PHOTOCATALYTIC REGENERATION OF GRANULAR ACTIVATED CARBON SATURATED WITH SULFUR DIOXIDE

Date
2020
Authors
Niimoto, Kacie
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Higgins, Scott R.
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Mechanical Engineering
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A significant challenge to implementing fuel cell technology into transportation is the performance degradation associated with air contaminants entering the fuel cell from the surrounding environment. Since fuel cells are costly, extended lifetimes are crucial to its operation and can be achieved with effective air purification. Granular activated carbon is an excellent filtration material but must undergo multiple adsorption-regeneration cycles to ensure both economic and environmental security. Thermal regeneration is conventionally used but results in high energy costs and limited cycles. Therefore, this study investigated a photocatalytic regeneration method for activated carbon saturated with sulfur dioxide. Two methods of attachment were studied for its effectiveness in modifying activated carbon with titanium dioxide and graphene oxide. Physical attachments were promoted by mixing activated carbon in a titanium dioxide-graphene oxide composite solution. This technique resulted in non-uniform, aggregated particle coating, and poor regeneration capabilities. Particles were observed to dislodge from the surface of activated carbon during regeneration, indicating weak adhesion between the particles and the surface. As a result, attachment by chemical bonds was then explored using a hydrothermal synthesis technique. In material TGAC-6, a nano-scale uniform coating was achieved when using activated carbon pretreated with nitric acid and minimal quantities of titanium dioxide and graphene oxide. The combined net effect of acid treatment and particle coating reduced the adsorption abilities of activated carbon by about 50%, with a measured adsorption capacity of 0.074 and 0.002 g/g [mean and standard deviation, n=2]. The regeneration abilities of TGAC-6 was compared with and without UV exposure to identify the contributions of photocatalysis. Regeneration without UV was found to restore 67% of the initial capacity through water regeneration, while regeneration with UV restored 87% of the initial capacity. This study suggests that photocatalytic regeneration is feasible for activated carbon saturated with sulfur dioxide.
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Environmental engineering, Nanotechnology, Chemical engineering, activated carbon, adsorption, photocatalysis, regeneration, synthesis
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40 pages
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