The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Rajamani Krishna - One of the best experts on this subject based on the ideXlab platform.
-
Enhancing Gas Sorption and Separation Performance via Bisbenzimidazole Functionalization of Highly Porous Covalent Triazine Frameworks
2018Co-Authors: Yuchuan Liu, Rajamani Krishna, Yuanzheng Cui, Shun Wang, Yunling Liu, Xiaowei Song, Zhiqiang LiangAbstract:In this paper, a series of bisbenzimidazole-functionalized highly porous covalent triazine frameworks (CTF-BIBs) has been constructed from a new organic building block, 1,4-bis(5-cyano-1H-benzimidazole-2-yl)benzene, via ionothermal polymerization. The physical porosity and gas adsorption properties of these CTF-BIBs were characterized, and the resulting CTF-BIBs exhibit significantly high Brunauer–Emmett–Teller surface areas (1636–2088 m2 g–1) and notable CO2 uptakes (86.4–97.6 cm3 g–1 at 273 K and 1 bar; 48.5–56.8 cm3 g–1 at 298 K and 1 bar). More importantly, these CTF-BIBs exhibit excellent selective separation abilities for CO2/N2, CO2/CH4, C2H6/CH4, and C3H8/CH4, particularly for equimolar mixtures C3H8/CH4 (386.6 for CTF-BIB-1 under 1 bar and 298 K). Furthermore, transient breakthrough simulations were carried out for equimolar CO2/C3H8/C2H6/CH4 mixtures, and CTF-BIBs display good separation performance in industrial fixed Bed Adsorbers. These results clearly demonstrate that the synthesized CTF-BIBs may serve as potential materials for CO2 capture and adsorptive separation for small hydrocarbons
-
screening metal organic frameworks for mixture separations in fixed Bed Adsorbers using a combined selectivity capacity metric
RSC Advances, 2017Co-Authors: Rajamani KrishnaAbstract:The separation performance of a fixed Bed adsorption unit is dictated by a combination of two metrics: selectivity and uptake capacity. Most commonly, the screening of adsorbent materials on the basis of either of these metrics leads to contradicting hierarchies. To resolve this dilemma, this article defines a combined metric, termed the separation potential (ΔQ), that is calculable on the basis of the Ideal AdsorBed Solution Theory (IAST) for mixture adsorption equilibrium. For a binary mixture of A, and B in which B is more poorly adsorBed, ΔQ reflects the maximum productivity of pure B that can be recovered in the adsorption cycle of transient fixed Bed operations; the same concept holds for recovery of pure A in the desorption cycle. For validation of the combined metric, transient breakthrough simulations were performed for separation of mixtures of Xe/Kr, C2H2/CO2, C2H2/C2H4, C2H4/C2H6, C3H6/C3H8, CO2/CH4, CO2/N2, CO2/H2, CO2/CO/CH4/H2, and hydrocarbon isomers in fixed Beds packed with a wide variety of metal–organic frameworks (MOFs). In every case, the productivities determined from transient breakthrough simulations are determined to be linearly related to the values of ΔQ; the actual values are lower because of the distended nature of concentration breakthroughs in fixed Beds. Indeed, if the “fronts” of the concentrations traverse the fixed Bed in the form of “shock waves”, the productivity values for fixed Beds coincide precisely with ΔQ. The important conclusion to be drawn is that MOFs can be compared and evaluated on the basis of IAST calculations of the combined metric, thus obviating the need for performing transient breakthrough calculations.
-
Separating mixtures by exploiting molecular packing effects in microporous materials
Physical Chemistry Chemical Physics, 2015Co-Authors: Rajamani KrishnaAbstract:We examine mixture separations with microporous adsorbents such as zeolites, metal–organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs), operating under conditions close to pore saturation. Pore saturation is realized, for example, when separating bulk liquid phase mixtures of polar compounds such as water, alcohols and ketones. For the operating conditions used in industrial practice, pore saturation is also attained in separations of hydrocarbon mixtures such as xylene isomers and hexane isomers. Separations under pore saturation conditions are strongly influenced by differences in the saturation capacities of the constituent species; the adsorption is often in favor of the component with the higher saturation capacity. Effective separations are achieved by exploiting differences in the efficiency with which molecules pack within the ordered crystalline porous materials. For mixtures of chain alcohols, the shorter alcohol can be preferentially adsorBed because of its higher saturation capacity. With hydrophilic adsorbents, water can be selectively adsorBed from water–alcohol mixtures. For separations of o-xylene–m-xylene–p-xylene mixtures, the pore dimensions of MOFs can be tailored in such a manner as to allow optimal packing of the isomer that needs to be adsorBed preferentially. Subtle configurational differences between linear and branched alkane isomers result in significantly different packing efficiencies within the pore topology of MFI, AFI, ATS, and CFI zeolites. A common characteristic feature of most separations that are reliant on molecular packing effects is that adsorption and intra-crystalline diffusion are synergistic; this enhances the separation efficiencies in fixed Bed Adsorbers.
