration of 8 min. Sampling results revealed that the adsorptive capacity of the homemade fiber was 2.5-34.6 times that of a polyacrylate (PA) fiber for alcohols (methanol, ethanol, isopropyl alcohol, n-butyl alcohol), and about 1.4-1.6 times and 2.5-5.1 times that of an activated carbon fiber (ACF) for alcohols and BTEX (benzene, toluene, ethylbenzene, and xylenes), respectively. It is confirmed from FTIR (Fourier transform infrared spectrophotometer) and SEM (scanning electron microscope) analyses that the improvement in the adsorptive performance attributed to increased surface energy and roughness of the graphite fiber. Using gas chromatography (GC)-flame-ionization detector (FID), the limits of detection (LODs) of the alcohols and BTEX ranged between 0.19 and 3.75 μg L -1 , the linear ranges were between 0.6 and 35619 μg L -1 with good linearity (R 2 = 0.9964-0.9997). It was demonstrated that nonthermal plasma offers a fast and simple method for preparing an efficient graphite SPME fiber, and that SPME using the homemade fiber represents a sensitive and selective extraction method for the analysis of a wide range of organic compounds

Preparation by low-temperature nonthermal plasma of graphite fiber and its characteristics for solid-phase microextraction

Energy Technology Data Exchange (ETDEWEB)

Luo Fan [Department of Environmental Engineering, State Key Laboratory of Clean Energy Utilization, Key Laboratory of Polluted Environment Remediation and Ecological Health, MOE, Zhejiang University, Hangzhou 310027 (China); Wu Zucheng [Department of Environmental Engineering, State Key Laboratory of Clean Energy Utilization, Key Laboratory of Polluted Environment Remediation and Ecological Health, MOE, Zhejiang University, Hangzhou 310027 (China)], E-mail: wuzc@zju.edu.cn; Tao Ping [Institute of Structural Mechanics, China Academy of Engineering Physics, Mianyang 621900 (China); Cong Yanqing [College of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China)

2009-01-05

Low-temperature nonthermal plasma has been used to prepare solid-phase microextraction (SPME) fibers with high adsorbability, long-term serviceability, and high reproducibility. Graphite rods serving as fiber precursors were treated by an air plasma discharged at 15.2-15.5 kV for a duration of 8 min. Sampling results revealed that the adsorptive capacity of the homemade fiber was 2.5-34.6 times that of a polyacrylate (PA) fiber for alcohols (methanol, ethanol, isopropyl alcohol, n-butyl alcohol), and about 1.4-1.6 times and 2.5-5.1 times that of an activated carbon fiber (ACF) for alcohols and BTEX (benzene, toluene, ethylbenzene, and xylenes), respectively. It is confirmed from FTIR (Fourier transform infrared spectrophotometer) and SEM (scanning electron microscope) analyses that the improvement in the adsorptive performance attributed to increased surface energy and roughness of the graphite fiber. Using gas chromatography (GC)-flame-ionization detector (FID), the limits of detection (LODs) of the alcohols and BTEX ranged between 0.19 and 3.75 {mu}g L{sup -1}, the linear ranges were between 0.6 and 35619 {mu}g L{sup -1} with good linearity (R{sup 2} = 0.9964-0.9997). It was demonstrated that nonthermal plasma offers a fast and simple method for preparing an efficient graphite SPME fiber, and that SPME using the homemade fiber represents a sensitive and selective extraction method for the analysis of a wide range of organic compounds.

Preparation by low-temperature nonthermal plasma of graphite fiber and its characteristics for solid-phase microextraction.

Science.gov (United States)

Luo, Fan; Wu, Zucheng; Tao, Ping; Cong, Yanqing

2009-01-05

Low-temperature nonthermal plasma has been used to prepare solid-phase microextraction (SPME) fibers with high adsorbability, long-term serviceability, and high reproducibility. Graphite rods serving as fiber precursors were treated by an air plasma discharged at 15.2-15.5 kV for a duration of 8 min. Sampling results revealed that the adsorptive capacity of the homemade fiber was 2.5-34.6 times that of a polyacrylate (PA) fiber for alcohols (methanol, ethanol, isopropyl alcohol, n-butyl alcohol), and about 1.4-1.6 times and 2.5-5.1 times that of an activated carbon fiber (ACF) for alcohols and BTEX (benzene, toluene, ethylbenzene, and xylenes), respectively. It is confirmed from FTIR (Fourier transform infrared spectrophotometer) and SEM (scanning electron microscope) analyses that the improvement in the adsorptive performance attributed to increased surface energy and roughness of the graphite fiber. Using gas chromatography (GC)-flame-ionization detector (FID), the limits of detection (LODs) of the alcohols and BTEX ranged between 0.19 and 3.75 microg L(-1), the linear ranges were between 0.6 and 35,619 microg L(-1) with good linearity (R(2)=0.9964-0.9997). It was demonstrated that nonthermal plasma offers a fast and simple method for preparing an efficient graphite SPME fiber, and that SPME using the homemade fiber represents a sensitive and selective extraction method for the analysis of a wide range of organic compounds.

Combination of sawdust from teak wood and rice husk activated carbon as adsorbent of Pb(II) ion and its analysis using solid-phase spectrophotometry (sps)

Science.gov (United States)

Saputro, S.; Mahardiani, L.; Wulandari, D. A.

2018-03-01

This research aimed to know the usage of sawdust of teak wood and rice husk waste as Pb (II) ion adsorbents in simulated liquid waste, the combined optimum mass required adsorbent to adsorb Pb(II) ion, the sensitivity of the solid-phase spectrophotometry (sps) method in determining the decrease of Pb (II) metal ion levels in the μg/L level. This research was conducted by experimental method in laboratory. Adsorbents used in this study were charcoal of sawdust sawdust activated using 15% ZnCl2 solution and activated rice husk using 2 N NaOH solution. The adsorption processes of sawdust and rice husk with Pb(II) solution was done by variation of mass combination with a ratio of 1: 0; 0: 1; 1: 1; 1: 2; and 2: 1. Analysis of Pb(II) ion concentration using SPS and characterization of sawdust and rice husk adsorbent ads using FTIR. The results showed that activated charcoal from sawdust of teak wood and rice husks can be used as Pb (II) metal ion adsorbents with adsorption capacity of 0.86 μg/L, charcoal from sawdust of teak wood and rice husk adsorbent with a combination of optimum mass contact of sawdust and rice husk is 2:1 as much as 3 grams can adsorb 42.80 μg/L. Solid-phase spectophotometry is a sensitive method for analysis of concentration decreasing levels of Pb(II) ion, after it was absorbed by sawdust of teak wood and rice husk with high sensitivity and has the limit of detection (LOD) of 0.06 μg/L.

Study of Cr(VI) adsorption onto magnetite nanoparticles using synchrotron-based X-ray absorption spectroscopy

Science.gov (United States)

Chen, Yen-Hua; Liu, Dian-Yu; Lee, Jyh-Fu

2018-04-01

In this study, the efficiency of Cr(VI) adsorption onto nano-magnetite was examined by batch experiments, and the Cr(VI) adsorption mechanism was investigated using synchrotron-based X-ray absorption spectroscopy. Magnetite nanoparticles with a mean diameter of 10 nm were synthesized using an inexpensive and simple co-precipitation method. It shows a saturation magnetization of 54.3 emu/g, which can be recovered with an external magnetic field. The adsorption data fitted the Langmuir adsorption isotherm well, implying a monolayer adsorption behavior of Cr(VI) onto nano-magnetite. X-ray absorption spectroscopy results indicate that the adsorption mechanism involves electron transfer between Fe(II) in nano-magnetite (Fe2+OFe3+ 2O3) and Cr(VI) to transform into Cr(III), which may exist as an Fe(III)-Cr(III) mixed solid phase. Moreover, the Cr(III)/Cr(VI) ratio in the final products can be determined by the characteristic pre-edge peak area of Cr(VI) in the Cr K-edge spectrum. These findings suggest that nano-magnetite is effective for Cr(VI) removal from wastewater because it can transform highly poisonous Cr(VI) species into nontoxic Cr(III) compounds, which are highly insoluble and immobile under environmental conditions.

Phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption infrared spectroscopy.

Science.gov (United States)

Shin, Sunghwan; Kang, Hani; Kim, Jun Soo; Kang, Heon

2014-11-26

We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created by heterogeneous nucleation at the acetone-water interface, with resultant crystal growth, whereas the isotropic crystalline phase in CCl4 is formed by homogeneous crystal growth starting from the bulk region of the acetone sample.

Second Order Kinetic Modeling of Headspace Solid Phase Microextraction of Flavors Released from Selected Food Model Systems

Directory of Open Access Journals (Sweden)

Jiyuan Zhang

2014-09-01

Full Text Available The application of headspace-solid phase microextraction (HS-SPME has been widely used in various fields as a simple and versatile method, yet challenging in quantification. In order to improve the reproducibility in quantification, a mathematical model with its root in psychological modeling and chemical reactor modeling was developed, describing the kinetic behavior of aroma active compounds extracted by SPME from two different food model systems, i.e., a semi-solid food and a liquid food. The model accounted for both adsorption and release of the analytes from SPME fiber, which occurred simultaneously but were counter-directed. The model had four parameters and their estimated values were found to be more reproducible than the direct measurement of the compounds themselves by instrumental analysis. With the relative standard deviations (RSD of each parameter less than 5% and root mean square error (RMSE less than 0.15, the model was proved to be a robust one in estimating the release of a wide range of low molecular weight acetates at three environmental temperatures i.e., 30, 40 and 60 °C. More insights of SPME behavior regarding the small molecule analytes were also obtained through the kinetic parameters and the model itself.

Solid-phase micro-extraction in bioanalysis, exemplified by lidocaine determination

NARCIS (Netherlands)

de Jong, GJ; Koster, EHM

2000-01-01

Solid-phase micro-extraction (SPME) is a never sample preparation technique that can be used for gaseous, liquid or solid samples in conjunction with GC, HPLC or CE (e.g. [1]). The use of SPME for the analysis of drugs in biofluids is also becoming popular (e.g. [2]). The principle is that a fused

Application of mixture experimental design in formulation and characterization of solid self-nanoemulsifying drug delivery systems containing carbamazepine

OpenAIRE

Krstić Marko Z.; Ibrić Svetlana R.

2016-01-01

One of the problems with orally used drugs is their poor solubility, which can be overcame by creating solid self-nanoemulsifying drug delivery systems (SNEDDS). Aim is choosing appropriate SNEDDS using mixture design and adsorption of SNEDDS on a solid carrier to improve the dissolution rate of carbamazepine. Self-emulsifying drug delivery systems (SEDDS) consisting of oil phase (caprilic-capric triglycerides), a surfactant (Polisorbat 80 and Labrasol® (1:...

Development of headspace solid-phase microextraction method for ...

African Journals Online (AJOL)

A headspace solid-phase microextraction (HS-SPME) method was developed as a preliminary investigation using univariate approach for the analysis of 14 multiclass pesticide residues in fruits and vegetable samples. The gas chromatography mass spectrometry parameters (desorption temperature and time, column flow ...

Solid phase separation technique for use in radioimmunoassays

International Nuclear Information System (INIS)

Tu, J.I.

1979-01-01

A radioimmunoassay procedure, and article of manufacture for carrying out that procedure, are disclosed herein. The solid phase separation technique utilized in the radioimmunoassay of this invention utilizes a test tube, the internal surface of which has been coated with two antibody layers

Organically Modified Silica with Pyrazole-3-carbaldehyde as a New Sorbent for Solid-Liquid Extraction of Heavy Metals

Directory of Open Access Journals (Sweden)

Smaail Radi

2013-12-01

Full Text Available A new chelating matrix, SiNP, has been prepared by immobilizing 1.5-dimethyl-1H-pyrazole-3-carbaldehyde on silica gel modified with 3-aminopropyl-trimethoxysilane. This new chelating material was well characterized by elemental analysis, FT-IR spectroscopy, cross polarization magic angle spinning solid state 13C-NMR, nitrogen adsorption-desorption isotherm, BET surface area, BJH pore size, and scanning electron microscopy (SEM. The new product exhibits good chemical and thermal stability as determined by thermogravimetry curves (TGA. The new prepared material was used as an adsorbent for the solid-phase extraction (SPE of Pb(II, Cd(II, Cu(II and Zn(II from aqueous solutions using a batch method, prior to their determination by flame atomic adsorption spectrometry. The adsorption capacity was investigated using kinetics and pH effects. Common coexisting ions did not interfere with separation and determination.

Unconventional phase transitions in a constrained single polymer chain

International Nuclear Information System (INIS)

Klushin, L I; Skvortsov, A M

2011-01-01

Phase transitions were recognized among the most fascinating phenomena in physics. Exactly solved models are especially important in the theory of phase transitions. A number of exactly solved models of phase transitions in a single polymer chain are discussed in this review. These are three models demonstrating the second order phase transitions with some unusual features: two-dimensional model of β-structure formation, the model of coil–globule transition and adsorption of a polymer chain grafted on the solid surface. We also discuss models with first order phase transitions in a single macromolecule which admit not only exact analytical solutions for the partition function with explicit finite-size effects but also the non-equilibrium free energy as a function of the order parameter (Landau function) in closed analytical form. One of them is a model of mechanical desorption of a macromolecule, which demonstrates an unusual first order phase transition with phase coexistence within a single chain. Features of first and second order transitions become mixed here due to phase coexistence which is not accompanied by additional interfacial free energy. Apart from that, there exist several single-chain models belonging to the same class (adsorption of a polymer chain tethered near the solid surface or liquid–liquid interface, and escape transition upon compressing a polymer between small pistons) that represent examples of a highly unconventional first order phase transition with several inter-related unusual features: no simultaneous phase coexistence, and hence no phase boundary, non-concave thermodynamic potential and non-equivalence of conjugate ensembles. An analysis of complex zeros of partition functions upon approaching the thermodynamic limit is presented for models with and without phase coexistence. (topical review)

The study of long-term stability in liquid-solid phases for HLW disposal

International Nuclear Information System (INIS)

Wei, Y.Y.; Tseng, C.L.; Yang, J.Y.; Ke, C.H.; Wang, T.H.; Jan, Y.L.; Lee, C.B.; Lan, P.L.; Hsu, C.N.; Tsai, S.C.; Li, M.H.; Teng, S.P.

2005-01-01

Full text of publication follows: This study is conducted to observe changes in both chemical properties of buffer materials and liquid phases over an experimental period of 2 years. In our experiments, bentonite powder and crushed granite are separately mixed with synthetic groundwater, synthetic seawater and de-ionised water at a fixed liquid-solid ratio of 30. A mixed set with both bentonite and granite together as solid phase is also investigated. During this study, aliquots of the liquid phases are sampled every two months and pH and Eh values are measured immediately. Concentrations of Na, Mg, K, Al, Ca, Ti, Mn, Ba, Fe, Sr, Li and Th are analyzed in the liquid phase directly by ICP-AES. After separation by centrifugation followed by freeze drying and digestion, the solid phases are analyzed as well for elemental composition. Alteration of solid phases during the experimental period is discussed. The preliminary results show that the pH values of the three solutions vary considerably in the individual experimental systems containing bentonite, granite or the mixed system. In general, higher pH values are found in DI-water for all solid phases. Eh values fluctuate a lot in the range 100 to 300 mV in all experiment sets. Different to the experiments with granite for which similar Eh values are found in all solutions, a significantly different Eh-value is found in the experiment with bentonite in DI-water as compared to the other solutions. The results from element analysis indicate that equilibrium is achieved after only two months and element concentrations change only slightly thereafter. We conclude from our experiments that both bentonite and granite keep their characteristics as radionuclide sorbents in the vicinity of a nuclear waste repository. Reaction equilibria appear to be attained rapidly. Because there are just a few alterations in this study, it would be a huge error source in analyzing from the inhomogeneous solid phase such as granite and losses

Studies in Solid Phase Peptide Synthesis: A Personal Perspective

Energy Technology Data Exchange (ETDEWEB)

Mitchell, A R

2007-06-01

By the early 1970s it had became apparent that the solid phase synthesis of ribonuclease A could not be generalized. Consequently, virtually every aspect of solid phase peptide synthesis (SPPS) was reexamined and improved during the decade of the 1970s. The sensitive detection and elimination of possible side reactions (amino acid insertion, N{sup {alpha}}-trifluoroacetylation, N{sup {alpha}{var_epsilon}}-alkylation) was examined. The quantitation of coupling efficiency in SPPS as a function of chain length was studied. A new and improved support for SPPS, the 'PAM-resin', was prepared and evaluated. These and many other studies from the Merrifield laboratory and elsewhere increased the general acceptance of SPPS leading to the 1984 Nobel Prize in Chemistry for Bruce Merrifield.

Resorcinol adsorption from aqueous solution over activated carbon

International Nuclear Information System (INIS)

Blanco, Diego A; Giraldo, Liliana; Moreno, Juan C

2007-01-01

In this paper, the adsorption behavior of Resorcinol a monohydroxylated phenol, poorly acid to 298 K, over activated carbon is analyzed by studying the solution's pH influence and the surface reduction in the adsorption process. To do this, an activated carbon of lignocellulose origin and a reduced activated carbon was used. The interaction solid solution is characterized by the analyses of adsorption in the isotherms to 298 K and pH values of 7. 00, 9.00 and 11.00 for a period of 48 hours. The capacity adsorption of activated carbons increases when the solution's pH decreases and the retained amount increases in the reduced coal to the pH of maximum adsorption.

