© A.W.Marczewski 2002

Reload Adsorption Guide

Notation
in preparation

See also: Adsorption Glossary, Basics and References
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
A
specific surface area, [m2/g] (see also S), typically ABET or AL (determined by fitting BET or Langmuir isotherm)
a, A, ads, Ads
(true) adsorbed amount, [mol/g], [mol/m2] ("n" is usually recommended)
am
monolayer capacity (see "a") - maximum adsorption in monolayer, [mol/g], [mol/m2]
amic
micropore (adsorption) capacity (see "a") - maximum adsorption in micropores, [mol/g], [mol/m2]
ao
adsorption capacity (see "a") - maximum adsorption - less specific than am or amic, [mol/g], [mol/m2]
α
interaction coefficient in FG (Fowler-Guggenheim) isotherm [-],
B
B
parameter of DR (Dubinin-Radushkevich) and DA (Dubinin-Astakhov) isotherm equations, [-]
C
c, C
molar concentration of solute, [mol/dm3]
cs, Cs
molar concentration at saturation, [mol/dm3]
C
adsorption equilibrium constant in BET isotherm equation([1/Pa]; may be dimensionless if relative pressure, x, is used) - the same as K
χ(ε)
differential energy distribution function ([mol/kJ] for energy ε)
χ(E)
differential energy distribution function ([-] for reduced energy E)
D
Δn
n-dimensional integration space
E
ε
adsorption energy, [kJ/mol]
εij
energy of adsorption of component "i" replacing desorbed component "j", εij = εi - εj (competitive adsorption) [kJ/mol]
E
reduced adsorption energy, E = ε/RT , [-]
Eij
reduced energy of adsorption of component "i" replacing desorbed component "j", Eij = Ei - Ej (competitive adsorption) [-]
F
ø
volume fraction (other notation details are the same as for molar fractions, x) [-]
F(ε)
integral (cumulative) energy distribution function, dF/dε ([mol/kJ] for energy ε)
F(E)
integral (cumulative) energy distribution function, dF/dE ([-] for reduced energy E)
G
H
I
J
K
K
adsorption equilibrium constant, K = Koexp(ε/RT) (gas: [1/Pa], solute: [dm3/mol]; may be dimensionless if relative pressure or concentration, x, is used)
Ki
adsorption equilibrium constant for i-th component
Kij
adsorption equilibrium constant for the competition of components "i" and "j",
Kij = Ki/Kj
Kij = Ko,ij exp(εij/RT) = Ko,i/Ko,j exp[(εi - εj)/RT]
Ko
pre-exponential (entropic) factor (gas: [1/Pa], solute: [dm3/mol]; may be dimensionless if relative pressure or concentration, x, is used)
Kn
association constant in Kiselev isotherm, [-]
L
M
m
heterogeneity parameter (F, GF, LF, Tóth, GL ... isotherm equations; 0 < m ≤ 1 ) [-]
N
n
heterogeneity parameter (LF, GL isotherm equations; 0 < m ≤ 1 ) [-]
n
parameter of DA (Dubinin-Astakhov) isotherm (DR: n=2, F: n=1; typical DA: 3 or 4) [-]
n
no. of mixture components [-]
i(n)
i(n) (in index)
for i-th component in n-component mixture
n (in index)
n-component vector
n
ni
amount [mol] of species/component "i"
ne
nei
excess adsorption, excess adsorbed amount, [mol/g], [mol/m2]; index "i" - component "i"
O
P
p, P
gas/vapor pressure, [Pa], [mmHg]
ps, Ps
vapor pressure at saturation, [Pa], [mmHg]
Q
R
R
Universal gas constant, 8.314 [J/mol K]
S
S
specific surface area, [m2/g] (see also A), typically SBET or SL (determined by fitting BET or Langmuir isotherm)
σ
cross-section area (e.g. 0.162 nm2 for N2)
σE
dispersion of reduced adsorption energy [-]
T
T
Absolute temperature [K]
θ
relative adsorption, adsorption coverage
θ = adsorption / monolayer capacity
θ = adsorption / adsorption capacity (also for micropores)
U
V
v
gas volume
V
adsorbed amount expressed as volume of gas/vapor adsorbate at STP (1013.25hPa, 273K) per adsorbent mass, [cm3/g STP]
Vm
monolayer capacity (determined by fitting the BET eq.) expressed as volume of gas/vapor adsorbate at STP (1013.25hPa, 273K) per adsorbent mass, [cm3/g STP]
Vmic
micropore capacity (determined by t-plot or αs method) expressed as volume of liquid adsorbate per adsorbent mass, [cm3/g]
Vmeso
mesopore capacity (determined by e.g. BJH method) [cm3/g]
V0.98
total pore capacity determined at relative pressure x = 0.98 [cm3/g]
X
x
molar fraction, [-]
xsi(n)
xli(n)
molar fraction of component "i" in n-component mixture in surface ("s") or bulk ("l") phase, [-]
xsi(n)l
xsi(n)t
molar fraction of component "i" in n-component mixture in surface ("s") phase - for local patch/particular site type (subscript "l") or total - averaged for entire surface phase (subscript "t"), [-]
x
relative vapor pressure, x = p/ps, [-]
relative solute concentration, x = c/cs, [-]
Y
Z
z(F)
relative reduced adsorption energy, z(F) = E(F) - Eo (Eo - characteristic reduced energy, e.g. average or minimum reduced energy E); z(F) is inverse function to the integral (cumulative) energy distribution F(z) = F(E-Eo)

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