Experimental Study and Modeling of Uranium (VI) Sorption onto a Spanish Smectite

2008 ◽  
Vol 1124 ◽  
Author(s):  
Tiziana Missana ◽  
Ursula Alonso ◽  
Miguel Garcia-Gutierrez ◽  
Nairoby Albarran ◽  
Trinidad Lopez
Keyword(s):  
Ionic Strength ◽  
Exchange Process ◽  
Surface Complexation ◽  
Sorption Isotherms ◽  
Sorption Behavior ◽  
Ionic Exchange ◽  
Experimental Conditions ◽  
Sorption Data ◽  
Model Combining ◽  
Wide Range

AbstractAdsorption of uranium onto a Spanish smectite was studied, analyzing the effects of the most important parameters such as pH, ionic strength, radionuclide concentration and solid to liquid ratio. Batch sorption studies, in anoxic conditions under N2 atmosphere, were carried out on the bentonite previously purified and converted into the homoionic Na-form. In the sorption edges, two regions could be clearly distinguished. At pH lower than 5, sorption depended strongly on the ionic strength, possibly indicating the predominance of the uranyl ionic exchange process. At higher pH, sorption did not depend on the ionic strength but only on pH. The sorption behavior in this region suggested the predominance of a surface complexation mechanism. Sorption isotherms showed a non linear behavior in the concentration range used. Sorption data were interpreted using a non electrostatic standard model combining surface complexation, with the weak and strong SOH sites of the clay, and ionic exchange. The acid – base properties of the weak SOH sites were determined by potentiometric titrations. The model used was able to reproduce, in a very satisfactory way, all the data in a wide range of experimental conditions.

Modelling of Pu Sorption onto the Surface of Goethite and Magnetite as Steel Corrosion Products

2003 ◽  
Vol 807 ◽  
Author(s):  
Lara Duro ◽  
Tiziana Missana ◽  
Sonia Ripoll ◽  
Mireia Grivé ◽  
Jordi Bruno
Keyword(s):  
Ionic Strength ◽  
Surface Complexation ◽  
Reduction Process ◽  
Steel Corrosion ◽  
Corrosion Products ◽  
Sorption Data ◽  
Titration Data ◽  
Corrosion Of Steel ◽  
Simple Surface ◽  
Sorption Edge

ABSTRACTWe have studied the surface interaction between tetravalent plutonium and two different steel corrosion products: magnetite, which is the final product of the anoxic corrosion of steel, and goethite, which exemplifies a further oxidation of the steel surface due to the presence of active oxidants in the system. The pH of the experiments has been varied from 2 to 10 and the ionic strength from 0.001 to 0.1 M NaClO4. All the sorption experiments were carried out under N2 atmosphere. No significant effect of ionic strength was observed under the conditions studied.The pHpcz of the solids (7.78 for goethite and 6.95 for magnetite) was determined by modelling potentiometric titration data.The results of the experiments show that the sorption edge of plutonium occurs between pH 3 and 4 when using goethite as a sorbing surface and between pH 4 and 5 when magnetite is used.We have modelled the sorption data by using a simple surface complexation approach with no electrostatic term. The model used involves a reduction process of Pu(IV) to Pu(III) in the presence of magnetite, which can be explained by the interaction of the actinide with the ferrous iron present in the solid. In the case of the experiments conducted with goethite, this reduction process is not possible and, therefore, in the model we have included the sorption of tetravalent Pu.

β-Zeolite modified by ethylenediamine for sorption of Th(IV)

2017 ◽  
Vol 105 (6) ◽  
Author(s):  
Liu Peng ◽  
Wu Hanyu ◽  
Yuan Ni ◽  
Yin Zhuoxin ◽  
Pan Duoqiang ◽  
...  
Keyword(s):  
Steady State ◽  
Humic Acid ◽  
Ionic Strength ◽  
Contact Time ◽  
Surface Complexation ◽  
Sorption Isotherms ◽  
Ph Values ◽  
Β Zeolite ◽  
Batch Technique ◽  
Pseudo Second Order

Abstractβ-Zeolite-EDA was modified with ethylenediamine (EDA) after synthesized. The synthesized material was characterized and used for removal of Th(IV) from aqueous solutions. The influences of pH, ionic strength, contact time, temperature and humic acid (HA) on Th(IV) sorption onto synthesized β-zeolite-EDA was studied by batch technique. The dynamic process showed that the sorption of Th(IV) onto β-zeolite-EDA matched the pseudo-second-order kinetics model. The sorption of Th(IV) on β-zeolite-EDA was significantly dependent on pH values, the sorption percentage increased markedly at pH 3.5–4.5, and then maintained a steady state as pH values increased. Through simulating the sorption isotherms by Langmuir, Freundlich and Dubini–Radushkevich (D–R) models, it could be seen respectively that the sorption pattern of Th(IV) on β-zeolite-EDA was mainly controlled by surface complexation, and that the sorption processes was endothermic and spontaneous. The presence of HA increased Th(IV) sorption on β-zeolite-EDA.

