Multicomponent Adsorption Research Articles

Development of mean isosteric heat activity coefficient model for the prediction of multicomponent liquid phase adsorption equilibria

A purely predictive thermodynamically consistent adsorbed phase activity coefficient model has been proposed for the prediction of multicomponent liquid phase adsorption equilibria. The interaction parameters for this model have been estimated by a novel interaction correction parameter and mean isosteric heat (MIH) of adsorption which only requires pure vapor phase isotherms. The infinite isosteric heat values of Clausius-Clapeyron equation coupled with Dubinin-Astakhov isotherm were avoided by implementing extrapolations at saturated and zero loading limits. The resulting MIH activity coefficient model predicted the positive and negative deviations from ideality, and for adsorbates with close minimum dimension, the results were in excellent agreement with experimental data. Using adsorbed and bulk phase activity in a thermodynamic modeling procedure the excess amount adsorbed was estimated for polar and non-polar systems. The estimations of the proposed model were compared with the Ideal Adsorbed Phase (IAP) assumption and Hansen and Fackler's (H-F) approach. The results showed that excess amount adsorbed calculated with MIH model has an average mean absolute error value considerably less than IAP and H-F methods (0.0899, 0.268 and 0.533, respectively).

A Review of the Modeling of Adsorption of Organic and Inorganic Pollutants from Water Using Artificial Neural Networks

The application of artificial neural networks on adsorption modeling has significantly increased during the last decades. These artificial intelligence models have been utilized to correlate and predict kinetics, isotherms, and breakthrough curves of a wide spectrum of adsorbents and adsorbates in the context of water purification. Artificial neural networks allow to overcome some drawbacks of traditional adsorption models especially in terms of providing better predictions at different operating conditions. However, these surrogate models have been applied mainly in adsorption systems with only one pollutant thus indicating the importance of extending their application for the prediction and simulation of adsorption systems with several adsorbates (i.e., multicomponent adsorption). This review analyzes and describes the data modeling of adsorption of organic and inorganic pollutants from water with artificial neural networks. The main developments and contributions on this topic have been discussed considering the results of a detailed search and interpretation of more than 250 papers published on Web of Science ® database. Therefore, a general overview of the training methods, input and output data, and numerical performance of artificial neural networks and related models utilized for adsorption data simulation is provided in this document. Some remarks for the reliable application and implementation of artificial neural networks on the adsorption modeling are also discussed. Overall, the studies on adsorption modeling with artificial neural networks have focused mainly on the analysis of batch processes (87%) in comparison to dynamic systems (13%) like packed bed columns. Multicomponent adsorption has not been extensively analyzed with artificial neural network models where this literature review indicated that 87% of references published on this topic covered adsorption systems with only one adsorbate. Results reported in several studies indicated that this artificial intelligence tool has a significant potential to develop reliable models for multicomponent adsorption systems where antagonistic, synergistic, and noninteraction adsorption behaviors can occur simultaneously. The development of reliable artificial neural networks for the modeling of multicomponent adsorption in batch and dynamic systems is fundamental to improve the process engineering in water treatment and purification.

Review on the kerogen deformation mechanism

Shale gas is unconventional natural gas energy stored in shale, and is one of the important substitutes for conventional oil and gas resources. Since amorphous kerogen is the main component of shale organic matter and has a high degree of deformation ability, it is a key factor to improve shale gas recovery. As an emerging mining technology CS-EGR, the CO2 injection method replaces the hydraulic pressure method, thereby alleviating the greenhouse effect and energy crisis. The basic understanding of the microscopic mechanism of the multicomponent competitive adsorption and diffusion of the adsorbate in kerogen will provide a theoretical basis and guidance for further understanding of kerogen deformation and further CS-EGR. Starting from the summary of experimental research, this paper systematically summarizes the kerogen model used for kerogen deformation research and discusses the effects of adsorbate, load, moisture, temperature, pressure, and geological depth on different kerogen structures of different maturity. The effect of kerogen deformation.

