JournalTOCs

Adsorption
Journal Prestige (SJR): 0.703

Citation Impact (citeScore): 2
Number of Followers: 4

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1572-8757 - ISSN (Online) 0929-5607
Published by Springer-Verlag

[2352 journals]

Binary and ternary adsorption equilibria for CO 2 /CH 4 /N 2 mixtures on
Zeolite 13X beads from 273 to 333 K and pressures to 900 kPa
- Authors: Ghazal Avijegon; Gongkui Xiao; Gang Li; Eric F. May
  Pages: 381 - 392
  Abstract: Reliable adsorption equilibrium data and theoretical models for their accurate representation are crucial to the design of any adsorption based separation. The adsorption equilibria of carbon dioxide, methane and nitrogen are particularly important to the development of industrial pressure swing adsorption processes intended to separate CO2 and N2 from a variety of conventional as well as unconventional natural gas sources. The adsorption equilibrium capacities of gas mixtures needed for process design and simulation are often predicted from pure component adsorption data using various models including the ideal adsorbed solution theory (IAST). In this work, we present the adsorption equilibrium capacity data for a ternary gas mixture of CO2, CH4 and N2 as well as pure and binary gas mixtures of the same components on a commercial zeolite 13X, measured at temperatures of (273, 303 and 333 K) and pressures from (25 to 900 kPa) using a dynamic column breakthrough (DCB) apparatus. Although previous adsorption studies have reported the adsorption equilibria of pure and to a lesser degree binary gas mixtures on zeolite 13X, no experimental data are available in the literature for a ternary gas mixture of CO2, CH4 and N2 on zeolite 13X APG-III, a promising adsorbent for carbon capture and natural gas separation. The measured pure component adsorption capacities were regressed to a Toth isotherm model and the obtained Toth parameters were used to implement an IAST model for binary and ternary adsorption predictions. The IAST predictions of mixture gas adsorption represented the binary and ternary adsorption equilibria well with their corresponding maximum deviations being 0.055 and 0.3 mmol/g, respectively. This indicates the IAST can be applied successfully to these adsorption systems even though they involve molecules with different adsorption affinity and adsorbents with heterogeneous surfaces.
  PubDate: 2018-05-01
  DOI: 10.1007/s10450-018-9952-3
  Issue No: Vol. 24, No. 4 (2018)
Computational study of the CO adsorption and diffusion in zeolites:
validating the Reed–Ehrlich model
- Authors: Vladimir Berezovsky; Sven Öberg
  Pages: 403 - 413
  Abstract: Molecular simulations have been employed to explore at the microscopic scale the adsorption of CO in zeolites (MFI, CHA and DDR). On the basis of classical force fields, grand canonical Monte Carlo simulations are performed to predict the adsorption properties (isotherms) of these types of zeolites up to high pressure. Subsequent careful analysis yields details the microscopic mechanism in play, along the whole adsorption process, together with a considering of the arrangements of CO in MFI at high pressure. This work also summarizes an approach which uses single component diffusion data in prediction of multicomponent diffusion.
  PubDate: 2018-05-01
  DOI: 10.1007/s10450-018-9948-z
  Issue No: Vol. 24, No. 4 (2018)
On the use of the IAST method for gas separation studies in porous
materials with gate-opening behavior
- Authors: Guillaume Fraux; Anne Boutin; Alain H. Fuchs; François-Xavier Coudert
  Pages: 233 - 241
  Abstract: Highly flexible nanoporous materials, exhibiting for instance gate opening or breathing behavior, are often presented as candidates for separation processes due to their supposed high adsorption selectivity. But this view, based on “classical” considerations of rigid materials and the use of the Ideal Adsorbed Solution Theory (IAST), does not necessarily hold in the presence of framework deformations. Here, we revisit some results from the published literature and show how proper inclusion of framework flexibility in the osmotic thermodynamic ensemble drastically changes the conclusions, in contrast to what intuition and standard IAST would yield. In all cases, the IAST method does not reproduce the gate-opening behavior in the adsorption of mixtures, and may overestimates the selectivity by up to two orders of magnitude.