scholarly journals Sorption capacity of phosphate in mineral soils: I Estimation of sorption capacity by means of sorption isotherms

1990 ◽  
Vol 62 (1) ◽  
pp. 1-8
Author(s):  
Raina Niskanen
Keyword(s):  
Ionic Strength ◽  
Sorption Capacity ◽  
Sorption Isotherms ◽  
Clay Content ◽  
Langmuir Equation ◽  
Soil Samples ◽  
Organic Carbon Content ◽  
Sorption Data ◽  
Mineral Soils ◽  
Extractable Al

The sorption capacity of phosphate in seven soil samples (clay content 1—70 %, organic carbon content 0.8—10.7 %, soil pH 4.2—5.3, oxalate-extractable Al 11—222 and Fe 11—202 mmol/kg soil) was studied by means of sorption isotherms. The soils were equilibrated, for two to seven days at +5 and +20°C, with solutions containing phosphate 0—10 mmol/l (0—200 mmol/kg soil) at a constant ionic strength of 0.01 . Prolongation of the reaction time increased the sorption of phosphate only partially. The rise in temperature, from +5 to +20°C, increased the sorption from higher phosphate concentrations. At +20°C, the sorption curves of three soils showed a sorption maximum of 4, 19 and 34 mmol/kg soil. The sorption data of six soils was in accordance with the Langmuir equation; the sorption maximum ranged from 15 to 119 mmol/kg soil, and were of the same magnitude as the maximums determined experimentally.

Modeling the sorption of Np(V) on Na-montmorillonite – effects of pH, ionic strength and CO2

2019 ◽  
Vol 107 (7) ◽  
pp. 615-622
Author(s):  
Raphael Scholze ◽  
Samer Amayri ◽  
Tobias Reich
Keyword(s):  
Ionic Strength ◽  
Surface Complexation ◽  
Ambient Air ◽  
Batch Type ◽  
Wide Range ◽  
Effects Of Ph ◽  
Ph Range

Abstract Results from batch type experiments were modeled using the 2 SPNE SC/CE model developed by Bradbury and Baeyens. This work focused on the applicability of this model to the sorption of Np(V) on Na-montmorillonite under high saline conditions (0.1–3.0 M NaCl) in the pH range of 2–10 and in the presence of dissolved CO2 (p(CO2) = 10−3.3 atm). Under ambient air conditions two additional surface complexation species had to be taken into account, which are ternary species involving one carbonate ligand (≡SONpO2(CO3)2−, ≡SONpO2(CO3)Na−). The gained set of complexation parameters was successfully tested over a wide range of Np(V) concentrations (10−4 to 10−12 M) under Ar atmosphere and ambient air condition.

scholarly journals Multireaction Modeling of Lead (Pb) and Copper (Cu) Sorption/Desorption Kinetics in Different Soils

Soil Systems ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 38
Author(s):  
Tamer A. Elbana ◽  
H. Magdi Selim
Keyword(s):  
Sorption Isotherms ◽  
Langmuir Equation ◽  
Sorption Behavior ◽  
Desorption Kinetics ◽  
Alkaline Soils ◽  
Nonlinear Sorption ◽  
Wide Range ◽  
Desorption Hysteresis ◽  
Insight Into ◽  
Different Soils

Batch kinetic experiments were carried out to quantify and describe the sorption/desorption of Cu and Pb in ten soils that exhibited a wide range of properties. Sorption isotherms were quantified using the Langmuir equation, whereas modeling of sorption/desorption kinetics was described using multireaction model (MRM). Results revealed the nonlinear sorption behavior of Cu and Pb in all soils. The ten soils exhibited higher affinity to Pb (6.4 to 36.5 mmol kg−1) in comparison to Cu (3.6 to 22.4 mmol kg−1). Simulation of Cu and Pb kinetic data indicated that the rate of sorption reaction was two orders of magnitude higher than the rate of release. Considering one irreversible site in addition to one-reversible kinetic site improved the estimation of rates of reaction for both Cu and Pb in acidic and alkaline soils. All soils exhibited sorption/desorption hysteresis where Pb-releases ranged between <0.2% and 14.4% of the total sorbed. The respective Cu releases ranged from <0.85% and 23.4%. The multireaction model, which was successful in describing Cu and Pb for all ten soils, provided insight into the processes of sorption/desorption of Cu and Pb in all soils.

scholarly journals Drying kinetics and sorption behavior of two varieties banana (sagor and sabri) of Bangladesh