Solid phase stability of molybdenum under compression: Sound velocity measurements and first-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xiulu [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China); Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, 621010 Mianyang, Sichuan (China); Liu, Zhongli [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China); College of Physics and Electric Information, Luoyang Normal University, 471022 Luoyang, Henan (China); Jin, Ke; Xi, Feng; Yu, Yuying; Tan, Ye; Dai, Chengda; Cai, Lingcang [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China)

2015-02-07

The high-pressure solid phase stability of molybdenum (Mo) has been the center of a long-standing controversy on its high-pressure melting. In this work, experimental and theoretical researches have been conducted to check its solid phase stability under compression. First, we performed sound velocity measurements from 38 to 160 GPa using the two-stage light gas gun and explosive loading in backward- and forward-impact geometries, along with the high-precision velocity interferometry. From the sound velocities, we found no solid-solid phase transition in Mo before shock melting, which does not support the previous solid-solid phase transition conclusion inferred from the sharp drops of the longitudinal sound velocity [Hixson et al., Phys. Rev. Lett. 62, 637 (1989)]. Then, we searched its structures globally using the multi-algorithm collaborative crystal structure prediction technique combined with the density functional theory. By comparing the enthalpies of body centered cubic structure with those of the metastable structures, we found that bcc is the most stable structure in the range of 0–300 GPa. The present theoretical results together with previous ones greatly support our experimental conclusions.

Temperature and compositional dependence of solid-liquid interfacial energy: application of the Cahn-Hilliard theory

International Nuclear Information System (INIS)

Shimizu, I.; Takei, Y.

2005-01-01

A simple thermodynamic method to estimate the solid-liquid interfacial energy (or interfacial tension) is proposed, based on the Cahn-Hilliard theory. In the model, the liquid is treated as a regular solution, and the interfacial layers are assumed to have liquid-like thermodynamic properties. In eutectic systems, interfacial adsorption occurs within a few atomic layers, and interfacial energy monotonously increases with decreasing concentration of the solid species in the liquid phase. If non-ideal atomic interaction is strong and the liquid immiscibility region appears in the phase diagrams (this is the case of monotectic systems), the interfacial thickness drastically increases and the interfacial energy is reduced around the immiscibility gap

Investigation of binary solid phases by calorimetry and kinetic modelling

NARCIS (Netherlands)

Matovic, M.

2007-01-01

The traditional methods for the determination of liquid-solid phase diagrams are based on the assumption that the overall equilibrium is established between the phases. However, the result of the crystallization of a liquid mixture will typically be a non-equilibrium or metastable state of the

Development and Application of Solid Phase Extraction Method for ...

African Journals Online (AJOL)

NICO

for the addition of organic modifier, sample load volume, conditioning solvent, washing solvent and ... Solid phase extraction, polycyclic aromatic hydrocarbons, water samples, ... such as polymeric, activated carbon or silica modified with.

Ion-selective solid-phase electrode sensitive to ammonium ions

International Nuclear Information System (INIS)

Vlasov, Yu.G.; Milonova, M.S.; Antonov, P.P.; Bychkov, E.A.; Ehfa, A.Ya.

1983-01-01

Ammonium phosphomolybdate is investigated for the purpose of using it as membrane material of ammonium-selective solid-phase electrodes. Estimation of proton mobility and ion conductivity of ammonium phosphomolybdate is performed

Rapid Determination of Trace Palladium in Active Pharmaceutical Ingredients by Magnetic Solid-Phase Extraction and Flame Atomic Absorption Spectrometry

Science.gov (United States)

Yin, Q. H.; Zhu, D. M.; Yang, D. Z.; Hu, Q. F.; Yang, Y. L.

2018-01-01

Clutaraldehyde cross-linked magnetic chitosan nanoparticles were synthesized and used as an adsorbent for the dispersive solid-phase extraction of palladium in active pharmaceutical ingredients (APIs) prior to analysis by a flame atomic absorption spectrophotometer. FT-IR, X-ray diffraction, and TEM were used to characterize the adsorbent. Various parameters of experimental performance, such as adsorbent amount, pH, adsorption time, desorption solutions, coexisting ions, and adsorbent reusability, were investigated and optimized. Under the optimized conditions, good linearity was achieved in the 5.0-500 μg/L concentration range, with correlation coefficients of 0.9989. The limit of detection is 2.8 μg/L and the recoveries of spiked samples ranged from 91.7 to 97.6%. It was confirmed that the GMCNs nanocomposite was a promising adsorbing material for extraction and preconcentration of Pd in APIs.

Adsorption of uranyl in SiO2 porous glass

International Nuclear Information System (INIS)

Benedetto, F. E.; Prado, M. O.

2013-01-01

Vitreous SiO 2 porous matrices can be used in many applications involving the uptake of chemical species on its solid surface. In this work, vitreous silica sponges were prepared from a sodium borosilicate glass manufactured in our laboratory. The product obtained was then separated into phases with subsequent leaching of the soluble phase rich in B and Na. The resulting porous matrices have a specific surface of 35 m2/gr. Adsorption of uranyl ions onto the SiO 2 porous surface was studied to evaluate the use of this material as a filter for treatment of uranium containing water. The effects of contact time, adsorbent mass and equilibrium concentration of solution were studied. The porous adsorbent exhibits a pseudo-second-order kinetic behavior. The sponges with adsorbed uranium were thermally sealed as a way of U immobilization. Retention of uranium was confirmed during the matrix sealing by TGA. Uranium concentration before and after adsorption tests were made by means of ICP-OES. For uranium concentration of 800 ppm, 72 hours contact time and pH of 3.5, the amount of uranium adsorbed was 21.06 ± 0.02 mg U per gram of vitreous porous SiO 2 . (author)

Solid phase extraction of uranium(VI) onto benzoylthiourea-anchored activated carbon

Energy Technology Data Exchange (ETDEWEB)

Zhao Yongsheng; Liu Chunxia; Feng Miao; Chen Zhen; Li Shuqiong; Tian Gan; Wang Li; Huang Jingbo [College of Chemistry, Sichuan University, 29 Wangjiang Lu, Chengdu, 610064, Sichuan (China); Li Shoujian, E-mail: sjli000616@scu.edu.cn [College of Chemistry, Sichuan University, 29 Wangjiang Lu, Chengdu, 610064, Sichuan (China)

2010-04-15

A new solid phase extractant selective for uranium(VI) based on benzoylthiourea anchored to activated carbon was developed via hydroxylation, amidation and reaction with benzoyl isothiocyanate in sequence. Fourier transform infrared spectroscopy and total element analysis proved that benzoylthiourea had been successfully grafted to the surface of the activated carbon, with a loading capacity of 1.2 mmol benzoylthiourea per gram of activated carbon. The parameters that affect the uranium(VI) sorption, such as contact time, solution pH, initial uranium(VI) concentration, adsorbent dose and temperature, have been investigated. Results have been analyzed by Langmuir and Freundlich isotherm; the former was more suitable to describe the sorption process. The maximum sorption capacity (82 mg/g) for uranium(VI) was obtained at experimental conditions. The rate constant for the uranium sorption by the as-synthesized extractant was 0.441 min{sup -1} from the first order rate equation. Thermodynamic parameters ({Delta}H{sup 0} = -46.2 kJ/mol; {Delta}S{sup 0} = -98.0 J/mol K; {Delta}G{sup 0} = -17.5 kJ/mol) showed the adsorption of an exothermic process and spontaneous nature, respectively. Additional studies indicated that the benzoylthiourea-anchored activated carbon (BT-AC) selectively sorbed uranyl ions in the presence of competing ions, Na{sup +}, Co{sup 2+}, Sr{sup 2+}, Cs{sup +} and La{sup 3+}.

Adsorption of Pb(II) ions present in aqueous solution on the oxy hydroxides: boehmite (γ-AIOOH), goethite (α-FeOOH) and manganite (γ-MnOOH)

International Nuclear Information System (INIS)

Arreola L, J. E.

2013-01-01

Boehmite, goethite and manganite were synthesized by different methods and characterized using X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric study , N 2 physisorption measurements, scanning electron microscopy (Sem), semiquantitative elemental analysis (EDS), as well as additional studies were determined the surface active sites concentration and zero point of charge. Furthermore, we studied the Pb(II) ion adsorption capacity present in aqueous solution on these synthesized materials by batch-type experiments at room temperature, as a function of contact time between the phases liquid-solid system (adsorption kinetics), initial concentration of the adsorbate (adsorption isotherms), ph and temperature. The adsorption equilibrium time of adsorption processes in these studied systems was found at 60 minutes for boehmite and 30 minutes for goethite and manganite respectively after contacting the solid-liquid phase systems. The adsorption capacity of the lead ions on these adsorbent materials depended of lead concentration, ph and temperature of the systems. Were evaluated lead adsorption capacities in these materials to different contact times using an initial concentration of 20 mg/L of Pb(II) ions at ph = 4, the results of three systems were adjusted to second pseudo kinetic model order. With respect to the study of the adsorbate concentration effect, boehmite-Pb(II) and goethite-Pb(II) systems were adjusted to Langmuir isotherm model which proposes that the adsorption is carried out in a monolayer, moreover manganite-Pb(II) system was adjusted Temp kin isotherm model, which assumes that the adsorption heat of all the molecules in the layer decreases linearly with coverage due to adsorbent-adsorbate interactions and adsorption is characterized by a uniform distribution of the binding energies. Were studied the ph effect of Pb(II) ions solution on the adsorption capacity of such adsorbents, it was found that as the ph increases lead solution

Co-adsorption of surfactants and water at inorganic solid surfaces.

Science.gov (United States)

Cooper, Timothy G; de Leeuw, Nora H

2002-07-21

Computer simulations of the co-adsorption of water and methanoic acid at a range of surface features of calcite and fluorite minerals have shown that the relative adsorption energies for the two minerals are reversed when solvent effects are included in the calculations, a finding which is important in the search for effective surfactant reagents in flotation techniques, which are used extensively in the mining and pharmaceutical industries and in environmental remediation processes.

Immunoglobulin adsorption on modified surfaces

NARCIS (Netherlands)

Bremer, M.G.E.G.

2001-01-01

Preservation of biological functioning of proteins during immobilisation is of special interest in various biomedical and biotechnical applications. In industry physical adsorption of immunoglobulins (IgGs) onto solid surfaces is still the predominant immobilisation procedure because it is

Kinetics of a gas adsorption compressor

Science.gov (United States)

Chan, C. K.; Tward, E.; Elleman, D. D.

1984-01-01

Chan (1981) has suggested that a process based on gas adsorption could be used as a means to drive a Joule-Thomson (J-T) device. The resulting system has several advantages. It is heat powered, it has no sealing, there are no mechanical moving parts, and no active control is required. In the present investigation, a two-phase model is used to analyze the transients of a gas adsorption compressor. The modeling of the adsorption process is based on a consideration of complete thermal and mechanical equilibrium between the gaseous phase and the adsorbed gas phase. The experimental arrangement for two sets of kinetic tests is discussed, and data regarding the experimental results are presented in graphs. For a theoretical study, a two-phase model was developed to predict the transient behavior of the compressor. A computer code was written to solve the governing equations with the aid of a standard forward marching predictor-corrector method.

Liquid-phase extraction coupled with metal-organic frameworks-based dispersive solid phase extraction of herbicides in peanuts.

Science.gov (United States)

Li, Na; Wang, Zhibing; Zhang, Liyuan; Nian, Li; Lei, Lei; Yang, Xiao; Zhang, Hanqi; Yu, Aimin

2014-10-01

Liquid-phase extraction coupled with metal-organic frameworks-based dispersive solid phase extraction was developed and applied to the extraction of pesticides in high fatty matrices. The herbicides were ultrasonically extracted from peanut using ethyl acetate as extraction solvent. The separation of the analytes from a large amount of co-extractive fat was achieved by dispersive solid-phase extraction using MIL-101(Cr) as sorbent. In this step, the analytes were adsorbed on MIL-101(Cr) and the fat remained in bulk. The herbicides were separated and determined by high-performance liquid chromatography. The experimental parameters, including type and volume of extraction solvent, ultrasonication time, volume of hexane and eluting solvent, amount of MIL-101(Cr) and dispersive solid phase extraction time, were optimized. The limits of detection for herbicides range from 0.98 to 1.9 μg/kg. The recoveries of the herbicides are in the range of 89.5-102.7% and relative standard deviations are equal or lower than 7.0%. The proposed method is simple, effective and suitable for treatment of the samples containing high content of fat. Copyright © 2014 Elsevier B.V. All rights reserved.

Facile synthesis of aliphatic isothiocyanates and thioureas on solid phase using peptide coupling reagents

DEFF Research Database (Denmark)

Boas, Ulrik; Andersen, Heidi Gertz; Christensen, Jørn B.

2004-01-01

Peptide coupling reagents can be used as versatile reagents for the formation of aliphatic isothiocyanates and thioureas on solid phase from the corresponding solid-phase anchored aliphatic primary amines. The formation of the thioureas is fast and highly chemoselective, and proceeds via formatio...

Adsorption and desorption dynamics of citric acid anions in soil

KAUST Repository

Oburger, E.

2011-07-26

The functional role of organic acid anions in soil has been intensively investigated, with special focus on (i) microbial respiration and soil carbon dynamics, (ii) nutrient solubilization or (iii) metal detoxification and reduction of plant metal uptake. Little is known about the interaction dynamics of organic acid anions with the soil matrix and the potential impact of adsorption and desorption processes on the functional significance of these effects. The aim of this study was to characterize experimentally the adsorption and desorption dynamics of organic acid anions in five agricultural soils differing in iron and aluminium oxide contents and using citrate as a model carboxylate. Results showed that both adsorption and desorption processes were fast in all soils, reaching a steady state within approximately 1 hour. However, for a given total soil citrate concentration (ct) the steady state was critically dependent on the starting conditions of the experiment, whether most of the citrate was initially present in solution (cl) or held on the solid phase (cs). Specifically, desorption-led processes resulted in significantly smaller steady-state solution concentrations than adsorption-led processes, indicating that hysteresis occurred. As it is not possible to distinguish between different adsorption and desorption pools in soil experimentally, a new dynamic hysteresis model that relies only on measured soil solution concentrations was developed. The model satisfactorily explained experimental data and was able to predict dynamic adsorption and desorption behaviour. To demonstrate its use, we applied the model to two relevant situations involving exudation and microbial degradation. The study highlighted the complex nature of citrate adsorption and desorption dynamics in soil. We conclude that existing models need to incorporate both temporal and hysteresis components to describe realistically the role and fate of organic acids in soil processes. © 2011 The

Adsorption behavior of alpha -cypermethrin on cork and activated carbon.

Science.gov (United States)

Domingues, Valentina F; Priolo, Giuseppe; Alves, Arminda C; Cabral, Miguel F; Delerue-Matos, Cristina

2007-08-01

Studies were undertaken to determine the adsorption behavior of alpha -cypermethrin [R)-alpha -cyano-3-phenoxybenzyl(1S)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate, and (S)-alpha-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] in solutions on granules of cork and activated carbon (GAC). The adsorption studies were carried out using a batch equilibrium technique. A gas chromatograph with an electron capture detector (GC-ECD) was used to analyze alpha -cypermethrin after solid phase extraction with C18 disks. Physical properties including real density, pore volume, surface area and pore diameter of cork were evaluated by mercury porosimetry. Characterization of cork particles showed variations thereby indicating the highly heterogeneous structure of the material. The average surface area of cork particles was lower than that of GAC. Kinetics adsorption studies allowed the determination of the equilibrium time - 24 hours for both cork (1-2 mm and 3-4 mm) and GAC. For the studied alpha -cypermethrin concentration range, GAC revealed to be a better sorbent. However, adsorption parameters for equilibrium concentrations, obtained through the Langmuir and Freundlich models, showed that granulated cork 1-2 mm have the maximum amount of adsorbed alpha-cypermethrin (q(m)) (303 microg/g); followed by GAC (186 microg/g) and cork 3-4 mm (136 microg/g). The standard deviation (SD) values, demonstrate that Freundlich model better describes the alpha -cypermethrin adsorption phenomena on GAC, while alpha -cypermethrin adsorption on cork (1-2 mm and 3-4 mm) is better described by the Langmuir. In view of the adsorption results obtained in this study it appears that granulated cork may be a better and a cheaper alternative to GAC for removing alpha -cypermethrin from water.

Structural and adsorptive properties of activated carbons prepared by carbonization and activation of resins.

Science.gov (United States)

Leboda, R; Skubiszewska-Zieba, J; Tomaszewski, W; Gun'ko, V M

2003-07-15

Four activated carbons (S1-S4) possessing different structural characteristics were prepared by carbonization of commercial resins (used for ion exchange) and subsequent activation. Their textural parameters were determined on the basis of nitrogen adsorption-desorption at 77.4 K, analyzed by applying several local and overall adsorption isotherm equations. The nature of carbon surface functionalities was analyzed by FTIR spectroscopy. The GC and solid-phase extraction (SPE) techniques were applied to study the influence of the texture of carbonaceous materials on their adsorptive properties. The adsorption efficiency of synthesized carbons with respect to alkylhalides used as probe compounds in the GC measurements varied over a range from 28% (C(2)H(3)Cl(3)/S2) to 85% (CHBr(3)/S1) depending on the type of adsorbates and adsorbents. The concentrating efficiency of these carbons in SPE of explosive materials changed over a larger range from 12% (trinitroglycerin/S4) and 13% (trinitrotoluene/S2) up to 100% (octogen/S1). Active carbon prepared using Zerolite 225x8 as a precursor demonstrated better results than other carbons in two types of adsorption with average values of the efficiency of 75.4% for explosives and 60.8% for alkylhalides.

