for Journals by Title or ISSN for Articles by Keywords help
 Subjects -> ENGINEERING (Total: 2298 journals)     - CHEMICAL ENGINEERING (192 journals)    - CIVIL ENGINEERING (192 journals)    - ELECTRICAL ENGINEERING (104 journals)    - ENGINEERING (1209 journals)    - ENGINEERING MECHANICS AND MATERIALS (385 journals)    - HYDRAULIC ENGINEERING (55 journals)    - INDUSTRIAL ENGINEERING (69 journals)    - MECHANICAL ENGINEERING (92 journals) ENGINEERING (1209 journals)                  1 2 3 4 5 6 7 | Last
 Adsorption   [SJR: 0.774]   [H-I: 52]   [4 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1572-8757 - ISSN (Online) 0929-5607    Published by Springer-Verlag  [2355 journals]
• Physical meaning of the parameters used in fractal kinetic and generalised
• Authors: Taher Selmi; Mongi Seffen; Habib Sammouda; Sandrine Mathieu; Jacek Jagiello; Alain Celzard; Vanessa Fierro
Pages: 11 - 27
Abstract: Abstract The aim of the present study was to clarify the physical meaning of the parameters used in fractal kinetic and generalised isotherm models of Brouers–Sotolongo. For this purpose, adsorption of methylene blue (MB) and methyl orange (MO) onto four activated carbons (ACs) was carried out. These ACs were characterised in terms of composition, surface area, pore volumes and pore size distributions, carbon nanotexture and surface chemistry. Adsorption isotherms were carried out at 25 °C, and at pH 2.5 and 8 for MO and MB, respectively, and fitted with Langmuir, Freundlich, Jovanovich, Hill–Sips, Brouers–Sotolongo, Brouers–Gaspard and General Brouers–Sotolongo (GBS) models. Adsorption kinetics were fitted by traditional pseudo-first and pseudo-second order models and compared to the Brouers–Sotolongo (BSf) fractal kinetic model. GBS and BSf were found to be the best models describing adsorption isotherms and kinetics, respectively. This finding suggests that MB and MO adsorption is probabilistic and closely correlated to the heterogeneous character of the adsorbent surface. Moreover, BSf and GBS parameters were correlated with surface area and amount of surface functional groups. In particular, higher surface area and amount of functional groups respectively decreased and increased the constants τc and α of the BSf stochastic model.
PubDate: 2018-01-01
DOI: 10.1007/s10450-017-9927-9
Issue No: Vol. 24, No. 1 (2018)

• Towards polymer grade ethylene production with Cu-BTC: gas-phase SMB
versus PSA
• Authors: Vanessa F. D. Martins; Ana M. Ribeiro; Jong-San Chang; José M. Loureiro; Alexandre Ferreira; Alírio E. Rodrigues
Abstract: Abstract The recovery of ethylene as a product from ethylene/ethane mixtures by adsorptive processes has been attracting great interest due to the high operating and capital costs of the cryogenic distillation traditionally practiced. This search for novel economical ways to separate olefins from paraffins by adsorptive processes has motivated the appearance of improved materials. The trend of developing new materials, such as metal–organic frameworks (MOF) and the challenge of improving the existing technologies, such as pressure swing adsorption (PSA) and simulated moving bed (SMB) leave the horizon open for new alternatives. In the present work, PSA and SMB in gas phase were tested to produce ethylene at high purity on Cu-BTC MOF in beads form. For the first time, the olefin/paraffin separation by SMB technology, using a MOF as adsorbent, was achieved. Both technologies were successfully implemented experimentally and simulated. In the best cycle performed by VPSA for the 20/80 ethane/ethylene feed composition, the ethylene was obtained with a purity of 98.0% at a recovery of 70.2% and a productivity per unit mass of stationary phase of 1.55 molC2 h−1 kg−1adsorbent. Additionally, for the 50/50 ethane/ethylene mixture only 43.2% of the ethylene is recovered at a purity of 95.4% and a productivity of 0.52 molC2 h−1 kg−1adsorbent. In the two cycles performed by SMB, to separate 39/61 ethane/ethylene mixture, ethylene was obtained with a purity of 95%, a recovery above 90% and productivity between 0.50 and 0.66 molC2 h−1 kg−1adsorbent. All the experiments were well predicted by the axial dispersion flow model with the LDF approximation.
PubDate: 2018-01-05
DOI: 10.1007/s10450-017-9930-1

