Ternary Isotherms Research Articles

Ion Exchange of Selected Group II Metals and Lead by Crystalline Silicotitanate and Competition for Cs Exchange Sites

ABSTRACT A series of batch contact tests were conducted to evaluate the exchange behavior of Ba, Ca, Pb, and Sr onto crystalline silicotitanate (CST) in support of an expedited Cs removal and pretreatment system at the Hanford site. Binary Na/M2+ and ternary Na/Cs/M2+ isotherms were generated to understand selectivity, capacity, and competitive impact of each analyte on Cs uptake from a simple 1 M NaOH/4.6 M NaNO3 simulant. Analyte loading from a 0.1 M NaOH/5.5 M NaNO3 simulant was assessed to determine the effect of hydroxide concentration on binary Na/M2+ isotherms. Results from binary and ternary isotherms indicated that Group II metals Ca, Sr, and Ba (and Pb) do not impact CST performance toward Cs removal at concentrations expected in Hanford tank-waste supernate.

The use of rice and coffee husks for biosorption of U (total), 241Am, and 137Cs in radioactive liquid organic waste.

Rice and coffee husks (raw and chemically activated) are examined as potential biosorption materials regarding their capacity to remove U (total), 241Am, and 137Cs. The physical parameters evaluated were the morphological characteristics of the biomass, real and apparent density, and surface area. Contact times for the batch experiments were 0.5, 1, 2, and 4h, and the concentrations tested ranged between 10% of the total concentration and the radioactive waste itself without any dilution. The results were evaluated by experimental sorption capacity, ternary isotherm, and kinetics models. The kinetics results showed that equilibrium was reached after 2h for all biomass. Raw coffee husk showed the best adsorption results in terms of maximum capacity (qmax) for all three radionuclides, which were 1.96, 39.4 × 10-6, and 46.6 × 10-9mgg-1 for U, Am, and Cs, respectively. The biosorption process for the raw and activated rice husks was best represented by the Langmuir ternary isotherm model with two sites. For the coffee husk, in the raw and activated states, the biosorption process was best described by the modified Jain and Snoeyink ternary model. These results suggest that biosorption with these biomaterials can be applied in the treatment of liquid organic radioactive waste containing mainly uranium and americium.

Experimental study and thermodynamic modelling of the Cu-Fe-Si-U sub-systems

The vitrification is a possible treatment for the conditioning of the metallic Long-Lived Intermediate-Level nuclear waste. This process is characterised by the presence of immiscible oxide and metallic liquids that react each other. A thermodynamic model using the Calphad method is then required to predict the composition of the treated waste and the speciation of uranium in this complex system. The quaternary Cu-Fe-Si-U is chosen as the most representative to describe the metallic liquids that appear at high temperature. Key sub-systems of this quaternary are experimentally investigated and thermodynamically modelled. The description of the liquidus in the Si-rich corner of the binary Cu-Si is improved. The Cu-U is assessed with the Calphad method for the first time; it is characterised by a large miscibility gap in the liquid phase. Some new ternary isotherms of the ternary Cu-Fe-Si are then proposed: a large liquid miscibility gap appears also in this system in agreement with the observed behaviour of the metallic liquid during the experimental investigations. The Cu-Si-U system is characterised by three ternary intermetallic compounds: CuSiU, Cu2Si2U and Cu4Si4U3. A first description is proposed, but more data are still required to improve the thermodynamic modelling of this system.

Understanding the adsorption of Pb2+, Hg2+ and Zn2+ from aqueous solution on a lignocellulosic biomass char using advanced statistical physics models and density functional theory simulations