Zirconium determination in rocks by solid-phase spectrophotometry

International Nuclear Information System (INIS)

Brykina, G.D.; Lebedeva, G.G.; Agapova, G.F.; AN SSSR, Moscow

1990-01-01

A method was developed for determination of zirconium in rocks by solid-phase spectrophotometry using AV-17x8-Cl anion exchanger modified with xylenol orange. Relative standard deviation at the level of (2-4.9)x10 -3 % ZrO 2 was about 0.245

Adsorption and diffusion of hydrogen in Zircaloy-4

International Nuclear Information System (INIS)

Torres, E.; Desquines, J.; Baietto, M.C.; Coret, M.; Wehling, F.; Blat-Yrieix, M.; Ambard, A.

2015-01-01

Hydrogen in zirconium alloys is considered in many nuclear safety issues. Below 500 Celsius degrees, rather limited knowledge is available on the combined hydrogen adsorption at the sample surface and diffusion in the metal. A modeling of hydrogen gaseous charging has been established starting with a set of relevant laws and parameters derived from open literature. Simulating the hydrogen charging process requires simultaneous analysis of gaseous surface adsorption, hydrogen solid-solution diffusion and precipitation, when exceeding the material solubility limit. The modeling has been extended to reproduce the solid-gas exchange. Gaseous charging experiments have been performed at 420 C. degrees on Stress Relieved Annealed (SRA) Zircaloy-4 cladding samples to validate the model. The sample hydrogen content has been systematically measured after charging and compared to the calculated value thus providing a validation of the adsorption modeling. Complementary tests have been carried out on Recrystallized Annealed (RXA) Zircaloy-4 rods to characterize the combined diffusion and adsorption process. The hydrogen concentration distribution has been characterized using an inverse technique based on destructive analyses of the samples. This additional set of data was relevant for the validation of the hydrogen combined adsorption/diffusion modeling up to 420 C. degrees. (authors)

Solid Phase Radioimmunoassay for Measuring Serum Prolactin Using Antibody Coupled Magnetizable Particles

International Nuclear Information System (INIS)

El-Bayoumy, A.S.A.

2012-01-01

The objective of the present work was to prepare solid phase radioimmunoassay (RIA) reagents. Development as well as optimization and validation of RIA system using solid phase magnetic particles for the measurement of prolactin (PRL) in human serum are described. The production of polyclonal antibodies was carried out by immunizing three Balb/C mice intraperitoneal through primary injection and two booster doses. Low density magnetizable cellulose iron oxide particles have been used to couple covalently to the IgG fraction of polyclonal anti-prolactin using carbonyl diimidazole activation method and applied as a solid phase separating agent for RIA of serum prolactin. Preparation of 125 I-PRL tracer was prepared using lactoperoxidase method and it was purified by gel filtration using sephadex G-100. The PRL standards were prepared using a highly purified PRL antigen with assay buffer as standard matrix. Optimization and validation of the assay were carried out. The results obtained provide a low cost, simple, sensitive, specific and accurate RIA system of prolactin based on magnetizable solid phase separation. These magnetic particles retain their characteristics during storage for 6 months at 4 degree C. In conclusion, this assay could be used as a useful diagnostic tool for pituitary dysfunction and possible reproductive disability.

The influence of oxygen and hydrogen adsorption on the magneticstructure of the ultrathin iron film on the Ir(001) surface

Czech Academy of Sciences Publication Activity Database

Máca, František; Kudrnovský, Josef; Drchal, Václav; Redinger, J.

2013-01-01

Roč. 88, č. 4 (2013), "045423-1"-"045423-7" ISSN 1098-0121 R&D Projects: GA AV ČR IAA100100912; GA ČR GA202/09/0775 Institutional support: RVO:68378271 Keywords : surface magnetism * magnetic overlayer * gas adsorption * magnetic phase stability * density functional calculation * STM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.664, year: 2013

Solid Phase Characterization Of Heel Samples From Tank 241-C-110

International Nuclear Information System (INIS)

Page, J.S.; Cooke, G.A.; Pestovich, J.A.; Huber, H.J.

2011-01-01

During sluicing operations of tank 241-C-110, a significant amount of solids were unable to be retrieved. These solids (often referred to as the tank 'heel') were sampled in 2010 and chemically and mineralogically analyzed in the 222-S Laboratory. Additionally, dissolution tests were performed to identify the amount of undissolvable material after using multiple water contacts. This report covers the solid phase characterization of six samples from these tests using scanning electron microscopy, polarized light microscopy, and X-ray diffraction. The chemical analyses, particle size distribution analysis, and dissolution test results are reported separately. Two of the samples were from composites created from as-received material - Composite A and Composite B. The main phase in these samples was sodium-fluoride-phosphate hydrate (natrophosphate) - in the X-ray diffraction spectra, this phase was the only phase identifiable. Polarized light microscopy showed the presence of minor amounts of gibbsite and other phases. These phases were identified by scanning electron microscopy - energy dispersive X-ray spectroscopy as sodium aluminosilicates, sodium diuranate, and sodium strontium phosphate hydrate (nastrophite) crystals. The natrophosphate crystals in the scanning electron microscopy analysis showed a variety of erosive and dissolution features from perfectly shaped octahedral to well-rounded appearance. Two samples were from water-washed Composites A and B, with no change in mineralogy compared to the as-received samples. This is not surprising, since the water wash had only a short period of water contact with the material as opposed to the water dissolution tests. The last two samples were residual solids from the water dissolution tests. These tests included multiple additions of water at 15 C and 45 C. The samples were sieved to separate a coarser fraction of > 710 μm and a finer fraction of < 710 μm. These two fractions were analyzed separately. The coarser

A novel polythiophene – ionic liquid modified clay composite solid phase microextraction fiber: Preparation, characterization and application to pesticide analysis

International Nuclear Information System (INIS)

Pelit, Füsun Okçu; Pelit, Levent; Dizdaş, Tuğberk Nail; Aftafa, Can; Ertaş, Hasan; Yalçınkaya, E.E.; Türkmen, Hayati; Ertaş, F.N.

2015-01-01

Highlights: • A novel polythiophene – ionic liquid modified clay surface has been prepared. • Polymerization was performed electrochemically on a stainless steel wire. • This material was used as a SPME fiber in head space mode. • This new SPME fiber was applied for analysis of pesticides in juice samples. • Fiber adsorption properties were improved by modification of ionic liquids. - Abstract: This report comprises the novel usage of polythiophene – ionic liquid modified clay surfaces for solid phase microextraction (SPME) fiber production to improve the analysis of pesticides in fruit juice samples. Montmorillonite (Mmt) clay intercalated with ionic liquids (IL) was co-deposited with polythiophene (PTh) polymer coated electrochemically on an SPME fiber. The surface of the fibers were characterized by using scanning electron microscopy (SEM). Operational parameters effecting the extraction efficiency namely; the sample volume and pH, adsorption temperature and time, desorption temperature and time, stirring rate and salt amount were optimized. In order to reveal the major effects, these eight factors were selected and Plackett–Burman Design was constructed. The significant parameters detected; adsorption and temperature along with the stirring rate, were further investigated by Box–Behnken design. Under optimized conditions, calibration graphs were plotted and detection limits were calculated in the range of 0.002–0.667 ng mL −1 . Relative standard deviations were no higher than 18%. Overall results have indicated that this novel PTh-IL-Mmt SPME surface developed by the aid of electrochemical deposition could offer a selective and sensitive head space analysis for the selected pesticide residues

A novel polythiophene – ionic liquid modified clay composite solid phase microextraction fiber: Preparation, characterization and application to pesticide analysis

Energy Technology Data Exchange (ETDEWEB)

Pelit, Füsun Okçu, E-mail: fusun.okcu@ege.edu.tr; Pelit, Levent; Dizdaş, Tuğberk Nail; Aftafa, Can; Ertaş, Hasan; Yalçınkaya, E.E.; Türkmen, Hayati; Ertaş, F.N.

2015-02-15

Highlights: • A novel polythiophene – ionic liquid modified clay surface has been prepared. • Polymerization was performed electrochemically on a stainless steel wire. • This material was used as a SPME fiber in head space mode. • This new SPME fiber was applied for analysis of pesticides in juice samples. • Fiber adsorption properties were improved by modification of ionic liquids. - Abstract: This report comprises the novel usage of polythiophene – ionic liquid modified clay surfaces for solid phase microextraction (SPME) fiber production to improve the analysis of pesticides in fruit juice samples. Montmorillonite (Mmt) clay intercalated with ionic liquids (IL) was co-deposited with polythiophene (PTh) polymer coated electrochemically on an SPME fiber. The surface of the fibers were characterized by using scanning electron microscopy (SEM). Operational parameters effecting the extraction efficiency namely; the sample volume and pH, adsorption temperature and time, desorption temperature and time, stirring rate and salt amount were optimized. In order to reveal the major effects, these eight factors were selected and Plackett–Burman Design was constructed. The significant parameters detected; adsorption and temperature along with the stirring rate, were further investigated by Box–Behnken design. Under optimized conditions, calibration graphs were plotted and detection limits were calculated in the range of 0.002–0.667 ng mL{sup −1}. Relative standard deviations were no higher than 18%. Overall results have indicated that this novel PTh-IL-Mmt SPME surface developed by the aid of electrochemical deposition could offer a selective and sensitive head space analysis for the selected pesticide residues.

The Effects of Solid Phase Additives on Sintering Properties of Alumina Bioceramic

Institute of Scientific and Technical Information of China (English)

WANG Xin-yu; LI Shi-pu; HE Jian-hua; JIANG Xin; LI Jian-hua

2003-01-01

In order to reduce the sintering temperature and improve the preparing conditions of alumina bioceramics,the Mg-Zr-Y composite solid phase additives were added into high purity Al2O3 micro-powder by chemical coprecipitation method.The powder was shaped under 200MPa cold isostatic pressure,and then the biscuits were sintered at 1600℃ under normal pressure.The sintered alumina materials were tested and the sintering mechanism was discussed.The results show that physical properties of the material were improved comparatively.The Mg-Zr-Y composite solid additives could promote the sintering of alumina bioceramics and the mechanism is solid phase sintering.

Solid-state phase equilibria in the Fe-Pt-Pr ternary system at 1173 K

International Nuclear Information System (INIS)

Ren Jing; Gu Zhengfei; Cheng Gang; Zhou Huaiying

2005-01-01

The solid-state phase equilibria in the Fe-Pt-Pr ternary system at 1173 K (Pr ≤ 70%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. The 1173 K isothermal section consists of 13 single-phase regions, 22 two-phase regions and 10 three-phase regions. At 1173 K, we have observed that the maximum solid solubility of Pt in α-Fe is below 1.5 at.% and the solid solution region of Pt in γ-Fe is from 2 to 35 at.%; the maximum solid solubility of Fe in Pt is 18 at.%. The maximum solubility of Fe in PrPt 5 , PrPt 3 , PrPt 2 , Pr 3 Pt 4 , PrPt, Pr 3 Pt 2 and Pr 7 Pt 3 is below 1 at.%. The maximum solubility of Pr in α-(Fe, Pt), γ-(Fe, Pt), FePt, FePt 3 and (Pt, Fe) (the solid solution of Fe in Pt) is 6, 2, 4, 4.5 and 1.5 at.%, respectively. In this work, it is found that the phase Pr 3 Pt 4 does not exist in the ternary system. The binary compounds Fe 7 Pr and Fe 2 Pr and any new ternary compounds were not observed

Practical solid and liquid phase markers for studying gastric emptying in man

International Nuclear Information System (INIS)

Thomforde, G.M.; Brown, M.L.; Malagelada, J.R.

1985-01-01

This paper presents a method used to evaluate solid and liquid phase markers for radionuclide gastric emptying studies. The authors conducted in vitro and in vivo comparative experiments employing several radiolabeled markers. Among the solid phase markers tested, Tc-99m-sulfur colloid in vivo-labeled liver and I-131-fiber performed optimally. However, Tc-99M sulfur colloid in scrambled egg showed very acceptable performance and it is significantly easier to prepare. Among liquid phase markers, they found In-111-DTPA stabilized with 1% albumin to be a good agent and appropriate for dual isotope emptying studies

Adsorption--from theory to practice.

Science.gov (United States)

Dabrowski, A

2001-10-08

Adsorption at various interfaces has concerned scientists since the beginning of this century. This phenomenon underlies a number of extremely important processes of utilitarian significance. The technological, environmental and biological importance of adsorption can never be in doubt. Its practical applications in industry and environmental protection are of paramount importance. The adsorption of substrates is the first stage in many catalytic processes. The methods for separation of mixtures on a laboratory and on an industrial scale are increasingly based on utilising the change in concentration of components at the interface. Moreover, such vital problems as purification of water, sewages, air and soil are involved here too. On the other hand, many areas in which technological innovation has covered adsorption phenomena have been expanded more through art and craft than through science. A basic understanding of the scientific principles is far behind; in part because the study of interfaces requires extremely careful experimentation if meaningful and reproducible results are to be obtained. In recent years, however, considerable effort has been increasingly directed toward closing the gap between theory and practice. Crucial progress in theoretical description of the adsorption has been achieved, mainly through the development of new theoretical approaches formulated on a molecular level, by means of computer simulation methods and owing to new techniques which examine surface layers or interfacial regions. Moreover, during the last 15 years new classes of solid adsorbents have been developed, such as activated carbon fibres and carbon molecular sieves, fullerenes and heterofullerenes, microporous glasses and nanoporous--both carbonaceous and inorganic--materials. Nanostructured solids are very popular in science and technology and have gained extreme interest due to their sorption, catalytic, magnetic, optical and thermal properties. Although the development

Some properties of solid helium and helium nanoclusters using the effective HFD-like interaction potential: Adsorption and desorption inside carbon nanotube

Science.gov (United States)

Abbaspour, M.; Akbarzadeh, H.; Banihashemi, S. Z.; Sotoudeh, A.

2018-02-01

We have calculated the zero equation of state of solid helium using a two-body Hartree-Fock dispersion (HFD)-like potential from molecular dynamics (MD) simulation. To take many-body forces into account, our simple and accurate empirical expression is used with the HFD-like potential without requiring an expensive three-body calculation. This potential model also includes the quantum effects for helium at low temperatures. The results indicate that our effective HFD-like potential improves the prediction of the classical two-body results to get better agreement with experiment than many other two-body and three-body potentials of helium reported in the literature. We have also simulated the adsorption and desorption processes of the (He)55, (He)147, (He)309, (He)561, and (He)923 icosahedral nanoclusters confined into the different armchair and zigzag CNTs from 0 to 50 K using our effective model. We have observed an interesting phenomenon at 0 K for helium. The nanoclusters adsorb to the inner CNT wall as a melting process. But, the heavier noble gas clusters (such as Ne and Xe) show the different behavior than the He clusters. They form a multilayered solid structure into the CNT at zero temperature and adsorb into the inner wall of the CNT at higher temperatures. Our results for He clusters show that the absolute value of the adsorption energy increases as the size of the nanocluster increases. The desorption process begins at a certain temperature and represents itself by a jump in the configurational energy values. We have also investigated the structural and dynamical properties of the confined helium nanoclusters during the adsorption and desorption processes at different temperatures.

Negative adsorption due to electrostatic exclusion of micelles.

Science.gov (United States)

Somasundaran, P; Ananthapadmanabhan, K P; Deo, Puspendu

2005-10-15

Interactions of surfactants with solid substrates are important in the controlling of processes such as flotation, coating, flocculation and sedimentation. These interactions usually lead to adsorption on solids, but can also result in an exclusion of the reagents with dire consequences. In this work electrostatic exclusion of negatively charged dodecylbenzene sulfonate micelles from quartz/water, Bio-Sil/water and alumina/water interfaces has been investigated as a function of pH and ionic strength. Measurable negative adsorption of these surfactants from similarly charged solid/liquid interface was observed in the micellar region. In the case of porous samples with large surface area, comparison of pore size with the micelle size is necessary to avoid any erroneous conclusions regarding the role of electrostatic exclusion in a given system. A theoretical model for the electrostatic exclusion of micelles is developed and used to calculate the adsorption of negatively charged dodecylbenzene sulfonate on negatively charged quartz (pH 7), silica (Bio-Sil A, pH 3) and alumina (pH 11) in the micellar concentration region. The micellar exclusion values calculated using the model are in excellent agreement with the experimental results.

Solid-phase synthesis of 3-amino-2-pyrazolines

DEFF Research Database (Denmark)

Nielsen, John

1998-01-01

The development of a solid-phase synthesis of 3-amino-2-pyrazolines is described. Conjugate addition of hydrazines to alpha,beta-unsaturated nitriles followed by cyclization yields 3-amino-2-pyrazolines. Acylation or sulfonation of the free amino-group yields a 24 member library of 3-amino-2...

Solid-Phase Extraction Combined with High Performance Liquid ...

African Journals Online (AJOL)

Methods: Solid-phase extraction method was employed for the extraction of the estrogen from milk and high performance liquid chromatography-diode array detector (HPLC-DAD) was used for the determination of estrogen. Results: Optimal chromatographic conditions were achieved on an Eclipse XDB-C18 column at a ...

Arsenic Adsorption Equilibrium Concentration and Adsorption Rate of Activated Carbon Coated with Ferric-Aluminum Hydroxides

Science.gov (United States)

Zhang, M.; Sugita, H.; Oguma, T.; Hara, J.; Takahashi, S.