• Effect of Zr and Li on high temperature CO 2 sorption characteristics of
CaO
• Authors: Rajangam Vinodh; Aziz Abidov; Muthiahpillai Palanichamy; Wang Seog Cha; Hyun Tae Jang
Pages: 1033 - 1039
Abstract: Abstract In this work, a series of Zr and Li incorporated synthetic CaO based sorbents were prepared by a simple precipitation method for high temperature (600–800 °C) CO2 capture. After impregnation and subsequent calcination, the sorbents were characterized by N2 adsorption isotherm, scanning electron microscopy and X-ray diffraction techniques. The cyclic performance in CO2 processes was evaluated by breakthrough measurements. ZrCa3Li4O7 exhibited the maximum CO2 sorption of 28.4 wt% and it showed excellent stability. The CO2 performance of ZrCa3Li4O7 still remained stable when tested under a high decarbonation temperature of 900 °C.
PubDate: 2017-11-01
DOI: 10.1007/s10450-017-9915-0
Issue No: Vol. 23, No. 7-8 (2017)

• Facile synthesis of magnetic hydroxyapatite-supported nickel oxide
nanocomposite and its dye adsorption characteristics
• Authors: Apakorn Phasuk; Suppachai Srisantitham; Thawatchai Tuntulani; Wipark Anutrasakda
Abstract: Abstract A novel magnetic hydroxyapatite-supported nickel oxide nanocomposite (NiO–HAP@γ-Fe2O3) was successfully prepared using a combination of co-precipitation and wet impregnation methods and was applied to the adsorption of methylene blue from aqueous solution. The presence of HAP, γ-Fe2O3, NiO and all elements in NiO–HAP@γ-Fe2O3 was confirmed by XRD, SEM–EDX and ICP-AES. The structure of the resulting nanocomposite was shown by TEM and SEM–EDX to be rod-shaped, measuring 55.8 ± 16.5 nm in length and 27.1 ± 6.2 nm in width, and on the surface of which was uniformly interspersed with NiO nanoparticles (about 21.4 nm average crystallite size) and γ-Fe2O3 nanoparticles (6.7 ± 2.6 nm in diameter). The novel NiO–HAP@γ-Fe2O3 exhibited a high adsorption rate during the first 20 min and reached an equilibrium within 3 h. The adsorption capacity of NiO–HAP@γ-Fe2O3 was significantly higher than that of its precursors (7.20 mg g−1 vs 0.79–1.31 mg g−1). The superior adsorption performance of the novel nanocomposite, which occurred despite its relatively low surface area, is likely attributable to the synergistic mechanisms facilitated by the presence of mixed metal oxides (NiO and γ-Fe2O3) on the adsorbent as well as by the Lewis acidity and basicity of the components of the adsorbent and the adsorbate. The adsorption kinetics and isotherms were well-fitted by the pseudo-second-order kinetic model and the Langmuir isotherm model, respectively.
PubDate: 2017-12-23
DOI: 10.1007/s10450-017-9931-0

• Chromium(VI) removal using in-situ nitrogenized activated carbon prepared
from Brewers’ spent grain
• Authors: S. R. H. Vanderheyden; K. Vanreppelen; J. Yperman; R. Carleer; S. Schreurs
Abstract: Abstract In-situ nitrogenised activated carbons (ACs) are prepared from brewers’ spent grain (BSG) using different activation procedures. Cr(VI) adsorption (10 mg/L, pH 2) on these ACs is compared to adsorption on commercial Norit GAC 1240 and Filtrasorb F400. The adsorption isotherms for both Cr(VI) and Cr total (Crtot) are determined for each AC, of which the best performing ones are chosen for kinetic experiments. The adsorption mechanism towards Cr(VI) is accompanied by its reduction to Cr(III), removing almost all Cr(VI) even at low dosages for all tested ACs. An optimal dosage (0.75 g/L) is found for each AC. For the best performing AC this dosage results in removal rates of over 99% of Cr(VI) and 88% of Crtot. The amount of reduced Cr(VI) increases with AC dosage, resulting in a higher Cr(III) equilibrium concentration above this optimal dosage. The redox reaction is more dominant in the commercial ACs. However, a faster removal rate for the ACBSGs for both Cr(VI) and Crtot is demonstrated.
PubDate: 2017-12-13
DOI: 10.1007/s10450-017-9929-7

