?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F39542%2F&rft.title=Adventitious+Hydrocarbon+Adsorption+and+Its+Effect+on+the+Solid-Liquid+Interface&rft.creator=Hurst%2C+Justin&rft.description=Atmospheric+hydrocarbon+adsorption+has+recently+been+revealed+to+mask+the+intrinsic+properties+of+some+surfaces.+The+prevalence+of+hydrocarbon+adsorption+was+previously+only+understood+in+vacuum+science%2C+but+as+new+sensitive+techniques+developed+it+became+possible+to+study+the+adsorption+behavior+in+ambient+air.+In+this+work%2C+we+have+studied+the+effect+of+atmospheric+adsorption+on+graphite+and+soil+minerals.%0D%0A%0D%0AWe+studied+the+change+in+capacitance+on+aqueous+graphite+electrodes+when+exposed+to+air+and+while+in+solution.+We+found+that+exposing+a+freshly+exfoliated+highly+oriented+pyrolytic+graphite+(HOPG)+surface+to+ambient+air+and+1-octadecene+vapor+(ca.+1+ppm)+caused+a+ca.+30%25+and+70%25+decrease+in+its+double+layer+capacitance%2C+respectively.+Similarly%2C+a+38%25+decrease+of+capacitance+was+observed+within+1500+min+after+a+freshly+cleaved+HOPG+was+immersed+in+1+M+NaCl+solution%3B+liquid+phase+ellipsometry+data+showed+that+a+contamination+layer+of+ca.+0.6+-+2+nm+was+formed+on+the+HOPG+surface+within+the+same+time+frame.+The+capacitance+of+a+contaminated+sample+can+be+partially+and+temporarily+restored+by+applying+a+high+or+low+potential+(-1.222+V+or+0.778+V+vs.+Ag%2FAgCl).+For+graphite+in+1-butyl-3-methylimidazolium+hexafluorophosphate%2C+we+found+a+slight+difference+between+the+capacitance+in+a+clean+hood+and+in+a+glove+box.+Solution+phase+capacitance+reduction+is+between+25-30%25+in+both+pure+solution+and+with+added+contaminant.+This+work+also+emphasized+the+U-shaped+capacitance+vs.+potential+curve+of+the+graphite-ionic+liquid+system%2C+contrary+to+recent+literature.%0D%0A%0D%0AThe+second+system+of+study+is+the+soil-water+interface.+In+this+work+we+showed+how+airborne+adventitious+hydrocarbons+can+adsorb+to+mineral+surfaces+to+contribute+to+soil-water+repellency.+The+water+contact+angle+(WCA)+was+shown+to+increase+from+0%C2%B0+to+25%C2%B0+for+silica%2C+and+to+65%C2%B0+for+alumina+after+4+days+of+exposure+in+ambient+air.+The+change+in+the+amount+of+hydrocarbons+was+monitored+by+spectroscopic+ellipsometry+(SE)+and+X-ray+photoelectron+spectroscopy+(XPS).+Water+drop+penetration+time+(WDPT)+was+measured+on+kaolinite+after+treatments+with+either+heat+or+ozone+to+show+that+adsorption+of+airborne+hydrocarbons+can+increase+the+WDPT+of+mineral+powders.&rft.date=2020-09-16&rft.type=University+of+Pittsburgh+ETD&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F39542%2F19%2FHurst%2520Final%2520ETD.pdf&rft.identifier=++Hurst%2C+Justin++(2020)+Adventitious+Hydrocarbon+Adsorption+and+Its+Effect+on+the+Solid-Liquid+Interface.++Doctoral+Dissertation%2C+University+of+Pittsburgh.++++(Unpublished)++