-
Methodologies for evaluation of metal–organic frameworks in separation applications
RSC Advances, 2015Co-Authors: Rajamani KrishnaAbstract:Metal–organic frameworks (MOFs) offer considerable potential for separating a wide variety of mixtures. For any given separation, there are several MOFs that could be employed. Therefore, there is a need for reliable procedures for screening and ranking MOFs with regard to their anticipated performance in fixed-Bed Adsorbers, commonly used in industry. Such fixed-Bed Adsorbers are invariably operated in a transient mode. The separation performance of fixed-Bed Adsorbers is governed by a number of factors that include adsorption selectivity, uptake capacity, and intra-crystalline diffusion limitations. We undertake a detailed analysis of the separations of several mixtures that include: C2H2/CO2, CO2/N2, CO2/CH4, H2S/CO2/CH4, H2/CO2/CO/CH4/N2, Xe/Kr, C2H2/C2H4, C2H4/C2H6, C3H6/C3H8, O2/N2, N2/CH4, hexane isomers, xylene isomers, and styrene/ethylbenzene. For each separation, we compare the performance of a few carefully selected MOFs by using transient breakthrough simulations that are representative of practical operations. These case studies demonstrate that screening MOFs on the basis of adsorption selectivity alone, as is common practice, often leads to wrong conclusions as regards their separation capability in fixed-Bed Adsorbers. High uptake capacities often compensate for low selectivities. Conversely, low uptake capacities diminish the separation performance of MOFs with high selectivities. Intra-crystalline diffusion limitations lead to distended breakthroughs, and diminished productivities in a number of cases. We also highlight the possibility of harnessing intra-crystalline diffusion limitations to reverse the adsorption selectivity; this strategy is useful for selective capture of nitrogen from natural gas, and in air separations.
-
Hydroquinone and Quinone-Grafted Porous Carbons for Highly Selective CO2 Capture from Flue Gases and Natural Gas Upgrading
2015Co-Authors: Jun Wang, Rajamani Krishna, Jiangfeng Yang, Shuguang DengAbstract:Hydroquinone and quinone functional groups were grafted onto a hierarchical porous carbon framework via the Friedel–Crafts reaction to develop more efficient adsorbents for the selective capture and removal of carbon dioxide from flue gases and natural gas. The oxygen-doped porous carbons were characterized with scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. CO2, CH4, and N2 adsorption isotherms were measured and correlated with the Langmuir model. An ideal adsorBed solution theory (IAST) selectivity for the CO2/N2 separation of 26.5 (298 K, 1 atm) was obtained on the hydroquinone-grafted carbon, which is 58.7% higher than that of the pristine porous carbon, and a CO2/CH4 selectivity value of 4.6 (298 K, 1 atm) was obtained on the quinone-grafted carbon (OAC-2), which represents a 28.4% improvement over the pristine porous carbon. The highest CO2 adsorption capacity on the oxygen-doped carbon adsorbents is 3.46 mmol g–1 at 298 K and 1 atm. In addition, transient breakthrough simulations for CO2/CH4/N2 mixture separation were conducted to demonstrate the good separation performance of the oxygen-doped carbons in fixed Bed Adsorbers. Combining excellent adsorption separation properties and low heats of adsorption, the oxygen-doped carbons developed in this work appear to be very promising for flue gas treatment and natural gas upgrading
Alexander P. Mathews - One of the best experts on this subject based on the ideXlab platform.
