107
Bacterial Cellulose Surface Modifications
This. is. mostly. due. to. the. presence. of. reducing. groups,. which. are. able. to.
initiate.the.precipitation.of.palladium,.gold,.and.silver.from.aqueous.solution..In.2003.Evans.et.al..successfully.precipitated.palladium.ions.into.BNC.
pellicles.by.soaking.these.membranes.in.an.ammonium.hexachloropalladate.
solution.. The. obtained. material,. termed. palladium-cellulose,. was. further.
explored.as.a.catalyst,.which.was.prepared.by.inserting.two.platinum.wires.
into.a.hydrated.cube.of.palladium-cellulose.
In.recent.years.palladized.BNC.was.studied.by.another.group.of.researchers.
as.a.versatile.and.bio-organic.catalyst.to.mediate.the.reductive.decolorization.
of.a.reactive.textile.dye,.Drimarene.Red,.in.a.rotating.catalyst.contact.reactor.
(Vyjayanthi.and.Suresh.2010)..In.this.work,.nano-size.zero.valent.form.palladium.(Pd 0 ).deposits.were.shown.to.be.irreversibly.impregnated.into.BNC.fibrils,.
and.allowing.approximately.90%.efficiency.regarding.dye.decolorization.
The.potential.of.BNC.to.act.as.an.adsorbent.and.an.ion.exchange.membrane.
has. also. been. explored. to. recover. heavy. metals. from. industrial. wastewater..
Choi.et.al..(2004).modified.a.BNC.membrane.with.cation.exchangeable.acrylic.
acid.using.ultraviolet.(UV).graft.polymerization.in.order.to.provide.BNC.with.
ion. exchange. capacity. and. with. greater. structural. density.. Briefly,. BNC. was.
immersed. in. a. benzophenone/methanol. solution. and,. after. drying,. irradiated.with.UV.light.for.a.few.minutes,.under.a.nitrogen.atmosphere,.in.order.to.
activate.the.BNC.membrane..Acrylic.acid.was.added.to.the.resulting.material,.
which.was.then.irradiated.again.with.UV.for.a.slightly.longer.period.of.time..
Acrylic-modified. BNC. membrane. showed. reasonable. mechanical. properties,.
mostly.due.to.the.high.crystallinity,.and.its.electrochemical.characteristics.were.
comparable.to.those.of.the.commercial.membrane.CMX..Moreover,.it.should.
be.noted.that.the.production.of.this.acrylic-modified.BNC.was.an.environmentally.compatible.procedure,.while.it.allows.the.easy.disposal.of.the.waste.ion.
exchange.membrane,.as.a.result.of.BNC’s.biodegradable.nature.
In.a.recent.work,.BNC.was.biosynthesized.and.used.as.a.substrate.for.the.production.of.BNC-titanium.oxide.(TiO 2 ).hybrid.nanofibers.(Sun.et.al..2010)..This.
was.attained.by.implanting.the.anatase.TiO 2 .nanoparticle.arrays.on.BNC.fibers.
using. a. molecular. imprinting. technique.. The. hybrid. nanofibers. were. mesoporous,.consisted.of.partially.cemented.anatase.particles.with.small.diameters.
(4.3–8.5.nm),.and.showed.high.photocatalytic.activity.(even.greater.than.that.of.
the.commercial.photocatalyst.P25)..Moreover,.it.was.observed.that.doping.the.
hybrid.nanofibers.with.nitrogen.greatly.increased.their.photocatalytic.activity.
Acknowledgment
The.authors.thank.the.Portuguese.Foundation.for.Science.and.Technology.
(FCT). for. funding. through. PTDC. and. COMPETE. funding. programs.. The.
Bacterial Cellulose Surface Modifications
This. is. mostly. due. to. the. presence. of. reducing. groups,. which. are. able. to.
initiate.the.precipitation.of.palladium,.gold,.and.silver.from.aqueous.solution..In.2003.Evans.et.al..successfully.precipitated.palladium.ions.into.BNC.
pellicles.by.soaking.these.membranes.in.an.ammonium.hexachloropalladate.
solution.. The. obtained. material,. termed. palladium-cellulose,. was. further.
explored.as.a.catalyst,.which.was.prepared.by.inserting.two.platinum.wires.
into.a.hydrated.cube.of.palladium-cellulose.
In.recent.years.palladized.BNC.was.studied.by.another.group.of.researchers.
as.a.versatile.and.bio-organic.catalyst.to.mediate.the.reductive.decolorization.
of.a.reactive.textile.dye,.Drimarene.Red,.in.a.rotating.catalyst.contact.reactor.
(Vyjayanthi.and.Suresh.2010)..In.this.work,.nano-size.zero.valent.form.palladium.(Pd 0 ).deposits.were.shown.to.be.irreversibly.impregnated.into.BNC.fibrils,.
and.allowing.approximately.90%.efficiency.regarding.dye.decolorization.
The.potential.of.BNC.to.act.as.an.adsorbent.and.an.ion.exchange.membrane.
has. also. been. explored. to. recover. heavy. metals. from. industrial. wastewater..
Choi.et.al..(2004).modified.a.BNC.membrane.with.cation.exchangeable.acrylic.
acid.using.ultraviolet.(UV).graft.polymerization.in.order.to.provide.BNC.with.
ion. exchange. capacity. and. with. greater. structural. density.. Briefly,. BNC. was.
immersed. in. a. benzophenone/methanol. solution. and,. after. drying,. irradiated.with.UV.light.for.a.few.minutes,.under.a.nitrogen.atmosphere,.in.order.to.
activate.the.BNC.membrane..Acrylic.acid.was.added.to.the.resulting.material,.
which.was.then.irradiated.again.with.UV.for.a.slightly.longer.period.of.time..
Acrylic-modified. BNC. membrane. showed. reasonable. mechanical. properties,.
mostly.due.to.the.high.crystallinity,.and.its.electrochemical.characteristics.were.
comparable.to.those.of.the.commercial.membrane.CMX..Moreover,.it.should.
be.noted.that.the.production.of.this.acrylic-modified.BNC.was.an.environmentally.compatible.procedure,.while.it.allows.the.easy.disposal.of.the.waste.ion.
exchange.membrane,.as.a.result.of.BNC’s.biodegradable.nature.
In.a.recent.work,.BNC.was.biosynthesized.and.used.as.a.substrate.for.the.production.of.BNC-titanium.oxide.(TiO 2 ).hybrid.nanofibers.(Sun.et.al..2010)..This.
was.attained.by.implanting.the.anatase.TiO 2 .nanoparticle.arrays.on.BNC.fibers.
using. a. molecular. imprinting. technique.. The. hybrid. nanofibers. were. mesoporous,.consisted.of.partially.cemented.anatase.particles.with.small.diameters.
(4.3–8.5.nm),.and.showed.high.photocatalytic.activity.(even.greater.than.that.of.
the.commercial.photocatalyst.P25)..Moreover,.it.was.observed.that.doping.the.
hybrid.nanofibers.with.nitrogen.greatly.increased.their.photocatalytic.activity.
Acknowledgment
The.authors.thank.the.Portuguese.Foundation.for.Science.and.Technology.
(FCT). for. funding. through. PTDC. and. COMPETE. funding. programs.. The.