This study reports the combination of new statistical physics models and density functional theory (DFT) for the analysis and understanding of the adsorption of heavy metals on a flamboyant biomass-based adsorbent. Single and ternary isotherms of the adsorption of Pb2+, Hg2+ and Zn2+ ions on an adsorbent obtained from the pyrolysis of flamboyant biomass were determined experimentally at pH 5 and 298–313 K. Experimental studies showed that the adsorption of Hg2+ on flamboyant char was higher than those of Zn2+ and Pb2+ in both single and ternary solutions. A strong antagonistic effect for the multicomponent adsorption of Zn2+ was identified due to the presence of other competitive metal ions in the ternary solution. The endothermic adsorption mechanism involved in both mono- and multi-metallic solutions was explained via the integration of the results from the adsorbent physicochemical characterization and calculations using statistical physics models and density functional theory. Theoretical studies showed that the single-compound adsorption of heavy metals correlated with the calculated DFT binding energies of oxygen-containing functionalities of flamboyant surface. On the other hand, the electronegativity and the thermodynamic stability of the metal – active site complexes determined the adsorbent selectivity and adsorption capacities in the simultaneous removal of these heavy metals. In particular, the carboxylic functional groups of flamboyant char were the main active sites involved in the adsorption of these heavy metals in both mono- and multi-component aqueous solutions. These new findings contribute to a deeper understanding of the mechanisms involved in the multicomponent adsorption of relevant water pollutants such as heavy metals using carbon-based adsorbents.

Adsorption of naturals hormones estrone, 17β-estradiol, and estriol by rice husk: monocomponent and multicomponent kinetics and equilibrium

ABSTRACTIn the present study, the use of the rice husk biomass as an alternative biosorbent for treating the estrone, 17 β-estradiol, and estriol hormones in monocomponent and multicomponent systems was investigated. The high-performance liquid chromatography technique (HPLC-UV) was applied in order to quantify the hormones, validating this method according to ANVISA and INMETRO. The biosorbent presented functional groups typical of cellulose, hemicellulose, lignin, and proteins, with an amorphous, fibrous, and porous surface. The best performance was obtained with a neutral pH and at room temperature (25C). The equilibrium times in batch systems were 60 min for the estrone, and 120 min for 17 βestradiol and estriol. The monocomponent kinetics of adsorption of estrone and estriol were adequately described by the pseudo-first-order model, whereas for the 17 β estradiol both pseudo-first-order and pseudo-second-order models well described the experimental data. For the multicomponent system, the kinetics of adsorption was appropriately represented by the pseudo-first-order model, demonstrating that the number of active sites was the limiting factor of the process. The monocomponent adsorption isotherms were adequately fitted by the Langmuir model, reaching adsorption capacities of 2.698, 1.649, and 0.979 mg g−1 for the estrone, 17 βestradiol, and estriol hormones, respectively. The ternary isotherm models did not represent the experimental data, indicating that there was no competition among the hormones. The reactions presented favourable and spontaneous characteristics. The rice husk biomass showed a great potential as an adsorbent when treating effluents contaminated with hormones.

An expanded Markham and Benton approach to describe multi-component adsorption of sugars on zeolite beta

Abstract Single- and multi-component adsorption isotherms of sorbitol, fructose, and glucose on zeolite beta (Na+BEA 150) were determined in sodium phosphate buffer using batch experiments. The standard Markham and Benton approach to predict binary isotherms from single-component data significantly overestimated the loading at high concentrations of two or more compounds. Therefore, an interaction parameter was introduced to the Markham and Benton model describing mutual blocking of binding sites in binary mixtures at high concentrations. With these changes, the expanded model was able to describe the multi-component isotherms of different binary mixtures in the concentration range from zero to 100 g/L for each compound. Moreover, the interaction parameters determined from binary isotherm data were used to predict ternary isotherms and a good agreement between model and experiments was achieved.

Effect of Zn content on Cu–Ni cross-interaction in Cu/Sn–xZn/Ni micro solder joints

The effect of Zn content on Cu–Ni cross-interaction in Cu/Sn–xZn/Ni (x = 1, 5, 9) micro solder joints during reflow at 250 °C was investigated. The cross-sectional microstructure, top-view morphology and phase composition of interfacial intermetallic compounds (IMCs) were examined to reveal IMC evolution. At the Ni side, Cu–Ni cross-interaction occurs in all the solder joints. However, the Cu–Ni cross-interaction is obviously weakened when the Zn content is higher than 5 wt% by forming Ni5Zn21-type or Ni3Sn4-type IMCs instead of Cu6Sn5-type IMC which is a typical reaction product under Cu–Ni cross-interaction. At the Cu side, Cu–Ni cross-interaction occurs in all the Cu/Sn–1Zn/Ni solder joints and the Cu/Sn–5Zn/Ni and Cu/Sn–9Zn/Ni solder joints after the initial Cu5Zn8-type IMC transforms into CuZn-type IMC. Zn can strongly retarded the Cu–Ni cross-interaction by dominating interfacial reaction. The reaction path at each interface is discussed based on the Sn-rich corner of Sn–Zn–Cu, Sn–Zn–Ni and Sn–Ni–Cu ternary isotherms.