Adsorption kinetic studies of activated carbon fabric for the removal of volatile organic components

Air pollution is a serious concern for the last three decades and is mainly due to unavoidable consequences of industrialization. Activated carbon fabric (ACF) is a recent addition in the adsorbent category due to its higher adsorption capacities, easy to use, regeneration capacity etc. Volatile Organic Components (VOCs) such as Benzene, Xylene and Toluene (BTX) are known as carcinogenic and mutagenic compounds. VOCs comprise more than 60% of total hazardous air pollutants that are emitted by major industrial point sources. Thus, the proposed study on performance evaluation of ACF for the removal of VOCs has become relevant. In case of multi component adsorption also, xylene shows maximum adsorbed among the three VOCs. Activated carbon fabric can be used to adsorb volatile organic components, especially xylene at low temperature.

Adsorption of gases on heterogeneous shale surfaces: A review

Many studies tied to adsorption on heterogeneous surfaces have been reported in the literature. However, finding an adsorption model that accurately describes the sorption mechanism in gas shales remains a challenge. This is due to the complex surface heterogeneity and the presence of multiple components in the formation. Modelling and simulation at reservoir conditions for adsorption studies are also computationally expensive. An optimized adsorption model is therefore essential because it can lead to an accurate estimation of the adsorbed gas amount and ultimately improve the production process. This work presents a review of the adsorption models that have been used in characterizing shale formation. Moreover, the mechanisms and factors that control adsorption in shale formation and their interaction are also analyzed. As observed from the current review, Langmuir is the most used adsorption model. However, like other existing models, it does not adequately represent the sorption phenomenon in shale formation where surface heterogeneity and the presence of multi-component are eminent. There has thus been works to improve and enhance it for use in shale formation. On the other hand, the advancement of molecular simulation presents an opportunity for better representation of the sorption mechanism. • Adsorption on solid heterogenous surfaces are discussed. • Factors affecting adsorption in gas shale are highlighted. • Various approaches to analyzing multicomponent adsorption are highlighted. • Existing adsorption models are analyzed for suitability to heterogeneous shale surfaces.

Fracture-Matrix Modeling Technique Unlocks CO2 Enhanced Shale Gas Recovery

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202222, “Fracture-Matrix Modeling of CO2 Enhanced Shale Gas Recovery in Compressible Shale,” by Dhruvit Satishchandra Berawala, SPE, Equinor, and Pål Østebø Andersen, University of Stavanger. The paper has not been peer reviewed. With technology available at the time of writing, only 3–10% of gas from tight shale is recovered economically through natural depletion, demonstrating a significant potential for enhanced shale gas recovery (ESGR). Experimental studies have demonstrated that shale kerogen/organic matter has a higher adsorption affinity for carbon dioxide (CO2) than methane (CH4). CO2 is preferentially adsorbed over CH4 with a ratio of as much as 5:1. The complete paper examines CO2 ESGR in compressible shale during huff ’n’ puff injection to understand better the parameters controlling its feasibility and effectiveness. The authors present a mathematical model in the complete paper in which the CO2/CH4 substitution mechanism is implemented in an injection/production setting representative of field implementation. Introduction Modeling of CO2 injection and the interplay between CO2 and CH4 sorption has been extremely challenging for scientists and engineers. The presence of CO2 with methane during the CO2 ESGR process makes gas-desorption behavior and measurement more difficult. Few researchers have evaluated the efficiency of CO2 ESGR in compressible shale. To improve the understanding of this technique, the authors present a numerical modeling approach using a 1D+1D fracture-matrix model in order to study the feasibility of CO2 injection in shale formations. The model consists of a high-permeability fracture extending from a well perforation, symmetrically surrounded by a shale matrix as shown in Fig. 1 of the complete paper. The fracture is assumed to have fixed width for simplicity. The system is assumed to consist of free gas in the pores as well as adsorbed gas in the matrix. When pressure in the well is reduced, free and adsorbed gas from the matrix flows toward the fracture and then to the well. The pressure-based advective forces, along with concentration-based diffusive forces, are considered the main transport mechanisms in this work. After the CH4 production cycle, CO2 is injected from the same well into the fracture and to the matrix. Injection of CO2 leads to an increase in total gas pressure in the system. CH4/CO2 adsorption kinetics are modeled using a multicomponent adsorption isotherm presented in earlier works by the authors. Apparent permeability is used to account for gas slippage effect, effective stress, adsorption, and other flow regimes relevant to the nanopore structure of the shale formation. The effect that compressible rock has on the porosity and apparent permeability changes with CH4 production. CO2 injection also is considered. The resulting model is composed of nonlinear partial differential equations that are solved numerically using an operator splitting approach. The geometry, mole conservation, pressure-dependent parameters, and initial and boundary conditions of the mathematical model are detailed in the complete paper, including mathematical definitions and solution procedures in its appendix.

