scholarly journals Laponites® for the Recovery of 133Cs, 59Co, and 88Sr from Aqueous Solutions and Subsequent Storage: Impact of Grafted Silane Loads

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 572
Author(s):  
Thomas Thiebault ◽  
Jocelyne Brendlé ◽  
Grégoire Augé ◽  
Lionel Limousy
Keyword(s):  
Competitive Adsorption ◽  
Saline Solution ◽  
Covalent Binding ◽  
Adsorption Properties ◽  
Inorganic Cations ◽  
Adsorption Sites ◽  
Initial Load ◽  
Subsequent Storage ◽  
Saline Solutions

In this study, silylated Laponites® (LAP) were synthetized with various loads of 3-aminopropyltriethoxysilane (APTES) to evaluate their adsorption properties of 133Cs, 59Co, and 88Sr during single-solute and competitive experiments. The increase in the initial load of APTES increased the adsorbed amount of APTES in the resulted grafted clay. The characterization of LAP-APTES exhibited a covalent binding between APTES and LAP and emphasized the adsorption sites of APTES for each tested load. In comparison with raw LAP, LAP-APTES displayed significantly higher adsorption properties of Co2+, Cs+, and Sr2+. The competitive adsorption of these three contaminants provides a deeper understanding of the affinity between adsorbate and adsorbent. Therefore, Co2+ displayed a strong and specific adsorption onto LAP-APTES. Except for Cs+, the adsorption capacity was improved with increasing the load of APTES. Finally, the desorption behavior of the three contaminants was tested in saline solutions. Cs+ and Sr2+ were significantly released especially by inorganic cations displaying the same valence. Conversely, desorption of Co2+ was very low whatever the saline solution. LAP-APTES, therefore, presented suitable adsorption properties for the removal of radionuclides especially for Co2+, making this material suitable to improve the decontamination of radioactive wastewaters.

scholarly journals Hydrodynamic and adsorption properties of anionic acrylamide copolymers in water-salt media

2019 ◽  
Vol 55 (4) ◽  
pp. 455-463
Author(s):  
D. N. Davlyud ◽  
P. D. Vorobiev ◽  
Yu. V. Lipai ◽  
E. V. Vorobieva ◽  
S. V. Bucha ◽  
...  
Keyword(s):  
Potassium Chloride ◽  
Saline Solution ◽  
Adsorption Properties ◽  
Capillary Viscometer ◽  
Ionic Groups ◽  
Low Concentrations ◽  
Mass Transfer Mechanism ◽  
Water Salt ◽  
Saline Solutions ◽  
Acrylamide Copolymers

Rheological properties and concentration cross-overs of anionic acrylamide copolymers in saline solutions (potassium chloride) were investigated by using capillary viscometer method. Area of non-overlapping coils between the crossover concentration and the concentration of fluctuation mesh formation was determined; it was shown that with increase of salt concentration this area practically disappears, i.e. mass transfer mechanism changes near the crossover concentration. It was shown that at low concentrations of potassium chloride increasing the content of ionic groups of macromolecules leads to reduction in the crossover concentration and increase in the effective volume. It is found that the kaolin adsorption capacity decreases when polymers are adsorbed from saline solution, and the adsorption constant is significantly higher in the presence of salt than in water.

scholarly journals Molecular simulation of gases competitive adsorption in lignite and analysis of original CO desorption

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jing Zhang ◽  
Jiren Wang ◽  
Chunhua Zhang ◽  
Zongxiang Li ◽  
Jinchao Zhu ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Molecular Simulation ◽  
Competitive Adsorption ◽  
Air Leakage ◽  
Adsorption Characteristics ◽  
Adsorption Sites ◽  
Simulation Based ◽  
Lignite Coal ◽  
Model C ◽  
Grand Canonical

AbstractTo study the adsorption characteristics of CO, CO2, N2, O2, and their binary-components in lignite coal, reveal the influence of CO2 or N2 injection and air leakage on the desorption of CO in goafs, a lignite model (C206H206N2O44) was established, and the supercell structure was optimized under temperatures of 288.15–318.15 K for molecular simulation. Based on molecular dynamics, the Grand Canonical Monte Carlo method was used to simulate the adsorption characteristics and the Langmuir equation was used to fit the adsorption isotherms of gases. The results show that for single-components, the order of adsorption capacity is CO2 > CO > O2 > N2. For binary-components, the competitive adsorption capacities of CO2 and CO are approximate. In the low-pressure zone, the competitive adsorption capacity of CO2 is stronger than that of CO, and the CO is stronger than N2 or O2. From the simulation, it can be seen that CO2, N2 or O2 will occupy adsorption sites, causing CO desorption. Therefore, to prevent the desorption of the original CO in the goaf, it is not suitable to use CO2 or N2 injection for fire prevention, and the air leakage at the working faces need to be controlled.