• Efficient defluoridation of water by Monetite nanorods
• Authors: Junjie Shen; Marina Franchi Evangelista; Godfrey Mkongo; Haibao Wen; Richard Langford; Georgina Rosair; Martin R. S. McCoustra; Valeria Arrighi
Abstract: Abstract Novel Monetite nanorods were successfully prepared for fluoride removal for the first time. The fluoride adsorption on the Monetite nanorods was studied by the batch adsorption technique. The Monetite nanorods were characterized by transmission electron microscope (TEM), X-ray powder diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), and the point of zero charge (pHPZC) measurement. The results revealed that the Monetite nanorods transformed to fluorapatite after adsorbing fluoride. The adsorption kinetics followed the pseudo-second-order model, and the adsorption isotherms could be well described by the Sips model. The maximum adsorption capacity was 222.88 mg g−1 at pH 7, 328 K when the initial fluoride concentration was 300 mg L−1 and the Monetite dose was 1 g L−1. The thermodynamic parameters revealed that the adsorption of fluoride onto Monetite nanorods was spontaneous and endothermic. The effects of different parameters including adsorbent dosage, pH, initial fluoride concentration and co-existing anions were investigated to understand the adsorption behaviour of Monetite nanorods under various conditions. Their adsorption capacities decreased with the increase of adsorbent dosage, and also decreased with the increase of pH. Electrostatic attraction and ion exchange were found to be the major mechanisms governing the adsorption of fluoride onto Monetite nanorods. Furthermore, a field study was conducted with the water from a fluoride endemic area in Tanzania. This study demonstrated that the synthesized Monetite nanorods were very effective adsorbents for defluoridation applications.
PubDate: 2017-12-11
DOI: 10.1007/s10450-017-9928-8

• Chromium adsorption into a macroporous resin based on
vinylpyridine–divinylbenzene copolymers: thermodynamics, kinetics, and
process dynamic in a fixed bed column
• Authors: José Antonio Arcos-Casarrubias; Martín R. Cruz-Díaz; Judith Cardoso-Martínez; Jorge Vázquez-Arenas; Francisco Vidal Caballero-Domínguez
Abstract: Abstract The synthesis of the poly(4-vinylpyridine-co-ethylvinylbenzene) resin is investigated and its performance to remove Cr(VI) from aqueous solutions is evaluated as a function of pH using batch and fixed bed column adsorptions. The rate of Cr(VI) removal is observed to increase as the pH solution shifts to acidic conditions due to an enhanced protonation of the 4-vinylpyridine group in the polymer, which favors its electrostatic attraction with Cr(VI) oxyanions. This finding is supported with Density Functional Theory (DFT) calculations, revealing that the interaction between $${\text{CrO}}_{4}^{{2 - }}$$ (predominant species at pH < 6) and protonated 4VP is more favorable than a bond formed with $${\text{HCrO}}_{4}^{ - }$$ species (pH > 6) due to a higher charge delocalization arising in the O atoms. Experimental isotherms are approximated with the Langmuir and Radke-Prausnitz adsorption models. This former approach generates the best fitting to the data, whereby it was incorporated into a nonlinear transient model to account for the Cr(VI) adsorption in a fixed bed, and evaluating its capacity to predict experimental adsorption data. The model enables to infer that the resin presents a fast kinetic for Cr(VI) sorption, and the Cr(VI) intra-particle diffusion across the adsorbent pores is the rate-determining step for sorption.
PubDate: 2017-11-30
DOI: 10.1007/s10450-017-9925-y

• Oxygen sorption/desorption kinetics of SrCo 0.8 Fe 0.2 O 3−δ perovskite
adsorbent for high temperature air separation
• Authors: Peixuan Hao; Yixiang Shi; Shigang Li; Shuguang Liang
Abstract: Abstract Perovskites with high selectivity for oxygen are expected to be advantageous for oxygen production by vacuum pressure swing adsorption (VPSA). However, the kinetics of this process has only been investigated by thermogravimetric analysis (TGA) and fixed-bed setups, which cannot simulate the vacuum desorption process. Furthermore, the adsorption and desorption performances at high pressures are rarely discussed. In this study, the perovskite SrCo0.8Fe0.2O3−δ (SCF82) is prepared, and its isotherm and oxygen sorption and desorption kinetics are studied at 400 °C using both TGA and a high-pressure adsorption instrument. The high pressure adsorption and desorption performance confirms that VPSA is more suitable for oxygen production than pressure swing adsorption (PSA). The high-pressure adsorption instrument simulates the vacuum desorption process more effectively than TGA. A high vacuum desorption rate was found, indicating that the adsorption rate has a greater influence than the desorption rate when considering perovskite oxide adsorbents for use with VPSA techniques.
PubDate: 2017-11-29
DOI: 10.1007/s10450-017-9922-1

