Deposition of Carbon particulates on zeolite surfaces through Electron-Beam evaporation by graphite Authors: Andrew Morgan, Marcia R Silva*, Joseph Corrao, David Garman Presentation by: Andrew Morgan

Background Information Porous particles are composed of alumina and silica Contain large pores over the surface Naturally occurring: found in volcanic and sedimentary rock formations Adsorption properties can be improved by treatments such as deposition Adsorption Properties: Environmental and Medical applications

Experimental Design Kurt J Lesker Lab-18 Modular Thin Film Deposition System Graphite Pellets (3-6 mm pieces) Graphite electron beam crucible Kapton Tape (2” diameter)

Experimental Design Porous particles (10 mg) were spread uniformly along adhesive on Kapton tape Kapton tape (6” length) was folded over to expose adhesive on both sides Tape covered with porous particles was aligned directly above the electron beam source Low vacuum of 5x10-6 Torr after pump down Graphite pellets were exposed to electron beam at a variety of powers between 390W and 740W. Ramp and soak cycles for electron beam with deposition rate between 0.10 Å/s and 1.0 Å/s.

Evidence of Amorphous Carbon on Particle Surface Figure 1 Figure 2 Figure 3 Pure graphite shows intense D/G bands (Raman Spectra: Figure 1) Comparison of the D/G band ratios gives information on the bonding present in the deposited carbon (ordered vs disordered) Less intense, broader peaks for the coated particles is evidence for the presence of amorphous carbon on the particle surface. The Si-O-Si (rocking and bending) absorbance peaks on the coated particles are slightly shifted and less intense compared to that of the clean porous particles (Figure 2). This is evidence that the carbon coating has an effect on the naturally occurring Si-O bonding within the particle. Figure 3 clearly shows a decreased alumina absorbance intensity for the carbon-coated particles. This is evidence that the carbon coating has an effect on the Al-O bonding within the porous particles.

Evidence of Amorphous Carbon on Particle Surface Figure 4: non-coated particle Figure 5: coated particle Table 1: Gas Sorption Analysis Table 1 describes the changes in pore volume and radius as well as the surface area changes of the clean particles without carbon compared to the particles coated with 0.45 kA of amorphous carbon It can be seen that the surface area changes drastically when coated with carbon The pore volume increases after the carbon coating has been deposited and the pore radius decreases. Decreased pore radius is indicative of a microporous topography change after coating the particle surface Figures 4 & 5 are SEM images at 100k which clearly show topographical surface changes between the clean particles and the coated particles. The shape of the surface changes due to the presence of carbon (less detailed)

Conclusion Carbon effects the natural bonding modes (bending/stretching) of silica present in the natural porous particles FTIR and Raman interpretation confirms the structure of carbon on the surface of these particles is amorphous in nature Surface chemistry is altered by the presence of amorphous carbon deposition: increased surface area, decreased pore radius, increased pore volume Potential medical and environmental applications, specifically adsorption properties may be enhanced due to increased surface area after carbon deposition

Acknowledgments Authors thank Morgan’s Fall 2015 SURF grant and RGI grant # 101-253120-4101x322 that supported J. Corrao Thanks to Steve Hardcastle for assistance and use of UWM AAF facility. Autosorb technical support provided by Remy Guillet of Quantachrome Instruments IR Tracer 100 Technical Support provided by Shimadzu

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