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The activated carbon industry uses many terms and we know that it can sometimes be confusing.
Under this section we have collected the most common terms for your reference. |
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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
Absorption
A process in which fluid molecules are taken up by a liquid or solid and distributed throughout the body of that liquid or solid.
Acid extractable material
substances dissolved by an acid under specified conditions.
Activated carbon
A family of carbonaceous substances manufactured by processes that develop adsorptive properties.
Activation
Any process whereby a substance is treated to develop adsorptive properties.
Activity
A generic term used to describe the capacity to adsorb in general; also, the adsorptive capacity of an adsorbent as measured by a standard test.
Adsorbate
Any substance that is or can be adsorbed.
Adsorbent
Any solid having the ability to concentrate significant quantities of other substances on its surface.
Adsorption
A process in which fluid molecules are concentrated on a surface by chemical or physical forces, or both.
Adsorption wave
see mass transfer zone.
Adsorption zone
See mass transfer zone.
As is basis
As received.
Ash
Residue after the combustion of a substance under specified conditions.
Ash Content of Activated Carbon
This test method describes a procedure for the determination of total ash content of activated carbon.
C
Carbon Tetrachloride (CTC) Activity of Activated Carbon
This test method covers the determination of the activation level of activated carbon. Carbon tetrachloride (CCl4) activity is defined herein as the ratio (in percent) of the weight of CCl 4 adsorbed by an activated carbon sample to the weight of the sample, when the carbon is saturated with CCl4 under conditions listed in this test method.
Chemical adsorption
See chemisorption.
Chemisorption (chemical adsorption)
The binding of an adsorbate to the surface of a solid by forces whose energy levels approximate those of a chemical bond.
Critical bed depth
The minimum depth of an adsorbent bed required to contain the mass transfer zone.
Crushing strength
The property of a particle to resist physical breakdown when contained and subjected to a slowly increasing continuously applied force.
D
Degassing
Removal of gases. Density, absolute or true - the mass under specified conditions of a unit volume of a solid sorbent excluding its pore volume and inter - particle voids
Density, apparent (density, bulk)
The mass under specified conditions of a unit volume of a solid sorbent including its pore volume and inter - particle voids.
Density, block
See density, particle.
Density, bulk
See density, apparent.
Density, particle (density, block)
The mass under specified conditions of a unit volume of a solid sorbent including its pore volume but excluding inter - particle voids.
Desorption
The separation of an adsorbate as such from a sorbent.
Differential heat of adsorption
The heat evolved during the adsorption of an incremental quantity of adsorbate at a given level of adsorption.
Dosage
The quantity of substance applied per unit weight or volume of the fluid being treated.
Dry basis
Exclusive of any moisture which may be present.
Dust
An imprecise term referring to particulates capable of temporary suspension in air or other gases; also, particles smaller than an arbitrarily selected size.
Dynamic adsorptive capacity
The quantity of a given component adsorbed per unit of adsorbent from a fluid, or fluid mixture moving through a fixed bed at the breakpoint for that component.
E
Effective size
The particle size, in millimetres, which corresponds to 10 percent finer on the cumulative particle size distribution curve.
Electrical conductivity of a particulate substance
The current flowing through a unit cross section for an imposed unit potential gradient under specified conditions of packing.
Electrophoresis
Migration of dispersed solid, liquid or gaseous material to one of two electrodes under the influence of an impressed direct current voltage.
End point
The occurrence in the effluent of the maximum permissible concentration of an adsorbate of interest.
Equilibrium adsorptive capacity
The quantity of a given component adsorbed per unit of adsorbent from a fluid or fluid mixture at equilibrium temperature and concentration, or pressure.
Expanded bed
A bed of granular particles through which a fluid flows upward at a rate sufficient to slightly elevate and separate the particles without changing their relative positions.
F
Filterability
The rate at which particles can be separated from a slurry by means of a permeable medium under specified conditions.
Fines
Particles smaller than the smallest nominal specification particle size.
Fixed bed
A bed of granular particles through which a fluid flows without causing substantial movement of the bed.
Freundlich adsorption isotherm
a logarithmic plot of quantity of component adsorbed per unit of adsorbent versus concentration of that component at equilibrium and at constant temperature, which approximates the straight line postulated by the Freundlich adsorption equation
X/M = kCn
where:
X = quantity adsorbed,
M = quantity of adsorbent, C = concentration, k and n = constants.
G
Granular activated carbon
Activated carbon in particle sizes predominantly greater than 80 mesh.
H
Hardness
A generic term referring to the resistance of a particle to breakdown as measured by specific tests.
Heat of adsorption
The heat evolved during adsorption.
Hydrolytic adsorption
The adsorption of a weakly ionised acid or base formed by the hydrolysis of some types of salts in aqueous solution.
I
Ignition temperature (kindling point)
The lowest temperature at which combustion will occur spontaneously under specified conditions.
Impact strength
The property of a particle to resist physical breakdown when subjected to a rapidly increasing applied force.
Integral heat of adsorption
The sum of the differential heats of adsorption from zero to a given level of adsorption.
Intermittent moving bed (pulse, slug)
An adsorption process characterized by upward flow of a fluid through a fixed bed of granular adsorbent with periodic withdrawal of spent adsorbent from the bottom of the bed and additions of reprocessed or virgin adsorbent to the top of the bed.
Iodine Number of Activated Carbon
This test method covers the determination of the relative activation level of unused or reactivated carbons by adsorption of iodine from aqueous solution. The amount of iodine absorbed (in milligrams) by 1 g of carbon using test conditions listed herein is called the iodine number.