  PubDate: 2018-04-01
  DOI: 10.1007/s10450-018-9942-5
  Issue No: Vol. 24, No. 3 (2018)
Assessing the potential of nanoporous carbon adsorbents from polyethylene
terephthalate (PET) to separate CO 2 from flue gas
- Authors: P. A. S. Moura; E. Vilarrasa-Garcia; D. A. S. Maia; M. Bastos-Neto; C. O. Ania; J. B. Parra; D. C. S. Azevedo
  Pages: 279 - 291
  Abstract: A series of nanoporous carbons was obtained by physical activation of polyethylene terephthalate and investigated for the separation of CO2 from flue gas. The prepared carbons exhibited extremely low functionalization—negligible content in oxygen and other heteroatoms—accompanied by well-developed porous networks consisting of gradually increasing surface areas and micropore volumes. Such features allowed to study the role of nanopore confinement in the separation of carbon dioxide in CO2/N2 gas mixtures. The analysis of the adsorption isotherms of individual gases and their mixtures revealed different trends for the CO2 uptake and the selectivity. Whereas CO2 uptake was larger in the carbons with higher burn-off degree, the selectivity of CO2 over N2 was favored in the carbons with a higher fraction of narrow micropores. The differential adsorption enthalpy curves are typical of highly microporous samples reaching values close to those found in zeolites for low loadings. Data also show that the choice of the best adsorbent for cyclic gas adsorption and separation processes should consider a broad context, taking into account various parameters simultaneously such as gas selectivity, working capacity, adsorption enthalpy and energy consumption in the synthesis of the adsorbent.
  PubDate: 2018-04-01
  DOI: 10.1007/s10450-018-9943-4
  Issue No: Vol. 24, No. 3 (2018)
Expanded bed adsorption of albumin and immunoglobulin G from human serum
onto a cation exchanger mixed mode adsorbent
- Authors: Pedro Ferreira Gomes; José Miguel Loureiro; Alírio E. Rodrigues
  Pages: 293 - 307
  Abstract: Adsorption of human serum albumin (HSA) and immunoglobulin G (IgG), two most relevant proteins in blood serum were measured separately on a new mixed-mode adsorbent (MabDirect MM), especially designed for expanded bed adsorption process. Expanded bed behavior characterization by residence time distribution experiments for different columns (Streamline 50 for HSA study, Omnifit 66/20 and XK 16/20 for IgG study) are presented together with breakthrough adsorption of HSA and IgG for different conditions and compared with simulation results by a mathematical model. Regarding HSA adsorption, all four experiments were conducted at the same buffer solution (pH 5.0 without salt), and it was obtained a dynamic binding capacity of 8.9, 9.7, 7.5 and 7.0 mg·gdry−1 (24.8, 27.0, 21.0 and 19.5 mg·cm−3) at 10% of breakthrough, corresponding to a 41, 39, 38 and 30% of the saturation capacity for runs 1–4, respectively. The results from the simulation of the mathematical model fitted well with the breakthrough experiments. Elution stage was optimized by lowering flow rate and changing the buffer solution pH and NaCl concentration. Concerning IgG adsorption, for IgG feed concentration of 0.53 g·dm−3 in 20 mM citrate buffer, pH 5.0 with 0.4 M NaCl, at 2.2 cm3·min−1, it was obtained a DBC of 3.3 mg·gdry−1 (9.1 mg·cm−3) at 10% of breakthrough, representing 22% of the saturation capacity. While for a feed concentration of 0.11 g·dm−3 of IgG in the same buffer solution, at 6 cm3·min−1, it was obtained a DBC of 2.7 mg·gdry−1 (7.4 mg·cm−3) at 10% of breakthrough, representing 34% of the saturation capacity.