Adsorption of Pb(II), Cu(II), Cd(II), Ni(II), and Co(II) ions by newly synthesized 2-(2′-Hydroxyphenyl)Benzothiazole-functionalized silica

This study employed chemically functionalized silica to adsorptively remove Pb(II), Cu(II), Cd(II), Ni(II), and Co(II) ions from water samples. The adsorbent was prepared by chemically immobilizing newly synthesized 5-chloro-2-(2′-hydroxyphenyl)benzothiazole (Cl-HPBT) on the silica surface using 3-aminopropyl-trimethoxysilane (APTMES), and the final structure was named SiO2-NH-HPBT. The novel Cl-HPBT ligand was characterized by FT-IR and 1H NMR spectroscopy and elemental analysis. FT-IR spectroscopy, elemental analysis, SEM, and EDX determined the structures of the silica particles before and after modification. The initial concentrations of the metal ions, the contact time, and the pH of the solution were optimized. Single- and multi-component adsorption experiments investigated the selective removal of target metal ions from aqueous solutions. The adsorption mechanism was ascertained by fitting the Langmuir, Freundlich, and Dubinin-Radushkevich isotherms to the adsorption data. The adsorption isotherm conformed to the Langmuir model with a correlation coefficient of 0.99. The adsorption kinetics indicated that the Lagergren pseudo 2nd–order kinetic model was more appropriate. The maximum adsorption capacities of SiO2-NH-HPBT were found to be 68.6 ± 0.55, 20.5 ± 0.50, 24.7 ± 0.35, 23.0 ± 0.60, and 13.8 ± 0.50 mg/g for Pb(II), Cu(II), Cd(II), Ni(II), and Co(II), respectively. Single- and multi-component adsorption experiments evaluated the adsorption performance of SiO2-NH-HPBT in synthetic wastewater. Multi-component adsorption results demonstrated that Cu(II) and Pb(II) could be removed from synthetic wastewater by SiO2-NH-HPBT.

Use of Microfluidic Capillary Electrophoresis for the Determination of Multi-Component Protein Adsorption Isotherms: Application to High-Throughput Analysis for Hydrophobic Interaction Chromatography.

Chromatography is a widely used separation process for purification of biopharmaceuticals that is able to obtain high purities and concentrations. The phenomena that occur during separation, mass transfer and adsorption are quite complex. To better understand these phenomena and their mechanisms, multi-component adsorption isotherms must be investigated. High-throughput methodologies are a very powerful tool to determine adsorption isotherms and they waste very small amounts of sample and chemicals, but the quantification of component concentrations is a real bottleneck in multi-component isotherm determination. The behavior of bovine serum albumin, Corynebacterium diphtheriae CRM197 protein and lysozyme, selected as model proteins in binary mixtures with hydrophobic resin, is investigated here. In this work we propose a new method for determining multi-component adsorption isotherms using high-throughput experiments with filter plates, by exploiting microfluidic capillary electrophoresis. The precision and accuracy of the microfluidic capillary electrophoresis platform were evaluated in order to assess the procedure; they were both found to be high and the procedure is thus reliable in determining adsorption isotherms for binary mixtures. Multi-component adsorption isotherms were determined with a totally high-throughput procedure that turned out to be a very fast and powerful tool. The same procedure can be applied to every kind of high-throughput screening.

