Development of innovative reactors and treatments for solar water decontamination
Looking for a sustainable way of ensuring a safe water supply
As society becomes more and more specialised, so does chemistry: in fact, the number of new chemicals increase exponentially year by year (1). Naturally, a good amount of these man-made materials end up in water bodies. In this context, developing efficient water-decontamination processes become increasingly important, but also equally challenging. Breaking up these complex molecules requires energy (or highly oxidative chemicals), and sunlight can provide some of this energy.
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This research project, carried out at the Research Group in Advanced Oxidation Processes (AdOx) at the University of Sao Paulo and sponsored by the Sao Paulo Research Foundation (2018/21721-6), aims at tackling this important problem while also looking at the sustainability and environmental footprints of the water treatment process. We try to promote innovation by exploring two key points to make the use of sunlight-based water treatment more efficient: (i) changing the design of solar reactors, by adapting to them supplementary, low-consumption UV light-sources; and (ii) developing sunlight-tailored catalysts - substances that will convert sunlight into the highly oxidative chemicals we need to destroy organic contaminants.
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More specifically, we explore novel synthesis routes to obtain modified metal-oxide nanomaterials (ZnO, TiO2, WO3), capable of absorbing photons with energies within the range of visible light (with wavelenghts between 400 to 800 nm) and converting them efficiently into highly reactive species in aqueous media.
Design of nanoparticulate semiconducting metal-oxides for Artificial Photosynthesis
Using light to convert carbon dioxide into fuels
Every night we see all sorts of news regarding the planet's climate: hurricanes, typhoons, wildfires, draughts, floods, huge ice caps melting and detaching, and so on. To some extent, a good deal of the so-called "extreme weather" phenomena are caused by Global Warming.
One of the biggest drivers of Global Warming is the increasing atmospheric levels of carbon dioxide (CO2). CO2 is the product of many natural and man-made processes, which, unfortunately, will still require a long time to be phased-out and replaced by sustainable alternatives. In this context, technologies for capturing and reusing CO2 become an important mitigating strategy to try and reduce the impact of our activities on the stability of the planet's temperature. Some of these technologies involve the chemical reduction of carbon dioxide into species such as carbon monoxide, methanol, formic acid or methane: less stable structures, used in well-established industrial processes to produce staple chemicals and energy. This chemical reduction requires energy, which can be supplied thermally, electrically or photochemically. When the latter is used, the process is often called "artificial photosynthesis", since it captures the same principles of its biochemical counterpart.
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This research project aims at exploring the structure of nanoparticule metal-oxides (TiO2, ZnO, Fe2O3) to improve their charge-separation and charge-transport properties, and to control the segregation of species within their microstructure. With the design of tailored materials, we expect to control important processing parameters, such as the adsorption-affinity of the oxides towards CO2, H2O and other relevant species, the energies of the conduction and valence band-edges of the oxides, and the lifetime of the photogenerated charges.
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This project is run by the Laboratory of Ceramics Processing (LPC) at the University of Sao Paulo, within the multi-institutional Research Centre in Gas Innovation (RCGI) - a joint structure between the Sao Paulo Research Foundation (FAPESP), the Sao Paulo University and the multinational petrochemical company Shell. The research is supported by FAPESP (2019/10109-6).
Environmental fate of pesticides in central Brazilian river basins
Understanding the impact of emerging pollutants in the Environment
Brazil is the leading producer (and exporter) of worldwide consumed agricultural products, such as soybeans and coffee. In fact, the Brazilian agricultural exports comprise about 28% of all our exports. The state of Goias was, in 2019, the 4th largest grain producer in Brazil: soybeans represented about 35% of the state's exports. The pressure to keep productivity leads to an excessive use of pesticides and herbicides, which end up contaminating soil and water.
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This research project, carried out at the Research Group in Advanced Oxidation Processes (AdOx) at the University of Sao Paulo in partnership with the Goias State University and sponsored by the Sao Paulo Research Foundation (2019/24158-9), aims at investigating the persistence of emerging pollutants in Brazilian river waters, using a combination of experimental and theoretical approaches.
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We investigate the persistence of commonly used chemicals in Goias state agricultural farms, particularly Ametryn, Picloram and Diuron, using competitive kinetics, photochemical persistence essays and a combination of Quantum Chemical and Molecular Simulation tools to clarify reaction mechanisms, calculate reaction rates, and estimate toxicitiy.
Manufacturing of functional ceramic parts for chemical processing
Developing ceramics processing technologies for intensified chemical equipment
Ceramics are excellent materials for the construction of chemical processing equipment, especially when a functionalized material is desired. In the case of microreactors with supported catalysts, one can imagine the possibility of increasing the surface area through the use of porous ceramics; or even explore the use of dense ceramics as supports for thin catalytic films with high thermal and electrical resistance. In the case of the development of electrochemical cells, the versatility of ceramic materials allows a refined control of the electronic and ionic transport properties through the control of the chemical composition of the ceramic material and the segregation of additives in its structure.
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The processing of ceramic precursors (usually powder materials) into manufactured parts involves a series of steps that range from powder preparation, through its initial shaping to the dimensional completion of the part. The construction of microfluidic parts, for example, requires a combination of suitable forming and sintering strategies to ensure the fidelity of the designed geometry and the maintenance of the mechanical and chemical properties of interest.
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In this project, linked to the Research Center for Greenhouse Gas Innovation, we seek to optimize some of the fundamental ceramic processing techniques to obtain microstructured pieces of varying (and controlled) degree of porosity, applicable to different ceramic formulations. This project is supported by FAPESP (21/10919-8), in partnership with IQ-USP and IFSC-USP.
