Environmental Engineering Reference
In-Depth Information
stage I, those contaminants in water with a greater affinity for the carbon are concen-
trated on the carbon by a process called adsorption. The removal depends not only
on the rate of transport of compounds from water to carbon (the realm of kinetics),
but also on the ultimate capacity of the carbon bed (the realm of thermodynamics). In
stage II, we have to regenerate the medium within the reactor so that it can be reused.
Moreover, in stage II, we need information on how fast the pollutant can be recov-
ered from the activated carbon, and also the fate and transformation of the adsorbed
pollutant (that is, the kinetic aspects).
TABLE 1.3
Applications of Chemical Thermodynamics and Kinetics in Environmental
Processes
Typical Equilibrium
Thermodynamic
Process
Representation
Property
Kinetic Property
Saturation solubility, C i
Solubility in water
A (pure) A (water)
Dissolution rate
Absorption in
water
A (air) A (water)
Henry's law constant, K H
Absorption rate
Precipitation from
water
A (water)
A (crystal)
Solubility product, K sp
Precipitation rate
Volatilization from
water
A (water)
A (air)
Henry's law constant, K H
Volatilization rate
Vapor pressure, P i
Evaporation from
pure liquid
A (pure) A (vapor)
Evaporation rate
A A + H +
Acid/base
dissociation
Acidity or basicity
constant, K a or K b
Acidification rate
A + + BX BA + X +
Ion exchange
Ion-exchange partition
constant, K exc
Ion-exchange rate
Oxidation/reduction A ox + B red A red + B ox
Equilibrium constant, K i
Redox reaction rate
Adsorption from
water
A (water) A (surface)
Soil/water partition
constant, K SW
Adsorption rate
Adsorption from
air
A (air) A (surface)
Particle/air partition
constant, K AP
Adsorption rate
Uptake by biota
A (water) A (biota)
Bio-concentration factor,
K BW
Rate of uptake
Uptake by plants
A (air) A (plant)
Plant/air partition
constant, K PA
Rate of uptake
A + B Products
Chemical reaction
Equilibrium constant, K eq
Rate of chemical
reaction
Photochemical
reaction
A + ( h ν ) Products
Equilibrium constant, K eq
Rate of photolysis
Biodegradation
reaction
A
+
(enzymes)
Products
Equilibrium constant, K eq
Michaelis-Menten
and Monod
kinetics constants
 
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