Environmental Engineering Reference
In-Depth Information
nanomaterials..Thus,.as.with.many.environmental.questions,.the.fate.and.transport.
of.nanomaterials.must.be.considered.on.a.case-by-case.basis.
The.fate.and.transport.of.nanomaterials.in.the.environment.depend.on.physical.
and.chemical.considerations.different.than.those.applied.for.simple.molecular.chemi-
cals..The.environmental.stability.of.nanoparticles.is.not.as.dependent.on.redox-type.
reactions,. but. rather. on. physisorption. properties. that. permit. them. to. interact. with.
environmental.constituents.at.low.energies..Furthermore,.because.particle.sizes.and.
related.properties.continue.to.change.after.a.release.due.to.agglomeration.and.other.
environmental.reactions,.assumptions.of.equilibrium.may.be.highly.misleading,.par-
ticularly.when.multiple.reaction.products.or.intermediates.are.possible..It.therefore.is.
important.to.consider.the.kinetics.of.the.nanoparticle.interactions.within.the.context.
of. the. time. course. of. concomitant. environmental. interactions. involved. in. fate. and.
transport.
The. models. provided. in. this. chapter. represent. initial. steps. in. developing. the.
means. that. can. be. applied. to. predict. the. behavior. of. speciic. materials. within. the.
environment,.and.thereby.to.determine.the.potential.for.an.adverse.effect..They.are.
the.logical.replacement.for.properties.such.as.solubility,.Henry's.Law.constants,.and.
partition.coeficients.that.are.the.basis.for.
a priori
evaluation.of.the.environmental.
fate. of. smaller. and. more. typical. environmental. contaminants.. The. derivations. in.
this. chapter. also. indicate. the. need. to. broaden. our. understanding. of. the. physical.
properties. of. nanomaterials.. Properties. such. as. zeta. potentials. and. dielectric. and.
Hamaker. constants. will. become. critical. to. adequately. predict. fate. and. transport,.
thereby.allowing.for.due.consideration.and.precaution.in.the.introduction.and.han-
dling.of.nanomaterials.in.the.environment.
. list oF sYMbols
A
Hamaker.constant
E
(
C
)
XX´
. Potential.energy.arising.from.the.Coulomb.forces.between.two.particles
E
(
w
)
XX
´
. Intermolecular.potential.energy
F
↓.
Vector.settling.force
F
T
Total.force.ield
F
R
Electrostatic.repulsive.(Coulomb).force
F
vdw
van.der.Waals.forces
F
s
Forces.of.solvency
g
Gravitational.constant
∆
G
.
Net.free.energy.difference
h
Linear.measure.of.particle.separation
Δ
H
a
Enthalpy.of.adsorption
i
Constituent.index
k
Boltzmann.constant
k
XX
Collision.rate.constant.for.two.identical.entities
k
as
Apparent.solubility
k
′
Reaction.rate
MR
Molar.refractivity
n
Number.of.binding.sites.on.the.nanoparticle