Environmental Chemistry within the Mills group - Green Impact "Platinum day" Dr Katherine Lawrie
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Environmental Chemistry within the Mills group
Green Impact “Platinum day”
Dr Katherine Lawrie
19th March 2014
Photochemistry and Optical
Sensors
• Photocatalytic organic synthesis
• Photocatalytic water reduction and oxidation
• Photocatalytic destruction of organic pollutants
– Standardised testing of photocatalytic surfaces
– Assessment of self-cleaning films
– Photocatalytic destruction of organic pollutants in water
• Regeneration of tarnished metal surfaces
• Optical sensors for water purification
• Optical sensors for food packaging
Semiconductor Photocatalysis
A chemical reaction induced by photoabsorption of a
solid material, or photocatalyst, which remains
chemically unchanged during and after the reaction.
h
SC SC*
DRed
SED
SC(e-)
DOx
SEDOx
Semiconductor Photocatalysis
A chemical reaction induced by photoabsorption of a
solid material, or photocatalyst, which remains
chemically unchanged during and after the reaction.
h
SC SC*
DOx
SEA
SC(h+)
DRed
SEARed
Photocatalytic organic synthesis • Low environmental impact • Photogenerated radicals avoid the use of ionic or highly polar species • Nontoxic semiconductor, easily filtered or immobilised on a suitable support • High-level of control • Selectivity • Room temperature and pressure
• Photocatalysed oxidation of toluene in
acetonitrile
• Carbon–carbon coupling of phenoxyacetic
acid with N-substituted maleimides
• C-C coupling of phenoxyacetic acid and
acrylamide
• Carboxylic Acid Alkylations of Alkenes and
Cascade Addition−Cyclizations
A. Mills and C. O’Rourke, J. Photochem. Photobiol. A; Chem., 2012, 233, 34-39,
A. Mills, C. O’Rourke, Journal of Photochemistry and Photobiology A: Chemistry, 2013, 268, 7–16
D. W. Manley, R. T. McBurney, P. Miller, J. C. Walton, A. Mills and C. O’Rourke, J. Org. Chem. 2014, 79, 1386−1398
A. Mills, C. O’Rourke, Catalysis Today, 2013, http://dx.doi.org/10.1016/j.cattod.2013.10.083
Photocatalytic water reduction
and oxidation
• Rising cost of energy in both
environmental and economic terms
• Alternative, renewable energy sources
– Solar energy for water splitting
• Photodiode where the gases are
generated at different sides of the device.
• 2H2O + 4h+ → O2 + 4H+
• 2H2O + 2e- → H2 + 2OH-
• Substrate
– Titanium
– Glass
– Steel
• Semiconductor
– TiO2
– Doped TiO2
• Hydrogen Catalyst
– Platinum
• Oxygen Catalyst
– TiO2
G. Hyett, J.A. Darr, A. Mills, I.P. Parkin, Chemistry – A European Journal, 2010, 16, 10546-10552
S. Kundu, A. Kafizas, G. Hyett, A. Mills, J.A. Darr and I.P. Parkin, J. Materials, Chemistry, 2011, 21, 6854-6863
P. Carmichael, D. Hazafy, D. S. Bhachu, A. Mills, et al, Phys.Chem. Chem. Phys., 2013, 15, 16788-16794
Photocatalytic destruction of
organic pollutants
• Environmentally hazardous pollutants
• Photomineralisation of
– Volatile pollutants
• NO
• Toluene
– Organic films
• stearic acid
• oleic acid
– Water-based pollutants
• 4-chlorophenol
• dyestuffs
Standardised testing of
photocatalytic surfaces
• Air purification
– GC-FID
– NOx analyser
• Water purification
– HPLC
– UV/vis
• Self-cleaning films
– Contact angle
• Light sources
– UV radiometer
• Photosterilisation
– Bacterial testing
A. Mills, C. Hill and P.K.J. Robertson, J. Photochem. Photobiol. A; Chem., 2012, 237, 7-23
A. Mills, Appld. Catal. B: Environmental, 2012, 128, 144-149.Assessment of self-cleaning films
• Highly reactive species convert organic
materials to CO2 and mineral acids which
are easily washed away.
• With more easily oxidised components in
an ink, a dye can simply change colour.