Detailed calculation of complex fluid phase equilibrium sections for ternary systems

Phase equilibrium diagrams of fluid phases in ternary systems can have a high complexity. In this work, a strategy and calculation methods for the computation of complete sections of ternary fluid phase equilibrium surfaces is proposed. To illustrate the methodology, we present computed results for the fluid phase equilibrium of an isothermal section for the ternary highly non-ideal system CO2+H2O+2-propanol(IPA), as described by a given model and given set of values of the model parameters. The calculation method is based on the prior identification of (univariant) key points (KPs) of the ternary isotherm. From such KPs, it is possible to build the different equilibrium lines that constitute the ternary isothermal diagram, with the help of a numerical continuation method. The results show a high level of complexity including a number of three-phase loci, critical loci, and ternary critical endpoints, together with a ternary four-phase equilibrium point.

Features of Zr-rich corner of the Zr-N-O ternary system by controlled low-pressure oxidation and thermodynamic analysis

ABSTRACTIn order to clarify the Zr-rich corner of the Zr-N-O ternary system, a series of nitridation and controlled low-pressure oxidation heatings were made on zirconium metal plates. The experiments were made in separated reaction sequences, which were (1) oxidation of pre-nitrided zirconium, and (2) simultaneous nitridation and oxidation of zirconium. Low-partial pressures of oxygen were obtained by using a redox couple of either Mo/MoO2 or Cu2O/CuO. The samples were characterized by X-ray diffraction, optical microscopy, and electron probe micro analysis. Experimental results were coupled with a preliminary thermodynamic analysis with a sublattice formalism to draw a provisional ternary isotherm at 1373 K.

Liquid‐liquid phase split in ionic liquid + toluene mixtures induced by CO2

High pressure carbon dioxide was dissolved in ionic liquid + toluene mixtures to obtain the conditions of pressure and composition where a liquid‐liquid phase split occurs at constant temperature. Ionic liquids (ILs) with four different cations paired with the bis(trifluoromethylsulfonyl)imide ([Tf2N]−) anion were selected: 1‐hexyl‐3‐methylimidazolium ([hmim]+), 1‐hexyl‐3‐methylpyridinium ([hmpy]+), triethyloctylphosphonium ([P2228]+), and tetradecyltrihexylphosphonium ([P66614]+). The solubility of CO2 was measured in the liquid mixtures at temperatures between 298 and 333 K and at pressures up to 8 MPa, or until the second liquid phase appeared, for initial liquid phase compositions of 0.30, 0.50, and 0.70 mole fraction of IL. Ternary isotherms were compared with the binary solubility of CO2 in each IL and pure toluene. The lowest pressure for separating toluene in a second liquid phase was achieved by decreasing the temperature of the system, increasing the amount of toluene in the initial liquid mixture and using [hmim][Tf2N]. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2968–2976, 2015

Modeling Langmuir isotherms with the Gillespie stochastic algorithm

The overall goal of this work is to develop a robust modeling approach that is capable of simulating single and multicomponent isotherms for biological molecules interacting with a variety of adsorbents. Provided the ratio between the forward and reverse adsorption/desorption constants is known, the Gillespie stochastic algorithm has been shown to be effective in modeling isotherms consistent with the Langmuir theory and uptake curves that fall outside this traditional approach. We have used this method to model protein adsorption on ion-exchange adsorbents, hydrophobic interactive adsorbents and ice crystals. In our latest efforts we have applied the Gillespie approach to simulate binary and ternary isotherms from the literature involving gas–solid adsorption applications. In each case the model is consistent with the experimental results presented.