• Adsorption of short chain carboxylic acids from aqueous solution by
swellable organically modified silica materials
• Authors: Paul L. Edmiston; Alyssa R. Gilbert; Zachary Harvey; Noël Mellor
Abstract: Abstract The adsorption of C2–C6 short chain carboxylic acids was measured for swellable organically modified silicas (SOMS), hydrophobic polysilsesquioxane based materials prepared via the sol–gel process. Adsorption was measured for SOMS materials that were either hydrophobic or incorporated variable amounts of quaternary amine groups to serve as ion exchange sites. Batch equilibrium experiments were performed for carboxylic acids and alcohols to standard hydrophobic SOMS. Results show that SOMS has partition coefficients for short chain alcohols that are approximately 3× greater than liquid–liquid extraction into octanol, and 10× greater for the extraction of short chain carboxylic acids. Affinity for valeric acid was similar to commercially available Amberlite XAD-4 resins, however the organosilica derived sorbent had a 3× higher total adsorption capacity which was attributed to the ability of the pores to expand. Column experiments using SOMS were used to measure breakthrough curves for valeric acid across a wide range of concentrations. The isotherm for dynamic adsorption was linear indicating that capacity to adsorb valeric acid was controlled by equilibrium and not limited by set pore volume capacity. Addition of quaternary amine sites to SOMS improved adsorption affinity of valeric acid at low concentrations, but those modifications reduced the swelling of the matrix and lowered capacity at higher concentrations. Overall, SOMS was found to be poorly suited to extract organic acids at concentrations < 10 mM, but has high capacity for adsorption at higher concentrations (up to 700 mg/g). Adsorbed valeric acid could be recovered by solvent rinse.
PubDate: 2017-11-29
DOI: 10.1007/s10450-017-9923-0

• Modeling and simulation of a pressure–temperature swing adsorption
process for dehydration of natural gas
• Authors: Abbas Aleghafouri; Mehdi Davoudi
Abstract: Abstract Water vapor in a natural gas stream can result in line plugging due to hydrate formation, reduction of line capacity due to collection of free water in the line, and increased risk of damage to the pipeline due to the corrosive effects of water. Therefore, water vapor must be removed from natural gas to prevent hydrate formation and corrosion from condensed water. Molecular sieves are considered as one of the most important materials that are used as desiccant materials in industrial natural gas dehydration. This paper focuses on modeling of pressure–temperature swing adsorption (PTSA) process in a commercial two-layer adsorption system during sequential steps of cyclic operation to remove water from natural gas. The dynamic model equations were constructed from 4 mol balances; model molecule of water vapor in natural gas, a total mass balance, a pressure drop equation and two energy balances of solid and gas phases in the adiabatic column. Results reveal that about 1 m of the bed was overdesigned by vendor and it doesn’t work in optimum condition. The influential parameters of the process were investigated through a parametric analysis of the process efficiency. For the sake of energy saving some suggestions were proposed for upgrading the design conditions with no significant effect on the purification performance. Results show that optimum conditions will be obtained using adsorption time 22 h and regeneration time 9 h with maximum temperature of 240 °C.
PubDate: 2017-11-29
DOI: 10.1007/s10450-017-9924-z

