Lecture 3a

Potentialities of
photocatalytic process
in decomposition of pollutants
from food technologies
Introduction
Photocatalytic processes enable a transformation of light
energy into electric or chemical one.
An expansion of following branches which are connected
with research and application of photocatalytic
technologies can be expected:
• Electricity production using photovoltaic cells
• Controlled biomass production using a photosynthetic
ability of green plants, algae, etc.
• Photocatalytic transformation of carbon dioxide into
substances of high energy content
• Degradation of pollutants
• A light illuminating a semiconductor particle causes an
electron excitation from the energy lower valence band into
the higher conduction band and creates electrically charged
centres:
photon + semiconductor =
h+ + e-
where e- is a mobile electron and h+ is the positive centre.
• The electron causes reduction and an oxidation occurs in the
positive centre.
• Positives centres are strong oxidants. Radicals OH, the
strongest known oxidizer, arise in presence of water.
• Organic compounds on the catalyst surface or near the
catalyst are oxidized into carbon dioxide, water and inorganic
salts.
Principles of photokatalytic process
Photocatalytic reaction is affected by:
a)
the energy of the illuminating light,
b)
the ability of the catalyst to absorb light quantum,
which is given by the size of particles and their chemical and
crystallographic structure in a nano-scale,
- nanocrystalline TiO2
c)
the technical design
…
Advantages of practical applications
of photocatalytic processes
•
•
•
•
The photocatalysis is a modern technology, whose
number of applications grows exponentially. It fulfils a
conception of sustainable development and improvement
of quality of life in a near future:
High energy demands tends to use other alternative energy
sources like the solar energy, whose application does not
increase an amount of carbon dioxide in the atmosphere.
Photocatalytic oxidation processes use natural resources
without chemicals.
Photocatalytic degradation of organic compounds used in air
and water purification does not produce other wastes burdening
the environment.
Connection of photocatalysis with membrane technologies
improves a potential of both technologies.
A potential of photocatalysis in an
area of agricultural and food
technologies:
• New ecological system for treatment of waste water,
groundwater and production of drinking water.
• Improved sanitation and hygienics in industrial
workplaces, households and application of surfaces with
photocatalytic coating.
• Higher air quality, removing of microorganisms, toxic
compounds, odours and ethylene in working and storage
areas.
• Economical benefits in comparison with conventional
techniques.
Phenolic substances
decomposition
Fotokatalytický rozklad fenolu - vliv teploty
1,00
0,90
0,80
oC
30 st.
C
c/co (mg/l)
0,70
oC
40 st.C
0,60
oC
50 st.C
0,50
0,40
0,30
0,20
0,10
0,00
0
5
10
15
20
čas (m
in)
Time
(min)
25
30
35
40
Decomposition of oxalic acid
Legend: p1, p2 – two trials made under the same conditions with catalyst,
pra – the same experiment with no catalyst used
10
9
conductivity (mS)
8
p2
7
pra
6
p1
5
4
3
2
1
0
0
20
40
60
80
100
time (min)
120
140
160
180
200
Thank you
for your
attention
MODELOVÁNÍ A SIMULACE
POTRAVINÁŘSKÝCH VÝROB
Modelling and simulation
of food processes and technology
Příklad 1: Kontinuální chromatografická separace
Příklad 2: Bezodpadová výroba cukru a ethanolu
v cukrovaru
Example 1: Continuous chromatography
separation
Example 2: Non-waste production of
etanol and sugar
Continuous chromatography separation
Diskontinuální a kontinuální chromatografická separace
KCHS-SMB-8-N
Continuous chromatographic
separator
kontinuální chromatografický separátor
princip založen na chromatografickém
systému se simulovaným tokem pevné
fáze
pevná fáze: Lewatit MDS 1368 Na
kolona: vnitřní objem 1 l, délka 2000 mm
maximální tlak 0.4 MPa
celkový příkon: 2 kW
Diskontinuální a kontinuální chromatografická separace
Modelování průběhu procesu
1
y
3
2
4
5
7
6
8
dm=ρdV=ρAdx
dmr,in/dτ
dmr,out/dτ
P1
1
2
3
4
0
x
x
x+dx
5
6
7
8
P2
Feed
Extract
Eluent
Raffinate
P3
c r  