J. Krysa, P. Novotná, Š. Kment, A. Mills , J. Photochem. Photobiol. A: Chem, 2011, 222, 81-86,
A. Mills, J. Hepburn, D. Hazafy et al Journal of Photochemistry and Photobiology A: Chemistry, 2013, 272, 18–20.• Range of commercial self-cleaning
building materials currently available
– glass (e.g. Pilkington glass),
– concrete (e.g. Italcementi),
– ceramic tiles (e.g. TOTO),
– paint (e.g. STO).
A. Mills, C. O’Rourke, K. Lawrie, and S. Elouali, ACS Appl. Mater. Interfaces, 2014, 6, 545–552
R. Quesada-Cabrera, A. Mills, et al, Applied Catalysis B: Environmental, 2014, 150–151, 338–344
A. Mills, N. Wells, C. O’Rourke, Catalysis Today, 2013, http://dx.doi.org/10.1016/j.cattod.2013.11.023Photocatalytic destruction of
organic pollutants in water
• 0.9 million tonnes of organic dye produced annually
– ca. 15% lost to the environment
• Photocatalytic and photosensitised bleaching
• Test pollutants
– Methylene Blue
– Acid Orange 7
– 4-chlorophenol
A. Mills and C. O’Rourke, Green, 2011, 1, 105-113,
A. Mills, C. O’Rourke, V. Kalousek and J. Rathousky, J. Hazardous Materials, 2012, 211/212, 182-187,
J. Krysa, S. Pausova, M. Zlamal and A. Mills, J. Photochem. Photobiol. A; Chem., 2012, 250, 66-71,Regeneration of tarnished metal
surfaces
• Stainless steel and other metal corrosion is a
major concern in many industries
– e.g. energy, construction and chemical
• UK estimated cost 4% of GNP per annum
• Thermodynamically unstable
• Durability due to thin metal oxides
• Upon further oxidation can become contaminated
with undesirable corrosion products• TiO2 paste film or TiO2 ink on stainless steel
• Heat treated to form a ‘bronze’ colouration due
to Fe2O3
• Irradiated with UV light
• Colouration rapidly disappears from the metal
coupon under the rectangle of TiO2 paste film
A. Mills and D. Hazafy, Chem. Commun., 2012, 48, 525-527.Optical sensors for water
purification
· 1.1 Billion people without access to safe water,
· 4 Billion cases of diarrhoea (88% due to unsafe water),
· 1.8 Million die each year (majority under 5 years).
· In use by more than 2 million people and in more than 28 countries around the globe,
· In a study in Kenya, children under age 6 using the SODIS technique were 7 times less
likely than non-SODIS users to contract cholera.• Need
– A device which informs users when
a bottle has been exposed to
sufficient amounts of sunshine and
the water is safe for drinking.
• Solutions
– Working with several companies
and research groups around the
world, previously focused on
electronic devices,
– Colour-changing materials are
proving to be more advantageous, 6 hours
especially in terms of cost. sunlight
• Change colour after approximately 6
hours in the sunOptical sensors for food packaging • Estimated half of all food is wasted worldwide • Intelligent systems aim to provide consumers with more information on the conditions inside the package • Package integrity can be compromised at any stage throughout the process from packaging to consumption • Overall intention of reducing food wastage
• Time-temperature indicators
(TTI)
– providing an indirect account of
package storage conditions
• Leakage/gas indicators
– supplying information on a
package’s head-space gases
• Off-gas/freshness indicators
– directly indicating product quality,
often by responding to a change in
pH as food goes off
A. Mills, K. Lawrie, J. Bardin, A. Apedaile, G. A. Skinner and C. O’Rourke, Analyst, 2012, 137, 106-112
K. Lawrie, A. Mills and D. Hazafy, Sensors and actuators B: Chemical, 2013, 176, 1154-1159
A. Mills and A. Graham, Analyst, 2013, 138, 6488-6493.
A. Mills, A. Graham and C. O’Rourke, Sensors and Actuators B: Chemical, 2014, 190, 907-912.Acknowledgments • Professor Andrew Mills • Mills group members past and present • EPSRC, INI, Insignia Ink and DEL • J. Darr, I. Parkin, J. Walton, J. Krysa, M. Saladin
You can also read