Functionalized Activated Carbon for Competing Adsorption of Volatile Organic Compounds and Water.

The interfacial interaction of activated carbon with volatile organic compounds (VOCs) is seriously affected by water vapor. Therefore, it is vital to enhance the hydrophobic performance of activated carbon for expanding its application in industrial and environmental fields. Herein, a series of hydrophobic activated carbon was fabricated by tailored mixed siloxane and applied in dynamic competitive adsorption at 0, 50, and 90% humidity. Simultaneously, the diffusion molecular models and multicomponent adsorption experiments were used to study the adsorption and diffusion mechanisms. The hydrophobicity of activated carbon was significantly improved by loading of mixed siloxane, in which the equilibrium water absorption decreased from 21.9 to 7.2% and the contact angles increased by 70.10°. Meanwhile, dynamic competitive adsorption at different humidities indicated that the siloxane-functionalized activated carbons (SACs) showed much better competitive adsorption performances for VOCs than original activated carbon, which was further confirmed by the theoretical calculations of adsorption energy. In addition, a remarkable adsorption selectivity and reusability could be demonstrated to VOCs with different polarities on SACs. This study not only provides a new strategy for the hydrophobic modification of activated carbon materials but also offers theoretical guidance for the treatment of gas streams with significant water contents.

Effects of Diffusion, Adsorption, and Hysteresis on Huff-n-Puff Performance in Ultratight Reservoirs with Different Fluid Types and Injection Gases

Cyclic solvent injection, known as solvent huff-n-puff, is one of the promising techniques for enhancing oil recovery from shale reservoirs. This study investigates the huff-n-puff performance in ultratight shale reservoirs by conducting large-scale numerical simulations for a wide range of reservoir fluid types (retrograde condensate, volatile oil, and black oil) and different injection gases (CO2, C2H6, and C3H8). A dual-porosity compositional model is utilized to comprehensively evaluate the impact of multicomponent diffusion, adsorption, and hysteresis on the production performance of each reservoir fluid and the retention capacity of the injection gases. The results show that the huff-n-puff process improves oil recovery by 4–6% when injected with 10% PV of gas. Huff-n-puff efficiency increases with decreasing gas-oil ratio (GOR). C2H6 provides the highest recovery for the black oil and volatile oil systems, and CO2 provides the highest recovery for retrograde condensate fluid type. Diffusion and adsorption are essential mechanisms to be considered when modeling gas injection in shale reservoirs. However, the relative permeability hysteresis effect is not significant. Diffusion impact increases with GOR, while adsorption impact decreases with increasing GOR. Oil density reduction caused by diffusion is observed more during the soaking period considering that the diffusion of the injected gas caused a low prediction error, while adsorption for the injected gas showed a noticeable error.

Multi-component ppm level adsorption of VOCs on the ZIF-8 and UiO-66 MOFs: Breakthrough analysis with selected ion flow tube mass spectrometry