2015-12-01

In some areas of developing countries, ground or well water contaminated with arsenic has been reluctantly used as drinking water. It is highly desirable that effective and inexpensive arsenic removal agents should be developed and provided to reduce the potential health risk. Previous studies demonstrated that activated carbon coated with ferric-aluminum hydroxides (Fe-Al-C) has high adsorptive potential for removal of arsenic. In this study, a series of experiments using Fe-Al-C were carried to discuss adsorption equilibrium time, adsorption equilibrium concentration and adsorption rate of arsenic for Fe-Al-C. Fe-Al-C used in this study was provided by Astec Co., Ltd. Powder reagent of disodium hydrogen arsenate heptahydrate was dissolved into ion-exchanged water. The solution was then further diluted with ion-exchanged water to be 1 and 10 mg/L as arsenic concentration. The pH of the solution was adjusted to be around 7 by adding HCl and/or NaOH. The solution was used as artificial arsenic contaminated water in two types of experiments (arsenic adsorption equilibrium and arsenic adsorption rate tests). The results of the arsenic equilibrium tests were showed that a time period of about 3 days to reach apparent adsorption equilibrium for arsenic. The apparent adsorption equilibrium concentration and adsorbed amount of arsenic on Fe-Al-C adsorbent could be estimated by application of various adsorption isotherms, but the distribution coefficient of arsenic between solid and liquid varies with experimental conditions such as initial concentration of arsenic and addition concentration of adsorbent. An adsorption rate equation that takes into account the reduction in the number of effective adsorption sites on the adsorbent caused by the arsenic adsorption reaction was derived based on the data obtained from the arsenic adsorption rate tests.

Synthesis of surface Cr (VI)-imprinted magnetic nanoparticles for selective dispersive solid-phase extraction and determination of Cr (VI) in water samples.

Science.gov (United States)

Qi, Xue; Gao, Shuang; Ding, Guosheng; Tang, An-Na

2017-01-01

A facile, rapid and selective magnetic dispersed solid-phase extraction (dSPE) method for the extraction and enrichment of Cr (VI) prior to flame atomic absorption spectrometry (AAS) was introduced. For highly selective and efficient extraction, magnetic Cr (VI)-imprinted nanoparticles (Fe 3 O 4 @ Cr (VI) IIPs) were prepared by hyphenating surface ion-imprinted with sol-gel techniques. In the preparation process, chromate (Cr(VI)) was used as the template ion; vinylimidazole and 3-aminopropyltriethoxysilane were selected as organic functional monomer and co-monomer respectively. Another reagent, methacryloxypropyltrimethoxysilane was adopted as coupling agent to form the stable covalent bonding between organic and inorganic phases. The effects of various parameters on the extraction efficiency, such as pH of sample solution, the amount of adsorbent, extraction time, the type and concentration of eluent were systematically investigated. Furthermore, the thermodynamic and kinetic properties of the adsorption process were studied to explore the internal adsorption mechanism. Under optimized conditions, the preconcentration factor, limit of detection and linear range of the established dSPE-AAS method for Cr (VI) were found to be 98, 0.29μgL -1 and 4-140μgL -1 , respectively. The developed method was also successfully applied to the analysis of Cr (VI) in different water samples with satisfactory results, proving its reliability and feasibility in real sample analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Adsorption of Ammonia on Municipal Solid Waste Incinerator Bottom Ash Under the Landfill Circumstance

Energy Technology Data Exchange (ETDEWEB)

Yao, Jun; Kong, Qingna; Zhu, Huayue; Zhang, Zhen [Taizhou University, Linhai (China); Long, Yuyang; Shen, Dongsheng [Zhejiang Gongshang University, Hangzhou (China)

2015-08-15

The adsorption characteristics of ammonia on MSWI bottom ash were investigated. The effect of the variation of the landfill environmental parameters including pH, anions and organic matter on the adsorption process was discussed. Results showed that the adsorption could be well described by pseudo-second-order kinetics and Langmuir model, with a maximum adsorption capacity of 156.2 mg/g. The optimum adsorption of ammonia was observed when the pH was 6.0. High level of ion and organic matter could restrict the adsorption to a low level. The above results suggested that MSWI bottom ash could affect the migration of ammonia in the landfill, which is related to the variation of the landfill circumstance.

The relative importance of the adsorption and partitioning mechanisms in hydrophilic interaction liquid chromatography.

Science.gov (United States)

Gritti, Fabrice; Höltzel, Alexandra; Tallarek, Ulrich; Guiochon, Georges

2015-01-09

We propose an original model of effective diffusion along packed beds of mesoporous particles for HILIC developed by combining Torquatos model for heterogeneous beds (external eluent+particles), Landauers model for porous particles (solid skeleton+internal eluent), and the time-averaged model for the internal eluent (bulk phase+diffuse water (W) layer+rigid W layer). The new model allows to determine the analyte concentration in rigid and diffuse W layer from the experimentally determined retention factor and intra-particle diffusivity and thus to distinguish the retentive contributions from adsorption and partitioning. We apply the model to investigate the separation of toluene (TO, as a non-retained compound), nortriptyline (NT), cytosine (CYT), and niacin (NA) on an organic ethyl/inorganic silica hybrid adsorbent. Elution conditions are varied through the choice of a third solvent (W, ethanol, tetrahydrofuran (THF), acetonitrile (ACN), or n-hexane) in a mobile phase (MP) of ACN/aqueous acetate buffer (pH 5)/third solvent (90/5/5, v/v/v). Whereas NA and CYT retention factors increase monotonously from W to n-hexane as third solvent, NT retention reaches its maximum with polar aprotic third solvents. The involved equilibrium constants for adsorption and partitioning, however, do not follow the same trends as the overall retention factors. NT retention is dominated by partitioning and NA retention by adsorption, while CYT retention is controlled by adsorption rather than partitioning. Our results reveal that the relative importance of adsorption and partitioning mechanisms depends in a complex way from analyte properties and experimental parameters and cannot be predicted generally. Copyright © 2014 Elsevier B.V. All rights reserved.

Silica Modified with Polyaniline as a Potential Sorbent for Matrix Solid Phase Dispersion (MSPD) and Dispersive Solid Phase Extraction (d-SPE) of Plant Samples

Science.gov (United States)

Sowa, Ireneusz; Wójciak-Kosior, Magdalena; Strzemski, Maciej; Sawicki, Jan; Staniak, Michał; Dresler, Sławomir; Szwerc, Wojciech; Mołdoch, Jarosław; Latalski, Michał

2018-01-01

Polyaniline (PANI) is one of the best known conductive polymers with multiple applications. Recently, it was also used in separation techniques, mostly as a component of composites for solid-phase microextraction (SPME). In the present paper, sorbent obtained by in situ polymerization of aniline directly on silica gel particles (Si-PANI) was used for dispersive solid phase extraction (d-SPE) and matrix solid–phase extraction (MSPD). The efficiency of both techniques was evaluated with the use of high performance liquid chromatography with diode array detection (HPLC-DAD) quantitative analysis. The quality of the sorbent was verified by Raman spectroscopy and microscopy combined with automated procedure using computer image analysis. For extraction experiments, triterpenes were chosen as model compounds. The optimal conditions were as follows: protonated Si-PANI impregnated with water, 160/1 sorbent/analyte ratio, 3 min of extraction time, 4 min of desorption time and methanolic solution of ammonia for elution of analytes. The proposed procedure was successfully used for pretreatment of plant samples. PMID:29565297

Prediction of adsorption from liquid mixtures in microporous media by the potential theory

DEFF Research Database (Denmark)

Monsalvo, Matias Alfonso; Shapiro, Alexander

2007-01-01

Despite its industrial importance, adsorption from the liquid phase has been studied much less extensively than adsorption from the gas phase. In this paper, we study the adsorption of liquid mixtures on the basis of the multicomponent potential theory of adsorption (MPTA). The MPTA is based on t...

Microwave-assisted solid-phase Ugi four-component condensations

DEFF Research Database (Denmark)

Nielsen, John

1999-01-01

An 18-member library was constructed from 2 isocyanides, 3 aldehydes and 3 carboxylic acids via microwave-assisted solid-phase Ugi reactions on TentaGel S RAM. Products of high purity were obtained in moderate to excellent yields after reaction times of 5 minutes or less (irradiation at 60W). (C...

Development of a solid-phase assay for measurement of proteolytic enzyme activity

International Nuclear Information System (INIS)

Varani, J.; Johnson, K.; Kaplan, J.

1980-01-01

A solid-phase, plate assay was developed for the measurement of proteolytic enzyme activity. In this assay procedure, radiolabeled substrates were dried onto the surface of microtiter wells. Following drying, the wells were washed two times with saline to remove the nonadherent substrate. When proteolytic enzymes were added to the wells, protein hydrolysis occurred, releasing radioactivity into the supernatant fluid. The amount of protein hydrolysis that occurred was reflected by the amount of radioactivity in the supernatant fluid. When 125 I-hemoglobin was used as the substrate, it was as susceptible to hydrolysis by trypsin in the solid-phase assay as it was in solution in a standard assay procedure. Protease activity from a variety of sources (including from viable cells as well as from extracellular sources) were also able to hydrolyze the hemoglobin on the plate. 125 I-Labeled serum albumen, fibrinogen, and rat pulmonary basement membrane were also susceptible to hydrolysis by trypsin in the solid phase. When [ 14 C]elastin was dried onto the plate, it behaved in a similar manner to elastin in solution. It was resistant to hydrolysis by nonspecific proteases such as trypsin and chymotrypsin but was highly susceptible to hydrolysis by elastase. The solid-phase plate assay has several features which recommended it for routine use. It is as sensitive as standard tube assays (and much more sensitive than routinely used colormetric assays). It is quick and convenient; there are no precipitation, centrifugation, or filtration steps. In addition, very small volumes of radioactive wastes are generated. Another advantage of the solid-phase plate assay is the resistance of the dried substrates to spontaneous breakdown and to microbial contamination. Finally, this assay is suitable for use with viable cells as well as for extracellular proteases

Innovative separation and preconcentration technique of coagulating homogenous dispersive micro solid phase extraction exploiting graphene oxide nanosheets.

Science.gov (United States)

Ghazaghi, Mehri; Mousavi, Hassan Zavvar; Rashidi, Ali Morad; Shirkhanloo, Hamid; Rahighi, Reza

2016-01-01

A uniquely novel, fast, and facile technique is introduced for the first time in which a scant amount of graphene oxide (GO), without modification, has been utilized in dispersive mode of solid phase extraction (SPE) for an efficient yet simple separation. The proposed method of coagulating homogenous dispersive micro solid phase extraction (CHD-µSPE) is based on coagulation of homogeneous GO solution with the aid of polyetheneimine (PEI). CHD-µSPE use full adsorption capacity of GO because in this method was used GO solution obtained from synthesis process without drying step and stacking nanosheets. In optimized condition, 30 µL GO solution (7 mg mL(-1)), obtained in synthesis process, was injected into 1.5 mL the sample solution followed by immediate injection of 53 µL PEI solution (1 mg mL(-1)). After inserting PEI, GO sheets aggregate and can be readily separated by centrifugation. PEI not only cause aggregation of GO, but also form three-dimensional network of GO with easy handling in following separation steps. Lead, cadmium, and chromium were selected as model analytes and the effecting parameters including the amount of GO, concentration of PEI, sample pH, extraction time, and type of desorption solvent were investigated and optimized. The results indicate that the proposed CHD-µSPE method can be successfully applied GO in dispersive mode of SPE without effecting on good capability adsorption of GO. The novel method was applied in determination of lead, cadmium, and chromium in water, human saliva, and urine samples by electrothermal atomic absorption spectrometry. The detection limits are as low as 0.035, 0.005, and 0.012 µg L(-1) for Pb, Cd, and Cr respectively. The intra-day precisions (RSDs) were lower than 3.8%. CHD-µSPE method showed a good linear ranges of 0.24-15.6, 0.015-0.95 and 0.039-2.33 µg L(-1) for Pb, Cd and Cr respectively. Method performance was investigated by determination of mentioned metal ions in river water, human urine and

CONTINUOUS AND SEMICONTINUOUS REACTION SYSTEMS FOR HIGH-SOLIDS ENZYMATIC HYDROLYSIS OF LIGNOCELLULOSICS

Directory of Open Access Journals (Sweden)

A. González Quiroga

2015-12-01

Full Text Available Abstract An attractive operation strategy for the enzymatic hydrolysis of lignocellulosics results from dividing the process into three stages with complementary goals: continuous enzyme adsorption at low-solids loading (5% w/w with recycling of the liquid phase; continuous liquefaction at high-solids content (up to 20% w/w; and, finally, continuous or semicontinuous hydrolysis with supplementation of fresh enzymes. This paper presents a detailed modeling and simulation framework for the aforementioned operation strategies. The limiting micromixing situations of macrofluid and microfluid are used to predict conversions. The adsorption and liquefaction stages are modeled as a continuous stirred tank and a plug flow reactor, respectively. Two alternatives for the third stage are studied: a train of five cascading stirred tanks and a battery of batch reactors in parallel. Simulation results show that glucose concentrations greater than 100 g L-1 could be reached with both of the alternatives for the third stage.

Investigation into process of solid-phase synthesis of calcium vanadates

International Nuclear Information System (INIS)

Fotiev, A.A.; Krasnenko, T.I.; Slobodin, B.V.

1983-01-01

Processes of solid-phase synthesis of calcium vanadates by Toubandt method, measuring electric conductivity and Ca 45 and V 48 radioactive indicators are investigated. It is shown that reaction diffusion during calcium vanadates production from oxides is ensured by calcium and oxygen ions or calcium ions and electrons through the product layer, as to oxygen - through the gas phase

The mechanism of reequilibration of solids in the presence of a fluid phase

International Nuclear Information System (INIS)

Putnis, Andrew; Putnis, Christine V.

2007-01-01

The preservation of morphology (pseudomorphism) and crystal structure during the transformation of one solid phase to another is regularly used as a criterion for a solid-state mechanism, even when there is a fluid phase present. However, a coupled dissolution-reprecipitation mechanism also preserves the morphology and transfers crystallographic information from parent to product by epitaxial nucleation. The generation of porosity in the product phase is a necessary condition for such a mechanism as it allows fluid to maintain contact with a reaction interface which moves through the parent phase from the original surface. We propose that interface-coupled dissolution-reprecipitation is a general mechanism for reequilibration of solids in the presence of a fluid phase. - Graphical abstract: A single crystal of KBr is transformed to a porous single crystal of KCl by immersion in saturated KCl solution. The image shows partial transformation of a crystal of KBr (core) to KCl (porous, milky rim) by an interface coupled dissolution-reprecipitation mechanism. The external dimensions and crystallographic orientation of the original crystal are preserved, while a reaction interface moves through the crystal

Aqueous Microwave-Assisted Solid-Phase Synthesis Using Boc-Amino Acid Nanoparticles

Directory of Open Access Journals (Sweden)

Yoshinobu Fukumori

2013-07-01

Full Text Available We have previously developed water-based microwave (MW-assisted peptide synthesis using Fmoc-amino acid nanopaticles. It is an organic solvent-free, environmentally friendly method for peptide synthesis. Here we describe water-based MW-assisted solid-phase synthesis using Boc-amino acid nanoparticles. The microwave irradiation allowed rapid solid-phase reaction of nanoparticle reactants on the resin in water. We also demonstrated the syntheses of Leu-enkephalin, Tyr-Gly-Gly-Phe-Leu-OH, and difficult sequence model peptide, Val-Ala-Val-Ala-Gly-OH, using our water-based MW-assisted protocol with Boc-amino acid nanoparticles.

Dynamic and thermodynamic mechanisms of TFA adsorption by particulate matter.

Science.gov (United States)

Guo, Junyu; Zhai, Zihan; Wang, Lei; Wang, Ziyuan; Wu, Jing; Zhang, Boya; Zhang, Jianbo

2017-06-01

Trifluoroacetic acid (TFA) in the atmosphere is produced by degradation of hydrochlorofluorocarbons and hydrofluorocarbons. In recent years, TFA has attracted global attention because of increased environmental concentrations, biological toxicity and accumulation in aqueous environments. This study focused on the mechanisms underlying the adsorption of TFA by particulate matter to identify the appropriate descriptive model for this process and thus improve estimation of TFA adsorption in future environmental monitoring. Onsite gas and particle phase sampling in Beijing, China, and subsequent measurement of TFA concentrations indicated that the TFA concentration in the gas phase (1396 ± 225 pg m -3 ) was much higher than that in the particle phase (62 ± 8 pg m -3 ) and that monthly concentrations varied seasonally with temperature. Based on the field results and analysis, an adsorption experiment of TFA on soot was then conducted at three different temperatures (293, 303, and 313 K) to provide parameters for kinetic and thermodynamic modelling. The proportion of atmospheric TFA concentration in the gas phase increased with temperature, indicating that temperature affected the phase distribution of TFA. The subsequent kinetic and thermodynamic modelling showed that the adsorption of TFA by soot could be described well by the Bangham kinetic model. The adsorption was controlled by diffusion, and the key mechanism was physical adsorption. The adsorption behavior can be well described by the Langmuir isotherm model. The calculated thermodynamic parameters ΔG° (-2.34, -1.25, and -0.15 kJ mol -1  at 293, 303, and 313 K, respectively), ΔH° (-34.34 kJ mol -1 ), and ΔS° (-109.22 J mol -1  K -1 ) for TFA adsorption by soot were negative, indicating that adsorption was a spontaneous, exothermic process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Magnetic micro-solid-phase extraction based on magnetite-MCM-41 with gas chromatography-mass spectrometry for the determination of antidepressant drugs in biological fluids.

Science.gov (United States)

Kamaruzaman, Sazlinda; Sanagi, Mohd Marsin; Yahaya, Noorfatimah; Wan Ibrahim, Wan Aini; Endud, Salasiah; Wan Ibrahim, Wan Nazihah

2017-11-01

A new facile magnetic micro-solid-phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite-MCM-41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 μg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite-MCM-41 at pH 12. The analyte was desorbed using 100 μL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05-500 μg/L (r 2  = 0.996-0.999). Good limits of detection (0.008-0.010 μg/L) were obtained for the analytes with good relative standard deviations of solid-phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Jäntti approach to adsorption with increasing gas pressure

NARCIS (Netherlands)

Poulis, J.A.; Massen, C.H.; Robens, E.

