Multicomponent Equilibria Research Articles

A concurrent approach for determining binary isotherm and optimizing moving bed adsorber for solid amine adsorbent in the coexistence of CO2 and H2O

A concurrent approach, which allows for determining multi-component equilibrium isotherms and designing a multi-component adsorption process within a realistic amount of time and effort, is demonstrated for the first time in a moving bed process using an amine-impregnated solid adsorbent in the presence of CO2 and H2O. The proposed approach extracts measurement points for the binary isotherms from the temperature and partial pressure regions that exist in the optimized process from all potential combinations of CO2 partial pressure, H2O partial pressure, and temperature. At the extracted points, the equilibrium adsorption amounts were measured experimentally to obtain multi-component adsorption amount data, with which the binary isotherm parameters were determined by the Tikhonov regularization. The accuracy of the equilibrium isotherm was further improved iteratively by repeating the steps described above. The proposed approach enables us to determine the binary interactions parameters in the isotherm model reducing the multi-component measurement points only to 12, while obtaining the optimized process operation at the same time.

Multicomponent Equilibrium Isotherms and Kinetics Study of Heavy Metals Removal from Aqueous Solutions Using Electrocoagulation Combined with Mordenite Zeolite and Ultrasonication

Multicomponent Equilibrium Isotherms and Kinetics Study of Heavy Metals Removal from Aqueous Solutions Using Electrocoagulation Combined with Mordenite Zeolite and Ultrasonication

Development and application of matte/speiss/metal thermodynamic database for optimization of processing of drosses, dusts and reverts from lead, zinc and copper production

Detrimental elements such as arsenic and antimony tend to accumulate in dusts and drosses of lead-zinc as well as copper smelters. These by-products are commonly treated in dedicated reductive smelting units producing Cu-rich matte, As-Sb-collecting speiss and Pb-rich metal, as well as liquid slag. Such process would have a complex distribution of elements (Cu, Fe, Pb, Zn, Ni, Sn, Sb, As, Ag, Au, S, etc.) among four liquid phases. Thermodynamic calculations can be used for predictions and optimization of such processes. They must rely on accurate models developed in integration with experimental program. Present study reports results of recent progress in experimental and modelling studies of As, Sb-containing speiss systems and demonstration of calculations relevant for industrial conditions. Experimental methodology consisted of equilibration, quenching and electron probe X-ray microanalysis. Calculations were performed using FactSage software and thermodynamic database developed based on the dedicated recent experiments. The main findings of the paper are: a set of binary and ternary diagrams relevant to matte and speiss formation conditions; distribution of Ag and Au among liquid Pb and speiss in key quaternary systems; and distributions of 10 main elements for industrially relevant matte/speiss/metal multicomponent equilibria.

Species-specific lipophilicities of fluorinated diketones in complex equilibria systems and their potential as multifaceted reversible covalent warheads

Combined molecular, physicochemical and chemical properties of electrophilic warheads can be applied to create covalent drugs with diverse facets. Here we study these properties in fluorinated diketones (FDKs) and their multicomponent equilibrium systems in the presence of protic nucleophiles, revealing the potential of the CF2(CO)2 group to act as a multifaceted warhead for reversible covalent drugs. The equilibria compositions of various FDKs in water/octanol contain up to nine species. A simultaneous direct species-specific 19F-NMR-based log P determination of these complex equilibria systems was achieved and revealed in some cases lipophilic to hydrophilic shifts, indicating possible adaptation to different environments. This was also demonstrated in 19F-MAS-NMR-based water-membrane partitioning measurements. An interpretation of the results is suggested by the aid of a DFT study and 19F-DOSY-NMR spectroscopy. In dilute solutions, a model FDK reacted with protected cysteine to form two hemi-thioketal regioisomers, indicating possible flexible regio-reactivity of CF2(CO)2 warheads toward cysteine residues.

