Solar photocatalytic process & solar photocatalytic reactors
PROCESS & SOLAR
Mechanism of solar photocatalysis
Solar photocatalytic reactors
What is solar photocatalysis:
Photocatalysis is the
acceleration of a photoreaction
in the presence of a catalyst.
Both light and catalyst are
necessary to achieve or to
accelerate a chemical reaction.
Ability of some nano materials
Which is also called photocatalyst is
used to speed up a certain
reaction as a catalyst
in combination with light.
Why TiO2 is mostly used as a
TiO2 is mostly used as a
due to its:
Non-toxic in nature.
Mechanism of solar
When photocatalyst titanium
dioxide absorbs Ultra violet
radiation from sun light or
illuminated light source, it will
produce a pair of electrons and
The electron of the valance band
titanium dioxide becomes excited
when illuminated by light.
The excess energy of this excited electron
promoted the electron to the conduction band
of titanium dioxide therefore creating the
negative-electron(e-) and positive-hole(h+)
pair. This stage is reffered to as the
semiconductors photo-excited state.
The energy difference between the valence
band and conduction band is known as the
The positive-hole of titanium dioxide breaks
apart the water molecule to form hydrogen gas
and hydroxyl radical. The negative-electron
reacts with oxygen molecule to form super
oxide anion.This cycle continues when light is
Solar photocatalytic reactors:
The implementation of most
photocatalytic processes at an effective
scale requires the use of a photoreactor.
A device which brings photons, a
photocatalyst and reactants into contact,
as well as collecting the reaction products.
Photocatalytic reactors can be classified
based on the two state of the photocatalyst
Suspended or attached. Photocatalytic
reactors can use either UV or solar
Types of photocatalytic reactors:
Immobilized TiO2 reactors.
TiO2 slurry reactors are most commonly
type used in water treatment.These
reactors show the largest photocatalytic
They provide a high total surface area of
photocatalyst per unit volume.
These reactors require sepration of the
sub-micron TiO2 particles from the
treated water which complicates the
Immobilized TiO2 reactors:
Photocatalytic reactors with
immobilized TiO2 are those in
which catalyst is fixed to support
via physical surface forces or
These reactors extend the benefit
of not requiring catalyst recovery
and permit the continuous use of
The photocatalytic membrane reactors
can be generalized in two categories:
1. Irradiation of the membrane module.
2. Irradiation of feed tank containing
photocatalyst in suspension.
Drawback of immobilized
These posses low surface area to
volume ratios, catalyst fouling and
significant pressure drop.
The other draw back is that
membrane photocatalytic reactors is
the diffusion of organic compounds
to the catalyst surface which is slow
particularly when the organic
compound concentration is low.
Advantages of solar
The process is used for waste water
This process is applied for both slurry
and immobilized reactor.
The photocatalyst used is of low cost.
The photocatalyst used in this process
is re-used and re-cycled.
Disadvantages of solar
The reactor used in this process
is of high cost.
The photocatalytic degradation
of organic compound can be
affected by pH value
Applications of solar
This process is used for:
Sterilization of surgical
instruments and removal of
unwanted fingerprints from
sensitive electrical and optical
Decomposition of crude oil with
Decontamination of water with
photocatalysis and adsorption: the
removal and destruction of organic
contaminants in groundwater can be
addressed through the impregnation of
adsorbents with photoactive catalysts.
The photocatalysis of organic compounds in water
with titanium dioxide is a promising technology.
Decontamination of water effluents is one of
the most successful photochemical applications of
solar photons . This process is best way to remove
impurities from water . No doubt that detoxifying
the water by photocatalysis is full of promise.
Offenbar haben Sie einen Ad-Blocker installiert. Wenn Sie SlideShare auf die Whitelist für Ihren Werbeblocker setzen, helfen Sie unserer Gemeinschaft von Inhaltserstellern.
Sie hassen Werbung?
Wir haben unsere Datenschutzbestimmungen aktualisiert.
Wir haben unsere Datenschutzbestimmungen aktualisiert, um den neuen globalen Regeln zum Thema Datenschutzbestimmungen gerecht zu werden und dir einen Einblick in die begrenzten Möglichkeiten zu geben, wie wir deine Daten nutzen.
Die Einzelheiten findest du unten. Indem du sie akzeptierst, erklärst du dich mit den aktualisierten Datenschutzbestimmungen einverstanden.