-
Linear driving force analysis of adsorption dynamics in stratified fixed-Bed Adsorbers
Separation and Purification Technology, 2021Co-Authors: Haripriya Naidu, Alexander P. MathewsAbstract:Abstract The linear driving force (LDF) model has been used to study adsorption dynamics in many gas and liquid phase applications and is particularly useful in the simulation of cyclic sorption operations. It is computationally a simpler alternative to the more complex models that use partial differential equations to represent diffusion within the sorbent particle. In this study, an LDF model that takes into account sorbent particle size distribution (PSD) within the adsorber is developed to study adsorption dynamics in fixed-Bed Adsorbers with different geometries and layering of particles of different sizes. Phenol and 2, 4-dichlorophenol (DCP), two trace contaminants in water supplies and wastewaters with differing adsorption characteristics, are studied in different adsorber configurations to determine the effects of Bed geometry on Bed capacity utilization. The convergent tapered stratified Bed with eight granular activated carbon (GAC) particle sizes was found to enhance Bed capacity utilization by 20% and 50% respectively for phenol and DCP over that of conventional stratified cylindrical Bed Adsorbers. The LDF model was found to provide good prediction and representation of adsorption dynamics in stratified fixed-Bed Adsorbers at much reduced computational effort. Sensitivity analyses indicate that the adsorption affinity of solute, Bed geometry, and particle stratification play key roles in the enhancement of Bed capacity utilization in fixed-Bed Adsorbers.
-
effect of adsorbent particle layering on performance of conventional and tapered fixed Bed Adsorbers
Journal of Environmental Engineering, 2005Co-Authors: Alexander P. MathewsAbstract:Experimental and modeling studies were conducted for the adsorption of phenol from aqueous solutions onto activated carbon in fixed Beds with the adsorbent particles layered according to particle size. In the conventional stratified cylindrical adsorber (SCA), the particles were layered according to natural stratification, and increased in size with column depth. In the reverse stratified tapered adsorber (RSTA), the particle size decreased with column depth, and the fluid velocity decreased in the direction of flow. Experimental data indicate that for a uniform particle size distribution, the breakthrough time for the RSTA was about 60% higher than for the SCA under identical carbon loading and flow conditions. The homogeneous solid phase diffusion model with Linear-Freundlich isotherm was used to model the layered Adsorbers. It provides excellent predictions for breakthrough curves at various column depths. Bed capacity utilization can be increased with the RSTA due to the sharpening of the solute front, and this will translate into lower capital and operating costs for the carbon adsorption system due to the smaller unit required, lower carbon inventory, and lower pumping costs.
-
Adsorption dynamics in a stratified convergent tapered Bed
Chemical Engineering Science, 2000Co-Authors: Alok Pota, Alexander P. MathewsAbstract:Mass transfer characteristics of a novel fixed-Bed adsorber configuration with a convergent tapered geometry and reverse layering of adsorbent particles is examined in this paper from both experimental and theoretical standpoint. In the tapered convergent Bed, the adsorbent particle diameters and the fluid flow velocity decrease in the direction of flow. Laboratory column studies conducted for the adsorption of trichloroethylene on activated carbon in tapered convergent Beds show that the solute front sharpens as it travels along the column depth, resulting in a longer time to breakthrough compared to a conventional stratified fixed-Bed adsorber. The experimental results were verified using a modified version of the homogeneous solid diffusion model (HSDM). Model simulations indicate that the mass transfer zone length in this adsorber is sensitive to the angle of taper of the Bed, particle size distribution, and influent concentration. With a modest taper angle of 1.5°, this system is shown to provide increase in breakthrough times ranging from 46 to 75% over that for conventional fixed-Bed Adsorbers operating under same conditions. The improved Bed utilization afforded by this arrangement can reduce adsorbent inventory and operating costs relative to a conventional stratified fixed-Bed adsorber.
Majid Bahrami - One of the best experts on this subject based on the ideXlab platform.
-
Thermal conductivity of AQSOA FAM-Z02 packed Bed Adsorbers in open and closed adsorption thermal energy storage systems
International Journal of Refrigeration, 2019Co-Authors: Mina Rouhani, Wendell Huttema, Majid BahramiAbstract:Abstract In this study, the effective thermal conductivity (ETC) of uniformly-sized packed Bed adsorber is modeled as a function of water uptake, number of adsorbent layers, particle size, Bed porosity, temperature, contact pressure, and interstitial gas pressure. The model is validated against experimental data for 2 mm AQSOA FAM-Z02, measured by heat flow meter method (ASTM standard C518), and the maximum relative differences between the predicted values and the experimental data are 2% for ETC and 8% for total thermal conductivity. For 0.32 kg kgads−1 water uptake, at 30 °C, ETC of an open-system 2 mm FAM-Z02 SC-arranged packed Bed adsorber is 2.2 times higher than the ETC of a closed-system (0.1031 W m−1 K−1 compared to 0.0474 W m−1 K−1). ETC charts are presented based on the equilibrium water uptake isotherms for 0.5 and 2 mm FAM-Z02 packed Beds, which provides a detailed and clear picture of ETC of packed Bed Adsorbers for both open and closed thermal energy storage applications. For each packed Bed storage volume, an optimum particle size can be predicted by the presented model, which ensures the highest packed Bed total thermal conductivity.