A Morphology of Diffusion Zone from Entropy Production Calculations

Interdiffusion plays a significant role in the formation and stability of metallic joints and coatings. It is also of critical importance in designing advanced materials. Because commercial alloys are usually multicomponent, the key target is prediction of a complex morphology of the diffusion zone which grows between the alloys, alloy-coating, etc. In a two-component system, the diffusion zone can be composed of single-phase layers of the intermetallic compounds and solid solutions. The evolution of the composition and thicknesses of such layers are fairly well understood and consistent with the phase diagrams. The situation is qualitatively different in multicomponent systems. For example, the diffusion zone in a ternary system can be composed of single-and two-phase sublayers. Their number and thicknesses depend on the initial conditions, i.e. composition, component diffusivities and geometry of the system. The usual way of presenting the sequence of the layers and their compositions is by drawing adiffusion path which is, by definition, a mapping of the stationary concentrations onto the isothermal section of the equilibrium phase diagram. The diffusion path connects initial compositions of the diffusion couple and can go across the single-, two-and three-phase fields. It starts at the composition of one alloy and ends at the other. The possibility of mapping the concentration profiles onto the ternary isotherm has been postulated in one from the seventeen theorems by Kirkaldy and Brown [] for the diffusion path. The detailed presentation of all theorems was recently done by Morral []. Here we remind the reader only of the chosen ones (shown in italics).

Thermodynamic assessment of orientationally disordered organic molecular crystals: Ternary system pentaerythritol–neopentylglycol–2-amino-2methyl-1,3, propanediol (PE–NPG–AMPL)

Organic crystals such as pentaerythritol [PE-C(CH2OH)4], neopentylglycol [NPG-(CH3)2C(CH2OH)2] and 2-amino-2methyl-1,3,propanediol [AMPL-(HOCH2)2C(NH2)CH3] store a large amount of thermal energy in their solid state high temperature phases with orientational disorder. There are very few pure compounds of these polyalcohol and amine family that are commercially available exhibiting these properties, leading to limited choices of energy storage materials. Binary and ternary solid solutions allow a wider selection of materials with different phase transition temperature, heat content, and compositions for practical applications. Thermodynamic calculations of the PE–NPG–AMPL system are presented that provide critical thermodynamic data for energy storage systems. Substitutional solution model is used for optimization of interaction parameters. Activities of binaries, ternary isotherms of PE–NPG–AMPL at various temperatures, and pseudo-binary isopleth are presented.

Influence of Boom Clay organic matter on the adsorption of Eu3+by illite – geochemical modelling using the component additivity approach

AbstractThe solid–liquid distribution of europium (Eu) between an adsorptive surface and a solution phase containing a competitive colloid is the result of a delicate balance between several individual chemical reactions. In this study, adsorption isotherms of Eu in presence of dissolved Boom Clay natural organic matter were experimentally determined under conditions relevant for a geological repository (trace Eu concentrations, anoxic conditions, ∼0.014 mol l−1NaHCO3background electrolyte). It was found that both the concentration and size distribution (or operational cut-off used to discriminate between “mobile” and “immobile” colloids) of natural organic matter has a strong influence on the observed solid–liquid distribution.The experimental data were subsequently modelled using a component additive approach with two well-established sorption/interaction models: the 2 SPNE SC/CE model for describing Eu adsorption on illite, and Humic Ion-Binding Model VI for describing Eu complexation to natural organic matter. Model parameters were gathered from dedicated measurements in batch systems containing only Eu and the interacting phase under study, under similar conditions as in the ternary isotherm experiments. Mutual interactions between illite and natural organic matter were studied and quantified. Under the experimental conditions of this study, it was found that these interactions were only of minor importance.The two models were subsequently combined to blind predict the Eu solid–liquid distribution in the ternary batch experiments. Within an error margin of 0.5logߙKdunits, the additivity approach succeeded well in predicting Eu uptake in all experimental systems studied. A sensitivity analysis was performed to select the most important model parameters influencing the Eu uptake, and the robustness of the model. This study has shown that the component additivity approach for describing and predicting uptake of trivalent lanthanides/actinides under Boom Clay conditions, is promising, and may help in unraveling the complex behaviour of these radionuclides witnessed in migration experiments.