2002-01-01

Jäntti introduced a method of calculating equilibrium adsorption from measurements where the pressure of the gas was varied in a stepwise manner. His aim was to shorten the time necessary for a given measurement. The method was applied to gas/solid systems in which simple adsorption processes

Solid phase radioimmunoassay for HBe Ag and anti-HBe

Energy Technology Data Exchange (ETDEWEB)

Froesner, G G; Deinhardt, F [Muenchen Univ. (Germany, F.R.). Inst. fuer Hygiene und Medizinische Mikrobiologie; Sugg, U [Tuebingen Univ. (Germany, F.R.). Abt. fuer Transfusionswesen mit Blutbank; Haas, H [Staedtische Krankenanstalten Esslingen (Germany, F.R.). Zentrallabor; Overby, R L [Abbott Labs., North Chicago, IL (USA)

1978-04-01

A highly sensitive solid phase radioimmunoassay for the detection of hepatitis Be-antigen (HBeAg) and anti-HBe is described. Iodine-125 labelled anti-HBe is used as a tracer. The assay is about 500 foLd more sensitive than immunodiffusion.

Solid phase extraction-electrospray ionization mass spectrometric method for the determination of palladium

International Nuclear Information System (INIS)

Pranaw Kumar; Telmore, Vijay M.; Jaison, P.G.; Sarkar, Arnab; Alamelu, D.; Aggarwal, S.K.

2015-01-01

Platinum group of element (PGEs) are extensively used as a catalyst and anticancer reagent. Due to the soft nature of PGEs, sulphur based donar ligands are used for the separation of these elements. Studies on the formation of different species are helpful for obtaining the ideas about separation of these elements from the complex matrices. Palladium (Pd) is studied as a representative element which is also formed by nuclear fission of fissile nuclides. In view of the relatively small amount of solvent required for separation, solid phase extraction is preferred over most of the separation methods. Solid phase extraction method using DPX as a stationary phase was previously reported for the separation of Pd in SHLLW using benzoylthiourea as a ligand. However, in case of large volume samples manual extraction by DPX is tedious task. In the present studies, the feasibility of extraction using benzoylthiourea on automated solid phase extraction system was carried out for the extraction of Pd

Phase relations and Gibbs energies of spinel phases and solid solutions in the system Mg-Rh-O

Energy Technology Data Exchange (ETDEWEB)

Jacob, K.T., E-mail: katob@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012 (India); Prusty, Debadutta [Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012 (India); Kale, G.M. [Institute for Materials Research, University of Leeds, Leeds, LS2 9JT (United Kingdom)

2012-02-05

Highlights: Black-Right-Pointing-Pointer Refinement of phase diagram for the system Mg-Rh-O and thermodynamic data for spinel compounds MgRh{sub 2}O{sub 4} and Mg{sub 2}RhO{sub 4} is presented. Black-Right-Pointing-Pointer A solid-state electrochemical cell is used for thermodynamic measurement. Black-Right-Pointing-Pointer An advanced design of the solid-state electrochemical cell incorporating buffer electrodes is deployed to minimize polarization of working electrode. Black-Right-Pointing-Pointer Regular solution model for the spinel solid solution MgRh{sub 2}O{sub 4} - Mg{sub 2}RhO{sub 4} based on ideal mixing of cations on the octahedral site is proposed. Black-Right-Pointing-Pointer Factors responsible for stabilization of tetravalent rhodium in spinel compounds are identified. - Abstract: Pure stoichiometric MgRh{sub 2}O{sub 4} could not be prepared by solid state reaction from an equimolar mixture of MgO and Rh{sub 2}O{sub 3} in air. The spinel phase formed always contained excess of Mg and traces of Rh or Rh{sub 2}O{sub 3}. The spinel phase can be considered as a solid solution of Mg{sub 2}RhO{sub 4} in MgRh{sub 2}O{sub 4}. The compositions of the spinel solid solution in equilibrium with different phases in the ternary system Mg-Rh-O were determined by electron probe microanalysis. The oxygen potential established by the equilibrium between Rh + MgO + Mg{sub 1+x}Rh{sub 2-x}O{sub 4} was measured as a function of temperature using a solid-state cell incorporating yttria-stabilized zirconia as an electrolyte and pure oxygen at 0.1 MPa as the reference electrode. To avoid polarization of the working electrode during the measurements, an improved design of the cell with a buffer electrode was used. The standard Gibbs energies of formation of MgRh{sub 2}O{sub 4} and Mg{sub 2}RhO{sub 4} were deduced from the measured electromotive force (e.m.f.) by invoking a model for the spinel solid solution. The parameters of the model were optimized using the measured

Adsorption of CO2 and H2O on supported amine sorbents

NARCIS (Netherlands)

Veneman, Rens; Zhao, W.; Li, Z.; Cai, N.; Brilman, Derk Willem Frederik

2014-01-01

In this work we have evaluated the H2O and CO2 adsorption characteristics of Lewatit VP OC 1065 in view of the potential application of solid sorbents in post combustion CO2 capture. Here we present single component adsorption isotherms for H2O and CO2 as well as co-adsorption experiments. It was

A Kinetic Model for β-Amyloid Adsorption at the Air/Solution Interface and Its Implication to the β-Amyloid Aggregation Process

Science.gov (United States)

Jiang, Dianlu; Dinh, Kim Lien; Ruthenburg, Travis; Zhang, Yi; Su, Lei; Land, Donald; Zhou, Feimeng

2011-01-01

The kinetics of adsorption at the air/buffer solution interface of amyloid beta peptide, Aβ(1–42), whose bulk concentration (submicromolar) is more than two orders of magnitude lower than that typically used in other in vitro aggregation studies, has been studied using a Langmuir-Blodgett trough. The pressure–time curves exhibit a lag phase, wherein the surface pressure essentially remains at zero, and a rising phase, corresponding to the Aβ adsorption at the interface. The duration of the lag phase was found to be highly dependent on both the Aβ bulk concentration and the solution temperature. A large activation energy (62.2 ± 4.1 KJ/mol) was determined and the apparent adsorption rate constant was found to be linearly dependent on the Aβ bulk concentration. Attenuated total reflection-IR spectra of the adsorbed Aβ transferred to a solid substrate and circular dichroism measurements of Aβ in the solution layer near the interface reveal that the natively unstructured Aβ in the bulk undergo a conformation change (folding) to mainly the α-helical structure. The results suggest that, prior to the adsorption step, an equilibrium between Aβ conformations is established within the subsurface. The kinetic equation derived from this model confirms that the overall Aβ adsorption is kinetically controlled and the apparent rate constant is proportional to the Aβ bulk concentration. This model also indicates that interfaces such as cell membranes and lipid bilayers may facilitate Aβ aggregation/fibrillation by providing a thin hydrophobic layer adjacent to the interface for the initial Aβ conformation change (misfolding) and accumulation. Such a preconcentration effect offers a plausible explanation of the fact that Aβ fibrillation occurs in vivo at nanomolar concentrations. Another important biological implication from our work is that Aβ misfolding may occur before its adsorption onto a cell membrane. This general kinetic model should also find

A kinetic model for beta-amyloid adsorption at the air/solution interface and its implication to the beta-amyloid aggregation process.

Science.gov (United States)

Jiang, Dianlu; Dinh, Kim Lien; Ruthenburg, Travis C; Zhang, Yi; Su, Lei; Land, Donald P; Zhou, Feimeng

2009-03-12

At the air/buffer solution interface the kinetics of adsorption of amyloid beta peptide, Abeta(1-42), whose bulk concentration (submicromolar) is more than 2 orders of magnitude lower than that typically used in other in vitro aggregation studies, has been studied using a Langmuir-Blodgett trough. The pressure-time curves exhibit a lag phase, wherein the surface pressure essentially remains at zero, and a rising phase, corresponding to the Abeta adsorption at the interface. The duration of the lag phase was found to be highly dependent on both the Abeta bulk concentration and the solution temperature. A large activation energy (62.2 +/- 4.1 KJ/mol) was determined and the apparent adsorption rate constant was found to be linearly dependent on the Abeta bulk concentration. Attenuated total reflection-IR spectra of the adsorbed Abeta transferred to a solid substrate and circular dichroism measurements of Abeta in the solution layer near the interface reveal that the natively unstructured Abeta in the bulk undergo a conformation change (folding) to mainly the alpha-helical structure. The results suggest that, prior to the adsorption step, an equilibrium between Abeta conformations is established within the subsurface. The kinetic equation derived from this model confirms that the overall Abeta adsorption is kinetically controlled and the apparent rate constant is proportional to the Abeta bulk concentration. This model also indicates that interfaces such as cell membranes and lipid bilayers may facilitate Abeta aggregation/ fibrillation by providing a thin hydrophobic layer adjacent to the interface for the initial A/beta conformation change (misfolding) and accumulation. Such a preconcentration effect offers a plausible explanation of the fact that Abeta fibrillation occurs in vivo at nanomolar concentrations. Another important biological implication from our work is that Abeta misfolding may occur before its adsorption onto a cell membrane. This general kinetic model

Solid-solid phase transformation via internal stress-induced virtual melting, significantly below the melting temperature. Application to HMX energetic crystal.

Science.gov (United States)

Levitas, Valery I; Henson, Bryan F; Smilowitz, Laura B; Asay, Blaine W

2006-05-25

We theoretically predict a new phenomenon, namely, that a solid-solid phase transformation (PT) with a large transformation strain can occur via internal stress-induced virtual melting along the interface at temperatures significantly (more than 100 K) below the melting temperature. We show that the energy of elastic stresses, induced by transformation strain, increases the driving force for melting and reduces the melting temperature. Immediately after melting, stresses relax and the unstable melt solidifies. Fast solidification in a thin layer leads to nanoscale cracking which does not affect the thermodynamics or kinetics of the solid-solid transformation. Thus, virtual melting represents a new mechanism of solid-solid PT, stress relaxation, and loss of coherence at a moving solid-solid interface. It also removes the athermal interface friction and deletes the thermomechanical memory of preceding cycles of the direct-reverse transformation. It is also found that nonhydrostatic compressive internal stresses promote melting in contrast to hydrostatic pressure. Sixteen theoretical predictions are in qualitative and quantitative agreement with experiments conducted on the PTs in the energetic crystal HMX. In particular, (a) the energy of internal stresses is sufficient to reduce the melting temperature from 551 to 430 K for the delta phase during the beta --> delta PT and from 520 to 400 K for the beta phase during the delta --> beta PT; (b) predicted activation energies for direct and reverse PTs coincide with corresponding melting energies of the beta and delta phases and with the experimental values; (c) the temperature dependence of the rate constant is determined by the heat of fusion, for both direct and reverse PTs; results b and c are obtained both for overall kinetics and for interface propagation; (d) considerable nanocracking, homogeneously distributed in the transformed material, accompanies the PT, as predicted by theory; (e) the nanocracking does not

Ni(II) ion-imprinted solid-phase extraction and preconcentration in aqueous solutions by packed-bed columns

International Nuclear Information System (INIS)

Ersoez, Arzu; Say, Ridvan; Denizli, Adil

2004-01-01

Solid-phase extraction (SPE) columns packed with materials based on molecularly imprinted polymers (MIPs) were used to develop selective separation and preconcentration for Ni(II) ion from aqueous solutions. SPE is more rapid, simple and economical method than the traditional liquid-liquid extraction. MIPs were used as column sorbent to increase the grade of selectivity in SPE columns. In this study, we have developed a polymer obtained by imprinting with Ni(II) ion as a ion-imprinted SPE sorbent. For this purpose, NI(II)-methacryloylhistidinedihydrate (MAH/Ni(II)) complex monomer was synthesized and polymerized with cross-linking ethyleneglycoldimethacrylate to obtain [poly(EGDMA-MAH/Ni(II))]. Then, Ni(II) ions were removed from the polymer getting Ni(II) ion-imprinted sorbent. The MIP-SPE preconcentration procedure showed a linear calibration curve within concentration range from 0.3 to 25 ng/ml and the detection limit was 0.3 ng/ml (3 s) for flame atomic absorption spectrometry (FAAS). Ni(II) ion-imprinted microbeads can be used several times without considerable loss of adsorption capacity. When the adsorption capacity of nickel imprinted microbeads were compared with non-imprinted microbeads, nickel imprinted microbeads have higher adsorption capacity. The K d (distribution coefficient) values for the Ni(II)-imprinted microbeads show increase in K d for Ni(II) with respect to both K d values of Zn(II), Cu(II) and Co(II) ions and non-imprinted polymer. During that time K d decreases for Zn(II), Cu(II) and Co(II) ions and the k' (relative selectivity coefficient) values which are greater than 1 for imprinted microbeads of Ni(II)/Cu(II), Ni(II)/Zn(II) and Ni(II)/Co(II) are 57.3, 53.9, and 17.3, respectively. Determination of Ni(II) ion in sea water showed that the interfering matrix had been almost removed during preconcentration. The column was good enough for Ni determination in matrixes containing similar ionic radii ions such as Cu(II), Zn(II) and Co(II)

Precipitation of Nd-Ca carbonate solid solution at 25 degrees C

International Nuclear Information System (INIS)

Carroll, S.A.

1993-01-01

The formation of a Nd-Ca carbonate solid solution was studied by monitoring the reactions of calcite with aqueous Nd, orthorhombic NdOHCO 3 (s) with aqueous Ca, and calcite with hexagonal Nd-carbonate solid phase as a function of time at 25 degrees C and controlled pCO 2 (g). All experiments reached steady state after 200 h of reaction. The dominant mechanism controlling the formation of the solid solution was precipitation of a Nd-Ca carbonate phase from the bulk solution as individual crystals or at the orthorhombic NdOHCO 3 (s)-solution interface. The lack of Nd adsorption or solid solution at the calcite-solution interface suggests that the solid solution was orthorhombic and may be modeled as a mixture of orthorhombic NdOHCO 3 (s) and aragonite. Orthorhombic NdOHCO 3 (s) was determined to be the stable Nd-carbonate phase in the Nd-CO 2 -H 2 O system at pCO 2 (g) 0.1 atmospheres at 25 degrees C. The equilibrium constant corrected to zero ionic strength for orthorhombic NdOHCO 3 (s) solubility is 10 10.41(±0.29) for the following: NdOHCO 3 (s) + 3H + = Nd 3+ + CO 2 (g) + H 2 O. Results are discussed in relation to radioactive waste disposal by burial, and specifically in relation to americium chemistry

The relationship between vacuum and atomic collisions in solids

International Nuclear Information System (INIS)

Carter, G.; Armour, D.G.

1980-01-01

Atomic collision events in solids are frequently stimulated by external irradiation with energetic heavy ions. This requires production, acceleration and manipulation of ion beams in vacuum system with ensuing problems arising in perturbations to ion beam quality from gas phase collisions. In addition the dynamic interaction between the gas phase and any surfaces at which atomic collisions are under investigation can lead to perturbation to the collision events by adsorbed contaminant. This review discusses both gas phase requirements for ion accelerators to minimize deleterious effects and outlines some of the processes which occur in atomic collisions due to the presence of adsorbed impurities. Finally it is shown how certain atomic collision processes involving elastic scattering may be employed to investigate surface adsorption and related effects. (author)

Solid-phase oligosaccharide and glycopeptide synthesis using glycosynthases

DEFF Research Database (Denmark)

Tolborg, Jakob Fjord; Petersen, Lars; Jensen, Knud Jørgen

2002-01-01

and the prospect of automatability. Here, we report the first application of glycosynthases to solid-phase oligosaccharide synthesis by use of the 51 kDa serine and glycine mutants of Agrobacterium sp. beta-glucosidase, Abg E358S and E358G. Acceptors were linked to PEGA resin through a backbone amide linker (BAL...

Transport of Carbonate Ions by Novel Cellulose Fiber Supported Solid Membrane

Directory of Open Access Journals (Sweden)

A. G. Gaikwad

2012-06-01

Full Text Available Transport of carbonate ions was explored through fiber supported solid membrane. A novel fiber supported solid membrane was prepared by chemical modification of cellulose fiber with citric acid, 2′2-bipyridine and magnesium carbonate. The factors affecting the permeability of carbonate ions such as immobilization of citric acid-magnesium metal ion -2′2-bipyridine complex (0 to 2.5 mmol/g range over cellulose fiber, carbon-ate ion concentration in source phase and NaOH concentration in receiving phase were investigated. Ki-netic of carbonate, sulfate, and nitrate ions was investigated through fiber supported solid membrane. Transport of carbonate ions with/without bubbling of CO2 (0 to 10 ml/min in source phase was explored from source to receiving phase. The novel idea is to explore the adsorptive transport of CO2 from source to receiving phase through cellulose fiber containing magnesium metal ion organic framework. Copyright © 2012 BCREC UNDIP. All rights reserved.Received: 25th November 2011; Revised: 17th December 2011; Accepted: 19th December 2011[How to Cite: A.G. Gaikwad. (2012. Transport of Carbonate Ions by Novel Cellulose Fiber Supported Solid Membrane. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 49– 57.  doi:10.9767/bcrec.7.1.1225.49-57][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1225.49-57 ] | View in 

Solid-Phase Synthesis of Smac Peptidomimetics Incorporating Triazoloprolines and Biarylalanines

DEFF Research Database (Denmark)

Le Quement, Sebastian T.; Ishoey, Mette; Petersen, Mette T.

2011-01-01

by deactivating proteolytic caspases. The Smac protein has an antagonistic effect on IAPs, thus providing structural clues for the synthesis of new pro-apoptotic compounds. Herein, we report a solid-phase approach for the synthesis of Smac-derived tetrapeptide libraries. On the basis of a common (N......-Me)AVPF sequence, peptides incorporating triazoloprolines and biarylalanines were synthesized by means of Cu(I)-catalyzed azide–alkyne cycloaddition and Pd-catalyzed Suzuki cross-coupling reactions. Solid-phase procedures were optimized to high efficiency, thus accessing all products in excellent crude purities...... and yields (both typically above 90%). The peptides were subjected to biological evaluation in a live/dead cellular assay which revealed that structural decorations on the AVPF sequence indeed are highly important for cytotoxicity toward HeLa cells....