Thermodynamic Analysis on the Fate of Ash Elements in Chemical Looping Combustion of Solid Fuels─Iron-Based Oxygen Carriers

Chemical looping combustion (CLC) enables efficient combustion of hydrocarbon fuels while also producing a gas stream with high CO2 concentrations, suitable for carbon capture and storage (CCS). CLC of biomass in combination with CCS results in efficient removal of carbon dioxide from the atmosphere, i.e., negative emissions. However, biomass and waste-derived fuels can contain significant fractions of aggressive ash precursors, which can affect the operability and functionality of oxygen carriers. In this paper, the fate of common ash elements will be investigated thermodynamically in a system utilizing iron-based oxygen carriers: ilmenite and iron oxide. Multiphase, multicomponent equilibrium calculations were performed using databases from FACT and a user-defined database, with a specific focus on alkali (K and Na) and heavy metals (Cu, Zn, and Pb). A detailed and comprehensive comparison with available literature data from experimental investigations was performed, and compounds not available in the databases were identified. Due to a lack of thermodynamic data in the literature, thermodynamic properties for four compounds, K0.85Fe0.85Ti0.15O2, K0.4Fe0.4Ti0.6O2, KTi8O16, and KTi8O16.5, were obtained from first-principles calculations. The fate of ash elements is studied for CLC of three biomass and waste-derived solid fuels under relevant CLC conditions: 950 °C in the fuel reactor and 1050 °C in the air reactor. Results show that the choice of the oxygen carriers largely influences the behavior of the ash elements. Compared to CLC with iron oxide, ilmenite is more beneficial with respect to high-temperature corrosion since less potassium is released into the gas phase since the titanium content in ilmenite immobilizes both potassium and calcium. For both oxygen carriers, the most corrosive compounds are expected to leave with the gas in the fuel reactor, keeping the air reactor free from chlorides. It was found that the compound KTi8O16 is stable in reducing conditions and low potassium concentrations. This is in conformity with previous experimental data, where this phase has been identified in the interior of ilmenite particles used in oxygen carrier aided combustion of wood chips.

Comprehensive experimental study of adsorptive separation process using industrial paraxylene separation as a case study from equilibrium, kinetic and breakthrough points of view

In this research, separation of paraxylene from mixed-xylene using industrial Eluxyl adsorbent was investigated through batch and dynamic analysis methods at real operating conditions (9 bar and 175 °C). The Ba-faujasite exchanged commercial adsorbent (SPX-3000 fine) was characterized through the BET, XRD, FE-SEM, EDS, XRF, and TGA methods. The single and multicomponent equilibrium and single component kinetics of the adsorption of the mixed-xylene and para diethylbenzene as the desorbent in Eluxyl process were studied. It was found that the Langmuir and non-modified Langmuir (NML) models describe very well experimental data for single and multicomponent isotherms, respectively. Also, Pseudo-second-order kinetic model was selected to predict experimental results. Selective and non-selective volume of adsorbent were calculated to be 0.153 and 0.561, respectively through multicomponent breakthrough analysis. Selectivity factor of PX to MX, OX and EB were determined as 3.7, 3.96 and 3.3, respectively. Finally, a hierarchical method composed of the both batch and dynamic analysis were presented for the evaluation of the adsorbents for any other adsorptive separation.

Clinopyroxene diversity and magma plumbing system processes in an accreted Pacific ocean island, Panama

Characterising equilibrium and disequilibrium crystal-melt processes is critical in determining the extent of magma mixing and crystallization conditions in the roots of volcanoes. However, these processes remain poorly investigated in most Pacific intraplate ocean settings that are difficult to access and study. To help address this issue, we investigated crystallization conditions of clinopyroxene phenocrysts in an accreted Palaeogene oceanic island in Panama. Petrographic and geochemical observations, petrological modelling of major and trace elements, and liquid-mineral multicomponent equilibrium tests were carried out using basalts, picrites, and hawaiites of the transitional tholeiitic shield to alkaline post-shield volcanic stages of the island. Five types of clinopyroxene crystals were identified, including (1) microphenocrysts with micron-scale oscillatory zoning, (2) primitive, yet resorbed picrite-hosted phenocrysts, (3) chemically homogeneous, anhedral crystals found in the remaining basalts, (4) Ti–rich euhedral hawaiite-hosted phenocrysts, and (5) evolved sector-zoned phenocrysts. Liquid-clinopyroxene multicomponent equilibrium tests in combination with textural analysis show that ~ 74% of the studied clinopyroxenes are in possible major element equilibrium with one of the available whole rock magma compositions, of which only 21% are equilibrated with their carrier liquid. To deconvolute clinopyroxene-melt pairings and determine plumbing system conditions, we combine rhyolite-MELTS modelling, geothermobarometry, and major- and trace-element equilibrium evaluations, limiting crystallization conditions to crustal levels (< 23 km depth). No migration of magmatic reservoirs to deeper levels is observed during the shield- to post-shield transition. These results suggest the occurrence of an extensive crystal mush system during the late shield to post-shield volcanic stages of this intraplate volcanic system, with both primitive and evolved crystallization domains sampled during eruptions.