• Interaction of photosynthetic pigments with single-walled carbon nanotube
(15, 15): a molecular dynamics study
• Authors: Majid Ghasemi-Kooch; Maryam Dehestani
Abstract: Abstract In this study, adsorption of photosynthetic pigments on the inner and outer surfaces of single-walled carbon nanotube (15, 15) has been investigated using molecular dynamics simulation. The binding free energy is calculated by using the linear interaction energy algorithm, that its value indicates the adsorption of all pigments is desirable in both positions. Also, despite the high similarity between each category of these pigments, their interaction with the nanotube is different, that this result can be useful to separate these pigments from one another. According to Lennard–Jones potential energy between the pigments and carbon nanotube, the interaction on the inner surface is stronger than that on the outer surface for all pigments. The chlorophylls phytol tail interacts more strongly with the nanotube compared with the porphyrin ring of chlorophylls. The ability of carotenoids to institute π–π stacking is attributed to conjugated system. Furthermore, xanthophylls due to hydrogen bonded to oxygen atom form semi-hydrogen bonds with carbon nanotube.
PubDate: 2017-11-27
DOI: 10.1007/s10450-017-9920-3

• Adsorption of toxic SO x molecules on heterostructured TiO 2 /ZnO
nanocomposites for gas sensing applications: a DFT study
• Authors: Amirali Abbasi; Jaber Jahanbin Sardroodi
Abstract: Abstract Using density functional theory (DFT) calculations, we predict the SOx sensing performance of heterostructured TiO2/ZnO nanocomposites with and without nitrogen doping. The interaction of SO2 and SO3 molecules with the considered nanocomposites were examined based on different orientations of the gas molecules towards the nanocomposite. The fivefold coordinated titanium atoms were found to be the binding sites on the TiO2 side of nanocomposite, whereas, on the ZnO side, the oxygen atom acts as a binding site. Our theoretical results demonstrate that the interaction of SOx molecules with N-doped nanocomposites is more energetically favorable than that with undoped ones, indicating that N-doped TiO2/ZnO nanocomposites show stronger chemisorption and greater electron transfer effects than undoped TiO2/ZnO. The electronic properties of the adsorption systems were investigated in terms of the projected density of states and molecular orbitals. After the adsorption process, all S–O bonds of the SOx molecules were elongated, which is probably attributed the electron density transfer from the S–O bonds to the newly formed bonds between the nanocomposite and SOx molecules. The charge transfer analysis revealed that N-doped nanocomposite acts as a donor. The N-doped nanocomposite induce dramatic changes of electronic properties of TiO2/ZnO, which can be useful feature for improving the gas sensing performance. Our calculation results aim to provide some information for future experiment.
PubDate: 2017-11-27
DOI: 10.1007/s10450-017-9926-x

equilibrium and breakthrough of 1,2-dichloroethane
• Authors: Lijuan Jia; Qiuyi Shi; Siyuan Xie; Chao Long
Abstract: Abstract Hot steam regeneration of an adsorbed bed is widely used in practical processes, so it is crucial to understand the effect of residual water contained in the adsorbent on VOCs adsorption. In this work, the influence of pre-adsorbed water in hypercrosslinked resin (HY-1) on the adsorption of 1,2-dichloroethane (DCE) was studied under both isothermal and pseudo-adiabatic conditions. Under isothermal conditions, the initial water had a slightly negative influence on adsorption capacities, and a negative influence on the breakthrough capacity lower than 9.3%, decreasing with higher DCE concentrations. Moreover, the influence of initial water in HY-1 on temperature rise and breakthrough adsorption capacities in fixed beds was also investigated under pseudo-adiabatic conditions. On the dry resin, a significant temperature rise (about 50 °C) inside the bed was observed when 200 mg/L of DCE was adsorbed. Compared to the dry resin, the temperature rise in the bed could be controlled to under 5 °C; the breakthrough adsorption capacities of DCE on the wet resin increased by 12.4–37.6%.
PubDate: 2017-11-22
DOI: 10.1007/s10450-017-9919-9