Determination of clenbuterol in bovine liver by combining matrix solid phase dispersion and molecularly imprinted solid phase extraction followed by liquid chromatography/electrospray ion trap multiple stage mass spectrometry

NARCIS (Netherlands)

Crescenzi, C; Bayoudh, S; Cormack, P.A G; Klein, T; Ensing, K

2001-01-01

Matrix solid-phase dispersion(MSPD) is a new sample pretreatment for solid samples. This technique greatly simplifies sample pretreatment but, nonetheless, the extracts often still require an extra cleanup step that is both laborious and time-consuming. The potential;of combining MSPD with

A Variational Model for Two-Phase Immiscible Electroosmotic Flow at Solid Surfaces

KAUST Repository

Shao, Sihong

2012-01-01

We develop a continuum hydrodynamic model for two-phase immiscible flows that involve electroosmotic effect in an electrolyte and moving contact line at solid surfaces. The model is derived through a variational approach based on the Onsager principle of minimum energy dissipation. This approach was first presented in the derivation of a continuum hydrodynamic model for moving contact line in neutral two-phase immiscible flows (Qian, Wang, and Sheng, J. Fluid Mech. 564, 333-360 (2006)). Physically, the electroosmotic effect can be formulated by the Onsager principle as well in the linear response regime. Therefore, the same variational approach is applied here to the derivation of the continuum hydrodynamic model for charged two-phase immiscible flows where one fluid component is an electrolyte exhibiting electroosmotic effect on a charged surface. A phase field is employed to model the diffuse interface between two immiscible fluid components, one being the electrolyte and the other a nonconductive fluid, both allowed to slip at solid surfaces. Our model consists of the incompressible Navier-Stokes equation for momentum transport, the Nernst-Planck equation for ion transport, the Cahn-Hilliard phase-field equation for interface motion, and the Poisson equation for electric potential, along with all the necessary boundary conditions. In particular, all the dynamic boundary conditions at solid surfaces, including the generalized Navier boundary condition for slip, are derived together with the equations of motion in the bulk region. Numerical examples in two-dimensional space, which involve overlapped electric double layer fields, have been presented to demonstrate the validity and applicability of the model, and a few salient features of the two-phase immiscible electroosmotic flows at solid surface. The wall slip in the vicinity of moving contact line and the Smoluchowski slip in the electric double layer are both investigated. © 2012 Global-Science Press.

Adsorption and separation of propane and propylene by porous hexacyanometallates

International Nuclear Information System (INIS)

Autie-Castro, G.; Autie, M.; Reguera, E.; Moreno-Tost, R.; Rodriguez-Castellon, E.; Jimenez-Lopez, A.; Santamaria-Gonzalez, J.

2011-01-01

The separation capability for mixtures of propane and propylene by porous frameworks representatives of transition metal hexacyanometallates was studied from adsorption data under equilibrium conditions at 273.15 K and from inverse gas chromatography profiles at different column temperatures. Samples of two porous solids were considered; Cd 3 [Co(CN) 6 ] 2 , which is representative of Prussian blue analogues (cubic structure) with a porous framework related to vacancies for building block, and Zn 3 [Co(CN) 6 ] 2 (rhombohedral phase) where the porous framework results from the tetrahedral coordination for the Zn atoms. The two materials were found to be able for the mixtures separation, with the highest separation ability for the rhombohedral phase under equilibrium conditions but, in dynamic conditions the cubic one shown a better separation, which was ascribed to a kinetic contribution related to a smaller windows size.

Vortex-Assisted Dispersive Micro-Solid Phase Extraction Using CTAB-Modified Zeolite NaY Sorbent Coupled with HPLC for the Determination of Carbamate Insecticides.

Science.gov (United States)

Salisaeng, Pawina; Arnnok, Prapha; Patdhanagul, Nopbhasinthu; Burakham, Rodjana

2016-03-16

A vortex-assisted dispersive micro-solid phase extraction (VA-D-μ-SPE) based on cetyltrimethylammonium bromide (CTAB)-modified zeolite NaY was developed for preconcentration of carbamate pesticides in fruits, vegetables, and natural surface water prior to analysis by high performance liquid chromatography with photodiode array detection. The small amounts of solid sorbent were dispersed in a sample solution, and extraction occurred by adsorption in a short time, which was accelerated by vortex agitation. Finally, the sorbents were filtered from the solution, and the analytes were subsequently desorbed using an appropriate solvent. Parameters affecting the VA-D-μ-SPE performance including sorbent amount, sample volume, desorption solvent ,and vortex time were optimized. Under the optimum condition, linear dynamic ranges were achieved between 0.004-24.000 mg kg(-1) (R(2) > 0.9946). The limits of detection (LODs) ranged from 0.004-4.000 mg kg(-1). The applicability of the developed procedure was successfully evaluated by the determination of the carbamate residues in fruits (dragon fruit, rambutan, and watermelon), vegetables (cabbage, cauliflower, and cucumber), and natural surface water.

Finite element modeling for integrated solid-solid PCM-building material with varying phase change temperatures

Energy Technology Data Exchange (ETDEWEB)

Zhang, D.; Fung, A.S.; Siddiqui, O. [Ryerson Polytechnic Univ., Toronto, ON (Canada). Dept. of Mechanical and Industrial Engineering

2008-08-15

Solid-solid phase change materials (SSPCMs) are used to enhance thermal storage performance and reduce indoor temperature fluctuations in buildings. In this study, a finite element model (FEM) was used to investigate the thermal properties of different types of SSPCMs. An effective heat capacity method was used to develop the model. An integrated PCM-building material was analyzed in relation to temperature and heat flux profiles. Governing equations for the heat transfer process were composed of Navier-Stokes momentum equations; a mass conservation equation; and an energy conservation equation. Effective heat capacity was described as a linear function of the latent heat of fusion on both the heating and cooling processes. Data from the simulation were then compared with an experiment suing drywall, concrete and gypcrete samples. Heat flux across the surfaces and temperatures on the surfaces of the materials were measured. Data were used to validate the finite element model (FEM). Results of the study suggested that heat flux profiles are an effective means of understanding phase change processes. It was concluded that PCMs with lower phase change temperatures lengthened energy releases and improved thermal comfort in the building. 12 refs., 2 tabs., 14 figs.

Paper-based solid-phase nucleic acid hybridization assay using immobilized quantum dots as donors in fluorescence resonance energy transfer.

Science.gov (United States)

Noor, M Omair; Shahmuradyan, Anna; Krull, Ulrich J

2013-02-05

A paper-based solid-phase assay is presented for transduction of nucleic acid hybridization using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) were FRET-paired with Cy3 acceptor. Hybridization of Cy3-labeled oligonucleotide targets provided the proximity required for FRET-sensitized emission from Cy3, which served as an analytical signal. The assay exhibited rapid transduction of nucleic acid hybridization within minutes. Without any amplification steps, the limit of detection of the assay was found to be 300 fmol with the upper limit of the dynamic range at 5 pmol. The implementation of glutathione-coated QDs for the development of nucleic acid hybridization assay integrated on a paper-based platform exhibited excellent resistance to nonspecific adsorption of oligonucleotides and showed no reduction in the performance of the assay in the presence of large quantities of noncomplementary DNA. The selectivity of nucleic acid hybridization was demonstrated by single-nucleotide polymorphism (SNP) detection at a contrast ratio of 19 to 1. The reuse of paper over multiple cycles of hybridization and dehybridization was possible, with less than 20% reduction in the performance of the assay in five cycles. This work provides an important framework for the development of paper-based solid-phase QD-FRET nucleic acid hybridization assays that make use of a ratiometric approach for detection and analysis.

Yield-determining factors in high-solids enzymatic hydrolysis of lignocellulose

Directory of Open Access Journals (Sweden)

Felby Claus

2009-06-01

Full Text Available Abstract Background Working at high solids (substrate concentrations is advantageous in enzymatic conversion of lignocellulosic biomass as it increases product concentrations and plant productivity while lowering energy and water input. However, for a number of lignocellulosic substrates it has been shown that at increasing substrate concentration, the corresponding yield decreases in a fashion which can not be explained by current models and knowledge of enzyme-substrate interactions. This decrease in yield is undesirable as it offsets the advantages of working at high solids levels. The cause of the 'solids effect' has so far remained unknown. Results The decreasing conversion at increasing solids concentrations was found to be a generic or intrinsic effect, describing a linear correlation from 5 to 30% initial total solids content (w/w. Insufficient mixing has previously been shown not to be involved in the effect. Hydrolysis experiments with filter paper showed that neither lignin content nor hemicellulose-derived inhibitors appear to be responsible for the decrease in yields. Product inhibition by glucose and in particular cellobiose (and ethanol in simultaneous saccharification and fermentation at the increased concentrations at high solids loading plays a role but could not completely account for the decreasing conversion. Adsorption of cellulases was found to decrease at increasing solids concentrations. There was a strong correlation between the decreasing adsorption and conversion, indicating that the inhibition of cellulase adsorption to cellulose is causing the decrease in yield. Conclusion Inhibition of enzyme adsorption by hydrolysis products appear to be the main cause of the decreasing yields at increasing substrate concentrations in the enzymatic decomposition of cellulosic biomass. In order to facilitate high conversions at high solids concentrations, understanding of the mechanisms involved in high-solids product inhibition

Operando Solid-State NMR Observation of Solvent-Mediated Adsorption-Reaction of Carbohydrates in Zeolites

Energy Technology Data Exchange (ETDEWEB)

Qi, Long; Alamillo, Ricardo; Elliott, William A.; Andersen, Amity; Hoyt, David W.; Walter, Eric D.; Han, Kee Sung; Washton, Nancy M.; Rioux, Robert M.; Dumesic, James A.; Scott, Susannah L.

2017-04-18

Liquid-phase processing of molecules using heterogeneous catalysts – an important strategy for obtaining renewable chemicals sustainably from biomass – involves reactions that occur at solid-liquid interfaces. In glucose isomerization catalyzed by basic faujasite zeolites, the catalytic activity depends strongly on the solvent composition: initially, it declines precipitously when water is mixed with a small amount of the organic co-solvent γ-valerolactone (GVL), then recovers as the GVL content increases. Using solid-state 13C NMR spectroscopy, we observed glucose isomers located inside the zeolite pores directly, and followed their transformations into fructose and mannose in real time. At low GVL concentrations, glucose is depleted in the zeolite pores relative to the liquid phase, while higher GVL concentrations in solution drive glucose inside the pores, resulting in up to a 32 enhancement in the local glucose concentration. Although their populations exchange rapidly, molecules present at the reactive interface experience a significantly different environment from the bulk solution.

New Solid Phases for Estimation of Hormones by Radioimmunoassay Technique

International Nuclear Information System (INIS)

Sheha, R.R.; Ayoub, H.S.M.; Shafik, M.

2013-01-01

The efforts in this study were initiated to develop and validate new solid phases for estimation of hormones by radioimmunoassay (RIA). The study argued the successful application of different hydroxy apatites (HAP) as new solid phases for estimation of Alpha fetoprotein (AFP), Thyroid Stimulating hormone (TSH) and Luteinizing hormone (LH) in human serum. Hydroxy apatites have different alkali earth elements were successfully prepared by a well-controlled co-precipitation method with stoichiometric ratio value 1.67. The synthesized barium and calcium hydroxy apatites were characterized using XRD and Ftir and data clarified the preparation of pure structures of both BaHAP and CaHAP with no evidence on presence of other additional phases. The prepared solid phases were applied in various radioimmunoassay systems for separation of bound and free antigens of AFP, TSH and LH hormones. The preparation of radiolabeled tracer for these antigens was carried out using chloramine-T as oxidizing agent. The influence of different parameters on the activation and coupling of the used apatite particles with the polyclonal antibodies was systematically investigated and the optimum conditions were determined. The assay was reproducible, specific and sensitive enough for regular estimation of the studied hormones. The intra-and inter-assay variation were satisfactory and also the recovery and dilution tests indicated an accurate calibration. The reliability of these apatite particles had been validated by comparing the results that obtained by using commercial kits. The results finally authenticates that hydroxyapatite particles would have a great potential to address the emerging challenge of accurate quantitation in laboratory medical application

A solid-phase-radioimmunoassay for total serum thyroxine

International Nuclear Information System (INIS)

Moedder, G.; Sokolowski, G.

1978-01-01

A new solid phase radioimmunoassay for total serum thyroxine was evaluated over a longer time under clinical routine conditions and compared with an established test system. The results show up that the T 4 values are precise, reliable and reproducible, the is incomplicate to handle and well suitable for semiautomatic pipetting systems. (orig.) 891 MG [de

Melting along the Hugoniot and solid phase transition for Sn via sound velocity measurements

Science.gov (United States)

Song, Ping; Cai, Ling-cang; Tao, Tian-jiong; Yuan, Shuai; Chen, Hong; Huang, Jin; Zhao, Xin-wen; Wang, Xue-jun

2016-11-01

It is very important to determine the phase boundaries for materials with complex crystalline phase structures to construct their corresponding multi-phase equation of state. By measuring the sound velocity of Sn with different porosities, different shock-induced melting pressures along the solid-liquid phase boundary could be obtained. The incipient shock-induced melting of porous Sn samples with two different porosities occurred at a pressure of about 49.1 GPa for a porosity of 1.01 and 45.6 GPa for a porosity of 1.02, based on measurements of the sound velocity. The incipient shock-induced melting pressure of solid Sn was revised to 58.1 GPa using supplemental measurements of the sound velocity. Trivially, pores in Sn decreased the shock-induced melting pressure. Based on the measured longitudinal sound velocity data, a refined solid phase transition and the Hugoniot temperature-pressure curve's trend are discussed. No bcc phase transition occurs along the Hugoniot for porous Sn; further investigation is required to understand the implications of this finding.

Effect of Micellization on the Adsorption Kinetics of Polymeric Surfactants to the Solid/Water Interface

Science.gov (United States)

Toomey, Ryan; Tirrell, Matthew

2002-03-01

We have studied the adsorption kinetics of two classes of hydrophobic/ionic diblock copolymer surfactants in aqueous environments to understand the role that micellization plays in the adsorption process. The two systems studied were poly(t-butyl styrene)-block-poly(styrene sulfonate) (PtBS-b-PSS) and polystyrene-block-poly(acrylic acid) (PS-b-PAA). It is found that by changing the hydrophobicity of the adsorbing surface, micelle adsorption can be turned on or off. When micelle adsorption occurs, the initial adsorption rate is always slower than the supply rate of micelles to the surface, indicating “reaction-limited” adsorption. Since these micelles have essentially frozen cores, the adsorption cannot be explained by the release of unimers from the micelles. Rather, micelles directly adsorb, and they have to overcome the potential barrier imposed by their corona. Due to micellization, the adsorption rate can also be a complex function of ionic strength. A regime was found where the initial adsorption rate decreased with increasing ionic strength. This anomaly can be explained by the onset of micellization. As the salt concentration is increased, more micelles are formed. However micelles adsorb roughly an order of magnitude slower than free chains. Therefore, if increasing the ionic strength produces more micelles, the adsorption rate will simultaneously decrease.

Determination of organophosphorus pesticides using molecularly imprinted polymer solid phase extraction

International Nuclear Information System (INIS)

Mohd Marsin Sanagi; Syairah Salleh; Wan Aini Wan Ibrahim

2011-01-01

Molecularly imprinted polymer solid phase extraction (MIP-SPE) method has been developed for the determination of organophosphorus pesticides (OPPs) in water samples. The MIP was prepared by thermo-polymerization method using methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as crosslinker, acetonitrile as porogenic solvent and quinalphos as the template molecule. The three OPPs (diazinon, quinalphos and chloropyrifos) were selected as target analytes as they are widely used in agriculture sector. Various parameters affecting the extraction efficiency of the imprinted polymers have been evaluated to optimize the selective preconcentration of OPPs from aqueous samples. The characteristics of the MIP-SPE method were validated by high performance liquid chromatography (HPLC). The accuracy and selectivity of the MIP-SPE process developed were verified using non-imprinted polymer solid phase extraction (NIP-SPE) and a commercial C 18 -SPE was used for comparison. The recoveries of the target analytes obtained using the MIPs as the solid phase sorbent ranged from 83% to 98% (RSDs 1.05 - 1.98 %; n=3) for water sample. The developed MIP-SPE method demonstrates that it could be applied for the determination of OPPs in water samples. (author)

Contaminants migration in the soil: the influence of transfer between the mobile and stationary phases

International Nuclear Information System (INIS)

Moreira, R.M.; Sabino, C.S.V.; Macedo, W.A.

1996-01-01

Three transport mechanisms control the contaminant migration in saturated soils: advection, diffusion and interchanges between liquid and solid phases. These interchanges define the retention by the soil and the contaminant delay related to the liquid phase flow. Therefore, the knowledge of the adsorption/desorption characteristics of the solute in solid surfaces is fundamental for the evaluation of toxic agent releases to the compartment soil. This communication reports the study which is being performed by the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) in this area, particularly with cesium and mercury by using X-ray absorption spectroscopy for contaminants migration

Effects of deep cryogenic treatment on the solid-state phase transformation of Cu-Al alloy in cooling process

Science.gov (United States)

Wang, Yuhui; Liao, Bo; Liu, Jianhua; Chen, Shuqing; Feng, Yu; Zhang, Yanyan; Zhang, Ruijun

2012-07-01

The solid-state phase transformation temperature and duration of deep cryogenic treated and untreated Cu-Al alloys in cooling process were measured by differential scanning calorimetry measurement. The solid-state phase transformation activation energy and Avrami exponent were calculated according to these measurements. The effects of deep cryogenic treatment on the solid-state phase transformation were investigated based on the measurement and calculation as well as the observation of alloy's microstructure. The results show that deep cryogenic treatment can increase the solid-phase transformation activation energy and shorten the phase transformation duration, which is helpful to the formation of fine grains in Cu-Al alloy.

