Environmental Engineering Reference
In-Depth Information
table . (Continued)
examples of Manufacturing Methods for target nanomaterials
nanomaterial
Process description
Ref.
Carbon.black
Carbon.black.is.produced.from.the.incomplete.combustion.or.thermal.
decomposition.of.hydrocarbons.under.controlled.conditions..As.the.
combustion.products.collide.in.the.reactor,.they.form.ever-larger.
particles.by.aggregation.and.agglomeration..Two.methods.produce.
most.of.the.commercial.carbon.black:.oil.furnace.and.thermal.black.
The.oil.furnace.process.produces.more.than.95%.of.commercial.
carbon.black..Preheated.oil.is.atomized.and.partially.combusted.in.a.
heated.gas.stream..The.gas.stream.is.quenched.with.water.and.carbon.
black.is.recovered.on.a.bag.ilter..Recovered.carbon.black.is.mixed.
with.water,.then.air-dried.
The.thermal.black.process,.which.entails.the.thermal.decomposition.of.
natural.gas,.accounts.for.most.of.the.remaining.production.of.carbon.
black.
[18,.19]
Carbon.
nanotubes
HiPco.process.of.gas-phase.chemical-vapor-deposition.is.currently.in.
commercial.use.to.manufacture.single-walled.carbon.nanotubes.
(SWNTs):
[10,.11]
.
.
Introduce.Fe(CO)
5
.catalyst.into.injector.low.via.pressurized.CO..
Heat.catalyst.stream.and.mix.with.CO.in.graphite.heater..Fe(CO)
5
.
decomposes.to.Fe.clusters..Standard.running.conditions:.450.psi.
CO.pressure,.1050°C.
.
.
.C.atoms.coat.and.dissolve.around.the.Fe.clusters,.forming.
nanotubes..Running.conditions.maintained.24-72.hours.
.
.
.Gas.low.carries.SWNTs.and.Fe.particles.out.of.the.reactor..
SWNTs.condense.on.ilters..CO.passes.through.NaOH.absorbtion.
beds.to.remove.CO
2
.and.H
2
O,.then.is.recycled.
Fullerenes.(C60.
or.buckyballs)
Fullerenes.can.be.manufactured.by.several.processes:
.
[10,.11,.
20]
.
.Fires.and.lightning.strikes.naturally.generate.small.amounts.of.
fullerenes.
.
.
.Production.in.laminar.benzene-oxygen-argon.lame..Carbon.arc.
discharged.from.graphite.electrodes.(Krätschmer-Huffman..
method).
excess. solution. and. nanomaterial;. this. can,. in. a. very. rough. sense,. be. considered.
similar.to.the.problem.of.collection.of.cutting.luids.in.machining.
With.respect.to.separation.of.the.nanomaterial.during.further.processing.or.dis-
posal,.an.important.question.is.the.strength.of.the.bonding..That.is,.how.easily.will.
the. nanomaterials. separate. from. a. substrate. and. then. potentially. be. freed. into. the.
environment?.At.the.nanoscale,.secondary.bonds.from.van.der.Waals.forces.play.a.
signiicant.role..These.bonds.are,.however,.not.as.strong.as.chemical.bonds.(physi-
sorption.vs..chemisorption),.although.there.are.strong.physisorption.and.weak.chemi-
sorption.conditions.that.approach.a.middle.ground..As.with.the.current.issues.facing.
recycling.of.multi-material.systems,.the.lip.side.to.undesired.nanomaterial.liberation.
is.the.desire.to.easily.separate.materials.for.reuse.upon.disposal.of.the.product.