Irreversible adsorption
Adsorption in which the desorption isotherm is displaced toward higher equilibrium adsorption capacities from the adsorption isotherm.
Isobar
A plot of quantity adsorbed per unit of adsorbent against equilibrium temperature when concentration or pres - sure is held constant.
Isotherm
A plot of quantity adsorbed per unit of adsorbent against equilibrium concentration, or pressure, when temperature is held constant.
L
Langmuir adsorption theory
The surface of an adsorbent has only uniform energy sites and adsorption is limited to a monomolecular layer.
Langmuir isotherm
A plot of isothermal adsorption data which to a reasonable degree fit the Langmuir adsorption equation.
M
Macropore
Pores with widths exceeding 50 nanometres (500 angstrom units).
Mass transfer zone (adsorption wave) (adsorption zone)
The region in which the concentration of the adsorbate of interest in the fluid decreases from influent concentration to the lowest detectable concentration.
Mean particle diameter
The weighted average particle size, in millimetres, of a granular adsorbent computed by multi - plying the percent retained in a size fraction by the respective mean sieve openings, summing these values and dividing by 100.
Mesopore
Pores of widths between 2 and 50 nanometres (20 and 500 angstrom units).
Micropore
Pores with widths not exceeding 2 nanometres (20 angstrom units).
Moisture content
The water content of a substance as measured under specified conditions.
Moisture in Activated Carbon
These test methods provide two procedures for the determination of the moisture content of activated carbon. The procedures may also be used to dry samples required for other tests. The oven-drying method is used when water is the only volatile material present and is in significant quantities, and the activated carbon is not heat-sensitive (some activated carbons can ignite spontaneously at temperatures as low as 150°C). The xylene-extraction method is used when a carbon is known or suspected to be heat sensitive or to contain nonwater-miscible organic compounds instead of or in addition to water. The oven-drying method described in these test methods may be used as the reference for development of instrumental techniques for moisture determination in activated carbon.
Monomolecular layer
An adsorbed film, one molecule thick.
Multimolecular layer
An adsorbed film more than one molecule thick.
O
Oven drying loss
The reduction in weight resulting when a substance is heated in an oven under specified conditions.
P
Particle Size Distribution (PSD) of Granular Activated Carbon
This test method covers the determination of the PARTICLE SIZE DISTRIBUTION of granular activated carbon. For purposes of this test, granular activated carbon is defined as a minimum of 90% retained on a 180-[mu]m Standard sieve.
Note 1-For extruded carbons, as the length/diameter ratio of the PARTICLEs increases, the validity of the test results might be affected.
The data obtained may also be used to calculate mean PARTICLE diameter (MPD), effective SIZE, and uniformity coefficient.
Pelleted activated carbon
A form of granular activated carbon that is cylindrical in shape.
Pelletized Activated Carbon
Extruded and cylindrical shaped. These are mainly used for gas phase applications because of their low pressure drop, high mechanical strength and low dust content.
pH in Activated Carbon
The measurement of acidity or alkalinity of the activated carbon matter.
Physical adsorption (van der Waals adsorption)
The binding of an adsorbate to the surface of a solid by forces whose energy levels approximate those of condensation.
Pore diameter
The diameter of a pore in a model in which the pores in a sorbent are assumed to be cylindrical in shape and which is calculated from data obtained by a specified procedure.
Pores
The complex network of channels in the interior of a particle of a sorbent.
Pore volume
Volume of the pores in a unit weight of a sorbent.
Pore volume distribution
The distribution of pore volume among pores of different size or diameter.
Powdered activated carbon
Activated carbon in particle sizes predominantly smaller than 200 mesh (75 microns).
Preferential adsorption
Adsorption in which a certain component or certain components are adsorbed to a much greater extent than others.
R
Reactivation (revivification)
Oxidation processes for restoring the adsorptive properties of a spent sorbent.
Regeneration
Distillation or elution - type processes for restoring the adsorptive properties of a spent sorbent.
Relative efficiency
The rating of the adsorptive capacity of an adsorbent based on a comparison of its performance with that of a reference adsorbent in a defined test.
Retentivity
The ability of an adsorbent to resist desorption of an adsorbate.
Reversible adsorption
Adsorption in which the desorption isotherm approximates the adsorption isotherm.
Revivification
See reactivation.
S
Service life (service time)
The elapsed time until the end point is reached in an adsorption process.
Service time
See service life.
Sorption
A process in which fluid molecules are taken up by absorption and adsorption.
Split feed
A liquid phase adsorption process in which a powdered adsorbent is added to the solution to be treated in two or more steps, with or without intermediate separation of the adsorbent.
Surface area (B.E.T.)
The total surface area of a solid calculated by the B.E. T. (Brunauer, Emmett, Teller) equation, from nitrogen adsorption or desorption data obtained under specified conditions.
Surface area distribution
The distribution of surface area according to some parameter such as pores of different size or diameter.
Surface oxides
Oxygen containing compounds and complexes formed at the surface of an adsorbent.
Synthetic test solution
A solution of two or more components prepared under specified conditions for use in evaluation of adsorbents.
T
Threshold concentration
The minimum concentration at which a substance can be detected by the taste or odour test method employed.
Threshold odour test
A method of evaluating the odour level in a fluid by dilution under specified conditions with an odour free fluid.
U
Uniformity coefficient
The ratio of the particle diameter corresponding to 60 % finer on the cumulative particle size distribution curve to the particle diameter corresponding to 10 % finer on the same distribution curve.
V
Van der Waals adsorption
See physical adsorption.
W
Water
Extractable material - substances dissolved from other substances by water under specified conditions.
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