In the recent years, Metal-Organic Frameworks (MOFs) emerged at a high and increasing pace and have been widely studied in the frame of applications such as gas storage, mixtures separation and heterogeneous catalysis. Nevertheless, the study of Volatile Organic Compounds (VOCs) adsorption on Metal-Organic Frameworks (MOFs) is still lagging behind compared to zeolites and other conventional adsorbent materials. The selection of an optimal adsorbent for the trapping of environmental VOCs, only present at ppmv levels, strongly relies on its low-coverage adsorption properties, which are often challenging to evaluate through conventional experimental methods. In this work, adsorption of VOCs on Metal-Organic Frameworks (MOFs) was investigated using a novel experimental methodology to measure breakthrough adsorption at ultra-low concentration amid 4–12 ppmv. Multicomponent breakthrough curves of a mixture of ethanol, ethyl acetate, 2-butanone and 2,3-butanedione were measured in anhydrous condition at 25 °C and 6 °C on two highly stable MOFs, namely ZIF-8 and UiO-66, using Selected Ions Flow Tube Mass Spectrometry (SIFT-MS) for monitoring. Furthermore, adsorption experiments were carried out at 6 °C and 90% RH to evaluate the effect of humidity on the VOCs uptake onto the selected MOFs. While ZIF-8 adsorption capacities were ranging between 0.3 and 1.8 mg g−1, UiO-66 exhibited significantly higher uptake towards the target compounds, with a concentration comprised between 1.8 and 51.9 mg g−1. Despite this relevant discrepancy, both MOFs shared a pronounced preferentiality towards the most hydrophobic molecules. Very large enrichment factors (between 100 and 5000) showed that these materials can increase many-fold the adsorbed phase over gas phase concentration, even when present at ppmv levels, which is crucial for the good operation of sensors based on affinity layers. Furthermore, VOCs adsorption on UiO-66 unveils intricate competitive mechanisms, leading to multiple steps of ethanol displacement while simultaneous adsorption of ethyl acetate, 2-butanon and 2,3-butanedione occurs.

Role of heat dissipation on carbon dioxide capture performance in biomethane upgrading system using pressure swing adsorption

The generation of huge amount of heat from the processes adversely affects the separation and purification performance. The scarcity of studies on the heat transfer effects on breakthrough curves and bed temperature profile of biomethane upgrading process in the literature prompt us to investigate these effects in a greater detail. In this work, a multi-component adsorption model is built to emulate the heat transfer effects on the performance of biomethane upgrading process under three heat dissipation systems i.e., rigorous, thin wall, and adiabatic. Adiabatic system represents the existing industrial purification technology being practiced today. Adiabatic system prohibits heat exchange between beds. In this work, the rigorous system which allows maximum heat transfer between adsorbing and desorbing beds shows the highest methane purity of 97%, followed by thin wall (93%) and adiabatic (92%) systems. The rigorous system also is capable of reaching the highest methane recovery of 80%, followed by thin wall (77%) and adiabatic (76%) systems. The highest biomethane upgrading performance is largely due to the comprehensive nature and efficient heat dissipation by the rigorous system.

Modeling a biogas upgrading PSA unit with a sustainable activated carbon derived from pine sawdust. Sensitivity analysis on the adsorption of CO2 and CH4 mixtures

Pressure Swing Adsorption (PSA) is one of the implemented technologies for removing carbon dioxide in biogas streams. Different adsorbents, mostly zeolite-based, and process configurations have been patented and commercially demonstrated. In this study, we have developed a numerical model to successfully describe the dynamic performance of biomass-derived activated carbon in biogas purification. It is the first step in designing a biomass-based carbon capture unit within the bioenergy and circular economy context.Microporous activated carbon pellets prepared from pine sawdust by physical activation with CO2 was the adsorbent material choice. The model was built with the fittings of single-component adsorption isotherms of CO2 and CH4 at different temperatures to the Langmuir-Freundlich model and the Ideal Adsorbed Solution Theory (IAST) to account for multicomponent adsorption. The kinetics of mass transfer in the solid phase was described by the Linear Driving Force model (LDF).The dynamic simulations were performed with the aid of the commercial software Aspen Adsorption and experimental data previously obtained in the laboratory used for the model validation [1]. The model was applied to address the separation performance of a biogas upgrading biomass-based PSA process by running a parametric study to determine the influence of key performance parameters. The sensitivity analysis concluded that a single stage 4-step PSA can produce methane with a purity above 95% and a recovery of around 60% in a configuration with P/F ratios (quotients of molar flows of CH4 in the purge and the feed streams) between 0.67 and 1 for an adsorption pressure of 3 bar.