-
effective thermal conductivity of packed Bed Adsorbers part 1 experimental study
International Journal of Heat and Mass Transfer, 2018Co-Authors: Mina Rouhani, Wendell Huttema, Majid BahramiAbstract:Abstract Low thermal conductivity in packed Bed Adsorbers is a crucial challenge facing widespread adoption of low-grade heat adsorption thermal energy storage systems. In this work, thermal conductivities of 2-mm diameter AQSOA FAM-Z02 packed Bed Adsorbers with different numbers of adsorbent layers are measured, using a NETZSCH HFM 436/3/1E Lambda, in the temperature range of 10–80 °C and under atmospheric pressure. Effects of thermal contact resistance (TCR) between the adsorbent particles and the Bed metal surfaces are deconvoluted from the total thermal resistance. Effective thermal conductivities of the adsorber packed Bed are 0.188 and 0.204 W m−1 K−1 at temperatures of 10 and 80 °C, respectively. It is observed that the relative importance of TCR compared to the total thermal resistance of a monolayer FAM-Z02 packed Bed, is 67% at 25 °C and under contact pressure of 0.7 kPa, which is significant and should be considered in the design of adsorption systems.
-
effective thermal conductivity of packed Bed Adsorbers part 2 theoretical model
International Journal of Heat and Mass Transfer, 2018Co-Authors: Mina Rouhani, Majid BahramiAbstract:Abstract In this study, a new comprehensive model is developed that can predict the effective thermal conductivity and thermal contact resistance of the packed Bed Adsorbers, as a function of water uptake, number of adsorbent layers, particle size, Bed porosity, temperature, contact pressure, and gas pressure. The proposed model is successfully validated against experimental data for AQSOA FAM-Z02, measured by a heat flow meter. The relative differences of the experimental data and predicted values for the packed Bed effective thermal conductivity are 2% and 3% at 25 and 80 °C, respectively. By increasing the water uptake from 0 to 0.3 kg kgads−1, effective thermal conductivity of a 2 mm FAM-Z02 randomly packed Bed is predicted to increase by 17% for temperature of 25 °C and 18% for temperature of 80 °C.
-
Effective thermal conductivity of packed Bed Adsorbers: Part 1 – Experimental study
International Journal of Heat and Mass Transfer, 2018Co-Authors: Mina Rouhani, Wendell Huttema, Majid BahramiAbstract:Abstract Low thermal conductivity in packed Bed Adsorbers is a crucial challenge facing widespread adoption of low-grade heat adsorption thermal energy storage systems. In this work, thermal conductivities of 2-mm diameter AQSOA FAM-Z02 packed Bed Adsorbers with different numbers of adsorbent layers are measured, using a NETZSCH HFM 436/3/1E Lambda, in the temperature range of 10–80 °C and under atmospheric pressure. Effects of thermal contact resistance (TCR) between the adsorbent particles and the Bed metal surfaces are deconvoluted from the total thermal resistance. Effective thermal conductivities of the adsorber packed Bed are 0.188 and 0.204 W m−1 K−1 at temperatures of 10 and 80 °C, respectively. It is observed that the relative importance of TCR compared to the total thermal resistance of a monolayer FAM-Z02 packed Bed, is 67% at 25 °C and under contact pressure of 0.7 kPa, which is significant and should be considered in the design of adsorption systems.
-
Effective thermal conductivity of packed Bed Adsorbers: Part 2 ─ Theoretical model
International Journal of Heat and Mass Transfer, 2018Co-Authors: Mina Rouhani, Majid BahramiAbstract:Abstract In this study, a new comprehensive model is developed that can predict the effective thermal conductivity and thermal contact resistance of the packed Bed Adsorbers, as a function of water uptake, number of adsorbent layers, particle size, Bed porosity, temperature, contact pressure, and gas pressure. The proposed model is successfully validated against experimental data for AQSOA FAM-Z02, measured by a heat flow meter. The relative differences of the experimental data and predicted values for the packed Bed effective thermal conductivity are 2% and 3% at 25 and 80 °C, respectively. By increasing the water uptake from 0 to 0.3 kg kgads−1, effective thermal conductivity of a 2 mm FAM-Z02 randomly packed Bed is predicted to increase by 17% for temperature of 25 °C and 18% for temperature of 80 °C.
