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1.
Fixed bed adsorption experiments were performed using four granular activated carbon (GAC) columns designed by packing two
size ranges of pulverized and sieved Filtrasorb 400 (d=0.5-0.59 and 1.0-1.19 mm) to two bed depths (L=10 and 20 cm), respectively. Continuous supplying of river water containing a lower content of natural organic matter (NOM)
allowed investigation of the breakthrough of aqueous natural organic matrices assessed with lumped quality indices of total
dissolved organic carbon (DOC) and ultraviolet absorbance at 260 nm (UV260). The capability of GAC columns in dealing with
sudden rise in the load of influent NOM was also displayed by intermittently adding to the influent river water a peaty field
groundwater that contained a higher content of NOM. Besides, assisted by the size-exclusion HPLC (SEHPLC), changes in the
apparent molecular weight distribution of NOM along the bed depth of GAC columns were evaluated, and an important finding
revealing relatively even adsorption for adsorbable NOM constituents within the entire molecular weight range of 1000-5200 g mol−1 as PSS (polystyrene sulfonates) detected for the river and groundwater NOM was obtained. Furthermore, using a previously
proposed hypothetical multi-component approach incorporating the ideal adsorbed solution theory and a plug flow homogeneous
surface diffusion model, the observed concentration profiles of the river water NOM were predicted. 相似文献
2.
Attila Bóta Krisztina László Lajos György Nagy Günter Subklew Heide Schlimper Milan J. Schwuger 《Adsorption》1997,3(1):81-91
The possibility of using pyrolyzed wastes produced in already working incineration plants, as adsorbents for waste water treatment,
was studied. Showing very poor adsorption properties, they were improved by steam activation technique used in the conventional
activated carbon manufacturing. It is concluded that various organic waste materials can be converted to carbonaceous final
products with a character similar to activated carbon. Their adsorption properties and pore size distribution are determined
by the structure of the starting material. Although most of these samples have a low specific surface area, their pore volume
is not negligible in the meso-and micropore range. Adsorption tests with model waste waters confirmed that adsorption properties
are strongly influenced by the character of the suface. The adsorption capacity of these samples can be utilized for the treatment
of strongly polluted industrial waste waters. Considering that the raw material ‘needed’ to manufacture these adsorbent is
produced permanently and the adsorbents do not have to be regenerated, it might be worthwhile using these kinds of adsorbents
in the primary treatment of industrial waste waters. 相似文献
3.
Jiaqi Liu 《International journal of environmental analytical chemistry》2013,93(11):1146-1158
Total organic halogen (TOX) is a collective parameter and a toxicity indicator for all the halogenated organic disinfection byproducts (DBPs) in a water sample. TOX measurement involves concentration of halogenated organic DBPs by adsorption onto activated carbon. Prior to activated carbon adsorption, quenching the chlorine residual in a water sample is an indispensable step to eliminate the positive interference resulting from continued chlorination with organic compounds adsorbed on the activated carbon surface or with the activated carbon surface itself. Arsenite is generally applied as the quenching agent. In this study, the arsenite quenching agent dose that was 100% of the stoichiometric amount of the chlorine residual in a water sample was demonstrated to be most appropriate. In practice, to ensure complete reduction of chlorine residual, slight overdose of arsenite is often recommended, but this was found to cause negative interferences in the TOX measurement due to two reasons. First, the competitive adsorption existed between halogenated organic DBPs and the excessive arsenite on the activated carbon. This competitive adsorption effect was pronounced within a quenching time of 15?min. After 15?min of quenching, a large fraction of arsenite might have reacted with some easily-reduced halogenated DBPs to become arsenate, which is partially ionized at pH 2 and less likely adsorbed on the activated carbon. In this case, more halogenated organic DBPs could be adsorbed on the activated carbon, resulting in the measured TOX concentrations to be much closer to the actual one contained in the sample. Second, excessive arsenite might lead to reduction or decomposition of halogenated organic DBPs with a prolonged quenching time (>60?min). Thus, to avoid the negative interferences, the appropriate quenching time should be 15–60?min. 相似文献
4.
Gubkina M. L. Polyakov N. S. Petukhova G. A. Kalmykova O. V. Ustinov E. A. 《Russian Chemical Bulletin》2001,50(4):595-598
The isotherms of water adsorption in the presence of an organic substance vapor with a specified concentration are calculated from experimental data on the joint frontal dynamics of adsorption of water vapor and several organic substances (benzene, hexane, cyclohexane, tetrachloromethane, and perfluorotripropylamine) on two samples of activated carbons. The influence of the organic substances on the equilibrium water adsorption decreases with an increase in the molecule size. 相似文献
5.
C. Moreno-Castilla M. A. Fontecha-Cámara M. A. Álvarez-Merino M. V. López-Ramón F. Carrasco-Marín 《Adsorption》2011,17(3):413-419
Removal of amitrole from water was studied by adsorption on an activated carbon cloth and by oxidation with hydrogen peroxide
using the same activated carbon cloth as catalyst. Study variables included the solution pH, ionic strength, and temperature
in the adsorption process and the solution pH and the surface chemistry of the activated carbon cloth in the oxidation process.
Results showed that amitrole adsorption on activated carbon cloth was not adequate to remove amitrole from water due to the
high solubility and low aromaticity of the herbicide, which reduced its adsorption on the carbon. A higher amitrole removal
rate was obtained with the activated carbon/H2O2 system. The best results were obtained on basic activated carbon surfaces at pH 7–10, when hydroxyl radical formation is
favored, achieving the removal of 35–45% of the AMT, compared with 20–25% under the best adsorption conditions. Importantly,
oxygen fixed on the carbon surface during AMT oxidation must be removed by heat treatment in order to regenerate the surface
basicity of the carbon before its reutilization in another oxidation cycle. 相似文献
6.
The adsorption equilibria of pesticides and metabolites (atrazine, deethylatrazine, deisopropylatrazine and simazine) are
studied onto activated carbon fibers –ACF– with a broad pore size distribution (32% mesopore volume, 68% micropore volume).
Mono-and multi-component isotherms have been determined for low concentrations, from 0.23×10−6 to 9.52×10−6 mol L−1. Single solute isotherms, modeled by Freundlich and Langmuir models, tend to prove the influence of the adsorbate's solubility
in the adsorption capacity of activated carbon fibers. Binary solute isotherms confirm the strong influence of pesticide solubility
on the competitive adsorption mechanism: the competition is higher in the case of adsorbates of different solubilities (atrazine
and DEA or DIA for example). Multicomponent experimental data were modeled by extended Langmuir-based equations and the Ideal
Adsorbed Solution theory. Whereas the first ones failed to model accurately binary adsorption due to restrictive hypothesis,
the IAS model showed a good agreement between experimental and predicted data. It emphasised also the difficulty in satisfying
the hypothesis of the model in the case of highly adsorbed compounds. Finally, the simultaneous adsorption of atrazine and
NOM (in a natural water, DOC = 18.2 mg L−1) shows no adsorption competition effects between natural organic matter and atrazine. This is due to the presence of secondary
micropores (0.8–2 nm) and mesopores in the ACF, which limit a pore blockage phenomenon by NOM. 相似文献
7.
Boleslav Taraba 《Journal of Thermal Analysis and Calorimetry》2012,107(3):923-926
Simple adaptation of the technique of immersion calorimetry enables determining both integral and differential adsorption
heats as well as the course of the adsorption isotherm of phenol on activated carbon. The innovative aspect of the applied
procedure consists in bringing the phenol aqueous solution to contact with the suspension of carbon with water. Thus, the “interfering” heat effect of carbon interaction with water is eliminated, and only the net
adsorption heat of phenol is monitored. The value of −52.5 kJ mol−1 was ascertained as the molar differential adsorption heat at the low surface coverage (cca 0.2 mmol g−1) of the sample of microporous carbon. As the adsorption process continues, for adsorption uptakes exceeding the value of
about 1 mmol g−1, molar differential adsorption heats appear to be established at a level of about −20 + 5 kJ mol−1. 相似文献
8.
Adsorption of vanadium(V) from aqueous solution onto ZnCl2 activated carbon developed from coconut coir pith was investigated to assess the possible use of this adsorbent. The influence
of various parameters such as agitation time, vanadium concentration, adsorbent dose, pH and temperature has been studied.
First, second order, Elovich and Bangham’s models were used to study the adsorption kinetics. The adsorption system follows
second order and Bangham’s kinetic models. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms have been employed
to analyze the adsorption equilibrium data. Equilibrium adsorption data followed all the four isotherms—Langmuir, Freundlich,
D-R and Temkin. The Langmuir adsorption capacity (Q
0) was found to be 24.9 mg g− 1 of the adsorbent. The per cent adsorption was maximum in the pH range 4.0–9.0. The pH effect and desorption studies showed
that ion exchange mechanism might be involved in the adsorption process. Thermodynamic parameters such as ΔG
0, ΔH
0 and ΔS
0 for the adsorption were evaluated. Effect of competitive anions in the aqueous solution such as PO4
3 −, SO4
2−, ClO4
−, MoO4
2−, SeO3
2−, NO3
− and Cl− was examined. SEM and FTIR were used to study the surface of vanadium(V) loaded ZnCl2 activated carbon. Removal of vanadium(V) from synthetic ground water was also tested. Results show that ZnCl2 activated coir pith carbon is effective for the removal of vanadium(V) from water. 相似文献
9.
Sayed Z. Mohammadi Mohammad A. Karimi Daryoush Afzali Fatemeh Mansouri 《Central European Journal of Chemistry》2010,8(6):1273-1280
Two series of activated carbon have been prepared by chemical activation of Amygdalus Scoparia shell with phosphoric acid or zinc chloride for the removal of Pb(II) ions from aqueous solutions. Several methods were employed
to characterize the active carbon produced. The surface area was calculated using the standard Brunauer-Emmet-Teller method.
The microstructures of the resultant activated carbon were observed by scanning electron microscopy. The chemical composition
of the surface resultant activated carbon was determined by Fourier transform infrared spectroscopy. In the batch tests, the
effect of pH, initial concentration, and contact time on the adsorption were studied. The data were fitted with Langmuir and
Freundlich equations to describe the equilibrium isotherms. The maximum adsorption capacity of Pb(II) on the resultant activated
carbon was 36.63 mg g−1 with H3PO4 and 28.74 mg g−1 with ZnCl2. To regenerate the spent adsorbents, desorption experiments were performed using 0.25 mol L−1 HCl. Here we propose that the activated carbon produced from Amygdalus Scoparia shell is an alternative low-cost adsorbent for Pb(II) adsorption. 相似文献
10.
Adsorption of n-butanol and water from butanol–water mixtures is studied on adsorbents of different hydrophobicity (activated carbon and
hydrophobized montmorillonites). The shape of the adsorption isotherms of the hydrophobized clay minerals does not indicate
preferential adsorption of butanol. Therefore, the adsorption capacity cannot be determined on the basis of the Langmuir isotherm.
A new equation for determining the adsorption capacity is derived by combining the free enthalpy of adsorption with the adsorption
excess amount. Both collections of data are obtained from the surface excess isotherm. The reliability of the adsorption capacity
is checked by X-ray diffraction measurements.
Received: 1 November 1997 Accepted: 19 February 1998 相似文献
11.
Understanding the adsorption of water vapor onto activated carbons is important for designing processes to remove dilute contaminants
from humid gas streams, such as providing protection against chemical warfare agents (CWAs), or against toxic industrial compounds
(TICs) used in a terrorist chemical attack. Water vapor isotherms for Calgon BPL granular activated carbon (GAC), military
ASZM-TEDA GAC, electrospun activated carbon nanofibers (ACnF), Calgon Zorflex™ activated carbon cloth, and Novoloid-based activated carbon fiber cloth (ACFC) are presented. Of particular interest are
the ACFC isotherms, which exhibit an unusually high degree of hydrophobicity. The ACFC isotherms also show a correlation between
water vapor adsorption hysteresis and the level of activation. Water vapor isotherm models from the literature are compared. 相似文献
12.
Isotherms of the adsorption of benzene vapor from moist air on active carbon (AC) moistened to equilibrium are obtained from dynamic experiments. The experimental data on the adsorption equilibrium of some organic substances from a flow of moist air by a fixed bed of AC moistened to equilibrium are obtained. The data on the equilibrium adsorption of benzene vapor is analyzed using the Dubinin-Radushkevich equation (the theory of volume filling of micropores). It is revealed that the characteristic adsorption energy of benzene vapor decreases as the filling of the microporous volume with water molecules increases. The characteristic adsorption energy depends on the following factors: polarizability of a substance in the adsorption field created by micropores, the number of carbon atoms in the adsorbate molecules, and parameters of the porous structure. The equation for the calculation of the parameters of equilibrium adsorption of organic substances from moist air on AC moistened to equilibrium are obtained.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 434–438, March, 1995. 相似文献
13.
Marek Šváb Kateřina Sukdolová Martina Švábová 《Central European Journal of Chemistry》2011,9(3):437-445
Competitive adsorption of zinc and copper on activated carbon is studied in this article. Main aim was to suggest an advanced
model for competitive adsorption of both metals considering pH influence and precipitation. A surface-complexation approach
was employed for the modeling. Two models were considered: simple adsorption and ion exchange. System “The Geochemists Workbench”
was used for calculation of both static and dynamic adsorption tasks. From the batch experiments, concentration of four types
of sorbing sites on the carbon surface and its protonation and sorption constants were deduced. Then, batch competitive adsorption
experiments were compared with the models’ results. Finally, a column experiment (fixed bed adsorption) was carried out. It
was observed that the model of ion exchange can satisfyingly predict both chromatographic effect and increase of zinc concentration
in effluent over its initial value, although a quantitative agreement between the model and the experiment was not totally
precise. 相似文献
14.
X-ray microtomography coupled with image analysis was used to quantify the adsorption of vapours on activated carbon beds.
This technique was tested using three different challenges: CCl4, water vapour and a mixture of water- and organic vapour. It is shown that the used technique allows determining the adsorption
front progress in the case of organic vapour and mixture of water and organic vapour whereas the existence of this front was
not so obvious in the case of water vapour. Experimental results obtained for organic vapours were interpreted on the basis
of the Wheeler-Jonas equation: a good agreement was found between experimental and theoretical breakthrough times. 相似文献
15.
G. I. Berezin R. Sh. Vartapetyan A. M. Voloshchuk G. A. Petukhova N. S. Polyakov 《Russian Chemical Bulletin》1998,47(10):1879-1885
The mechanism of adsorption of water molecules on nonporous carbon adsorbents has been suggested in terms of two different
states of adsorbed water; stretched liquid water and water that occupies an intermediate state between the liquid and vapor.
Two stages of adsorption were distinguished: condensation and pre-condensation that assumes the formation of molecular associates.
The BET model was used to describe the pre-condensation stage. The equations of the adsorption isotherm for water vapor in
the region of condensation process and the expression for the determination of the specific hydrophilic surface of adsorbents
were found. Examination of the experimental data on adsorption of water vapor on nongraphitized samples of carbon adsorbents
shows that in the region of polymolecular adsorption, all isotherms fall into a common curve determined by the equation of
the stretched liquid film and can be calculated regardless of the properties of individual liquid water. The equation for
adsorption of water vapor on the hydrophobic surface was obtained.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1933–1939, October, 1998. 相似文献
16.
