{"626918":{"#nid":"626918","#data":{"type":"event","title":"PhD Defense by Qingxu (Bill) Jin","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003ESchool of Civil and Environmental Engineering\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EPh.D. Thesis Defense Announcement\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EFundamental Understanding of NOx Sequestration Capacity and Pathways in Nano-TiO2\u003C\/p\u003E\r\n\r\n\u003Cp\u003Eengineered Cementitious Materials\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EBy\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EQingxu (Bill) Jin\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EAdvisor:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Kimberly E. Kurtis (CEE)\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECommittee Members:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Lawrence F. Kahn (CEE), Dr. Yuanzhi Tang (EAS), Dr. Emily Grubert (CEE), and\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Jeffrey W. Bullard (CEE, Texas A\u0026amp;M)\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EDate \u0026amp; Time:\u003C\/strong\u003E Wednesday, October 16th, at 9:00 am\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ELocation:\u003C\/strong\u003E Mason Building, Room 2119\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cbr \/\u003E\r\nThe ubiquity of concrete in the urban environment and upscaling of nanomaterial production have prompted interest in the\u003Cbr \/\u003E\r\nincorporation of titania (TiO2) nanoparticles into cementitious materials. Air purification by TiO2-based cementitious materials\u003Cbr \/\u003E\r\noccurs by photocatalysts that capture nitrogen oxide species (NOx) from the atmosphere, oxidizing them into nitrite and nitrate\u003Cbr \/\u003E\r\nspecies. Because nitrite- and nitrate-based corrosion inhibitors are effective in improving corrosion resistance in reinforced\u003Cbr \/\u003E\r\nconcrete, there is potential to develop nano-TiO2 engineered cementitious materials that transform NOx into corrosion inhibitors.\u003Cbr \/\u003E\r\nTo provide guidelines for engineers and scientists to design such materials, a fundamental understanding of the NOx\u003Cbr \/\u003E\r\nsequestration capacity and pathways in cementitious materials is needed. This dissertation first develops a novel experimental\u003Cbr \/\u003E\r\napproach that combines water-based wet chemical extraction, UV-visible spectrophotometry, and ion chromatography to\u003Cbr \/\u003E\r\nquantify the NOx sequestration capacity in both plain and TiO2-modified cementitious pastes. Compared to plain cement pastes,\u003Cbr \/\u003E\r\nTiO2-modified cement pastes exhibit higher NOx uptake (in terms of nitrite and nitrate detected in the material) due to the\u003Cbr \/\u003E\r\nactivation of photocatalytic reactions, greater surface area, and an increased amount of micropores with the addition of TiO2.\u003Cbr \/\u003E\r\nThe detection of nitrite and nitrate ions in plain cement paste shows these materials have an intrinsic NOx sequestration\u003Cbr \/\u003E\r\ncapacity but, the difference in NOx uptake between TiO2-modified ordinary portland cement (OPC) and calcium aluminate\u003Cbr \/\u003E\r\ncement (CAC) indicates that different NOx sequestration pathways occurred in these cements, which is likely due to differences\u003Cbr \/\u003E\r\nin chemical composition and hydrated cementitious phases.\u003Cbr \/\u003E\r\nTo understand the NOx sequestration pathways in cementitious materials, various pure hydrated cementitious phases\u003Cbr \/\u003E\r\nwere synthesized and their NOx uptake capacities were evaluated. Among non-carbonated phases, the highest NOx uptake\u003Cbr \/\u003E\r\nwas measured in calcium silicate hydrate (C-S-H) phases. The NOx-converted nitrite and nitrate could either adsorb to the\u003Cbr \/\u003E\r\nsurface of C-S-H or dissolve in pore solution. For aluminum (Al)-bearing phases, nitrite and nitrate ions were found to substitute\u003Cbr \/\u003E\r\nfor the sulfate ions and form new phases. Because the main hydration product of OPC is a C-S-H phase and the primary\u003Cbr \/\u003E\r\nhydration product of CAC are aluminate-rich phases, the different NOx sequestration mechanisms and pathways between\u003Cbr \/\u003E\r\nC-S-H and Al-bearing phases explains the difference in the NOx uptake capacities of OPC and CAC. A synthetic calcite phase\u003Cbr \/\u003E\r\nwas also examined in this research to investigate the effect of carbonation, which significantly improved NOx uptake capacity\u003Cbr \/\u003E\r\ncompared to non-carbonated cementitious phases. The fundamental understanding of NOx sequestration pathways can be\u003Cbr \/\u003E\r\nused to design cementitious materials with optimized chemical composition for enhanced NOx sequestration and thus act as\u003Cbr \/\u003E\r\ncorrosion inhibitors.\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Fundamental Understanding of NOx Sequestration Capacity and Pathways in Nano-TiO2 engineered Cementitious Materials"}],"uid":"27707","created_gmt":"2019-09-30 18:49:29","changed_gmt":"2019-09-30 18:49:29","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2019-10-16T10:00:00-04:00","event_time_end":"2019-10-16T12:00:00-04:00","event_time_end_last":"2019-10-16T12:00:00-04:00","gmt_time_start":"2019-10-16 14:00:00","gmt_time_end":"2019-10-16 16:00:00","gmt_time_end_last":"2019-10-16 16:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78771","name":"Public"},{"id":"174045","name":"Graduate students"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}