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PhD Research Project: Photocatalytic production of hydrogen in novel microfluidics devices

Employer
Global Academy Jobs
Location
United Kingdom
Closing date
Sep 30, 2016

Job Details

Details

1.2 The production of hydrogen (H2) by solar photocatalytic reforming of organic/inorganic substances dissolved in water and wastewater is a green, carbon neutral and an environmentally significant process for simultaneous removal of pollutants and photochemical conversion and storage of solar energy.

Innovation:
This PhD project aims at understanding and improving semiconductor-mediated (CdS, metal/TiO2, Ag/AgCl plasmonic TiO2 nanofibers)3,4 photoconversion of organic and inorganic species present in industrial wastewater (refineries and biodiesel) to hydrogen, using a new generation of ultra-low cost microfluidic devices2 developed in our research group. These are based on mass manufactured microcapillary films (MCFs) fully transparent to the entire spectrum of incident light, from the visible to the UVC. The unique fluid-dynamics and optical properties of the MCF makes it ideal for exploring the key issues that affect phototransformation of glycerol (byproduct of biodiesel production) or sulfate/sulfite rich wastewater (from refineries) to hydrogen, and for the identification of transformation by-products and for the formulation of reaction mechanisms. The MCF photoreaction system is made of a flat fluoropolymer ribbon containing an array of microcapillaries running along it, usually in the range of 10 micron up to 1 mm internal diameter, which are irradiated by a source of light (see Figure). MCFs can be produced from Teflon® FEP by Lamina Dielectrics Ltd (Billingshurst, West Sussex, UK) or polyolefins by Down Europe (Switzerland) using a patented melt-extrusion process. Six unique properties are exemplified i) The MCF is fully transparent to visible and UV radiation, including UVC; (ii) The flat surface of the film (inset b in Figure) combined with the excellent optical transparency and low refractive index of fluoropolymers allows the irradiation of the entire volume of the fluid flowing in the microcapillaries with straight incident photon rays, without wall refraction effects (such effect is not realized in
glass/quartz tubular photoreactors); (iii) The small capillary diameters permit operation under low optical thicknesses (less than 0.1) with uniform irradiance of the flowing fluid (even for fluids that in conventional reactors appear to be opaque) and the capillary diameters can be fine-tuned to the incident light and its penetration depth; (iv) Fluid behaviour approaches the plug flow regime allowing a tight fluid residence time distribution at the reactor exit, and in consequence (in conjunction with (iii)), high reactants conversions and high products yield and selectivity; (v) The small capillary volumes results in extremely rapid photo-transformations of substrates which are complete in a matter of seconds, a result until now not attainable in other practical photoreactors; (vi) The flexible nature of the MCF make it easily scalable. We have demonstrated these capabilities with a range of applications, including the fast photoinactivation of a highly contagious enveloped Herpes HSV-1 virus particles5, the fast decolourization of a dye and the photodegradation of contaminants of emerging concern including a pharmaceutical compound (diclofenac) and a class I drug metabolite (benzoylecgonine, BLG)

Objectives:
In this study we will utilize novel microfluidics photoreactor devices for:
1. Exploring novel strategies for intensifying the reaction in a microenvironment by operating under plug flow conditions and uniform photon flux across the entire cross section of the microreactor to yield maximum H2 production.
2. Minimizing back reaction of photocatalytically produced hydrogen by controlling the microenvironment, the hydrodynamic conditions and explore the pervaporation rate of H2 through the polymeric membrane.
Deliverables:
The novel and key issues that will be addressed in the research include:
1. Understanding reaction mechanisms of H2 production in photoreactor systems
2. Understanding the role of microscale (hydrodynamics, micromixing, light penetration, mass transfer)
3. Accelerating the production of hydrogen by disruptive photoreactor design, which yield fast reaction times and very high products yields.
4. Novel devices for hydrogen production at microscale.

Impacts:
1) A radically new conceptual photoreactor design and the opportunity to study the underlying science.
2) A new technology that utilizes the internal energy of wastewater contaminants as a fuel and solar light for production of renewable energy (hydrogen).
3) Sustainable process: use of wastewater effluent solar light to produce hydrogen.
4) Collaboration in innovative research, knowledge exchange, technology development and people training.
5) High impact publications of research findings through journals and conferences.
 

Funding Notes

Fully funded by the Engineering and Physical Sciences Research Council with an annual stipend of £14,600

References

1. Reis, N. M., Li Puma, G. A novel microfluidics approach for extremely fast and efficient photochemical transformations in fluoropolymer microcapillary films, Chem. Commun. 51 (2015) 8414.
2. Daskalaki, V.M., Antoniadou, M., Li Puma, G., Kondarides, D.I., Lianos, P. Solar light-responsive Pt/CdS/TiO2 photocatalysts for hydrogen production and simultaneous degradation of inorganic or organic sacrificial agents in wastewater, Environ. Sci. Technol. 44 (2010) 7200.
3. Wang, D., Li, Y., Li Puma, G., Wang, C., Wang, P., Zhang, W., Wang, Q. Ag/AgCl @ Helical Chiral TiO2 Nanofibers as a Visible Light Driven Plasmon Photocatalyst, Chem. Commun. 49 (2013) 10367.
4. Wang, D., Li, Y., Li Puma, G., Wang, C., Wang, P., Zhang, W., Wang, Q., Dye sensitized photoelectrochemical cell on plasmonic Ag/AgCl @ chiral TiO2 nanofibers for treatment of urban wastewater effluents, with simultaneous production of hydrogen and electricity, Appl. Catal. B: Environ. 168 (2015) 25.
5. Wang, D., Li, Y., Li Puma, G., Wang, C., Wang, P., Zhang, W., Wang, Q., Mechanism and experimental study on the photocatalytic performance of Ag/AgCl @ chiral TiO2 nanofibers: The impacts of wastewater components, J. Hazard. Mater. 285 (2015) 277.
6. Ren. Y., Crump, C.M., Mackley, M.M., Li Puma, G., Reis, N.M. Photo inactivation of virus particles in microfluidic capillary systems Biotechnol. Bioeng. (2016) accepted.
7. Russo. D., Spasiano, D., Vaccaro, M., Andreozzi, R., Li Puma, G., Reis, N.M., Marotta, R. Direct photolysis of benzoylecgonine under UV irradiation at 254 nm in a continuous flow microcapillary film (MCF) array photoreactor’ Chem. Eng. J. 284 (2016) 243.
8. Russo. D., Spasiano, D., Vaccaro, M., Li Puma, G., Reis, N.M., Marotta, R. Removal of the major cocaine metabolite (benzoylecgonine) in wastewater effluents and surface waters by UV254/H2O2 process with a flow microcapillary film array photoreactor’ Water Res. (2016) accepted.

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