New insights into U(VI) sorption onto montmorillonite from batch sorption and spectroscopic studies at increased ionic strength

2021 ◽  
pp. 150653
Author(s):  
M. Stockmann ◽  
K. Fritsch ◽  
F. Bok ◽  
M. Marques Fernandes ◽  
B. Baeyens ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Spectroscopic Studies ◽  
Batch Sorption

Effect of seawater intrusion on radioactive strontium (90Sr) sorption and transport at nuclear power plants

2018 ◽  
Vol 106 (2) ◽  
pp. 147-160
Author(s):  
Seeun Chang ◽  
Wooyong Um ◽  
Won-Seok Kim ◽  
HyunJu Kim
Keyword(s):  
Ionic Strength ◽  
Seawater Intrusion ◽  
Fractured Rocks ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Fractured Rock ◽  
Column Experiments ◽  
Rock Samples ◽  
Batch Sorption

Abstract Batch sorption and column experiments were conducted to investigate and compare sorption and transport behavior of 90Sr on the assumption of seawater intrusion at nuclear power plants. Batch sorption experiments were carried out on fractured rocks and bedrocks using synthetic groundwater and seawater both spiked with 90Sr. In general, higher 90Sr sorption occurred on fractured rock samples than on bedrocks, because of the presence of weathered secondary minerals (iron oxide and clay) on fractured rock surfaces. However, one particular bedrock sample (WSP-B) which has higher porosity and carbon amount than fractured rock samples also showed the higher 90Sr sorption than its comparable fractured rocks. For all batch sorption studies, 90Sr sorption distribution coefficient, Kd decreased from groundwater to seawater environment due to the higher ionic strength of seawater (6.4×10−1–7.7×10−1 M) compared to groundwater (4.0×10−3–6.0×10−3 M). The three different ionic strength solutions were used in column experiments, and the results showed that transport behavior of Sr through a fractured rock had similar sorption trend to batch sorption results. The highest mobility (or least retardation) for Sr was found for 100% seawater solution compared to the highest retardation (or least mobility) for 100% groundwater solution. These sorption and transport data of Sr on solid materials contacted with various ionic strength solutions corroborate empirically defensible information for assessment of radioactive contamination in groundwater below the NPP sites located nearby shores. In addition, the experimental data will be incorporated to improve transport models of 90Sr in the subsurface environment for severe nuclear accidents.

scholarly journals Soil management and ionic strength on selenite retention in oxidic soils

2018 ◽  
Vol 42 (4) ◽  
pp. 395-407 ◽  
Author(s):  
Anderson Mendes Araujo ◽  
Josimar Henrique de Lima Lessa ◽  
Liniker André Ferreira ◽  
Luiz Roberto Guimarães Guilherme ◽  
Guilherme Lopes
Keyword(s):  
Ionic Strength ◽  
Crop Production ◽  
Adsorption Mechanism ◽  
Agricultural Practices ◽  
Soil Management ◽  
Outer Sphere ◽  
Spectroscopic Studies ◽  
Sodium Selenate ◽  
Native Soils ◽  
Cultivated Soils

ABSTRACT Sorption of selenium (Se) on soils may be influenced by factors that are changed though agricultural practices usually performed for crop production, such as soil pH, competing anion and organic matter contents, among others. This study aimed to evaluate the influence of soil management and ionic strength (IS) on Se retention in Brazilian soils, which is important to predict Se availability in both systems, native and cultivated soils. For that, adsorption and desorption reactions of Se were evaluated in 16 soil samples (eight from cultivated soils and eight from native soils), using solutions containing 100 and 500 µg L-1 Se in the form of sodium selenate and in two IS, 15 and 150 mM. Se adsorption varied as a function of IS for most soils, which may indicate that the adsorption mechanism by outer-sphere complex is important for selenate retention in the studied soils, but future studies involving other techniques, such as spectroscopic studies, are needed to more clearly confirm the adsorption mechanism. In general, adsorption varied in relation to soil characteristics, and native soils adsorbed larger Se amounts than the cultivated soils. In terms of desorption, soils which had larger Se adsorbed amounts also presented larger desorbed amounts. Finally, IS and soil management influenced the availability of selenate in the studied soils.

Sorption of Atrazine (AT) on Nano-SiO2 and Nano-Kaolinite

2012 ◽  
Vol 557-559 ◽  
pp. 639-643
Author(s):  
Jia Juan Lu ◽  
Xun Feng Xia ◽  
Xiao Min Yan ◽  
Dong Sheng Wang ◽  
Qing Ru Fan
Keyword(s):  
Ionic Strength ◽  
Aggregate Size ◽  
Nano Particles ◽  
Nano Particle ◽  
Sorption Data ◽  
Batch Sorption ◽  
Particle Aggregate ◽  
Aqueous Contaminants

With the increasing use of nano-SiO2and nano-kaolinite, it is imperative to investigate their effect on the transport of aqueous contaminants. In this study, the extent and reversibility of sorption of AT on nano-SiO2and nano-kaolinite were examined using batch sorption experiments. Influence of ionic strength, pH and temperature was investigated. Sorption data were well fitted with Freundlich models. The sorption capacities were larger at low ionc strengths and low pHs. Nano-particle aggregate size is an important factor for the pH influencing process, which increase as the pH approach pHzpc. The sorption of AT on the two nano-particles is spontaneous.