• Development of averaged solid–fluid potential energies for layers and
solids of various geometries and dimensionality
• Authors: Lumeng Liu; Yonghong Zeng; D. D. Do; D. Nicholson; Junjie Liu
Abstract: Abstract The solid–fluid (SF) interaction energy describes the affinity between one adsorbate molecule and a solid. Its quantification is an essential input for the simulation of the adsorption isotherm, the isosteric heat and details of the microscopic structure of the adsorbate. A good approximation to the SF energy can be obtained by direct summation of all effective pairwise interaction energies (LJ plus electrostatic) between an adsorbate molecule and all the atoms in the solid. To repeat this summation for each new configuration in a simulation is very time-consuming. One resolution is to construct database tables of the solid–fluid potentials, which leads to massive databases if the grid separation used is very small. For solids that have simple geometries an alternative is to determine the approximate solid–fluid potential by ignoring the discrete atomic structure of the solid. This level of approximation is adequate for many simulations of engineering interest where fine details, for example in the first adsorbate layer, are not necessary. In this paper, we report comprehensive derivations of solid–fluid potentials for a wide range of solids, in layered structures with constant surface atom density or solid structures with constant atom density, and various curvatures and dimensions. These solids are common in engineering applications and the derived analytical solutions will be of value to scientists and engineers. We take a finite solid as an example of the application of the SF potential equations developed in this paper, and show the spatial variation of the solid–fluid potential energy in the neighbourhood of the edges of the solid, which is found to be remarkably different from the usual 1D potential energy equation commonly used in the adsorption literature.
PubDate: 2017-11-20
DOI: 10.1007/s10450-017-9921-2

• Bio-butanol downstream processing: regeneration of adsorbents and
selective exclusion of fermentation by-products
• Authors: R. Goerlitz; L. Weisleder; S. Wuttig; S. Trippel; K. Karstens; P. Goetz; H. Niebelschuetz
Abstract: Abstract Due to the decreasing availability of fossil resources and the negative effects on the global climate, an alternative to the petrochemical industry for the production of chemicals and fuels has to be developed. Bio-butanol is one of the most promising substitutes for gasoline and platform chemicals. However, the economical production of butanol by fermentation is limited by several factors. Since butanol is toxic for the cells, only low concentrations can be achieved in the fermentation broth. A recovery of butanol by distillation consumes more energy than the purified product contains and therefore is uneconomic. As an alternative, the purification of butanol by adsorption is a promising energy efficient technique. In this work adsorption isotherms for the resin SP-207 and the activated carbons AC 207C and CAL TR were determined for butanol solutions and synthetic fermentation broths at pH 4 and 5. The specific loading for butanol in the synthetic fermentation broth with pH 4 was decreased up to 53% at a butanol concentration of 4 g L− 1 compared to the pure butanol–water solution. The reduction was mainly caused by a replacement of butanol by butyric and acetic acid. To prevent the replacement, a selective pre-separation of the acids by the anion exchange resin MP 62 WS was tested. The resin showed affinity for the acids only, no solvent adsorption was observed. A pH shift of the medium from 4 to 5 led to a strong increase of the butanol adsorption. Furthermore, a screening test for the thermal regeneration of the three adsorption materials showed a drop of the butanol loading after the first cycle for the activated carbons, but not for the resin and allowed a pre-selection for further desorption tests.
PubDate: 2017-11-15
DOI: 10.1007/s10450-017-9918-x

critical conditions. Part IV: inorganic multi-atomic species, halocarbons
and oxygenated hydrocarbons data evaluation and modeling
• Authors: Kevin F. Loughlin; Dana Abouelnasr; Alaa al Mousa
Abstract: Abstract The saturation loadings for subcritical adsorption of multi-atomic inorganic species, halocarbons and oxygenated hydrocarbons on 13X zeolite are modeled using the modified Rackett model of Spencer and Danner (J. Chem. Eng. Data 17(2):236–240, 1972) for the saturated liquid densities combined with crystallographic data for the 13X zeolite. A similar equation is used for supercritical adsorption involving supercritical adsorbate densities and crystallographic data for the 13X zeolite employing a different f(Tr) expression than used by Spencer and Danner. Adsorption data from the literature are first critically evaluated and then compared to the model. Log–log plots are used to determine whether each isotherm is near saturation; isotherms that exhibit a $$\left( {\partial \ln q} \right)/\left( {\partial \ln p} \right)$$ slope of zero at the maximum pressure point are assumed to be saturated (capillary condensation points are deleted). The highest loading is used from each isotherm that approaches saturation. Unsaturated isotherms are not considered further. The theoretical equation satisfactorily models the available experimental data for the data that is subcritical except for water and methanol. However, steric factors are required in the model for tetrafluoromethane, sulfur hexafluoride and the aldehydes. The adsorption data for ethyl acetate is questionable. A significant amount of data in the supercritical region (tetrafluouromethane, and hexafluoroethane) revealed a decreasing trend with increasing Tr. For this data a f(Tr) is modeled using TCAR and the slope of the decreasing linear plot against Tr. The physical phenomenom causing this effect is attributed to increasing molecular vibration in the cavity reducing the total molecular loading with temperature rise.
PubDate: 2017-11-15
DOI: 10.1007/s10450-017-9916-z