  PubDate: 2018-04-01
  DOI: 10.1007/s10450-018-9940-7
  Issue No: Vol. 24, No. 3 (2018)
Transesterification of propylene glycol methyl ether by reactive simulated
moving bed chromatography using homogeneous catalyst
- Authors: Jungmin Oh; Balamurali Sreedhar; Megan E. Donaldson; Timothy C. Frank; Alfred K. Schultz; Andreas S. Bommarius; Yoshiaki Kawajiri
  Pages: 309 - 324
  Abstract: A reactive chromatography process was investigated for a transesterification reaction of propylene glycol methyl ether (DOWANOL™ PM) using a homogeneous catalyst, a sodium alkoxide. In the proposed process, fresh catalyst is supplied with desorbent, which allows independent optimization of the adsorption properties of the stationary phase. Deactivation of catalytic activity can be avoided, which had been found to be the bottleneck in our previous study for heterogeneous catalysis. To model and optimize this process, a series of batch reaction experiments, and pulse injection tests with a chromatographic column with and without reaction were carried out. From the experimental data, equilibrium and kinetic parameters were estimated using the inverse method. Using this model, a simulated moving bed reactor was designed that achieves a conversion of 95% using the homogeneous catalysis concept.
  PubDate: 2018-04-01
  DOI: 10.1007/s10450-018-9941-6
  Issue No: Vol. 24, No. 3 (2018)
Axial dispersion effects with small diameter adsorbent particles
- Authors: Aaron Moran; Mihir Patel; Orhan Talu
  Pages: 333 - 344
  Abstract: Macropore diffusion is traditionally assumed to control the mass transfer rate in columns packed with zeolite particles in an oxygen production process. While numerous studies have confirmed this assumption for the particle size used in industrial size pressure swing adsorption (PSA) processes, it has not been validated for the much smaller particle size used in rapid PSA (RPSA). Smaller particles improve the mass transfer rate by increasing interfacial area per volume as well as decreasing diffusion distance. Despite this reduction, RPSA simulations often still assume a mass transfer rate solely limited by macropore diffusion. This approach fails to adequately account for the influence of other mass transfer mechanisms whose impact increases due to particle size reduction. This study experimentally demonstrates the dominant mass transfer mechanism is no longer macropore diffusion for the particle size used in RPSA for small scale oxygen production. Depending on the gas velocity, axial dispersion effects either become the limiting mechanism or equally as important as macropore diffusion. It also shows that improperly accounting for axial dispersion effects has a significant impact on the mass transfer coefficient estimation, often measured with breakthrough experiments.
  PubDate: 2018-04-01
  DOI: 10.1007/s10450-018-9944-3
  Issue No: Vol. 24, No. 3 (2018)
Interaction of sulfur trioxide molecules with armchair and zigzag
stanene-based nanotubes: electronic properties exploration by DFT
calculations
- Authors: Amirali Abbasi; Jaber Jahanbin Sardroodi
  Abstract: Using the density functional theory calculations, we investigated the electronic properties of the armchair (6, 6) and (8, 8) and zigzag (8, 0) stanene based nanotubes as promising sensing materials for SO3 molecules. We analyzed the structural and electronic properties of the adsorption system including the adsorption energies, band structures and projected density of states. We examined both molecular and dissociative adsorption of SO3 on the aforementioned nanotubes. Different orientation of the SO3 molecule towards the nanotube gives rise to the different adsorption configurations. The results suggest that the molecular adsorption of SO3 on the nanotubes is more energetically favorable than the dissociative adsorption, indicating that SO3 tends to be molecularly adsorbed on the buckled nanotubes. Besides, the adsorption of SO3 molecule on the (8, 8) nanotube is much more favorable in energy than the adsorption on the (6, 6) one, suggesting that (8, 8) stanene based nanotube can react with SO3 molecule more efficiently. The considerable adsorption energy values indicate that SO3 molecule chemisorbed on the stanene based nanotubes. This is well confirmed by the large overlaps between the PDOS spectra of the interacting atoms. Mulliken charge analysis reveals a noticeable charge transfer from the stanene based nanotube to the adsorbed gas molecule, suggesting that SO3 acts as a charge acceptor. The calculated band gaps for the armchair (6, 6) and (8, 8) nanotubes are 0.33 and 0.24 eV, respectively while that of zigzag (8, 0) is estimated to be 0.207 eV, which indicate the semiconductor characteristics of the mentioned nanotubes. By analyzing the gas sensing response, we found that the stanene based nanotube would be promising SO3 sensor device. Our obtained results thus provide a theoretical basis for future fabrications of highly efficient sensing materials.
  PubDate: 2018-05-28
  DOI: 10.1007/s10450-018-9954-1
Nickel ferrite nanoparticles for removal of polar pharmaceuticals from
water samples with multi-purpose features
- Authors: Valeria Springer; Luisa Barreiros; Marcelo Avena; Marcela A. Segundo
  Abstract: This paper reports the removal of two widely used pharmaceuticals, namely dipyrone and diclofenac, by magnetic nickel ferrite nanoparticles. A method combining nickel ferrite nanoparticles and high-performance liquid chromatography was applied for the simultaneous monitoring of these polar compounds. The adsorption process of the target compounds on nickel ferrite nanoparticles was performed by using only 800 mg L−1 of the adsorbent at pH 5.8. From the experimental adsorption isotherms, maximum adsorption resulted 31.2 mg g−1 for dipyrone and 16.8 mg g−1 for diclofenac, with dipyrone having a slightly higher affinity for the surface than diclofenac. The presence of dissolved salts in water samples affected the adsorption with removal efficiency remaining between 30–42% for diclofenac and 40–60% for dipyrone. On the other hand, desorption of the drugs was achieved using methanol for diclofenac and ascorbic acid for dipyrone. This research provides the understanding of the adsorption behavior of polar pharmaceuticals on bare nickel ferrite nanoparticles, which promotes the large-scale application of these magnetic nanoparticles to the removal of pharmaceuticals from water samples and their further selective recovery.
  PubDate: 2018-05-11
  DOI: 10.1007/s10450-018-9953-2
Armin Bunde, Jǖrgen Caro, Jȍrg Kȁrger and Gero Vogl (eds): Diffusive
spreading in nature, technology and society
- Authors: Douglas Ruthven
  PubDate: 2018-04-26
  DOI: 10.1007/s10450-018-9950-5
Microstructure effect of carbon materials on the low-concentration methane
adsorption separation from its mixture with nitrogen
- Authors: Donglei Qu; Ying Yang; Kai Lu; Lin Yang; Ping Li; Jianguo Yu; Ana Mafalda Ribeiro; Alirio E. Rodrigues
  Abstract: Due to the weak polarities of CH4 and N2 and their similar physicochemical properties, the microporous adsorbents have a little amount of adsorption capacity for the low-concentration methane, and the separation of CH4/N2 is also very difficult to accomplish by the adsorption-based process. Microstructure of carbon materials plays a decisive role for CH4/N2 effective separation and CH4 enrichment from the low-concentration methane gas mixed with nitrogen. This work focuses on the research of carbon material microstructure, including the selection of raw material or precursor for the carbon skeleton formation, effect of the specific surface area of carbon material on the low-concentration methane adsorption amount, the relationship between micropore size distribution of carbon material and CH4/N2 adsorption separation mechanism, and effect of different activator on the weak polar methane adsorption capacity. According to the microstructure analysis, the granular activated carbons (GACs) are prepared in lab-scale with the optimal preparation conditions, raw coconut shell carbonization for 2 h at 1073 K under N2 atmosphere and KOH activation for 1 h at 1073 K under N2 atmosphere with the KOH to carbonized material ratio of 3:1. And then, the home-made GACs (about 200 g) were packed in a column. A four-step one-bed vacuum pressure swing adsorption (VPSA) process was adopted to evaluate the low-concentration methane adsorption separation performance from its mixture with nitrogen.
  PubDate: 2018-04-23
  DOI: 10.1007/s10450-018-9951-4
Theoretical insights into the mechanism of CO 2 physisorption on Al–N
ring doped on the carbon nanotube: a DFT study
- Authors: A. S. Ghasemi; F. Ashrafi; H. Pezeshki; M. Molla; M. Rokni
  Abstract: Carbon nanotubes are the most important nanotechnology combinations, one of their most important applications being in the science of nano-electronic segments. In the present study, CO2 molecule interaction with the outer surface of Zigzag (5,0) and Armchair (5,5) carbon nanotubes with specified and optimized lengths and diameters has investigated. Significance of this study is injection of insoluble carbon dioxide gas expanded in the reservoir, causing fluid movement towards the wellhead. Therefore, theoretical approaches have used to investigate the adsorption of CO2 on single-wall carbon nanotubes, identify the adsorption structure and the attached carbon-to-gas configuration, and to calculate the parameters such as energy gap in carbon-gas nanotube structures that can help to identify carbon-gas nanotube complex stability. Results revealed that CO2 molecule reaction with nanotube surface generates diverse adsorption structures. The best CO2 gas adsorption has obtained on the surface of carbon nanotubes (5,5) doped with the Al–Nitride ring.
  PubDate: 2018-04-21
  DOI: 10.1007/s10450-018-9949-y
Effect of adsorbent heterogeneity on performance of a PSA process for bulk
gas separation: a parametric simulation
- Authors: Rama Rao Vemula; Shivaji Sircar
  Abstract: The effect of adsorbent heterogeneity on the performance of an adiabatic pressure swing adsorption (PSA) process for separation of bulk C2H4 from an inert gas (helium) using the BPL carbon as the adsorbent was numerically estimated employing a detailed mathematical model for the process. The heterogeneous Toth model was used to describe the equilibrium adsorption isotherms for C2H4 and a linear driving force model was used to describe the adsorbate mass transfer rate in the simulation. The variations in the isosteric heat of adsorption of C2H4 with adsorbate loading was included in the simulation. The study indicates that adsorbent heterogeneity negatively affects the key process performance variables by increasing the bed size factor and reducing the helium recovery. Actual performance data for a PSA process using a bench or pilot scale unit is required to reliably estimate the complexity introduced by adsorbent heterogeneity.
  PubDate: 2018-03-31
  DOI: 10.1007/s10450-018-9947-0
Confinement effect on enthalpy of fusion and melting point of organic
phase change materials in cylindrical nanospace of mesoporous silica and
carbon
- Authors: Jihye Choi; Hirotaka Fujita; Masaru Ogura; Akiyoshi Sakoda
  Abstract: Organic phase change materials (PCMs) were successfully confined into mesopores of host materials independently via vapor transportation to precisely investigate the changes in the enthalpy of fusion and the melting point of such confined PCMs under various conditions. Paraffins, fatty acids, and fatty alcohols with long hydrocarbon chains were employed as guest PCMs. Mesoporous silica SBA-15s and soft-templated mesoporous carbons with cylindrical mesopores were employed as host materials of the guest PCMs. It was elucidated that mesopore diameter, functional groups of both PCMs and functional groups of host materials result in significant changes in the enthalpy of fusion and the melting point of confined PCMs. Furthermore, it was concluded that the host materials with mesopores of diameter 10–20 nm and minimum interaction between PCM molecules and the functional group on the wall of mesopores of host materials are required to obtain an enthalpy of fusion of confined PCMs as much as 50% of that in its bulk phase.
  PubDate: 2018-03-26
  DOI: 10.1007/s10450-018-9946-1
Enhanced $$\text {CO}_2$$ CO 2 selectivity within the cavity of gmelinite
frameworks
- Authors: Anastasios Gotzias; Michael Kainourgiakis; Athanassios Stubos
  Abstract: We simulate the adsorption of $\text {CO}_2$ mixtures in three zeolitic imidazolate frameworks, namely ZIF70, ZIF80 and ZIF82. The structures display a dual pore composition with a network topology that resembles the cavity of the gmelinite zeolite. We compute the adsorption density in the pore partitions of the cavities by allocating the particle distributions of the mixture components at the individual regions of the pore network. We detect that the $\text {CO}_2$ adsorption and the selectivity performance, are enhanced in one group of pore channels. For ternary mixtures adsorption simulations, within the hexahedral pore channels of ZIF82, we evaluate $\simeq 14$ for $\text {CO}_2$ / $\text {CH}_4$ and $\simeq 34$ for $\text {CO}_2$ / $\text {N}_2$ selectivity at 1 bar and 298 K, which are among the highest reported selectivity values at such conditions, for the class of porous frameworks, including the metal organic frameworks (MOFs).
  PubDate: 2018-03-15
  DOI: 10.1007/s10450-018-9945-2
Analysis of ideal sorption compressor cycles operating with gas mixtures
- Authors: N. Tzabar; H. J. M. ter Brake
  Abstract: Sorption-based compressors are thermally driven and because of the absence of moving parts they are vibration free, and have the potential for long life. Sorption-based compressors have been reported to operate Joule–Thomson (JT) cryogenic coolers with pure working fluids. However, using mixed refrigerants instead of pure refrigerants is attractive since that would dramatically improve the system coefficient of performance. Our on-going research aims to develop an efficient JT sorption cryocooler, operating with mixed refrigerants, and is focused on studying the characteristics of the sorption compressor cycle. This paper presents the results of an advanced numerical analysis, which is based on a previous model, and its experimental verification. The analysis relates to the ideal cycle of a sorption compressor operating with a gas mixture. Obviously, dynamics and kinetics play a major rule in a real sorption compressor cycle. However, since there are no reported gas-mixture sorption compressors and the existing experience in this field is poor, a preliminary ideal cycle analysis is considered. Satisfying agreement between the numerical and experimental results is obtained and the processes in the sorption cycle are discussed. The outcomes of the current study are the basis for the next phase in which a sorption compressor prototype will be built operating with gas mixtures.
  PubDate: 2018-02-26
  DOI: 10.1007/s10450-018-9937-2
Chloride adsorption on Fe- and Al-(hydr)oxide: estimation of Gibbs free
energies
- Authors: N. Y. Acelas; E. Flórez
  Abstract: In this study, we used chemical quantum methods to analysis the adsorption of chloride on Al and Fe-(hydr)oxide clusters. Inner and outer sphere complexes were the generating complexes during the adsorption process on variably charged Al- and Fe-(hydr)oxide clusters. For the chloride adsorption on Al-(hydr)oxide, the outer sphere complexes—H-bonded—were favored for all clusters, while the adsorption modes as inner sphere complexes—BB or MM—were not favored. It was found, that the H-bonded complex on neutral clusters was the most thermodynamically favored with an adsorption energy of − 63.4 kJ/mol. For iron clusters, thermodynamic favorability was observed for both outer (− 70.5 kJ/mol) and inner monodentate (− 65.8 kJ/mol) sphere complexes. These theoretical results indicated that the thermodynamic favorability of chloride adsorption on Fe and Al-(hydr)oxide was directly related to positive surface charge.
  PubDate: 2018-02-21
  DOI: 10.1007/s10450-018-9939-0
New hybrid composite honeycomb monolith with 13X zeolite and activated
carbon for CO 2 capture
- Authors: Maria João Regufe; Alexandre F. P. Ferreira; José Miguel Loureiro; Yixiang Shi; Alírio Rodrigues; Ana Mafalda Ribeiro
  Abstract: Due to the industrialization, it is urgent to reduce the carbon dioxide emissions. For that, diverse technologies can be applied. In adsorption processes, the development of new materials is an emerging challenge in order to increase the CO2 adsorption capacity of materials and the efficiency of the processes. In this work, a new hybrid honeycomb monolith composed by zeolite and activated carbon was produced by extrusion process. Single adsorption equilibrium isotherms of carbon dioxide and nitrogen were measured by a gravimetric method using a Rubotherm® magnetic suspension balance at three temperatures, 303, 333 and 373 K. The experimental points were well described by Dual-Site Langmuir model. The material presented a carbon dioxide adsorption capacity of 2.63 mol kg−1 at 1 bar and 303 K. Binary breakthrough curves were obtained at 298 K and 2.4 bar with different feed mixtures. The experimental results of adsorption equilibrium were validated with the Dual-Site Langmuir isotherm extended to multicomponent mixtures. A mathematical model was applied to predict the dynamic behaviour of the adsorption bed.
  PubDate: 2018-02-17
  DOI: 10.1007/s10450-018-9938-1
Characterization of hydroxylated amorphous silica: a numerical approach
- Authors: Nicholas W. Suek; Maxime C. Guillaume; Jean-Yves P. Delannoy; Frederik Tielens
  Abstract: Hydroxylated amorphous silica nanoparticles were modeled using a combination of computational techniques at different levels of length scales from Ångström to hundreds of nanometers. Using quantum chemical ab initio methods, force field Monte Carlo methods, reactive force field simulations, and numerical model calculations, including BET theory calculations it was possible to describe and model the physico-chemical properties of hydroxylated amorphous silica. The results are compared with experimental data and found to be in good agreement with the theory, confirming the reliability of the computational method and the silica model structure.
  PubDate: 2018-02-12
  DOI: 10.1007/s10450-018-9936-3
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: 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