Microstructural Characterization of U-Nb-Zr, U-Mo-Nb, and U-Mo-Ti Alloys via Electron Microscopy

Ternary uranium molybdenum alloys are being examined for use as dispersion and monolithic nuclear fuels in research and test reactors. In this study, three such ternary alloys, with compositions U-10Nb-4Zr, U-8Mo-3Nb, and U-7Mo-3Ti in wt.%, were examined using scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) with high angle annular dark field (HAADF) imaging via scanning transmission electron microscopy (STEM). These alloys were homogenized at 950 °C for 96 h and were expected to be single-phase bcc-γ-U. However, upon examination, it was determined that despite homogenization, each of the alloys contained a small volume fraction precipitate phase. Through SEM and XRD, it was confirmed that the matrix retained the bcc-γ-U phase. TEM specimens were prepared using site-specific focused ion beam (FIB) in situ lift out (INLO) technique to include at least one precipitate from each alloy. By electron diffraction, the precipitate phases for the U-10Nb-4Zr, U-8Mo-3Nb, and U-7Mo-3Ti alloys were identified as bcc-(Nb,Zr), bcc-(Mo,Nb), and bcc-(Mo,Ti) solid solutions, respectively. The composition and phase information collected in this study was then used to construct ternary isotherms for each of these alloys at 950 °C.

Al-Dy-Sb (Aluminum-Dysprosium-Antimony)

The Al-Dy [Massalski2] phase diagram shows the following intermediate phases: AlDy2 (C23, Co2Si-type orthorhombic), Al2Dy3 (Zr3Al2-type tetragonal), AlDy (ErAl-type orthorhombic), Al2Dy (C15, MgCu2-type cubic), aAl3Dy (D024, Ni3Ti-type hexagonal), and bAl3Dy (stable between 1090 and 1005 C; HoAl3-type rhombohedral). The Al-Sb phase diagram [Massalski2] depicts the stoichiometric compound AlSb (B3, Sphalerite-type cubic). The Dy-Sb phase diagram [Massalski2, 2009Zen] has the following intermediate phases: Dy5Sb3 (D88, Mn5Si3-type hexagonal), bDy4Sb3, aDy4Sb3 (D73, Th3P4-type cubic), DySb (B1, NaCl-type cubic), and Dy2Sb5 (monoclinic, P21/m). Ternary Isothermal Section

Adsorption Behavior of the Three Species of the Biprotic Peptide Phe-Ala onto an End-Capped C18-Bonded Organic/Inorganic Hybrid Stationary Phase

We recorded the overloaded elution band profiles of the dipeptide phenylalanine-alanine (Phe-Ala) on a column packed with C18-bonded organic (ethyl)/inorganic (silica) hybrid porous particles (BEH), eluted with a series of buffered methanol-water mobile phases (20/80, v/v). The (W)(S)pHs of the mobile phases were successively adjusted with addition of suitable buffers to values of 1.67, 2.44, 3.83, 4.94, 7.41, and 10.71 (where the notation (W)(S)pH means that the pH of the solution is directly measured in the solution (S) after the electrode was calibrated in pure water (W)). The ionic strength of the eluent was kept constant at 20 mM. The injected samples had different sizes and concentrations. The retention of the low-concentration samples was minimum at an intermediate (W)(S)pH (k' approximately 0.5) and maximum for the lowest (k' approximately 1.3) and highest (k' approximately 3.5) (W)(S)pHs showing that the zwitterion (+Phe-Ala-) is less strongly adsorbed than the positively (+Phe-Ala) and negatively (Phe-Ala-) charged species of the dipeptide onto BEH-C18. The elution profiles of the concentrated samples demonstrated that the adsorption isotherm of the zwitterionic species is an anti-Langmuirian Moreau isotherm due to significant adsorbate-adsorbate interactions, whereas the isotherms of the charged species are more conventional Langmuir isotherms. A simple ternary isotherm for the coadsorption of the three dipeptide species is proposed. It accounts well for the complex band profiles observed when large concentrated samples of the peptide are injected under controlled pH conditions. The slight departure between the calculated and the experimental band profiles obtained under uncontrolled pH conditions suggests the possible adsorption of the buffer components onto the packing material and the possible influence of microenvironment effects near the stationary phase surface, which would affect the local pH along the column. Preparative chromatography of peptides should preferentially be operated at intermediate (W)(S)pHs or with high ionic strength buffers under acidic or basic (W)(S)pHs.