Modeling of Spiral Structure in a Multi-Component Milky Way-Like Galaxy

Using recent observational data, we construct a set of multi-component equilibrium models of the disk of a Milky Way-like galaxy. The disk dynamics are studied using collisionless-gaseous numerical simulations, based on the joined integration of the equations of motion for the collision-less particles using direct integration of gravitational interaction and the gaseous SPH-particles. We find that after approximately one Gyr, a prominent central bar is formed having a semi-axis length of about three kpc, together with a multi-armed spiral pattern represented by a superposition of m= 2-, 3-, and 4-armed spirals. The spiral structure and the bar exist for at least 3 Gyr in our simulations. The existence of the Milky Way bar imposes limitations on the density distributions in the subsystems of the Milky Way galaxy. We find that a bar does not form if the radial scale length of the density distribution in the disk exceeds 2.6 kpc. As expected, the bar formation is also suppressed by a compact massive stellar bulge. We also demonstrate that the maximum value in the rotation curve of the disk of the Milky Way galaxy, as found in its central regions, is explained by non-circular motion due to the presence of a bar and its orientation relative to an observer.

Fluoroarene Separations in Metal-Organic Frameworks with Two Proximal Mg2+ Coordination Sites.

Fluoroarenes are widely used in medicinal, agricultural, and materials chemistry, and yet their production remains a critical challenge in organic synthesis. Indeed, the nearly identical physical properties of these vital building blocks hinders their purification by traditional methods, such as flash chromatography or distillation. As a result, the Balz-Schiemann reaction is currently employed to prepare fluoroarenes instead of more atom-economical C-H fluorination reactions, which produce inseparable mixtures of regioisomers. Herein, we propose an alternative solution to this problem: the purification of mixtures of fluoroarenes using metal-organic frameworks (MOFs). Specifically, we demonstrate that controlling the interaction of fluoroarenes with adjacent coordinatively unsaturated Mg2+ centers within a MOF enables the separation of fluoroarene mixtures with unparalleled selectivities. Liquid-phase multicomponent equilibrium adsorption data and breakthrough measurements coupled with van der Waals-corrected density functional theory calculations reveal that the materials Mg2(dobdc) (dobdc4- = 2,5-dioxidobenzene-1,4-dicarboxylate) and Mg2(m-dobdc) (m-dobdc4- = 2,4-dioxidobenzene-1,5-dicarboxylate) are capable of separating the difluorobenzene isomers from one another. Additionally, these frameworks facilitate the separations of fluoroanisoles, fluorotoluenes, and fluorochlorobenzenes. In addition to enabling currently unfeasible separations for the production of fluoroarenes, our results suggest that carefully controlling the interaction of isomers with not one but two strong binding sites within a MOF provides a general strategy for achieving challenging liquid-phase separations.

Dynamic column breakthrough experiments for measurement of adsorption equilibrium and kinetics

This paper provides a set of comprehensive guidelines for the use of dynamic column breakthrough experiments to measure single and multi-component equilibria and kinetics. Recommendations are made for the design of the experimental rig, experimental procedures, and data processing methods to minimize errors and increase data reliability. Designing experiments to identify the transport mechanism, and quantitatively interpreting the breakthrough responses via modeling and optimization are also enumerated. Results reported in relevant published literature are also used to illustrate the ideas and concepts.

Simultaneous Adsorption of Phenol Derivatives from Water Onto Spherical Activated Carbon

Abstract The paper examines single- and multicomponent adsorption onto granular activated carbon. The quantities adsorbed in the study were determined using HPLC with UV detection. The experimental data were analysed using the Langmuir, the Freundlich and the Sips adsorption isotherms. With a single component being adsorbed, high coefficients of determination and low mean square errors indicated that the Sips isotherm fitted the adsorption equilibrium well. Further experiments were carried out using aqueous solutions containing two or three adsorbed components in different proportions. For these solutions, the literature methods of predicting multicomponent equilibrium using single-component data did not yield positive results. Assuming that in the investigated range of concentrations no competitive adsorption occurred, the authors propose a method for calculating the equilibrium concentrations in the liquid phase using the equations obtained for individual components. The results achieved correspond very well to the experimental data.

