The swelling characteristics and permeability of bentonite are influenced by various factors, including temperature, stress history, and the salinity of groundwater (Bai et al., 2019; Herbert et al., 2008; Wang et al., 2012; Xiang et al., 2020).The findings of various studies have demonstrated that the salinity levels in groundwater adjacent to coastal nuclear waste …
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Factors Affecting Equilibria. According to the Le Chatelier's Principle, states that if a system under equilibrium is subjected to a change in pressure, temperature or concentration, in this case, the equilibrium shifts further reducing as well as to counteract the effect of the change. The factors that affect equilibria are:
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Altering the rate of collisions results in a change in the speed of a given reaction. The major factors affecting the collision rate (and hence of a reaction) are the following: Concentration of reactants ; Temperature ; Presence of a catalyst ; Spatial orientation of reactant molecules ; Phase of reactants ; Surface area of reactants
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In addition, bentonite has been used as a base for cutaneous therapy, by stabilizing zinc ointment or emulsifying oil and water (Hopkins 1946). Factors affecting adsorption of drugs onto montmorillonite. Various drugs are adsorbed onto montmorillonite by interacting with the surface of the clay sheets.
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Therefore, although both bentonite clays are swelling materials, the high tendency of water absorption from Na + ions in sodium bentonite makes it prone to absorbing relatively large amounts of ...
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In the mid 1990s, the term "quantum sieving" was proposed by Beenakker et al. to denote the quantum effect that arises when the difference between pore size and adsorbate size is close to the de Broglie wavelength of the adsorbate (it must be noted that it is conceived mainly as a kinetic effect but may also affect equilibrium adsorption ...
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The sodium bentonite was stirred at 70 °C for 4 h. The synthesis of sodium bentonite supported with catechol chromium is shown in Figure 2. After cooling down to room temperature, the mixture was centrifuged, washed until it was colorless, and dried at 70 °C. The powdered sodium bentonite-supported metal complex was marked as SBCCr.
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As written above in Reaction (3), we would say that in the forward reaction, iron oxide and hydrogen gas, the reactants, produce the products iron and steam. During the reverse reaction, iron reacts with steam to produce the products iron oxide and hydrogen gas. It is important to understand the terminology, and to use the terms correctly.
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GMZ07 sodium bentonite is an off-white powder with a montmorillonite fraction of about 62 %. ... (5 %) and plagioclase (9 %). The cation exchange capacity is 72.86 mmol/100 g and the main exchangeable cations are Na + (33.71 mmol/100 g), ½Ca 2+ (23. ... Katti and Katti, 2006), resulting in a larger swelling reaction in the compaction direction ...
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Firstly, Fe corrosion leads to the formation of hydrogen, which in turn reduces structural ferric iron in the smectites (both at room temperature or elevated temperatures). …
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On the basis of the compiled data, it is highly probable that surface diffusion plays a significant role in the transport of cations in bentonite clays. Moreover, easily soluble compounds in bentonite can affect the ionic strength of porewater and, consequently, exclusion, equilibrium between cations, and surface diffusion.
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The alkaline reaction of FEBEX bentonite: a contribution to the study of the performance of bentonite/concrete engineered barrier systems La reacción alcalina de la bentonita FEBEX: una ...
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The bentonite in a GCL consists primarily of thin smectite particles which are negatively charged. The negative charge is balanced by cations in a thin layer of bound water surrounding the clay particle (Rowe et al., 2004).Examining the transport of clay particles with deionized water through fissures in bedrock, Moreno et al. (2011) found that a clay structure is …
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The requirements for drilling bentonites are tightening due to ever-increasing demands for petroleum resources, coupled with cost and reaction technology constraints. In addition to raising the risk of drilling, bentonite's poor performance also raises the possibility of safety incidents and significant financial losses. Organically modified bentonites effectively …
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Based on this, it may be said that the composition of smectite in bentonite affects the orientation property of clay particle and also affects diffusion. Furthermore, a penetrated …
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This study investigated the influence of cation type on the sodium deactivation of Brazilian bentonite varieties. Four bentonite clays were studied, including three mixed-cationic and one …
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The composite microstructure changes when exposed to NaCl and CaCl₂ solutions. When sodium ions (Na⁺) enter bentonite interlayers, they reduce electrostatic repulsion between clay …
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The toxic heavy metals-containing wastewater is a great threat to human health [1].Among various heavy metals, lead ion (Pb 2+) is a common pollutant, which can enter the human body and cause loss of appetite, diarrhea, anemia, and long-term damage to the reproductive and nervous systems [2], [3].Therefore, developing sewage treatment technology …
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This study starts from a question: how would initial water content (wi) affect equilibrium swelling pressure (peq) of compacted bentonites in swelling pressure tests (ps …
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The main reasons attributed to the alkaline reaction of Na-montmorillonite with water are the hydrolysis of montmorillonite (exchange of Na + ions from bentonite with H + ions in water) and the ...
