Multiscale Process Intensification of Waste Valorization Reactions

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The central theme of my research program is the development of intensified and sustainable chemical processes for the recovery of metals, the sequestration of CO2, and the production of valuable inorganic materials, using wastes of industrial, urban and agricultural origins. A challenge when working with solid waste-fluid reactions is that mass transfer limitations across solid-liquid, solid-gas and gas-liquid interfaces and unfavorable thermodynamics lead to slow reaction rates, incomplete reaction conversions, high energy expenditure and processing costs, and inadequate product properties. The traditional approach to overcoming slurry reaction limitations is to adjust process variables, such as temperature, pressure, particle size, mixing rate, and concentration of reagents. These macro-scale approaches can be effective, however, they come at a cost to the environment: high consumption of energy and raw materials, vast generation of residues, and emissions of pollutants and greenhouse gases. In the treatment or valorization of low-grade and waste resources, such conventional approaches are often unfeasible at the industrial scale. Sustainable solutions are thus needed. The aim of this DG program is to overcome reaction rate limitations of slurry reactions of environmental relevance, by exploring and developing process intensification strategies that act over different scales of space and time. The long-term objective is to valorize three classes of solid wastes: (a) kimberlite and serpentine (mineral processing); (b) black/red liquors (pulp and paper); (c) fruit/vegetable pomace (fruit processing). The short-term research is clustered in three areas: (1) reaction and reactor design; (2) reactive separations; and (3) solvomechanochemistry. For these areas, five multiscale intensification approaches are investigated: (i) converting mechanically stirred batch reactions into sonicated plug flow continuous reactions; (ii) developing novel catalytic minerals for specific waste conversion reactions; (iii) functionalizing inert solid media with superhydrophobic molecules; (iv) using immiscible organic phases and metal-organic framework (MOF) compounds for reactive extraction; and (v) replacing aqueous reaction media with green solvents for reactive absorption and solvomechanochemistry. Ultimately, the purpose of this research program is to encourage the adoption of process intensification technologies in place of conventional processes, in industry and among the research community, and to catalyze the development of the types of sustainable processes required by the chemical, metallurgical and minerals industries (Canada's economic drivers) to reduce their environmental impact and carbon emissions. Moreover, the multiscale process intensification approaches developed may also be extended to other industrial, urban and agricultural processes where reduction of energy intensity, carbon intensity and environmental footprint could be achieved.