• Authors: Shivaji Sircar
Abstract: Abstract An alternative to the conventional ‘pore filling model’ for describing Gibbsian surface excess (GSE) isotherm from a liquid mixture on a porous adsorbent is proposed where the adsorbed phase volume is treated as a variable. The new model is tested using GSE isotherm data on various micro and mesoporous adsorbents. The adsorbed phase volume is found to be system specific but always less than the adsorbent pore volume, irrespective of the pore size.
PubDate: 2017-11-02
DOI: 10.1007/s10450-017-9914-1

• Adsorption of phosphoric acid anions on platinum (111)
• Authors: Lynndle C. Square; Christopher J. Arendse; Theophillus F. G. Muller
Abstract: Abstract The adsorption of phosphoric acid anions on the platinum (111) plane is investigated using Monte Carlo and density functional theory methods. The minimum energy structure is used to generate the adsorption configurations, indicating the preferred adsorption sites. The bond lengths was found from density functional theory calculations and used to gain further insight on the structure due to adsorption. From the density functional calculations the scanning tunnelling microscopy image of the specie with the lowest adsorption energy configuration and shortest bond length was produced.
PubDate: 2017-10-13
DOI: 10.1007/s10450-017-9912-3

• Experimental adsorption isotherms of CO 2 and CH 4 on STT zeolite:
comparison with high- and pure-silica zeolites
• Authors: Hafez Maghsoudi; Azam Aidani
Abstract: Abstract Adsorption isotherms of CO2 and CH4 on a high-silica STT zeolite (Si/Al = 27), an odd zeolite which consists of 7- and 9-MR window openings, were measured over pressure range of 0–100 kPa at temperatures 298, 323 and 348 K. The isotherms follow typical Type-I according to the BDDT classification. Experimental isotherms data of CH4 and CO2 are well described by Langmuir-type isotherms. Calculation of isosteric heats of adsorption along with the isotherms types revealed that CH4 adsorption system is energetically homogeneous while that is heterogeneous for CO2 adsorption. Furthermore, comparison of STT adsorptive performance with high- and pure-silica zeolites led to development of a trade-off plot, i.e. CO2/CH4 selectivity against CO2 adsorption, by ideal adsorbed solution theory (IAST) calculations. The results revealed that Silicalite-1 has the lowest CO2/CH4 selectivity while SSZ-45 is the most selective adsorbent. Additionally, DD3R has the minimum CO2 adsorption amount whereas STT has the highest capacity. CO2/CH4 selectivity of STT is just ~ 12% smaller than that of SSZ-45 (13.30 against 15.12) but its CO2 adsorption is 63% greater than that of SSZ-45 (1.42 against 0.867 mol kg−1). Thus, STT zeolite is superior to the other high- and pure silica zeolite as it has simultaneously both high selectivity and capacity in CO2/CH4 separation.
PubDate: 2017-10-06
DOI: 10.1007/s10450-017-9911-4

• Quantitative analysis porous structure of activated carbon with classical
density functional theory
• Authors: Guodong Wang; Jianchun Jiang
Abstract: Abstract Towards development of a more reliable theoretical procedure, we apply a modified classical density functional theory for porous analysis on solid heterogeneity. Such novel theoretical procedure has been used to analyze the pore size distribution (PSD) of five activated carbon samples and to predict the adsorption isotherms of these materials. As for the characterization sensitive with the adopted numerical algorithms, we evaluate the representative of the required PSD by three numerical methodologies with their predictive capability. It is notable that P1 method with B-spline function as prior PSD function form is suitable for the pore-size analysis of activated carbon for its smallest average deviation on isotherm fitting and prediction. Moreover, the effect of hypothesis form on solid heterogeneity is also discussed according to its contribution on the accuracy and stability of the numerical procedure. According to the proposed feature pore width range theory, we discuss the relationship between the numerical procedure and the predictive capability of the characterized PSD. With the fluctuated experimental temperature into consideration, we also make predictive calculation on adsorption capacity of activated carbon within certain error range, which is meaningful for the development of predictive functional in PSD model.
PubDate: 2017-10-03
DOI: 10.1007/s10450-017-9904-3

JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327

Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs