Attainment of equilibrium in activated carbon isotherm studies

Peel, Russell G.; Benedek, Andrew

doi:10.1021/es60161a013

Cited by 83 publications

(27 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…First is a strong decrease during the first five hours and second is a slow reduction observed in a metal concentration for the next 67 hours. It can be explained by diffusion and transport processes within macropores and subsequently by slow transport within meso-and micropores (Peel andBenedek 1980, Abbasi andStreat 1994). Van Lier (1983) describes three steps of adsorption kinetics, which explains attaining equilibrium.…”

Section: Resultsmentioning

confidence: 99%

Adsorption of copper, cadmium and silver from aqueous solutions onto natural carbonaceous materials

Hanzlik¹,

Jehlička²,

Weishauptová³

et al. 2004

PLANT SOIL ENVIRON

View full text Add to dashboard Cite

Twelve carbonaceous materials were investigated for adsorption of Cd, Cu and Ag from water solutions. Before the adsorption experiments the chemical and structural characterization of all materials were made. The batch adsorption experiment was used. The kinetic of the adsorption process was very fast for the first five hours but very slow for approximately the next 65 hours. Nevertheless the maximum amount of metal removed was achieved during the first stage of about five hours. Biological materials (milled wood, bark, cork) exhibited a very low affinity for adsorption of metals. The best results were obtained for materials in an intermediate degree of carbonisation with a high content of oxygen rich functional groups. Although the highly carbonised materials exhibited low ability to adsorb copper or cadmium, their capacity to bind silver was very high.Keywords: adsorption; copper; cadmium; silver; wood; peat; coal; activated carbon Supported by the Ministry of Education, Youth and Sports of the Czech Republic, Project FRVŠ 1718. 258PLANT SOIL ENVIRON., 50, 2004 (6): 257-264 posed of highly oxidised phytoclasts. Oxidation at Bílina is related to paleofires. Leonardite is highly oxidised form of lignite. Our sample represents paleoweathered coal. Other studied materials were: bituminous coal from Kladno (CZ) and anthracite from Lhotice (CZ). This series was completed with industrial carbon-rich materials: coke, activated carbon Filtrasorb F-400 and Multisorb TM 100 (Multisorb TM 100 is the peat-based adsorbent manufactured by PEATEC Corporation, USA). All materials were dried at laboratory temperature, disintegrated and sieved. The fraction size of 1-2 mm was used for all adsorption experiments and surface properties characterization. Fine fraction under 1 mm was used for elementary analyses. The elementary composition was determined by pyrolysis accompanied with measurements using a CarboErba microanalysator (Borkovcová et al. 1986). The relative amount of oxygen containing surface functional groups was determined by Fourier transform infrared (FTIR) spectroscopy. FTIR spectra were recorded with Nicolet 740 spectrometer using the standard KBr pellet technique (Borkovcová et al. 1986). The relative amount of the carboxylic groups was obtained from the FTIR spectrum by integration of the area in the zone between 1500 and 1800/cm (Yang 1997). The cation exchangeable capacity (CEC) was determined in a leachate of 0.1M BaCl 2 (Plume 1990). The mesoand macroporosity were determined by highpressure Hg porosimetry (Mayer and Stowe 1965). This method essentially consists of measuring the extent of mercury penetration into the evacuated solid as a function of applied hydrostatic pressure.The Porosimeter 2000 was used for this purpose. The surface area was measured by the BrunnauerEmmet-Teller (BET) method (Brunauer et al. 1938) with Sorptomatic 1800 CarloErba apparatus. The BET method is based on the measurement of nitrogen adsorption isotherm at the liquid N 2 temperature. Adsorption properties of carbonaceous a...

show abstract

Section: Resultsmentioning

confidence: 99%

Adsorption of copper, cadmium and silver from aqueous solutions onto natural carbonaceous materials

Hanzlik¹,

Jehlička²,

Weishauptová³

et al. 2004

PLANT SOIL ENVIRON

View full text Add to dashboard Cite

show abstract

“…The isotherms were run for extended periods (Peel and Benedek, 1979). and periodically checked until equilibrium attainment was assured.…”

Section: Isothermsmentioning

confidence: 99%

A branched pore kinetic model for activated carbon adsorption

1981

Self Cite

View full text Add to dashboard Cite

A branched pore kinetic model for aqueous phase activated carbon adsorption is presented in which the carbon particle is separated into rapidly and slowly diffusing regions. The model was developed to overcome problems arising from a single rate parameter analysis and is shown to describe experimental data well. In addition to very different rates of transport in the two regions, parameters estimated by regression analysis indicated differences in the adsorptive characteristics. RUSSELL G. PEEL SCOPEActivated carbon is gaining ever-increasing usage as a general purpose adsorbent for organics from the aqueous phase. However, the actual mechanisms of transport and adsorption within the activated carbon particle are not yet well understood. Because of the complexity of the internal pore structure, activated carbon kinetics have generally been modelled with a single effective diffusion parameter active throughout the particle (Fleck, 1973;Crittenden and Weber, 1978a;Fritz et al, 1979), even though it is accepted that activated carbons have heterogeneous surface properties and a wide range of pore sizes.This single intraparticle parameter approach has led to inconsistencies between observed equilibrium and kinetic behavior. Consequently, it is the objective of this study to develop a model, based on present knowledge of the internal structure of activated carbon, which would enable a consistent treatment of both equilibrium and kinetic data. Such a model should give an accurate description of the adsorption process from initial contact through to equilibrium.In the phenolic adsorption studies of Snoeyink (1969) and Zogorski (1976), among others, a rapid initial uptake phase followed by a slow approach to equilibrium was noted. Such behavior is not consistent with the single effective diffusion parameter model. In addition, several authors (Beck and Schultz, 1970;Satterfield et al., 1973) have demonstrated that the effective diffusion parameter in small pores is a strong function of the pore diameter to solute diameter ratio, and that diffusion rates decrease with decreasing pore size. Since activated carbons have a wide range of pore sizes, a corresponding range of diffusion rates should be expected. Rapid saturation of the fast diffusing pores would result in a net decrease in effective diffusion rate as adsorption proceeds.As an approximation to the microscopic description of the diffusional process, a model has been developed in this work which divides the carbon particle into two regions of different diffusion rates. The regions are loosely termed macropores and micropores. (These terms should not be confused with their conventional uses to define certain pore size ranges.) Relatively rapid diffusion and adsorption occur in the macropores, and the remaining slow approach to equilibrium occurs in the micropores.The micropores are assumed to be homogeneously distributed throughout the particle and to branch off the larger macropore network which is responsible for radial transport. A schematic diagram of the propos...

show abstract

“…Accordingly, reducing particle size to improve PAC's adsorbate uptake rate is one measure to more efficiently utilize its adsorptive capacity. Although adsorption kinetics can be enhanced by reducing the activated carbon particle size, the overall adsorption capacity is unaffected by particle size because adsorption occurs in the internal pores of the activated carbon particles (Letterman et al, 1974;Peel and Benedek, 1980;and Leenheer, 2007). However, the recent advent of superfine powdered activated carbon (SPAC) has renewed discussions on the relationship between particle size and adsorption capacity as well as it has prompted new discussions on the relationship in the sub-micron domain (Matsui et al, 2004(Matsui et al, , 2005Heijman et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Geosmin and 2-methylisoborneol removal using superfine powdered activated carbon: Shell adsorption and branched-pore kinetic model analysis and optimal particle size

et al. 2013

View full text Add to dashboard Cite

2-Methylisoborneol (MIB) and geosmin are naturally occurring compounds responsible for musty-earthy taste and odor in public drinking-water supplies, a severe problem faced by many utilities throughout the world. In this study, we investigated adsorptive removal of these compounds by superfine powdered activation carbon (SPAC, particle size <1 µm) produced by novel micro-grinding of powdered activated carbon; we also discuss the optimization of carbon particle size to efficiently enhance the adsorptive removal. After grinding, the absorptive capacity remained unchanged for a 2007 carbon sample and was increased for a 2010 carbon sample; the capacity increase was quantitatively described by the shell adsorption model, in which MIB and geosmin adsorbed more in the exterior of a carbon particle than in the center. The extremely high uptake rates of MIB and geosmin by SPAC were simulated well by a combination of the branched-pore kinetic model and the shell adsorption model, in which intraparticle diffusion through macropores was

show abstract

Attainment of equilibrium in activated carbon isotherm studies

Cited by 83 publications

References 7 publications

Adsorption of copper, cadmium and silver from aqueous solutions onto natural carbonaceous materials

Adsorption of copper, cadmium and silver from aqueous solutions onto natural carbonaceous materials

A branched pore kinetic model for activated carbon adsorption

Geosmin and 2-methylisoborneol removal using superfine powdered activated carbon: Shell adsorption and branched-pore kinetic model analysis and optimal particle size

Contact Info

Product

Resources

About