Solid phase microextraction speciation analysis of triclosan in aqueous mediacontaining sorbing nanoparticles

NARCIS (Netherlands)

Zielinska, K.

2014-01-01

Solid phase microextraction (SPME) is applied in the speciation analysis of the hydrophobic compound triclosan in an aqueous medium containing sorbing SiO2 nanoparticles (NPs). It is found that these NPs, as well as their complexes with triclosan, partition between the bulk medium and the solid

Solid-phase microextraction for the analysis of biological samples

NARCIS (Netherlands)

Theodoridis, G; Koster, EHM; de Jong, GJ

2000-01-01

Solid-phase microextraction (SPME) has been introduced for the extraction of organic compounds from environmental samples. This relatively new extraction technique has now also gained a lot of interest in a broad field of analysis including food, biological and pharmaceutical samples. SPME has a

Silica Modified with Polyaniline as a Potential Sorbent for Matrix Solid Phase Dispersion (MSPD and Dispersive Solid Phase Extraction (d-SPE of Plant Samples

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Ireneusz Sowa

2018-03-01

Full Text Available Polyaniline (PANI is one of the best known conductive polymers with multiple applications. Recently, it was also used in separation techniques, mostly as a component of composites for solid-phase microextraction (SPME. In the present paper, sorbent obtained by in situ polymerization of aniline directly on silica gel particles (Si-PANI was used for dispersive solid phase extraction (d-SPE and matrix solid–phase extraction (MSPD. The efficiency of both techniques was evaluated with the use of high performance liquid chromatography with diode array detection (HPLC-DAD quantitative analysis. The quality of the sorbent was verified by Raman spectroscopy and microscopy combined with automated procedure using computer image analysis. For extraction experiments, triterpenes were chosen as model compounds. The optimal conditions were as follows: protonated Si-PANI impregnated with water, 160/1 sorbent/analyte ratio, 3 min of extraction time, 4 min of desorption time and methanolic solution of ammonia for elution of analytes. The proposed procedure was successfully used for pretreatment of plant samples.

Liquid Adsorption of Organic Compounds on Hematite α-Fe2O3 Using ReaxFF.

Science.gov (United States)

Chia, Chung-Lim; Avendaño, Carlos; Siperstein, Flor R; Filip, Sorin

2017-10-24

ReaxFF-based molecular dynamics simulations are used in this work to study the effect of the polarity of adsorbed molecules in the liquid phase on the structure and polarization of hematite (α-Fe 2 O 3 ). We compared the adsorption of organic molecules with different polarities on a rigid hematite surface and on a flexible and polarizable surface. We show that the displacements of surface atoms and surface polarization in a flexible hematite model are proportional to the adsorbed molecule's polarity. The increase in electrostatic interactions resulting from charge transfer in the outermost solid atoms in a flexible hematite model results in better-defined adsorbed layers that are less ordered than those obtained assuming a rigid solid. These results suggest that care must be taken when parametrizing empirical transferable force fields because the calculated charges on a solid slab in vacuum may not be representative of a real system, especially when the solid is in contact with a polar liquid.

Estrogenic and AhR activities in dissolved phase and suspended solids from wastewater treatment plants.

Science.gov (United States)

Dagnino, Sonia; Gomez, Elena; Picot, Bernadette; Cavaillès, Vincent; Casellas, Claude; Balaguer, Patrick; Fenet, Hélène

2010-05-15

The distribution of estrogen receptor (ERalpha) and Aryl Hydrocarbon Receptor (AhR) activities between the dissolved phase and suspended solids were investigated during wastewater treatment. Three wastewater treatment plants with different treatment technologies (waste stabilization ponds (WSPs), trickling filters (TFs) and activated sludge supplemented with a biofilter system (ASB)) were sampled. Estrogenic and AhR activities were detected in both phases in influents and effluents. Estrogenic and AhR activities in wastewater influents ranged from 41.8 to 79 ng/L E(2) Eq. and from 37.9 to 115.5 ng/L TCDD Eq. in the dissolved phase and from 5.5 to 88.6 ng/g E(2) Eq. and from 15 to 700 ng/g TCDD Eq. in the suspended solids. For both activities, WSP showed greater or similar removal efficiency than ASB and both were much more efficient than TF which had the lowest removal efficiency. Moreover, our data indicate that the efficiency of removal of ER and AhR activities from the suspended solid phase was mainly due to removal of suspended solids. Indeed, ER and AhR activities were detected in the effluent suspended solid phase indicating that suspended solids, which are usually not considered in these types of studies, contribute to environmental contamination by endocrine disrupting compounds and should therefore be routinely assessed for a better estimation of the ER and AhR activities released in the environment. Copyright 2010 Elsevier B.V. All rights reserved.

Determination of 8 Synthetic Food Dyes by Solid Phase Extraction ...

African Journals Online (AJOL)

Keywords: Synthetic colors, Food, Fruit flavored drinks, Solid phase extraction, RP-HPLC. Tropical Journal of ..... food dyes by thin-layer chromatography-fast atom bombardment ... food dyes in soft drinks containing natural pigments by.

Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5.

Science.gov (United States)

Ding, Wenjin; Baracchini, Giulia; Klumpp, Michael; Schwieger, Wilhelm; Dittmeyer, Roland

2016-08-25

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 °C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 °C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 °C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 °C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example.

Immobilization and functional reconstitution of antibody Fab fragment by solid-phase refolding.

Science.gov (United States)

Kumada, Yoichi; Hamasaki, Kyoto; Nakagawa, Aya; Sasaki, Eiju; Shirai, Tatsunori; Okumura, Masahiro; Inoue, Manami; Kishimoto, Michimasa

2013-12-31

In this study, we demonstrated the successful preparation of a Fab antibody-immobilized hydrophilic polystyrene (phi-PS) plate via one- and two-step solid-phase refolding methods. Both polystyrene-binding peptide (PS-tag)-fused Fd fragment of heavy chain (Fab H-PS) and full-length of light-chain (Fab L-PS) were individually produced in insoluble fractions of Escherichia coli cells, and they were highly purified in the presence of 8M of urea. Antigen-binding activities of Fab antibody immobilized were correctly recovered by the one-step solid-phase refolding method that a mixture of Fab H-PS and Fab L-PS was immobilized in the presence of 0.5-2M urea, followed by surface washing of the phi-PS plate with PBST. These results indicate that by genetic fusion of a PS-tag, a complex between Fab H and Fab L was efficiently immobilized on the surface of a phi-PS plate even in the presence of a low concentration of urea, and was then correctly refolded to retain its high antigen-binding activity via removal of the urea. A two-step solid-phase refolding method whereby Fab H-PS and Fab L-PS were successively refolded on the surface of a phi-PS plate also resulted in Fab antibody formation on the plate. Furthermore, both the binding affinity and the specificity of the Fab antibody produced by the two-step method were highly maintained, according to the results of sandwich ELISA and competitive ELISA using Fab antibody-immobilized plate via two-step solid-phase refolding. Thus, the solid-phase refolding method demonstrated in this study should be quite useful for the preparation of a Fab antibody-immobilized PS surface with high efficiency from individually produced Fab H-PS and Fab L-PS. This method will be applicable to the preparation of a large Fab antibody library on the surface of a PS plate for use in antibody screening. © 2013. Published by Elsevier B.V. All rights reserved.

New Approaches in Soil Organic Matter Fluorescence; A Solid Phase Fluorescence Approach

Science.gov (United States)

Bowman, M. M.; Sanclements, M.; McKnight, D. M.

2017-12-01

Fluorescence spectroscopy is a well-established technique to investigate the composition of organic matter in aquatic systems and is increasingly applied to soil organic matter (SOM). Current methods require that SOM be extracted into a liquid prior to analysis by fluorescence spectroscopy. Soil extractions introduce an additional layer of complexity as the composition of the organic matter dissolved into solution varies based upon the selected extractant. Water is one of the most commonly used extractant, but only extracts the water-soluble fraction of the SOM with the insoluble soil organic matter fluorescence remaining in the soil matrix. We propose the use of solid phase fluorescence on whole soils as a potential tool to look at the composition of organic matter without the extraction bias and gain a more complete understand of the potential for fluorescence as a tool in terrestrial studies. To date, the limited applications of solid phase fluorescence have ranged from food and agriculture to pharmaceutical with no clearly defined methods and limitations available. We are aware of no other studies that use solid phase fluorescence and thus no clear methods to look at SOM across a diverse set of soil types and ecosystems. With this new approach to fluorescence spectroscopy there are new challenges, such as blank correction, inner filter effect corrections, and sample preparation. This work outlines a novel method for analyzing soil organic matter using solid phase fluorescence across a wide range of soils collected from the National Ecological Observatory Network (NEON) eco-domains. This method has shown that organic matter content in soils must be diluted to 2% to reduce backscattering and oversaturation of the detector in forested soils. In mineral horizons (A) there is observed quenching of the humic-like organic matter, which is likely a result of organo-mineral complexation. Finally, we present preliminary comparisons between solid and liquid phase

Adsorption of Monobutyl Phthalate from Aqueous Phase onto Two Macroporous Anion-Exchange Resins

Directory of Open Access Journals (Sweden)

Zhengwen Xu

2014-01-01

Full Text Available As new emerging pollutants, phthalic acid monoesters (PAMs pose potential ecological and human health risks. In the present study, adsorption performance of monobutyl phthalate (MBP onto two macroporous base anion-exchange resins (D-201 and D-301 was discussed. It was found that the adsorption isotherms were best fitted by the Langmuir equation while the adsorption kinetics were well described by pseudo-first-order model. Analyses of sorption isotherms and thermodynamics proved that the adsorption mechanisms for DBP onto D-201 were ion exchange. However, the obtained enthalpy values indicate that the sorption process of MBP onto D-301 is physical adsorption. The equilibrium adsorption capacities and adsorption rates of DBP on two different resins increased with the increasing temperature of the solution. D-301 exhibited a higher adsorption capacity of MBP than D-201. These results proved that D-301, as an effective sorbent, can be used to remove phthalic acid monoesters from aqueous solution.

Double-antibody solid-phase radioimmunoassay: a simplified phase-separation procedure applied to various ligands

International Nuclear Information System (INIS)

Tevaarwerk, G.J.M.; Boyle, D.A.; Hurst, C.J.; Anguish, I.; Uksik, P.

1980-01-01

The purpose was to develop a simplified and reliable method of separating free from antibody-bound ligand using a precipitating antibody linked to a cellulose derivative. Dose-response curves and control sera were set up in parallel for various pituitary and placental polypeptides, steroid hormones, insulin, glucagon, triiodothyronine, thyroxine, angiotensin I, calcitonin, gastrin, cyclic AMP, and digoxin. After first-antibody reactions had reached equilibrium, free and bound ligand were separated using a double-antibody solid-phase system in parallel with conventional methods, including dextran-coated charcoal, double-antibody precipitation, single-antibody solid phase, organic solvents, salt precipitation, and anion-exchange resins. The effect of variations in temperature, incubation time, protein content, pH, and amount of separating material added were studied. The results showed that separation was complete within 1 hr for small ligand molecules and within 2 hr for larger ones. Dose-response curves and control-sera results closely paralleled those obtained with conventional methods. The method was not affected by moderate variations in incubation variables. Nonspecific binding was less than 3% in all assays, while intra-assay and interassay coefficients of variation were similar to those obtained with conventional phase-separation methods. It is concluded that the method is a simple and rapid alternative phase-separation system. It has the advantage of being free from common nonspecific intersample variations, and can be applied to any assay system based on rabbit or guinea pig antibodies without preliminay time- or reagent-consuming titration or adjustments to establish optimum phase-separating conditions

Solid-State Gas Adsorption Studies with Discrete Palladium(II) [Pd2 (L)4 ]4+ Cages.

Science.gov (United States)

Preston, Dan; White, Keith F; Lewis, James E M; Vasdev, Roan A S; Abrahams, Brendan F; Crowley, James D

2017-08-04

The need for effective CO 2 capture systems remains high, and due to their tunability, metallosupramolecular architectures are an attractive option for gas sorption. While the use of extended metal organic frameworks for gas adsorption has been extensively explored, the exploitation of discrete metallocage architectures to bind gases remains in its infancy. Herein the solid state gas adsorption properties of a series of [Pd 2 (L) 4 ] 4+ lantern shaped coordination cages (L = variants of 2,6-bis(pyridin-3-ylethynyl)pyridine), which had solvent accessible internal cavities suitable for gas binding, have been investigated. The cages showed little interaction with dinitrogen gas but were able to take up CO 2 . The best performing cage reversibly sorbed 1.4 mol CO 2 per mol cage at 298 K, and 2.3 mol CO 2 per mol cage at 258 K (1 bar). The enthalpy of binding was calculated to be 25-35 kJ mol -1 , across the number of equivalents bound, while DFT calculations on the CO 2 binding in the cage gave ΔE for the cage-CO 2 interaction of 23-28 kJ mol -1 , across the same range. DFT modelling suggested that the binding mode is a hydrogen bond between the carbonyl oxygen of CO 2 and the internally directed hydrogen atoms of the cage. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of natural organic compounds on adsorption of actinoid on solid phase and interaction between colloid

Energy Technology Data Exchange (ETDEWEB)

Tominaga, Takeshi; Minai, Yoshitaka; Takahashi, Yoshio; Kohashi, Asaya [Tokyo Univ. (Japan); Yoshida, Zenko; Meguro, Yoshihiro; Kimura, Takaumi

1996-01-01

Two problems were studied such as, at first, the effects of calcium and magnesium on formation of complex of actinoid (III) and humic acid and, second, estimation of number of hydrate of europium (III) in polycarbonic acid complex by fluorescence lifetime measurements. With adding calcium and magnesium, the solubility of humic acid and apparent complex formation constant of actinoid (III)-humic acid complex decreased and amount of adsorption of humic acid on kaolinite increased. Apparent complex formation constant increased with increasing the dissociation degree but decreased with increasing the concentration of supporting electrolyte as same as that of humic acid. This result can be explained by the model of polymer electrolyte on the static electrical interaction with metal ions, because polycarbonic acid is polymer electrolyte with many dissociation groups in a molecule. (S.Y.)

Modeling and Analysis of a Three-Phase Solid-State Var ...

African Journals Online (AJOL)

Modeling and Analysis of a Three-Phase Solid-State Var Compensator (SSVC) ... Nigerian Journal of Technology. Journal Home ... The problems associated with the flow of reactive power in transmission and distribution lines are well known.

Analysis of malachite green in aquatic products by carbon nanotube-based molecularly imprinted - matrix solid phase dispersion.

Science.gov (United States)

Wang, Yu; Chen, Ligang

2015-10-01

A simple method based on matrix solid phase dispersion (MSPD) using molecularly imprinted polymers (MIPs) as sorbents for selective extraction of malachite green (MG) from aquatic products was developed. The MIPs were prepared by using carbon nanotube as support, MG as template, methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as crosslinker and methylene chloride as solvent. The MIPs were characterized by Fourier transform infrared spectrometry and transmission electron microscopy. The isothermal adsorption, kinetics absorption and selective adsorption experiments were carried out. We optimized the extraction conditions as follows: the ratio of MIPs to sample was 2:3, the dispersion time was 15min, washing solvent was 4mL 50% aqueous methanol and elution solvent was 3mL methanol-acetic acid (98: 2, v/v). Once the MSPD process was completed, the MG extracted from aquatic products was determined by high performance liquid chromatography. The detection limit of MG was 0.7μgkg(-1). The relative standard deviations of intra-day and inter-day were obtained in the range of 0.9%-4.7% and 3.4%-9.8%, respectively. In order to evaluate the applicability and reliability of the proposed method, it was applied to determine MG in different aquatic products samples including fish, shrimp, squid and crabs. The satisfied recoveries were in the range of 89.2%-104.6%. The results showed that this method is faster, simpler and makes extraction and purification in the same system. Copyright © 2015 Elsevier B.V. All rights reserved.

Solid-phase microextraction of phthalate esters in water sample using different activated carbon-polymer monoliths as adsorbents.

Science.gov (United States)

Lirio, Stephen; Fu, Chung-Wei; Lin, Jhih-Yun; Hsu, Meng-Ju; Huang, Hsi-Ya

2016-07-13

In this study, the application of different activated carbon-polymer (AC-polymer) monoliths as adsorbents for the solid-phase microextraction (SPME) of phthalate esters (PAEs) in water sample were investigated. The activated carbon (AC) was embedded in organic polymers, poly(butyl methacrylate-co-ethylene dimethacrylate) (poly(BMA-EDMA)) or poly(styrene-co-divinylbenzene) (poly(STY-DVB)), via a 5-min microwave-assisted or a 15-min water bath heating polymerization. Preliminary investigation on the performance of the native poly(BMA-EDMA) and poly(STY-DVB) demonstrated remarkable adsorption efficiencies for PAEs. However, due to the strong hydrophobic, π-π, and hydrogen bonding interactions between the analytes and polymers, low extraction recoveries were achieved. In contrast, the presence of AC in native polymers not only enhanced the adsorption efficiencies but also assisted the PAE desorption, especially for AC-poly(STY-DVB) with extraction recovery ranged of 76.2-99.3%. Under the optimized conditions, the extraction recoveries for intra-, inter-day and column-to-column were in the range of 76.5-100.8% (<3.7% RSDs), 77.2-97.6% (<5.6% RSDs) and 75.5-99.7% (<6.2% RSDs), respectively. The developed AC-poly(STY-DVB) monolithic column showed good mechanical stability, which can be reused for more than 30 extraction times without any significant loss in the extraction recoveries of PAEs. The AC-poly(STY-DVB) monolithic column was successfully applied in SPME of PAEs in water sample with extraction recovery ranged of 78.8%-104.6% (<5.5% RSDs). Copyright © 2016 Elsevier B.V. All rights reserved.