Deformation of Nanoporous Materials in the Process of Binary Adsorption: Methane Displacement by Carbon Dioxide from Coal

The phenomenon of adsorption-induced deformation of nanoporous materials has recently attracted a lot of attention in chemical, materials, and geoscience communities. Various theoretical and molecular simulation approaches have been suggested to predict the stress and strain induced by single component gas adsorption. Here, we develop a thermodynamic method based on the notion of the adsorption stress to predict the deformation effects upon multicomponent adsorption. As a practically important example, the process of the displacement of methane by carbon dioxide from microporous carbons is considered. This process is the foundation of secondary gas recovery from shales and coalbeds associated with carbon dioxide sequestration. Theoretical predictions are correlated with the original experimental data on CO2 and CH4 individual and binary adsorption on coal samples coupled with in situ strain measurements. With the model parametrized and verified against the experimental data at ambient temperature, the projections are made for the adsorption deformation at geological conditions of elevated pressure and temperature, which increase with the depth of the reservoir. The proposed approach may have multifaceted applications in modeling the behavior of hydrocarbon mixtures in nanoporous geomaterials, gas separations, and energy storage on flexible adsorbents.

Thermally active nano-aluminum particles with improved flowability prepared by adsorbing multi-component layer

The flowability of nano-aluminum (nAl) particles is poorly characterized or tailored but must be improved for their manufacturing or application of interest. In this work, a strategy was proposed to improve the fluidity of nAl particles and increase the active aluminum content of nAl particles to be higher than that of naturally passivated nAl with similar size by 14%. The main method was introducing the non-cohesive layers with high absorption ability to slow down the oxidizing gas diffusion on the nAl surface at room temperature. The gasses released by the adsorption layer combustion could inhibit the sintering of the produced nAl particles and thereby enhance the reaction efficiency at high temperatures, thus endowing nAl with thermal activity. Characterization and experimental results indicated that the multi-component adsorption layers were composed of amorphous carbon, thin oxide layer, and solvent molecules, which improved the flowability by weakening the cohesion between nAl particles. As a result, the produced nAl particles with improved flowability were evenly dispersed in the nAl/oxidizer mixture. This characteristic was conducive to the mass transfer and energy diffusion on the nAl surface during initial ignition and reaction propagation.

Simultaneous adsorption of methylene blue and heavy metals from water using Zr-MOF having free carboxylic group

Industrial effluents contain multiple pollutants, which affect the quality of water remediation operations. Hence, it is important to understand the outcome of the multicomponent adsorption system to develop efficient decontamination process. In this work, acid assisted hydrothermal method (reflux temperature at atmospheric pressure) was employed to synthesize zirconium based metal-organic framework (MOF) and utilized for the adsorptive removal of methylene blue (MB) dye and heavy metals (lead and cadmium) from aqueous solution. The adsorbent was characterized by powder X-ray diffraction (PXRD), which confirms the face centered cubic (FCC) crystal structure similar to previously reported UiO-66. Brunauer–Emmett–Teller (BET) and surface area analysis shows that, the MOF has surface area of 505 m2.g−1 and micropores ranging from 0.4 to 0.7 nm. Fourier transform infrared spectroscopy (FTIR) analysis corroborate the presence of free carboxylic groups at 1710 cm−1, apart from this FTIR confirms the presence of regular bands of metal-carboxylic bonds. X-ray photoelectron spectroscopy (XPS) analysis of the adsorbent was conducted to understand the nature of adsorbate-adsorbent interaction and to confirm the loading of metal ions on adsorbent after adsorption. The morphological nature of the MOF was analyzed by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Effects of various parameters such as pH, adsorbent dosage, adsorption time and effect of initial concentration of adsorbates on adsorption were evaluated. Kinetics and isotherm studies were conducted to understand the nature and extent of adsorption. Langmuir monolayer adsorption capacity of the adsorbent for cadmium, lead and methylene blue were found to be 37 mg.g−1, 100 mg.g−1 and 169 mg.g−1 respectively.