  (1   ) K r
qr  f (cr )  K r cr
  2 c r ( x)
c ( x) 
 Dr

 vr r
2
x 
x

cr (  0)  cr (  0; x)
v
 c r 
 r cr  c in


 x   0 Dr

QEx
4
Liquid p.
2
5
QRe
Section II
 c r 
0


 x  x L
QE
Section I
3
Section IV
Solid p.
1
8
QF

6
7
Section III
QRa
P5
Simulace procesu
Diskontinuální a kontinuální chromatografická separace
Řízení procesu – distribuované řízení
 výpočet distribučních koeficientů z diskontinuálních měření
 odhad operačních parametrů na počátku procesu
 archivace měřených hodnot
 vyhodnocování běžících procesů
 fuzzy řízení
Operátorský panel
Základní schéma řízení
SMB
CHROMATOGRAPHY
STATION
PC
Standard
Industrial
Signals
WinCC
PLC
OPC
SERVER
RS 232
conductivity, refraction
MATLAB
DATABASE
Diskontinuální a kontinuální chromatografická separace
 diskontinuální separace
 kontinuální separace
Aplikace
Desorption curve for lactose hydrolyzate
g/l
60
GOS
50
Lac
Glc
Gal
40
30
20
10
0
0
Frakcionace melasy:
- izolace betainu
- izolace sacharosy
10
20
30
40
50
60 t/min
Frakcionace hydrolyzované syrovátky:
- izolace galaktooligosacharidů
Modelling and Simulation
Non-waste production of
sugar and ethanol in sugar
factory
•Biofuel production
•Implementation of novel processes
•Crystallization of stillage
Standard scheme
Technological scheme of TTD
TTD scheme –cont.
Model of TTD scheme
Model of TTD
scheme :
5st part
New scheme of ICT Prague
New scheme of ICT Prague – cont.
Complete
technological
scheme that
would connect
sugar and
ethanol
production.
EXHAUSTED
PULP
Extraction
Raw juice filtration
(pulp separation)
RAW JUICE
Beet pulp
Microfiltration
of raw juice
RETENTATE
Film evaporating
(permeate thickening)
PERMEATE
Cooling crystallization
(during the campaign)
RAW SUGAR
Refinery
Fermentation
Partial stillage recirculation
Fig.:
SUGAR BEET
WHITE
SUGAR
ICT Prague
Storage of mother liquor
(during the campaign)
MOLASSES
Molasses
fermentation
MOTHER
LIQUOR
Dilution and fermentation of mother
liquor
(out of the campaign)
CRUDE
ETHANOL
Distillation
Refinery
STILLAGE
BIOETHANOL
DRIED BEET
PULP
Stillage thickening
Crystallization
NaSOKSO
24, 24
Drying
FEEDING PELLETS
Stillage
Crystallization
Fig. :
Results of
mass balance
 Model 1: 100 % of raw
juice is used for sugar
production, i.e. 100 % of
juice goes to purification
 Model 5: total processing
of raw juice to ethanol,
i.e. 0 % of juice goes to
purification.
Model 1:
CONCLUSION
If all raw juice is used for
sugar production, we could
obtain:
28 t/h of sugar,
19 t/h of ethanol,
40 t/h of feeding pellets
21 t/h of carbon dioxide
Model 5:
Using all raw juice for
fermentation yields:
0 t/h of sugar,
31 t/h of ethanol,
43 t/h of feeding pellets
36 t/h of carbon dioxide.
 The shown scheme provides large possibilities to
suggest production according to calculations
monitoring a financial profit from the product sales.
 A large amount of produced CO2 is also valuable byproduct for beverage industry.
 Salt content in dried beet pulp can be reduced by
crystallization. Also this potentiality will be evaluated.
Thank you for your
attention
Bezodpadová
výroba cukru
a ethanolu
v cukrovaru
Kombinovaná
technologie
VŠCHT:
Membránová
filtrace,
fermentace a
přímá krystalizace
surové šťávy