Krishna R. - One of the best experts on this subject based on the ideXlab platform.
-
Highlighting the origins and consequences of thermodynamic non-idealities in mixture separations using zeolites and metal-organic frameworks
2018Co-Authors: Krishna R., Van Baten J.m., Baur R.Abstract:The Ideal AdsorBed Solution Theory (LAST) is widely used for the estimation of the mixture adsorption equilibrium, and for quantitative modeling of separations using microporous adsorbents and membranes. With the aid of Configurational-Bias Monte Carlo (CBMC) simulations, the accuracy of the LAST estimations of the component loadings for mixture adsorption equilibrium is investigated for a wide variety of mixtures in zeolites, and metal organic frameworks (MOFs). The LAST estimations are found to be of inadequate accuracy under two different scenarios: (1) when there is molecular clustering, caused by strong hydrogen bonding between the adsorbates, as is the case for water/alcohol, alcohol/alcohol, and alcohol/aromatic mixtures, and (2) there is inhomogeneous, segregated, distribution of adsorbates within the pore network, caused by preferential siting and locations of guest molecules. For both these scenarios, quantitative agreement with CBMC simulations of mixture adsorption is realized by application of the Real AdsorBed Solution Theory (RAST) by incorporation of activity coefficients, suitably parameterized by the Wilson model for the excess Gibbs free energy of adsorption. The important consequences of thermodynamic non-idealities are underscored for transient operations of fixed Bed Adsorbers for which the LAST and RAST may anticipate opposite sequences of component breakthroughs. For water/alcohol separations in membrane pervaporation processes, the permeation selectivities predicted by the LAST and RAST may differ by an order of magnitude
-
Enhancing Gas Sorption and Separation Performance via Bisbenzimidazole Functionalization of Highly Porous Covalent Triazine Frameworks
2018Co-Authors: Du J., Krishna R., Liu Y., Yu Y., Cui Y., Wang S., Song X., Liang Z.Abstract:In this paper, a series of bisbenzimidazole-functionalized highly porous covalent triazine frameworks ( CTF-BIBs ) has been constructed from a new organic building block, 1,4-bis(5-cyano-1H-benzimidazole-2-yl)benzene, via ionothermal polymerization. The physical porosity and gas adsorption properties of these CTF-BIBs were characterized, and the resulting CTF-BIBs exhibit significantly high Brunauer–Emmett–Teller surface areas (1636–2088 m2 g–1) and notable CO2 uptakes (86.4–97.6 cm3 g–1 at 273 K and 1 bar; 48.5–56.8 cm3 g–1 at 298 K and 1 bar). More importantly, these CTF-BIBs exhibit excellent selective separation abilities for CO2/N2, CO2/CH4, C2H6/CH4, and C3H8/CH4, particularly for equimolar mixtures C3H8/CH4 (386.6 for CTF-BIB-1 under 1 bar and 298 K). Furthermore, transient breakthrough simulations were carried out for equimolar CO2/C3H8/C2H6/CH4 mixtures, and CTF-BIBs display good separation performance in industrial fixed Bed Adsorbers. These results clearly demonstrate that the synthesized CTF-BIBs may serve as potential materials for CO2 capture and adsorptive separation for small hydrocarbons
-
Methodologies for screening and selection of crystalline microporous materials in mixture separations
2018Co-Authors: Krishna R.Abstract:Ordered crystalline microporous materials such as zeolites, metal-organic frameworks (MOFs), and zeolitic imidazolate frameworks (ZIFs) offer considerable potential for separating a wide variety of mixtures. There are basically two different separation technologies that can be employed: (1) pressure swing adsorption (PSA) unit with a fixed Bed of adsorbent particles, and (2) membrane device, wherein the mixture is allowed to permeate through thin micro-porous crystalline layers. The fundamental physico-chemical principles underlying the separations in these two devices are fundamentally different. In fixed Bed Adsorbers, diffusional effects are usually undesirable because these tend to produce distended breakthroughs and diminished productivities. For membrane separations, both intra-crystalline diffusion and mixture adsorption equilibrium determine permeation selectivities, and diffusion selectivities are often the primary drivers for separations. Using Configurational-Bias Monte Carlo (CBMC) simulations of mixture adsorption equilibrium, and Molecular Dynamics (MD) simulations of guest diffusivities in a wide number of guest/host combinations, we demonstrate that adsorption and diffusion do not, in general, proceed hand-in-hand. Strong adsorption often implies lowered mobility. Consequently, the best material for use in fixed Bed Adsorbers does not always coincide with the ideal choice for use as thin layers in membrane devices. Methodologies for screening micro porous materials for use in fixed-Bed units and membrane devices are discussed using a large number of examples of industrially important separations