Adsorption of copolymers at polymer/air and polymer/solid interfaces

Science.gov (United States)

Oslanec, Robert

Using mainly low-energy forward recoil spectrometry (LE-FRES) and neutron reflectivity (NR), copolymer behavior at polymer/air and polymer/solid interfaces is investigated. For a miscible blend of poly(styrene-ran-acrylonitrile) copolymers, the volume fraction profile of the copolymer with lower acrylonitrile content is flat near the surface in contrast to mean field predictions. Including copolymer polydispersity into a self consistent mean field (SCMF) model does not account for this profile shape. LE-FRES and NR is also used to study poly(deuterated styrene-block-methyl-methacrylate) (dPS-b-PMMA) adsorption from a polymer matrix to a silicon oxide substrate. The interfacial excess, zsp*, layer thickness, L, and layer-matrix width, w, depend strongly on the number of matrix segments, P, for P 2N, the matrix chains are repelled from the adsorbed layer and the layer characteristics become independent of P. An SCMF model of block copolymer adsorption is developed. SCMF predictions are in qualitative agreement with the experimental behavior of zsp*, L, and w as a function of P. Using this model, the interaction energy of the MMA block with the oxide substrate is found to be -8ksb{B}T. In a subsequent experiment, the matrix/dPS interaction is made increasingly unfavorable by increasing the 4-bromostyrene mole fraction, x, in a poly(styrene-ran-4-bromostyrene) (PBrsbxS) matrix. Whereas experiments show that zsp* slightly decreases as x increases, the SCMF model predicts that zsp* should increase as the matrix becomes more unfavorable. Upon including a small matrix attraction for the substrate, the SCMF model shows that zsp* decreases with x because of competition between PBrsbxS and dPS-b-PMMA for adsorbing sites. In thin film dewetting experiments on silicon oxide, the addition of dPS-b-PMMA to PS coatings acts to slow hole growth and prevent holes from impinging. Dewetting studies show that longer dPS-b-PMMA chains are more effective stabilizing agents than shorter

Formation of organic solid phases in hydrocarbon reservoir fluids. Final report

Energy Technology Data Exchange (ETDEWEB)

Andersen, S.I.; Lindeloff, N.; Stenby, E.H.

1998-12-31

The occurrence of solid phases during oil recovery is a potential problem. The present work has mainly been concerned with wax formation due to cooling of oils with a large paraffin content. 8 oils have been included in this project, although only a few of these have till now been subject to all the experimental techniques applied. The oils and wax fractions from these have been characterized using techniques such as GC-MS and Ftir. The goal has in part been to get a detailed description of the oil composition for use in model evaluation and development and in part to get a fundamental understanding of waxy oil properties and behaviour. A high pressure (200 bar) equipment has been developed for automatic detection of wax appearance using a filtration technique and laser light turbidimetry. The latter was found to be far superior to the filtration. The filtration was used to sample the incipient solid phase for characterization. However entrapment of liquid in the filters currently used have hampered this part. A number of model systems and one gas condensate have been investigated. The GC-MS procedure was found only to been able to detect molecules up to n-C45 and the group type analysis was not accurate enough for modelling purposes. Using Ftir it was obvious that incipient phases may contain very complex molecules (asphaltenes) which are not captured by GC-MS especially when fractionation is done using the acetone precipitation at elevated temperature. The latter fractionation procedure has been investigated thoroughly as a tool for understanding wax distribution etc. Within thermodynamic modelling a delta lattice parameter model has been developed which incorporates the non-ideality of the solid phases into the calculation of SLE. The non-ideality is estimated from pure component properties. A new algorithm for phase equilibria involving gas-liquid-solid has been developed. Currently both the model work and the experimental works are continued. (au)

The Frontier Between Adsorption and Precipitation of Polyacrylic Acid on Calcium Carbonate Frontière entre adsorption et précipitation de l'acide polyacrylique sur le carbonate de calcium

Directory of Open Access Journals (Sweden)

Cabane B.

2006-12-01

Full Text Available Adsorption of polymers on mineral surfaces allowing colloidal stability have widespread applications in industrial processes. The binding mechanism has been quite well described on oxide surfaces. Mainly in terms of hydrogen bonds and electrostatic interactions between charged sites and polymer segments. This phenomenon has been modelized and the influence of pH. Ionic strentgh, and molecular weight can be calculated or predicted. In the case of sparingly soluble substrates such as BaSO4, CaCO3 or CaSO4, several problems arise : the difficulty for the identification of surface sites and the interference of ions coming from the material's solubility. In the case of calcite, the solubility imposes dissolved calcium ions in solution which could complex the polyelectrolyte and reduce its solubility. For that purpose, we have measured the binding energy using microcalorimetry. Microcalorimetric measurements have shown that the adsorption enthalpy is weakly enclothermic: about + 2 kj/mol. Interestingly, this value is very closed to that of calcium complexation with PANa. It is suggested that the driving force for adsorption is the net gain in entropy of the system. The microcalorimetric adsorption isotherm does not show any evidence for a strongly exothermic interaction between positive edges and negative segment of the polyion. Practically, in most cases, adsorption of polymers is calculated from the decrease of its concentration in the solution after separation of the solid by centrifugation. This procedure does not discriminate therefore between real adsorption and phase separation. To answer the question, we have performed adsorption experiments using a dialysis membrane to separate the solid particles from the solution. It has been established that in some circumstances, depending on the relative amount of calcite, calcium ions and polyelectrolyte, precipitation takes place rather than adsorption. This is especially the case at low polymer

Fluorocarbon adsorption in hierarchical porous frameworks

Energy Technology Data Exchange (ETDEWEB)

Motkuri, RK; Annapureddy, HVR; Vijaykumar, M; Schaef, HT; Martin, PF; McGrail, BP; Dang, LX; Krishna, R; Thallapally, PK

2014-07-09

Metal-organic frameworks comprise an important class of solid-state materials and have potential for many emerging applications such as energy storage, separation, catalysis and bio-medical. Here we report the adsorption behaviour of a series of fluorocarbon derivatives on a set of microporous and hierarchical mesoporous frameworks. The microporous frameworks show a saturation uptake capacity for dichlorodifluoromethane of >4 mmol g(-1) at a very low relative saturation pressure (P/P-o) of 0.02. In contrast, the mesoporous framework shows an exceptionally high uptake capacity reaching >14 mmol g(-1) at P/P-o of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption is found to generally correlate with the polarizability and boiling point of the refrigerant, with dichlorodifluoromethane >chlorodifluoromethane >chlorotrifluoromethane >tetrafluoromethane >methane. These results suggest the possibility of exploiting these sorbents for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling.

Molecular Simulation of Adsorption in Microporous Materials

Directory of Open Access Journals (Sweden)

Yiannourakou M.

2013-11-01

Full Text Available The development of industrial software, the decreasing cost of computing time, and the availability of well-tested forcefields make molecular simulation increasingly attractive for chemical engineers. We present here several applications of Monte-Carlo simulation techniques, applied to the adsorption of fluids in microporous solids such as zeolites and model carbons (pores < 2 nm. Adsorption was computed in the Grand Canonical ensemble with the MedeA®-GIBBS software, using energy grids to decrease computing time. MedeA®-GIBBS has been used for simulations in the NVT or NPT ensembles to obtain the density and fugacities of fluid phases. Simulation results are compared with experimental pure component isotherms in zeolites (hydrocarbon gases, water, alkanes, aromatics, ethanethiol, etc., and mixtures (methane-ethane, n-hexane-benzene, over a large range of temperatures. Hexane/benzene selectivity inversions between silicalite and Na-faujasites are well predicted with published forcefields, providing an insight on the underlying mechanisms. Also, the adsorption isotherms in Na-faujasites for light gases or ethane-thiol are well described. Regarding organic adsorbents, models of mature kerogen or coal were built in agreement with known chemistry of these systems. Obtaining realistic kerogen densities with the simple relaxation approach considered here is encouraging for the investigation of other organic systems. Computing excess sorption curves in qualitative agreement with those recently measured on dry samples of gas shale is also favorable. Although still preliminary, such applications illustrate the strength of molecular modeling in understanding complex systems in conditions where experiments are difficult.

Adsorption of elemental mercury vapors from synthetic exhaust combustion gas onto HGR carbon.

Science.gov (United States)

Musmarra, D; Karatza, D; Lancia, A; Prisciandaro, M; Mazziotti di Celso, G

2016-07-01

An activated carbon commercially available named HGR, produced by Calgon-Carbon Group, was used to adsorbe metallic mercury. The work is part of a wider research activity by the same group focused on the removal of metallic and divalent mercury from combustion flue gas. With respect to previously published papers, this one is aimed at studying in depth thermodynamic equilibria of metallic mercury adsorption onto a commercial activated carbon. The innovativeness lies in the wider operative conditions explored (temperature and mercury concentrations) and in the evaluation of kinetic and thermodynamic data for a commercially available adsorbing material. In detail, experimental runs were carried out on a laboratory-scale plant, in which Hg° vapors were supplied in a nitrogen gas stream at different temperature and mercury concentration. The gas phase was flowed through a fixed bed of adsorbent material. Adsorbate loading curves for different Hg° concentrations together with adsorption isotherms were achieved as a function of temperature (120, 150, 200°C) and Hg° concentrations (1.0-7.0 mg/m(3)). Experimental runs demonstrated satisfying results of the adsorption process, while Langmuir parameters were evaluated with gas-solid equilibrium data. Especially, they confirmed that adsorption capacity is a favored process in case of lower temperature and they showed that the adsorption heat was -20 kJ/mol. Furthermore, a numerical integration of differential equations that model the adsorption process was proposed. Scanning electron microscopy (SEM) investigation was an useful tool to investigate about fresh and saturated carbon areas. The comparison between them allowed identification of surface sites where mercury is adsorbed; these spots correspond to carbon areas where sulfur concentration is greater. Mercury compounds can cause severe harm to human health and to the ecosystem. There are a lot of sources that emit mercury species to the atmosphere; the main ones are

Radioimmuoassay study of antidigitoxin antibodies in liquid phase and after coupling on a solid phase

International Nuclear Information System (INIS)

Collignon, A.; German, A.; Scherrmann, J.M.; Bourdon, R.

1983-01-01

Antidigitoxin antibodies prepared by immunizing rabbits with a digitoxin-bovine serum albumin conjugate have been studied by radioimmunoassay in the native serum (homogeneous phase antibodies) and after coupling on glass beads (heterogeneous phase antibodies). Homogeneous phase antibodies present a satisfactory titer and affinity constant and react very specifically with digitoxin. Fixation of antibodies on a solid phase induce a loss of their immunoreactivity as it is showed by modification of the inhibition curves, by a greater sensitivity to the chemical structure of the tracer and by a decrease of the affinity constant. Reactionnal kinetic and sensitivity to the incubation temperature are not modified. Heterogeneous phase antibodies present a greater stability. Both antibodies types can be used for a digitoxin radioimmunoassay [fr

Phase characteristics of solid-state amplifiers in sub-harmonic bunchers

International Nuclear Information System (INIS)

Liu Rong; Ma Xinpeng; Zhao Fengli; Wang Xiangjian; Wang Guangwei; Huang Yongqing; Zhang Donghui

2009-01-01

To study the phase characteristics of solid-state amplifiers(20 kW/142.8 MHz,10 kW/571.2 MHz) in sub-harmonic bunchers(SHBs) of the BEPC II linear accelerator, phase shift in pulse and phase stability are measured using a digital measurement method based on field programmable gate array(FPGA). The hardware of the measurement system includes the frequency synthesizer, digital signal processing board(FPGA) and PC, and the software includes an internal algorithm on FPGA, communication procedures and PC client interface procedures. The measurement results of phase characteristics are consistent with the actual situation, which is the basis for the further implement of phase compensation in SHBs. (authors)

Liquid chromatography tandem mass spectrometry method using solid-phase extraction and bead-beating-assisted matrix solid-phase dispersion to quantify the fungicide tebuconazole in controlled frog exposure study: analysis of water and animal tissue

DEFF Research Database (Denmark)

Hansen, Martin; Poulsen, Rikke; Luong, Xuan

2014-01-01

and on tissue from exposed and non-exposed adult X. laevis. Using solid-phase extraction (SPE), the analytical method allows for quantification of tebuconazole at concentrations as low as 3.89 pg mL(-1) in 10 mL water samples. Using bead-beating-assisted matrix solid-phase dispersion (MSPD), it was possible...

Solid phase extraction and metabolic profiling of exudates from living copepods

DEFF Research Database (Denmark)

Selander, Erik; Heuschele, Jan; Nylund, Göran M.

2016-01-01

describe the development of a closed loop solid phase extraction setup that allows for extraction of exuded metabolites from live copepods. We captured exudates from male and female Temora longicornis and analyzed the content with high resolution LC-MS. Chemometric methods revealed 87 compounds...... that solid phase extraction in combination with metabolic profiling of exudates is a useful tool to develop our understanding of the chemical interplay between pelagic organisms....... Copepodamide G, known to induce defensive responses in phytoplankton, was among the ten compounds of highest relative abundance in both male and female extracts. The presence of copepodamide G shows that the method can be used to capture and analyze chemical signals from living source organisms. We conclude...

Comparison of solid and liquid-phase bioassays using ecoscores to assess contaminated soils

Energy Technology Data Exchange (ETDEWEB)

Lors, Christine [Universite Lille Nord de France, 1bis rue Georges Lefevre, 59044 Lille Cedex (France); Ecole des Mines de Douai, LGCgE-MPE-GCE, 941 rue Charles-Bourseul, 59500 Douai (France); Centre National de Recherche sur les Sites et Sols Pollues, 930 Boulevard Lahure, BP 537, 59505 Douai Cedex (France); Ponge, Jean-Francois, E-mail: ponge@mnhn.fr [Museum National d' Histoire Naturelle, Departement Ecologie et Gestion de la Biodiversite, CNRS UMR 7179, 4 Avenue du Petit-Chateau, 91800 Brunoy (France); Martinez Aldaya, Maite [Museum National d' Histoire Naturelle, Departement Ecologie et Gestion de la Biodiversite, CNRS UMR 7179, 4 Avenue du Petit-Chateau, 91800 Brunoy (France); Damidot, Denis [Universite Lille Nord de France, 1bis rue Georges Lefevre, 59044 Lille Cedex (France); Ecole des Mines de Douai, LGCgE-MPE-GCE, 941 rue Charles-Bourseul, 59500 Douai (France)

2011-10-15

Bioassays on aqueous and solid phases of contaminated soils were compared, belonging to a wide array of trophic and response levels and using ecoscores for evaluating ecotoxicological and genotoxicological endpoints. The method was applied to four coke factory soils contaminated mainly with PAHs, but also to a lesser extent by heavy metals and cyanides. Aquatic bioassays do not differ from terrestrial bioassays when scaling soils according to toxicity but they are complementary from the viewpoint of ecological relevance. Both aquatic and terrestrial endpoints are strongly correlated with concentrations of 3-ring PAHs. This evaluation procedure allows us to propose a cost-effective battery which embraces a wide array of test organisms and response levels: it includes two rapid bioassays (Microtox) and springtail avoidance), a micronucleus test and three bioassays of a longer duration (algal growth, lettuce germination and springtail reproduction). This battery can be recommended for a cost-effective assessment of polluted/remediated soils. - Highlights: > Comparison of liquid- and solid-phase bioassays on contaminated soils, using ecoscores. > Complementarity of liquid- and solid-phase bioassays for the evaluation of environmental hazards. > Proposal for a restricted battery of 5 most sensitive tests. > Use of this restricted battery for a cost-effective assessment of polluted/remediated soils. - Aqueous and solid phases of contaminated soils give similar results in terms of toxicity but are complementary for the evaluation of environmental hazards by ecoscores.

Effects of Humic Acid and Suspended Solids on the Removal of Heavy Metals from Water by Adsorption onto Granular Activated Carbon.

Science.gov (United States)

Sounthararajah, Danious P; Loganathan, Paripurnanda; Kandasamy, Jaya; Vigneswaran, Saravanamuthu

2015-08-27

Heavy metals constitute some of the most dangerous pollutants of water, as they are toxic to humans, animals, and aquatic organisms. These metals are considered to be of major public health concern and, therefore, need to be removed. Adsorption is a common physico-chemical process used to remove heavy metals. Dissolved organic carbon (DOC) and suspended solids (SS) are associated pollutants in water systems that can interact with heavy metals during the treatment process. The interactions of DOC and SS during the removal of heavy metals by granular activated carbon were investigated in batch and fixed-bed column experiments. Batch adsorption studies indicated that Langmuir adsorption maxima for Pb, Cu, Zn, Cd, and Ni at pH 6.5 were 11.9, 11.8, 3.3, 2.0, and 1.8 mg/g, respectively. With the addition of humic acid (HA) (DOC representative), they were 7.5, 3.7, 3.2, 1.6, and 2.5 mg/g, respectively. In the column experiment, no breakthrough (complete removal) was obtained for Pb and Cu, but adding HA provided a breakthrough in removing these metals. For Zn, Cd and Ni, this breakthrough occurred even without HA being added. Adding kaolinite (representative of SS) had no effect on Pb and Cu, but it did on the other metals.

Fluorocarbon adsorption in hierarchical porous frameworks

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