Carbon natural gas storage performance as predicted by multiscale modeling

Adsorbed natural gas (ANG) technology could help to facilitate the transition to environmentally friendly automobiles. Limits on total energy storage and the accumulation of higher hydrocarbons (C3+) present in natural gas are factors that restrict ANG broad application. Because experimental bed deactivation studies are extremely time-consuming, we propose a multiscale technique to study tank deactivation involving a mathematical model capable of predicting compositions of ANG tank cycles. The model is based on multicomponent ideal adsorption solution theory calculation and molecular simulation of the monocomponent adsorption equilibrium data using the representative pore method. We expect that this approach will save experimental effort and bring new insight to understanding the property-structure relation in activated carbons. The technique is validated using literature experimental data from tanks filled with activated carbons. Two target limits for the charge and discharge pressures (35–1 bar and 65–5.8 bar) are tested. The pressure range of 65–5.8 bar shows the best energy delivery for the three commercial carbons examined. The simulation shows that the amount of energy delivered is maximized for a pore size of 18.5 Å, larger than the 11.5 Å pore previously suggested for storage of pure methane. Maxsorb activated carbon showed similar performance to the metal-organic framework (MOF) NU-125 after approximately 100 charge and discharge cycles. In general, activated carbons are less expensive and more stable than MOFs. By accelerating bed deactivation assessment, the technique will allow the synthesis community to produce more efficient carbonaceous materials and facilitate ANG technology feasibility.

Batch adsorption isotherm models applied in single and multicomponent adsorption systems – a review

The advancement in urbanization and industrialization in recent times due to increase in population has led to generation of huge quantities of pollutants which are discharged into the biota without proper treatment leading to environmental pollution. This situation is causing a lot of concern to environmental conservationists. It has been proven that adsorption is superior to most of the conventional treatment techniques due to the fact that it is easy to design, insensitive to toxic pollutants, cheap and very efficient in removing pollutants at low solution concentrations. An adsorption isotherm relates the concentration of adsorbed adsorbate in the adsorbent to that in the bulk solution at constant pH and temperature. Hence isotherm modeling can predict the amount of adsorbate a given quantity of adsorbent can remove from solution under given conditions. This article reviewed various isotherm models used to describe adsorption systems whether singular or multiple-component. The applications, advantages and disadvantages are discussed. Error functions which bring out the closeness of predicted results to experimental data are discussed. The difficulty in predicting physisorption with isotherm models is mentioned suggesting that researches should be carried out applying IUPAC type VI Isotherms to resolve the problem.

Separation of multicomponent aromatic/aliphatic mixtures by simulated moving bed adsorption: Modeling and experiments

AbstractSimulated moving bed (SMB) adsorption has potential for efficient separation of many valuable chemical mixtures, but considerably less attention has been devoted to multicomponent feeds relative to binary mixtures. We take a rigorous experimental and modeling approach to study multicomponent separation of aromatics and aliphatics with a mesoporous silica adsorbent, which is relevant in many petrochemical applications such as separation of reformate and distillate streams. Our approach involves refining multicomponent adsorption, mass transfer, and SMB process parameters based upon detailed experimental inputs, with progressive addition of components. We develop a robust model that quantitatively predicts the influence of key operating parameters such as stream flow rates, desorbent/feed ratio, and switch time on the separation results and concentration profiles. The model is validated as a function of feed complexity by SMB experiments and column concentration profile measurements in a 16‐column mini‐plant. Furthermore, conditions for clear separation of each mixture are developed.

Upgrading Octane Number of Naphtha by a Robust and Easily Attainable Metal-Organic Framework through Selective Molecular Sieving of Alkane Isomers.

The separation of alkanes, particularly monobranched and dibranched isomers, is of paramount importance in the petrochemical industry for optimizing the feedstock of ethylene production as well as for upgrading the octane number of gasoline. Here, we report the full separation of linear/monobranched alkanes from their dibranched isomers by a robust and easily scalable metal-organic framework material, Co3 (HCOO)6 . The compound completely excludes dibranched alkanes but adsorbs their linear and monobranched isomers, as evidenced by single-component and multicomponent adsorption measurements. More importantly, the material exhibits excellent performance in separating naphtha and is capable of providing high quality feedstock for the production of ethylene and gasoline components with high octane number, making it a promising candidate for naphtha separation in petrochemical industry.