-
Screening metal-organic frameworks for separation of pentane isomers
2017Co-Authors: Krishna R., Van Baten J.m.Abstract:This article compares the performances of several metal–organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs) for the separation of pentane isomers: n-pentane (nC5), 2-methylbutane (2MB), and 2,2-dimethylpropane (= neo-pentane (neo-P)) in fixed Bed Adsorbers. The required input data on unary and mixture adsorption equilibria are obtained from Configurational-Bias Monte Carlo (CBMC) simulations for twelve different adsorbents. The best separation performance is realized with Fe2(BDP)3, where BDP2− = 1,4-benzenedipyrazolate, a MOF with triangular shaped 4.9 Å channels that affords the ideal pore topology to differentiate between the three pentane isomers; the linear nC5 aligns commensurately with the pore landscape. Using transient breakthrough simulations in fixed Bed Adsorbers, the separation performance of Fe2(BDP)3 is found to be significantly superior to that of other materials
-
Exploiting the gate opening effect in a flexible MOF for selective adsorption of propyne from C1/C2/C3 hydrocarbons
2016Co-Authors: Li L., Krishna R., Wang Y., Yang J., Wang X., Li J.Abstract:The separation of propyne from light hydrocarbon mixtures is of technological importance but poses considerable technical challenges. This article reports on the potential of a flexible metal-organic framework [Cu(dhbc)(2)(4,4'-bipy)], with gate-opening characteristics, that exhibits adsorption selectivity in favor of propyne in a C1/C2/C3 mixture of hydrocarbons. The separation potential of the flexible MOF is established using a judicious combination of measurements of unary isotherms, IAST calculations of mixture adsorption equilibrium, transient breakthrough simulations, along with transient breakthrough experiments. Our multi-tier investigation strategy confirms that propyne can be selectively adsorBed from C1/C2/C3 hydrocarbons in fixed Bed Adsorbers that are commonly employed in the process industries
L I Celemin - One of the best experts on this subject based on the ideXlab platform.
-
adsorption of methyl ethyl ketone and trichloroethene from aqueous solutions onto silicalite fixed Bed Adsorbers
Separation and Purification Technology, 2005Co-Authors: M A Uguina, J L Sotelo, J A Delgado, J M Gomez, L I CeleminAbstract:This work addresses the adsorption of methyl ethyl ketone (MEK) and trichloroethene (TCE) from aqueous solutions on agglomerated silicalite. Results from both equilibrium and fixed-Bed adsorption studies in aqueous solutions are given. The breakthrough curves of MEK could be descriBed adequately with a bidisperse model. It was observed that the mass transfer of MEK is controlled by both the external and the macropore transport. The breakthrough curves of TCE are also adequately descriBed with the same model, for which the micropore resistance was the most important one. The thermal regeneration of the agglomerated silicalite loaded with MEK by passing a purging gas through the Bed (nitrogen and air) was also studied. No decrease of the adsorption capacity with the number of regeneration cycles was observed.
-
adsorption of methyl ethyl ketone and trichloroethene from aqueous solutions onto activated carbon fixed Bed Adsorbers
Separation and Purification Technology, 2004Co-Authors: J L Sotelo, M A Uguina, J A Delgado, L I CeleminAbstract:This work addresses the adsorption of methyl ethyl ketone (MEK) and trichloroethene (TCE) from aqueous solutions on activated carbon. Results from both equilibrium and fixed-Bed adsorption studies in aqueous solutions are given. For TCE, the sorbent is saturated for liquid concentrations near its solubility, which can be explained in terms of a pore volume filling mechanism. MEK adsorbs less than TCE for the same liquid concentration. A specific adsorption mechanism onto basic surface groups seems more plausible for this solute, which explains the plateau of the adsorBed concentration observed at liquid concentrations much lower than its solubility. The fixed-Bed adsorption dynamics of both solutes can be descriBed with the pore diffusion model, considering external mass transfer and internal diffusion inside the activated carbon. The thermal regeneration of the activated carbon loaded with MEK by passing a purging gas through the Bed (nitrogen and air) is also studied.