Environmental Engineering Reference
In-Depth Information
•
Sporting.goods:
Wilson®.Tour.Davis.Cup.Oficial.Tennis.Ball.(Wilson®).—.incorporates.
“NanoPlay”.technology.to.increase.durability.
Head®.Nano.Titanium.Tennis.Racquet.(Head®).—.integrates.nanoscale.
materials.
Wilson®. [K]Factor®. Tennis. Racket. (Wilson®). —. contains. Karophite.
Black,.created.by.bonding.carbon.black,.graphite,.and.silicon.dioxide.
together.at.the.nano.level.
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•
•
Some.of.these.product.descriptions.illustrate.how.manufacturers.can.guard.the.
details.of.proprietary.technology.by.providing.little.information.about.the.nanoma-
terials.in.their.products..Many.of.these.consumer.products.do,.however,.contain.one.
or.more.of.the.nanomaterials.that.are.the.focus.of.this.topic..The.sections.below.pro-
vide.information.on.titanium.dioxide,.zero-valent.iron,.silver,.carbon.black,.carbon.
nanotubes,.and.fullerenes.
2.4.1 t
itanium
d
iOxide
Titanium.is.a.common.element,.found.in.the.minerals.rutile.(predominantly.titanium.
dioxide,.TiO
2,
.also.known.as.titania).and.ilmenite.(FeTiO
3
)..Manufacturers.have.long.
used.TiO
2
.as.a.pigment,.and.in.welding.electrodes,.ceramics,.and.catalysts..As.the.
primary.white.pigment,.it.is.used.to.color.paint,.plastics,.paper,.and.inks..The.func-
tions.of.TiO
2
.depend.on.its.ability.to.absorb.or.relect.light.of.different.wavelengths..
TiO
2
. acts. as. a. pigment. because. the. particles. can. scatter. visible. light,. a. function.
that.depends.on.particle.size..TiO
2
.also.can.absorb.UV.radiation..As.a.result,.coat-
ings.containing.TiO
2
.can.provide.protection.from.photochemical.degradation..Upon.
absorption.of.UV.light,.TiO
2
.can.generate.hydroxyl.radicals..The.TiO
2
.pigment.then.
acts.as.a.photocatalyst.[15].for.the.decomposition.of.organic.compounds..The.crys-
talline.structure.of.nanoscale.TiO
2
.particles.allows.those.particles.to.absorb.visible.
light.as.well.as.UV.light,.which.broadens.the.applications.for.TiO
2
.catalysts.[16].
Commercially.available.products.that.exploit.these.properties.of.nanoscale.TiO
2
.
include.[1]:
•
Sunscreens.by.more.than.a.dozen.manufacturers.rely.on.the.ability.of.TiO
2
.
to.absorb.UV.radiation.to.protect.the.skin.
T-2®.Photocatalyst.Environment.Cleaner.(T-2®).—.when.light.strikes.nano-
scale.TiO
2
.in.this.cleaner.after.it.is.applied.to.a.surface,.photocatalytic.reac-
tions.degrade.“organic.toxins,.odors,.and.more.”
Carrier®.Pure.Dew.Filtration.(Carrier®).—.this.air.puriier.contains.a.Nano.
Silver.ilter,.for.antibacterial.action,.and.a.Nano.Photocatalytic.ilter..The.
latter.contains.nano-sized.particles.of.TiO
2
.to.“get.rid.of.unpleasant.smell.
and.smoke.”
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•
2.4.2 Z
erO
-v
alent
i
rOn
Engineers.use.nanoparticles.of.elemental.iron.known.as.nano.zero-valent.iron.(nZVI),.
as. discussed. further. in. Chapter. 10,. to. treat. groundwater. containing. chlorinated.