scholarly journals Oxidized BPL Carbons

1993 ◽  
Vol 10 (1-4) ◽  
pp. 75-84 ◽  
Author(s):  
S.S. Barton ◽  
M.J.B. Evans ◽  
J.A.F. Macdonald
Keyword(s):  
Nitric Acid ◽  
Surface Area ◽  
Water Adsorption ◽  
Adsorption Properties ◽  
Bet Surface Area ◽  
Adsorption Sites ◽  
A Value ◽  
Nitrogen Desorption ◽  
Oxidized Carbon ◽  
Increasing Temperature

A series of oxidized carbons has been prepared by treatment of the carbon with concentrated nitric acid at various temperatures, and the surface and adsorption properties of the prepared carbons studied. Water adsorption was modelled using a recently derived equation capable of predicting a value for the primary adsorption sites on the surface of a microporous carbon while fitting the experimentally determined isotherm at high relative pressures. The concentration of primary sites was seen to increase with increasing temperature of oxidation. The very highly oxidized carbon samples were found to have a significantly lower BET surface area determined from nitrogen desorption at 77 K and higher apparent density measured from mercury displacement.

scholarly journals Statistical Thermodynamic Model of Gas Adsorption in a Metal-Organic Framework Harboring a Rotaxane Molecular Shuttle

2019 ◽  
Author(s):  
Jonathan Carney ◽  
David Roundy ◽  
Cory M. Simon
Keyword(s):  
Thermodynamic Model ◽  
Gas Adsorption ◽  
Metal Organic Framework ◽  
Adsorption Properties ◽  
Statistical Thermodynamic ◽  
Temperature Sensitive ◽  
Adsorption Sites ◽  
Metal Organic ◽  
Dynamic Components ◽  
Molecular Shuttle

Metal-organic frameworks (MOFs) are modular and adjustable nano-porous materials with applications in gas storage, separations, and sensing. Flexible/dynamic components that respond to adsorbed gas can give MOFs unique or enhanced adsorption properties. Here, we explore the adsorption properties that could be imparted to a MOF by a rotaxane molecular shuttle (RMS) in its pores. In an RMS-MOF, a macrocyclic wheel is mechanically interlocked with a strut. The wheel shuttles between stations on the strut that are also gas adsorption sites. We pose and analyze a simple statistical thermodynamic model of gas adsorption in an RMS-MOF that accounts for (i) wheel/gas competition for sites on the strut and (ii) the entropy endowed by the shuttling wheel. We determine how the amount of gas adsorbed, position of the wheel, and energy change upon adsorption depend on temperature, pressure, and the interactions of the gas/wheel with the stations. Our model reveals that, compared to an ordinary Langmuir material, the chemistry of the RMS-MOF can be tuned to render adsorption more or less temperature-sensitive and release more or less heat upon adsorption. The model also uncovers a non-monotonic relationship between temperature and the position of the wheel if gas out-competes the wheel for its preferable station.

scholarly journals HDPE/SILICA COMPOSITES- PART I: PREPARATION AND CHARACTERIZATION OF METHYLSILANE AND OCTYLSILANE-MODIFIED SILICAS

2019 ◽  
Vol 16 (32) ◽  
pp. 263-278
Author(s):  
Vanessa Machado Babinski RAMOS ◽  
Maurício Gammertt RÖHNELT ◽  
Rodrigo BRAMBILLA
Keyword(s):  
Silica Gel ◽  
Morphological Characteristics ◽  
Specific Area ◽  
Sem Images ◽  
Adsorption Sites ◽  
Pyrogenic Silica ◽  
The Mean ◽  
Complementary Techniques ◽  
Adsorption Desorption