2019 ◽  
Vol 16 (2) ◽  
pp. 181-193
Author(s):  
MH Rahman ◽  
MW Ahmed ◽  
MN Islam
Keyword(s):  
Solid Content ◽  
Drying Kinetics ◽  
Sorption Behavior ◽  
Chemical Compositions ◽  
Local Market ◽  
Slice Thickness ◽  
Sorption Data ◽  
Wide Range ◽  
Monolayer Moisture ◽  
Bet Equation

The study was concerned with determining the drying kinetics and sorption behavior of two varieties ripe banana of Bangladesh namely, Sagor and Sabri. The fresh ripe banana collected from the local market were sliced into three different thicknesses (4 mm, 6 mm and 8 mm) and dried at 45°C, 55°C and 65°C in a cabinet dryer. The result showed that the drying rate increases with the increase in temperature and decreases with the increase in slice thickness. The sorption properties of dried banana were studied over a wide range of water activity (0.11-0.93). The BET and GAB models were fitted to the sorption data. It was found that both varieties gave sigmoid (type II) shape isotherm and GAB equation gave the much higher value of monolayer moisture content compared to BET equation. The chemical compositions of fresh and dried banana were determined. The dried products gave substantially higher solid content as well as protein, ash and carbohydrate. SAARC J. Agri., 16(2): 181-193 (2018)

Sorption behavior of Florisil for the removal of antimony ions from aqueous solutions

2011 ◽  
Vol 63 (10) ◽  
pp. 2114-2122 ◽  
Author(s):  
Lei Zhang ◽  
Qing Lin ◽  
Xingjia Guo ◽  
Francis Verpoort
Keyword(s):  
Aqueous Solutions ◽  
Sorption Isotherms ◽  
Sorption Behavior ◽  
Order Kinetic ◽  
Sorption Data ◽  
Maximum Sorption ◽  
Boundary Layer Diffusion ◽  
Intra Particle Diffusion ◽  
Order Kinetic Model ◽  
The Mean

Florisil was employed for the sorption of antimony ions from aqueous solutions. A detailed study of the process was performed by varying the sorption time, pH, and temperature. The sorption was found to be fast, equilibrium was reached within 15 min. Moreover, a maximum sorption has been achieved from solution when the pH ranges between 1–10. From kinetic experiments it follows that the process correlate with the second-order kinetic model. The overall rate process appears to be influenced by both boundary layer diffusion and intra-particle diffusion. The Langmuir and Dubinin-Radushkevich (D-R) type sorption isotherms can be applied to fit and interpret the sorption data. The mean energy of adsorption (9.73 kJ mol−1) was calculated from the Dubinin-Radushkevich (D-R) adsorption isotherm at room temperature. Furthermore, the thermodynamic parameters for the sorption were also determined, and the ΔH0 and ΔG0 values indicate a spontaneous endothermic behavior.

Sorption and surface complexation modeling of 137Cs on Fe(II)-montmorillonite clay mineral relevant to nuclear waste disposal

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Santosh Chikkamath ◽  
Madhuri A. Patel ◽  
Aishwarya S. Kar ◽  
Bhupendra S. Tomar ◽  
Jayappa Manjanna
Keyword(s):  
Ionic Strength ◽  
Surface Complexation ◽  
Fission Products ◽  
Dominant Mode ◽  
High Yield ◽  
High Level Waste ◽  
Sorption Behavior ◽  
Surface Complexation Modeling ◽  
Dissolved Iron ◽  
High Level

AbstractBentonite, a natural clay, is a promising candidate to be used as a buffer/backfill material in the geological disposal systems for management of high level waste (HLW). Fe released due to corrosion of canister/overpack may result in alteration of Na-montmorillonite (Na-Mt), present in bentonite, to Fe-montmorillonite (Fe-Mt) in a span of several years after the emplacement of vitrified HLW in deep geological repositories. For realistic performance assessment, it is essential to understand the sorption behavior of altered Mt with regard to the radionuclides present in HLW. Cs is one of the high-yield (137Cs t1/2 = 30.1 y, 6%) and long-lived (135Cs t1/2 = 2 × 106 y) fission products in spent fuels. The objective of present study is to understand the effect of various parameters, viz., time (0–48 h), pH (3.0–9.0), ionic strength (0.001–1 M) [Cs(I)] (10−10–10−3 M) and Fe dissolution on sorption behavior of Cs(I) on Fe(II)-Mt through batch sorption experiments. Fe(II)-Mt was synthesized by reducing Fe(III)-Mt using ascorbic acid as reducing agent in N2 atmosphere. The near-constancy in Cs(I) sorption on Fe(II)-Mt with pH (≥4), and decrease with increasing ionic strength, illustrate the ion exchange as dominant mode of Cs(I) sorption. Further, Cs(I) sorption isotherm on Fe(II)-Mt is found to be linear. The estimation of dissolved iron in the supernatant of Fe(II)-Mt suspensions demonstrated that dissolved Fe decreased with increase in pH and increased with increase in ionic strength. Moreover, the Fe2+/Fetotal ratio determined in all experiments was close to unity, thereby depicting that Fe(II) did not oxidize to Fe(III), except when suspension pH was ≥ 5.5. For comparison, Cs(I) sorption was also studied on Na(I)-Mt and compared with that on Fe(III)-Mt. Surface complexation modeling of Cs(I) sorption on the three clay minerals, viz., Na-Mt, Fe(II)-Mt and Fe(III)-Mt, has been successfully carried out.