Phase constituents of Al-rich U–Mo–Al alloys examined by transmission electron microscopy

To supplement the understanding of diffusional interactions involving Al-rich region of the U–Mo–Al system, alloys with composition 85.7Al–11.44U–2.86Mo and 87.5Al–10U–2.5Mo in at.%, were examined to determine the equilibrium phase constituents at 500 °C. These alloys were triple arc-melted, homogenized at 500 °C for 200 h, and water-quenched to preserve the high temperature microstructure. X-ray diffraction, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (XEDS), and transmission electron microscopy (TEM) with high angle annular dark field (HAADF) imaging via scanning transmission electron microscopy (STEM) were employed for the characterization. Alloy specimens for TEM/STEM were prepared using site-specific focused ion beam (FIB) in situ lift-out (INLO) technique. Despite the homogenization time and temperature, five different phases, namely fcc-Al solid solution, cubic-UAl 3, orthorhombic-UAl 4, hexagonal-U 6Mo 4Al 43 and diamond cubic-UMo 2Al 20, were observed. Based on U–Al, U–Mo and Al–Mo binary phase diagrams, previously proposed U–Mo–Al isotherms, and the solidification microstructure of these alloys, the Al-rich region of the equilibrium ternary isotherm at 500 °C was constructed. The fcc-Al solid solution, orthorhombic-UAl 4, and diamond cubic-UMo 2Al 20 which were determined to be the equilibrium phases in 85.7Al–11.44U–2.86Mo and 87.5Al–10U–2.5Mo alloys.

Al-Pr-Sb (Aluminum-Praseodymium-Antimony)

The Al-Pr phase diagram [Massalski2] shows the following intermediate compounds: aPr3Al (D019, Ni3Sn-type hexagonal), bPr3Al (L12, AuCu3-type cubic), Pr2Al (C23, Co2Si-type orthorhombic), aPrAl (ErAl-type orthorhombic), bPrAl (CeAl-type orthorhombic), PrAl2 (C15, MgCu2-type cubic), PrAl3 (Ni3Sn-type hexagonal), PrAl4 or bPr3Al11 (D13, Al4Ba-type tetragonal), and aPr3Al11 (aLa3Al11-type orthorhombic). The Al-Sb phase diagram depicts the equiatomic compound AlSb, which melts congruently at 1058 C [Massalski2]. The Pr-Sb phase diagram [Massalski2] depicts the following compounds: Pr2Sb (La2Sb-type tetragonal), Pr5Sb3 (Mn5Si3-type hexagonal), Pr4Sb3 (Th3P4-type cubic), bPrSb (stable above 1950 C), aPrSb (NaCl-type cubic), and PrSb2 (SmSb2-type orthorhombic). Ternary Isothermal Section

Dy-Fe-Pt (Dysprosium-Iron-Platinum)

The Dy-Fe phase diagram [Massalski2] shows the following intermetallic compounds: Fe17Dy2 (Ni17Th2-type hexagonal), Fe23Dy6 (D8a, Mn23Th6-type cubic), Fe3Dy (Be3Nb-type rhombohedral), and Fe2Dy (C15, MgCu2type cubic). The Dy-Pt [2006Oka, 2007Lei] depicts the following compounds: Dy3Pt (D011, Fe3C-type orthorhombic), Dy2Pt (C23, Co2Si-type orthorhombic), Dy5Pt3 (D88, Mn5Si3-type hexagonal), Dy5Pt4 (Ge4Sm5type orthorhombic), DyPt (B27, FeB-type orthorhombic), Dy3Pt4 (Pd4Pu3-tpe rombohedral), DyPt2 (C15, MgCu2type cubic), DyPt3 (L12, AuCu3-type cubic), and DyPt5 (orthorhombic). The Fe-Pt phase diagram [Massalski2] shows three ordered phases: Fe3Pt (L12, AuCu3-type cubic), FePt (L10, AuCu-type tetragonal), and FePt3 (AuCu3-type cubic). Ternary Isothermal Section