Activated Carbon Adsorption of Some Phenolic Compounds Present in Agroindustrial Wastewater 总被引:3,自引:0,他引:3
Single solute and simultaneous experimental adsorption isotherms of three phenolic compounds: gallic acid, p-hydroxybenzoic acid and syringic acid, have been investigated at 20, 30 and 40°C, using a bituminous coal based activated carbon. Regardless of temperature, the capacity of the activated carbon used to adsorb these compounds presented the following order: syringic acid > p-hydroxybenzoic acid > gallic acid. The increase of temperature slightly favored the adsorption capacity of the phenolic compounds. In binary and ternary component adsorption, experimental data suggest that interactions between adsorbates improve the adsorption capacity of some of the phenolic acid compounds. On the contrary, at high organic concentrations, adsorbed gallic acid was partially removed from the activated carbon surface because of the presence of the other components. 相似文献
17.
G. I. Berezin 《Russian Chemical Bulletin》1999,48(8):1462-1466
The behavior of integral and differential heats of adsorption of water in the region of transition from the first stage of
adsorption (formation of clusters) to the second stage (formation of a stretched liquid film) was considered. The curve of
integral heat of adsorption has an inflection at the transition point, and the differential heat of adsorption changes jumpwise.
The values of these effects were estimated by the simplest model of formation of one and two hydrogen bonds between a water
molecule and an adsorption center on the surface of the carbon adsorbent. Curves of differential heat of adsorption with transition
points for real systems are presented.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1479–1483, August, 1999. 相似文献
18.
The adsorption of activated carbon prepared from Scenedesmus obliquus (algae) was evaluated through adsorption of Astrazon red. The adsorption efficiency of activated carbon was determined based on the specific surface area and pore size distribution. These results were compared with the results obtained with untreated algae. Approximately a 3-fold increase in the percentage of dye removal was observed for activated carbon compared to the untreated material. The primary reason for this observation may be the increase in specific surface area and total pore volume by chemical activation from 0.0136 to 423.7001?m2?g?1 and from 0.0012 to 0.1643?cm3?g?1, respectively. A pseudo-second-order model was fit with the kinetic data and the results indicate chemical adsorption. The maximum adsorption capacity of activated carbon was 181.82?mg?g?1 at 25°C according to Langmuir isotherm model. 相似文献
19.
B. Sturm H.-D. Knauth N. Theobald G. Wünsch 《Fresenius' Journal of Analytical Chemistry》1998,361(8):803-810
Solid-phase extraction (SPE) has been used to enrich organic micropollutants (hydrophobic chlorinated and polycyclic aromatic
hydrocarbons, CHC and PAH) from coastal water samples and to systematically study the influence of humic substances (HS) on
SPE. A reversed phase (RP) system with high flow rates (rapid chromatography, RC) was used to show the basic adsorption principles
and interaction processes which influence the enrichment of organic compounds. A model humic substance was found to hinder
the enrichment of individual hydrophobic micropollutants (MP), depending on their octanol-water distribution coefficient P
OW. This effect was found to be lower with natural humic substances. For longer contact time between water sample and adsorption
material, the pollutant/humic substance bonding proved to be reversible.
Received: 8 December 1997 / Revised: 2 March 1998 / Accepted: 4 March 1998 相似文献
20.
Methyl tertiary butyl ether (MTBE) is an organic compound thatis used to increase the gasoline octane number. At the beginning of 1980s, by discovering the undesirable effects of tetra ethyl lead usage in fuel, MTBE began to be used worldwide. But gradually the undesirable effects of MTBE on environment had been revealed. Adsorption is the most conventional and economical technology for MTBE removal from polluted water. In this research, some experiments have been done for studying the adsorption of MTBE on different solid adsorbent in continuous processes. In continuous experiments, the water polluted with known initial MTBE concentration passes through an adsorption column containing two kinds of adsorbent including granular activated carbon (GAC), powdered activated carbon (PAC). By measuring MTBE concentration in exit flow at different times the effect of different operating parameters such as temperature, pH, and flow rate have been studied and the optimum condition have been determined. The batch experimental results have been used to calculate the constant parameters of Langmuir adsorption isotherm equations. A dynamic simulation of MTBE adsorption on activated carbon in an adsorption column has been proposed. The comparison of the experimental data with the values given by the proposed model for similar operating conditions, verifies the accuracy of the proposed mathematical model. 相似文献