This paper reports the main results concerning the synthesis and characterization of methylsilane and octylsilane-modified silicas. The modification of the silicas with these groups aims to make the silica surface hydrophobic and thus compatible with high-density polyethylene (HDPE) in HDPE/silica composites. In the present work, two types of silica were organofunctionalized: a pyrogenic silica and a silica gel. The silicas were characterized by a series of complementary techniques with the objective of investigating the nature of the surface species and their textural and morphological characteristics. The SEM images showed that the modification of the silicas with organosilanes has been not resulted in changes on the morphology and on the size of silica particles. In relation to the texture properties, determined by N2 adsorption-desorption porosimetry, the silica modification resulted in a decrease of the specific area (SBET) and the mean pore volume, a behavior attributed to the partial coverage of the adsorption sites by the organosilane molecules. The TGA analysis showed that both the methylsilane groups and the octylsilane groups on the surface of silica and silica gel are thermally stable up to 200 ° C, which enables the organofunctionalized silicas in terms of thermal stability, for the process of preparing the composites by extrusion. The results of applying these organofunctionalized silicas in the development of HDPE/silica composites will be presented in a subsequent article, part II of this research.

scholarly journals Synthesis of Micro/nano Urchin-like VO2 Particles and Its Decolorization of Methylene Blue

2019 ◽  
Vol 35 (3) ◽  
Author(s):  
Nguyen The Manh ◽  
Duong Hong Quan ◽  
Vu Thi Ngoc Minh ◽  
Vuong Pham Hung
Keyword(s):  
Methylene Blue ◽  
Sodium Dodecyl ◽  
Adsorption Properties ◽  
Contaminated Water ◽  
Potential Applications ◽  
Synthesis Procedure ◽  
Water Treatments ◽  
Sds Surfactant ◽  
Mb Adsorption

Micro/nano urchin-like VO2 particles were synthesized successfully by hydrothermal method. Vanadium pentoxide (V2O5), oxalic acid (C2H2O4) and sodium dodecyl sulfate (SDS) surfactant were used as reagents for the synthesis of VO2. In this article, we have reported the synthesis procedure of VO2 nanorods and micro/nano urchin-like VO2 structure and evaluating the methylene blue (MB) adsorption properties. Morphology and particle size of VO2 were observed by FE-SEM. The phase formation of VO2 was studied by XRD. Raman spectroscopy was also used for characterization of VO2. Micro/nano urchin-like VO2 structure was showed good MB adsorption properties that have potential applications in dye-contaminated water treatments.

scholarly journals Effects of Saline Solutions on the Desiccation Cracking and Shrinkage Behavior of Gaomiaozi Bentonite

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Long Tan ◽  
Penglin Zheng ◽  
Qingbing Liu
Keyword(s):  
Water Content ◽  
Saline Solution ◽  
Shrinkage Strain ◽  
Sample Surface ◽  
Water Evaporation ◽  
Gmz Bentonite ◽  
Residual Water ◽  
High Concentration ◽  
Desiccation Cracking ◽  
Saline Solutions

Bentonite, when used as buffer/backfill material in the deep disposal of high-level radioactive waste (HLW), could undergo desiccation shrinkage or even cracking due to the heat released from HLW, impairing the efficiency of the barrier system. Furthermore, in-service buffer materials are inevitably in contact with the groundwater, which sometimes contain high salt concentrations. The groundwater salinity may modify the properties of bentonite and hence affect the process of desiccation and its performance. To investigate this effect, in this study, a series of temperature-controlled desiccation tests was conducted on compacted specimens of Gaomiaozi (GMZ) bentonite preliminarily saturated with two different saline solutions (NaCl and CaCl2) at the concentration varying from 0.5 to 2.0 mol/L. The experimental results indicated that, as the concentration of saline solution increases, the initial saturated water content of bentonite decreases, whereas the residual water content at the completion of the desiccation test increases. The water evaporation rate is reduced for the specimens saturated with a high-concentration saline solution, and CaCl2 has a more significant influence on water evaporation than NaCl. The evolution of cracks on the sample surface during the desiccation process can be divided into four stages: crack growth, maintenance, closure, and stabilization; an increase in the salt concentration effectively inhibits crack development. It was shown that the infiltration of saline solutions alters the microstructure of bentonite by changing the arrangement of clay particles from a dispersed pattern to more aggregate state, which results in a decrease in shrinkage strain and shrinkage anisotropy.

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