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Different salt solutions also affected the direction of movement of the soil particles, causing montmorillonite particles to either attract or repel each other. Studies have shown that …
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What Is Chemical Equilibrium? Chemical equilibrium refers to the state of a system in which the concentration of the reactant and the concentration of the products do not change with time, and the system does not display any further change in properties.. Table of Contents. Types of Chemical Equilibrium; Factors Affecting Chemical Equilibrium; Examples
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The Effect of Pore Structural Factors on Diffusion in Compacted Sodium Bentonite Japan Nuclear Cycle Development Institute, 4-33 Muramatsu, Tokai-mura, Naka-gun, Ibaraki ken 319-1194, Japan, Email: [email protected] ABSTRACT Four kinds of diffusion experiments; (1) through-diffusion (T -D) experiments for diffusion
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Bentonite has been widely used as buffer and backfill materials for nuclear waste disposal in last few decades. The main reasons of bentonite being selected for buffer and backfill materials include its low hydraulic permeability and high plasticity, which can restrict the transport of nuclear waste through the barrier and maintain the sealing ability of barrier, respectively, …
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The information available from the open literature and our studies on exclusion, sorption and diffusion mechanisms of ionic and neutral species in bentonite has been compiled and re-examined in relation to the microstructure of bentonite. The emphasis is placed on a more thorough understanding of the diffusion processes taking place in compacted bentonite. …
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The temperature of spontaneous nucleation T sn and the equilibrium freezing point T f vs. water content in bentonites with bivalent cations (B–Ca 2+ and B–Mg 2+). Download: Download full-size image; Fig. 5. The temperature of spontaneous nucleation T sn and the equilibrium freezing point T f vs. water content in sodium bentonite (B–Na +).
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Permeability Values for permeability of mica, kaolin, a calcium bentonite, and a sodium bentonite are given in Table 5.7 (after Endell et al., 1938). The values show the relative impermeability of sodium bentonite and the great reduction in permeability of sands with the addition of only very small amounts of sodium bentonite.
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free energy change has two components: enthalpy (H), i.e. the energy contained in the chemical bonds of reactants and products, and entropy (S), i.e. the degree of randomness of the system (the symbol Δ indicates the change in the …
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The way to successfully upgrade a phosphate ore is based on the full understanding of its mineralogy, minerals surface properties, minerals distribution and liberation. The conception of a treatment process consists of …
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(Acid Blue 193, AB 193) from aqueous solution onto bentonite and sepiolite samples were studied. These factors were saturation of the samples with cations (Na + and Ca 2+), the pH and the ionic strength of the dye solution. The Langmuir and Freundlich adsorption models were used to describe the equilibrium
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As a result, the equilibrium will change in favor of increasing the number of moles of gas. Changes in temperature. According to Le Chatelier's principle rules, when the temperature of an equilibrium system is raised, i.e. when heat is introduced, the equilibrium will …
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On the basis of the compiled data, it is highly probable that surface diffusion plays a significant role in the transport of cations in bentonite clays. Moreover, easily soluble …
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In this study, the effects of chemical factors on the swelling properties and permeability of bentonite-based materials were clarified based on one-dimensional swelling …
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Bentonite is the favoured material for use as the EBS and backfill in many radioactive waste repository designs [Sellin and Leupin, 2013; Pusch, 1977].A detailed knowledge of this EBS behaviour over a timescale of around 1 million years is required to demonstrate that a geological repository will be able to safely contain HHGWs [Sellin and Leupin, 2013].
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The presence of high calcium component from polymerization process can reinforce the treated material and the observed result was an appearance of the calcium alumina silicate hydrate (C-(A)-S-H) gel [3], [13].Duxson et al. [21] justified as the calcium provides extra nucleation sites for precipitation of dissolved species. A studied by Mingyu [17] proved that the …
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The rates at which reactants are consumed and products are formed during chemical reactions vary greatly. We can identify five factors that affect the rates of chemical reactions: the chemical nature of the reacting substances, the state of subdivision (one large lump versus many small particles) of the reactants, the temperature of the reactants, the …
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The nature of the solution chemistry determined in the aqueous phase has allowed us to calculate the chemical speciation and the saturation indices for the observed minerals. The evaluation of the equilibrium state in the system supports the dissolution of montmorillonite from undersaturation conditions as the driving process for the alkaline reaction of bentonite.
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(a) Is the system at equilibrium? (b) In which direction must the reaction occur to reach equilibrium? (c) What are the equilibrium concentrations of N 2, O 2, and NO? Solution. Use the known concentrations to calculate Q. Compare Q with K c to answer questions (a) and (b). Use an ICE table to answer part (c).
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