Environmental Engineering Reference
In-Depth Information
N
j=1,2,…,N x
(5.27)
a
eq
XK
=
c
C
ij
j
j
i
i
=
1
where, K j eq is the equilibrium constant for aqueous reaction j . The rate of
accumulation of component i due to aqueous reaction j ( R j aq ) is:
(5.28)
RaR
ji
aq
=
ji
j
The total rate of accumulation of component i due to all aqueous reactions
is given as:
N
N
∑∑
R
aq
=
X
R
aq
=
X
a R
(5.29)
i
ji
ji
j
j
=
1
j
=
1
5.3.5.3 Precipitation/dissolution reactions
It is important to incorporate the precipitation/dissolution reactions in
the mass transport model. In precipitation reactions, the chemical compo-
nents are assumed to be composed of products expressed as:
N c
j =1,2,…,N p
(5.30)
P
b C
j
ij
i
i
=
1
Where, P j is the chemical formula for precipitate j , b ij is the stoichio-
metric coefficient in precipitate j for component i , and N p is the number
of precipitates for component i . The production of the precipitate will not
occur until the solution is saturated. Therefore, the law of mass action is
written as:
N
b
j =1,2,…,N p
(5.31)
SP
K
c
C
ji
j
i
i
=
1
where, K j SP is the solubility product equilibrium constant for precipitate
j . The total rate of production of component i due to precipitation/dissolu-
tion reactions ( R j p ) is:
N
N
∑∑
p
p
p
R
=
p
R
=
p
b R
(5.32)
i
ij
ji
j
j
=
1
j
=
1
where, R j p is the rate of production of precipitate j .
 
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