Early formation of belite in cement clinker raw materials with slag

Analytical methods for characterising cement raw meal during heating in different atmospheres were investigated. The effect of replacing limestone with 10 wt% slag on the formation of incipient belite and precursors of the clinker liquid in the temperature range 600–1050°C was quantified using thermogravimetry, X-ray diffraction and equilibrium calculations. The results showed that when calculating the lime saturation factor, slags were favoured to sand, resulting in lower amounts of quartz and C2S in the samples containing slag than the reference sample. This suggests that silicon dioxide in slag minerals did not react in this temperature range. The multi-component equilibrium results supported the phase formation sequence established. Allowing for the possible kinetic influences the potential solids solutions offered with the software was a valuable asset. The results showed that the effect of using slags to reduce the carbonate and sand content in a raw meal on potential amounts of incipient C2S was negative. At present, more detailed knowledge is needed regarding how blast-furnace slag and basic oxygen furnace slag contribute to the formation of intermediary compounds such as incipient C2S, C3A, C2F and C4AF in the solid phase at temperatures over 1050°C and affect the formation of C3S.

The importance of steel chemistry and thermal history on the sensitization behavior in austenitic stainless steels: Experimental and modeling assessment

The sensitization of austenitic stainless steels is dependent on various factors such as chemical composition, heat treatment temperature and time. To study these effects, the degree of sensitization in five austenitic stainless steel compositions that were subjected to isothermal heat treatments in the temperature range 550–820 °C has been determined using double loop electrochemical potentiokinetic reactivation testing. The nucleation and growth of grain boundary M23C6 carbides, that are responsible for sensitization, has been modelled with the help of the precipitation and diffusion modules in Thermo-Calc, assuming local multicomponent equilibrium, flux balance at the carbide-matrix interface, to quantitatively predict the Cr depletion. Based on the Cr depletion characteristics, a depletion parameter has been established that can predict sensitization in austenitic stainless steels and predict the effects of individual alloying elements.

Hydrogeochemistry, isotopes and geothermometry of Ixtapan de la Sal–Tonatico hot springs, Mexico

The Ixtapan de la Sal–Tonatico hot springs are located in the geological setting of the Trans-Mexican Volcanic Belt, on the border of the Morelos–Guerrero Basin, which is carbonated region with limestone and silicic rocks. The temperature, electrical conductivity and pH of the thermal waters are 25.7–37.2 °C, 9520–13,920 µS/cm and 5.90–6.88, respectively. The hydrochemical family is NaCl (Cl− mean concentration of 2198 mg/L and Na+ mean concentration of 1396 mg/L). The minor and trace elements that are notable for their high concentrations are B (19.69–23.58 mg/L), Li (6.09–8.06 mg/L), Sr (4.80–6.18 mg/L) and As (0.30–1.97 mg/L). Isotope data (δ18O, δ2H) show δ18O enrichment of the thermal waters, which may be a result of isotopic exchange with the host rock at high temperatures, although the value was very small, which may be due to mixing with groundwater near the surface. The water samples were oversaturated with calcite, dolomite and quartz, verified in the field by the presence of precipitated rocks (travertines). The samples were undersaturated with chalcedony, silica gel, cristobalite, celestite and strontianite. Several chemical geothermometers and the results from multicomponent equilibrium suggest a reservoir temperature between 90 and 130 °C. Meanwhile, a temperature of 129 °C was estimated with the Cl–enthalpy mixing model. According to the conceptual model of the functioning of this system, considering that flow is characterized by the heating of water at deep zones due to the high geothermal gradient caused by recent tectonic activity. This water rises to the surface through fractures and faults. As it rises, thermal water mixes in different proportions with Ca-HCO3 groundwater.