scholarly journals Effects of ions on the characteristics of monolayer at brine/oil interfaces

2019 ◽  
Vol 89 ◽  
pp. 04003 ◽  
Author(s):  
Mohammed B. Alotaibi ◽  
Dongkyu Cha ◽  
Karam Chand ◽  
Ali A. Yousef
Keyword(s):  
Ionic Strength ◽  
Oil Recovery ◽  
Ionic Exchange ◽  
Surface Charges ◽  
High Salinity Water ◽  
Chemical Structures ◽  
Wide Range ◽  
Injection Water ◽  
Oil Components ◽  
Model Oil

The advanced waterflooding technologies through salinity and ionic content adjustment can make favorable impacts on rock wettability and oil recovery. In carbonate reservoirs, SmartWater at low ionic strength showed strong chemical interactions with carbonate minerals and oil components. As a result, several hypotheses are proposed in literature as ionic exchange, rock dissolution, surface charges and others. The applied macroscopic and microscopic technologies have certain limitations in identifying the structures at interfaces especially at monolayers. In this paper, advanced Sum Frequency Generation (SFG) spectroscopy is utilized for the first time to characterize the chemical structures of molecules at the brine/oil interfaces. Different brines recipes and model oil are tested to determine the effects of individual and combined ions on the monolayer structures. Stearic acid is also mixed with hydrocarbons to mimic the acidity condition of fluids in the reservoir. The change in the chemical structure is mo nitored with time at a broad wavenumber range from 1,000 to 3,800 cm-1. Distinct spectral signatures of oil components and water ions are detected at different pH conditions. The SFG data is compared with the previous macroscopic wettability results to predict the components that are highly affected during waterflooding and enhanced oil recovery (EOR) processes. This study brings new insights on understanding the chemical structures at the thin monolayers of flat and curved geometric at different aqueous interfaces. The measured spectra, coupled with a wide range of laser polarization settings, and signal intensity trends are discussed in terms of composition, and structure of organic and inorganic components. For example, the intensity for SmartWater at certain wavenumber is three folds higher when compared to high salinity water. This indicates that the interactions at oil/water interfaces are enhanced at lower ionic strengths. In addition, these findings are also confirmed with similar behaviors at a higher salinity brine as connate formation brine. The novelty of this interfacial study can provide better understanding of the reaction mechanisms altering the ionic strength and salinity of injection water and its impact due to the changes in geometric interfaces. Such understanding is also crucial to optimize the chemistry of injection water and its interaction with oil components and carbonate rock, to ultimately alter wettability toward water-wet.

scholarly journals Moisture Sorption Behavior of Cupuassu Powder

2019 ◽  
Vol 11 (1) ◽  
pp. 66-73 ◽  
Author(s):  
Joseane C. P. Pombo ◽  
Juliana R. Carmo ◽  
Adriano L. Araújo ◽  
Heloisa H. B. R. Medeiros ◽  
Rosinelson S. Pena
Keyword(s):  
Active Material ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Sorption Behavior ◽  
Powder Morphology ◽  
Sorption Data ◽  
Moisture Sorption Isotherms ◽  
Microbiological Stability ◽  
Hygroscopic Behavior ◽  
Soluble Components

Introduction: In this research, the hygroscopic behavior of cupuassu (Theobroma grandiflorum) powder containing 40% maltodextrin was studied via the moisture adsorption and desorption isotherms at 25°C. Methods: The experimental sorption data of the cupuassu powder were fitted using the Halsey, Henderson, Oswin, GAB and Peleg models. In addition, the powder morphology was assessed using scanning electron microscopy. Results: Moisture sorption isotherms curves showed type III behavior, typical of foods rich in soluble components, such as sugars, present in the samples. The adsorption curve indicated that the product requires greater attention when stored and handled in environments with relative humidity above 50%. The microbiological stability of the product is assured up to 11.5% moisture content. Conclusion: During the product storage, it is recommended to use packaging with water vapor and air impermeability, due to the presence of porous microspheres that affect the protection of the active material and facilitate the moisture gain. Among the models evaluated, the Peleg and GAB models presented good suitability on predicting the product’s sorption isotherms.

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