Absence of Hyperchromic Effect in DNA Heated Above Tm., in the Presence of Tryptophan

1969 ◽  
Vol 24 (5) ◽  
pp. 508-510 ◽  
Author(s):  
M. Pieber ◽  
Cl. Romero ◽  
C. Tirapegui ◽  
J. Tohá C.
Keyword(s):  
Ionic Strength ◽  
Melting Point ◽  
Strong Interaction ◽  
Thermal Denaturation ◽  
Spectroscopic Studies ◽  
Water Solutions ◽  
Hyperchromic Effect ◽  
Ph Variations

A strong interaction between DNA and Tryptophan in water solutions is described. This interaction determines the absence of hyperchromic effect in heated DNA above its melting point, when Tryptophan is present (base mol/tryptophan mol). At lower concentrations of Tryptophan only a shift of the Tm. of the DNA-Tryptophan solutions and a change in the shape of the thermal denaturation curves occurs. These effects are neither due to the ionic strength of the Tryptophan. nor to pH variations. P.M.R. spectroscopic studies confirm the interaction of the uracil ring of Uridine and the indol ring of Tryptophan.

Spectroscopic investigations on sorption of uranium onto suspended bentonite: effects of pH, ionic strength and complexing anions

2015 ◽  
Vol 103 (4) ◽  
Author(s):  
Parveen Kumar Verma ◽  
Priyanath Pathak ◽  
Manoj Mohapatra ◽  
Ashok Kumar Yadav ◽  
Sambhunath Jha ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Bentonite Clay ◽  
Sorption Behavior ◽  
Aerobic Conditions ◽  
Batch Sorption ◽  
Spectroscopic Investigations ◽  
Effects Of Ph ◽  
Complexing Anions

AbstractBatch sorption experiments were carried out under aerobic conditions to understand the sorption behavior of U(VI) onto bentonite clay under varying pH (2–8) and ionic strength (

The ionic strength dependence of chromatin folding

1978 ◽  
Vol 36 (2) ◽  
pp. 220-221
Author(s):  
F. Thoma ◽  
TH. Koller
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Ionic Strength ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Carbon Supports ◽  
Ionic Strength Dependence ◽  
Chromatin Folding ◽  
Strength Dependence ◽  
Preparation Techniques

Under a variety of electron microscope specimen preparation techniques different forms of chromatin appearance can be distinguished: beads-on-a-string, a 100 Å nucleofilament, a 250 Å fiber and a compact 300 to 500 Å fiber.Using a standardized specimen preparation technique we wanted to find out whether there is any relation between these different forms of chromatin or not. We show that with increasing ionic strength a chromatin fiber consisting of a row of nucleo- somes progressively folds up into a solenoid-like structure with a diameter of about 300 Å.For the preparation of chromatin for electron microscopy the avoidance of stretching artifacts during adsorption to the carbon supports is of utmost importance. The samples are fixed with 0.1% glutaraldehyde at 4°C for at least 12 hrs. The material was usually examined between 24 and 48 hrs after the onset of fixation.

Conformational Transitions in Escherichia coli Ribosomal RNAs as Visualized by Dedicated STEM

1988 ◽  
Vol 46 ◽  
pp. 176-177
Author(s):  
J.S. Wall ◽  
V. Maridiyan ◽  
S. Tumminia ◽  
J. Hairifeld ◽  
M. Boublik
Keyword(s):  
Ionic Strength ◽  
Three Dimensional ◽  
Conformational Transitions ◽  
Dark Field ◽  
Dimensional Structure ◽  
Ribosomal Rnas ◽  
Field Mode ◽  
Freeze Dried ◽  
High Resolution Images ◽  
Low Ionic Strength

The high contrast in the dark-field mode of dedicated STEM, specimen deposition by the wet film technique and low radiation dose (1 e/Å2) at -160°C make it possible to obtain high resolution images of unstained freeze-dried macromolecules with minimal structural distortion. Since the image intensity is directly related to the local projected mass of the specimen it became feasible to determine the molecular mass and mass distribution within individual macromolecules and from these data to calculate the linear density (M/L) and the radii of gyration.2 This parameter (RQ), reflecting the three-dimensional structure of the macromolecular particles in solution, has been applied to monitor the conformational transitions in E. coli 16S and 23S ribosomal RNAs in solutions of various ionic strength.In spite of the differences in mass (550 kD and 1050 kD, respectively), both 16S and 23S RNA appear equally sensitive to changes in buffer conditions. In deionized water or conditions of extremely low ionic strength both appear as filamentous structures (Fig. la and 2a, respectively) possessing a major backbone with protruding branches which are more frequent and more complex in 23S RNA (Fig. 2a).

The three-dimensional structure of frozen-hydrated left- and right-handed forms of bacterial flagellar filaments from an identical serotype

1986 ◽  
Vol 44 ◽  
pp. 298-299
Author(s):  
S. Trachtenberg ◽  
D. J. DeRosier
Keyword(s):  
Ionic Strength ◽  
Basal Body ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Protein Species ◽  
Liquid Environment ◽  
Bacterial Flagellum ◽  
Left And Right ◽  
Rotary Motor ◽  
Helical Parameters

The bacterial cell is propelled through the liquid environment by means of one or more rotating flagella. The bacterial flagellum is composed of a basal body (rotary motor), hook (universal coupler), and filament (propellor). The filament is a rigid helical assembly of only one protein species — flagellin. The filament can adopt different morphologies and change, reversibly, its helical parameters (pitch and hand) as a function of mechanical stress and chemical changes (pH, ionic strength) in the environment.

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