Application of a co-adsorption model for the design of CIL/CIP circuits

ABSTRACTOne of the main problems in the design of carbon adsorption circuits for the processing of high silver gold ores is that the commonly used gold adsorption models are unable to replicate the frequently observed displacement of silver on carbon by gold in the first contactors of carbon-in-pulp/carbon-in-leach (CIP/CIL) trains operating with high metal loadings on carbon and high silver gold ratios.A model has been developed by Curtin University’s Gold Technology Group to simulate the competitive co-adsorption of gold and silver by activated carbon. The model utilises multi-component equilibrium isotherms and film-diffusion rate equations to describe the adsorption of gold and silver onto activated carbon. The model has been validated using laboratory and plant data.Case studies are presented to demonstrate the application of the model for the design of a greenfield project processing a gold/silver ore.

Multi-scale Model of Reactive Transport in Fractured Media: Diffusion Limitations on Rates

Reactive transport in fractured media is conceptualized as a multi-scale problem that couples a pore-scale component, which comprises Navier–Stokes flow, multi-component transport and aqueous equilibrium in the fracture, and a Darcy-scale component, which comprises multi-component diffusive transport, aqueous equilibrium and mineral reactions in the porous matrix. The model that implements this multi-scale approach builds on an existing pore-scale model and is able to capture complex fracture geometries with the embedded-boundary method. The embedded boundary acts as the interface between pore- and Darcy-scale domains. Adaptive mesh refinement is used to match resolutions at the interface while using coarser resolution away from the interface when not needed in the Darcy-scale domain. The new model is validated and then compared to results from a pore-scale model. Multi-scale model results are shown to be equivalent to pore-scale results under diffusion-controlled reactions in the pore scale and very fast dissolution in the Darcy scale. The multi-scale model provides a more accurate solution for a given resolution as it effectively sets the equilibrium concentrations as boundary conditions. The multi-scale model is capable to capture flow channelization observed in an experimental fractured core and, at the same time, limitations in the dissolution of calcite by diffusive transport through an altered porous layer. Discrepancies in effluent calcium concentrations between the multi-scale results and results from a reduced-dimension Darcy-scale model for this fractured core experiment are attributed to the solution of the flow field and the gradients that develop inside the fracture. Discrepancies in effluent magnesium concentrations exemplify the limitations of the approach because the multi-scale model requires calibration of reactive surface areas as Darcy-scale continuum models.

Method for recovery of complete molecular composition of the Fischer-Tropsch synthesis products on the basis of incomplete experimental data

A method for calculational recovery of complete molecular composition of the Fischer-Tropsch synthesis products on the basis of incomplete experimental data is proposed. The method employs VTPR equation of state for analysing the available data on the composition of gaseous and liquid phases at the exit of a Fischer-Tropsch reactor. It is shown that in most cases such data are incomplete and misleading due to both instrumental limitations and inevitable losses at phase separation manipulations. The critical thermodynamic properties of the synthesis products, as well as the parameters of the equation of state for the calculation of multicomponent equilibrium using the group contribution method are determined. The results of the calculations are displayed along with experimental data from the literature and data obtained in the laboratory and industrial scale reactors.

Адаптация алгоритма расчета фазового равновесия многокомпонентной системы применительно к месторождениям с неопределенностью в исходных данных

Адаптация алгоритма расчета фазового равновесия многокомпонентной системы применительно к месторождениям с неопределенностью в исходных данных

Competitive Adsorption of Dye Species onto Biomass Nanoporous Carbon in Single and Bicomponent Systems

ABSTRACT We first present a cost-effective approach to simultaneously dispose of rutaceae plant waste (the discarded peels of orange, finger citron, pomelo and lemon) to yield biomass nanoporous carbons (BNCs). The adsorption of orange II (OII) and acid chrome blue K (ACBK) from aqueous solutions in single and binary dye systems by four types of BNCs were studied in a batch adsorption system. The adsorption studies include both equilibrium adsorption isotherms and kinetics. Four adsorption models for predicting the multicomponent equilibrium sorption isotherms have been compared in order to determine which one is the best fit model to predict or correlate binary adsorption data. The kinetic data were well described by the pseudo-second-order kinetic model. It was found that the adsorption capacity of orange peel-based nanoporous carbon (OPC) is much higher than those of the other types of BNCs. In addition, OPC also shows higher OII uptake capacities from binary dye solutions. The four types of BNCs could be employed as a low-cost alternative for the removal of textile dyes from effluents.

Structurally exploring multi-component equilibrium in biological systems

Structurally exploring multi-component equilibrium in biological systems