Environmental Engineering Reference
In-Depth Information
research. team. will. irradiate. solutions. or. suspensions. of. fullerenes. and. nanotubes.
and.monitor.the.subsequent.loss.rate.and.product.formation.rate,.as.well.as.the.spec-
troscopic. and. microscopic. characteristics. of. the. solutions.. The. water. will. contain.
various.naturally.occurring.substances.such.as.carbonates,.humic.acids,.and.oxygen.
[22]..No.progress.report.was.available.at.the.writing.of.this.topic
Few.publications.on.the.fate.and.transport.of.nanomaterials.in.sediments.were.
available.at.the.time.this.topic.was.written..Researchers.at.the.University.of.South.
Carolina.at.Columbia.currently.are.investigating.the.“chemical.and.biological.behav-
ior.of.carbon.nanotubes.in.estuarine.sedimentary.systems”.under.a.grant.funded.by.
NCER.for.the.period.from.2004.to.2007..The.objective.of.the.research.is.to.evaluate.
the.potential.for.single-walled.carbon.nanotubes.to.“be.transported,.accumulate.and.
cause.deleterious.effects.within.estuarine.environments”.[23]..The.initial.research.
results. showed. the. effect. of. salinity. on. agglomeration. of. nanotubes. in. the. water.
column..Single-walled.carbon.nanotubes.with.an.average.particle.size.of.200.to.250.
nm.could.exist.in.stable.colloidal.suspensions.at.neutral.pH.in.solutions.of.low.ionic.
strength.(10.mM)..Within.minutes.after.increasing.the.salinity.to.over.5.parts.per.
thousand,. the. nanotubes. formed. large. locs. with. an. average. particle. size. greater.
than.2.µm..Subsequent.research,.as.yet.unreported.in.the.literature,.has.focused.on.
the.distribution.of.single-walled.nanotubes.in.sediments.and.in.sediment-ingesting.
benthic.invertebrates.[24].
A. second. research. group. at. the. University. of. Michigan. has. received. funding.
from.NCER.to.evaluate.the.dispersion.states.of.carbon.nanotubes.under.typical.envi-
ronmental.conditions.and.to.evaluate.the.transport.behavior.of.these.nanomaterials.
in. different. types. of. soil. and. sediment. media. [25].. However,. no. progress. reports.
were.available.for.this.research.project.as.of.this.writing.
6.4.2 g
rOundwater
Various. studies. have. been. performed. to. evaluate. the. mobility. of. nanomaterials. in.
porous. media.. These. include. studies. of. the. fate. and. transport. of. nanomaterials. in.
certain. wastewater. treatment. processes,. such. as. iltration,. which. provide. insights.
into.the.potential.movement.of.nanoparticles.through.groundwater.
As.discussed.further.in.Chapter.7,.researchers.have.conducted.laboratory.experi-
ments. to. empirically. derive. the. attachment. eficiency,. a,. which. is. the. ratio. of. the.
rate.of.particle.deposition.to.the.rate.of.particle.collisions.with.a.ilter.medium..The.
attachment.eficiency.is.a.single.parameter.that.provides.a.measure.of.the.various.
forces. acting. on. a. particle. as. it. passes. through. a. porous. medium,. such. as. the. van.
der. Waals. forces,. electrostatic. repulsive. or. Coulomb. force,. and. force. of. solvency,.
described.previously.in.this.chapter.
Lecoanet,.Bottero,.and.Wiesner.conducted.column.experiments.to.quantify.the.
mobility.of.eight.different.manufactured.nanomaterials.in.a.porous.medium.of.glass.
beads,.which.they.indicated.would.be.representative.of.a.sandy.groundwater.aquifer.
[17]..The.nanomaterials.tested.included.two.sizes.of.silica,.titanium.dioxide,.ferrox-
ane,.alumoxane,.fullerol.(hydroxylated.C60),.nano-C60,.and.surface-modiied.single-
walled.carbon.nanotubes..The.results.indicated.that.different.forms.of.nanoparticles.
with.the.same.composition.have.different.mobilities..For.example,.of.the.carbon-based.
