{"629370":{"#nid":"629370","#data":{"type":"event","title":"PhD Defense by Weiqiu Zhang","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\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EOrganic Contaminants Destruction Using UV\/Free Chlorine Process: Mechanisms and Modeling\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EBy\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWeiqiu Zhang\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\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. John Crittenden (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\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Yongsheng Chen (CEE), Dr. Ching-Hua Huang (CEE), Dr. Sotira Yiacoumi (CEE), Dr. Donggang Yao (MSE)\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 December 6\u003Csup\u003Eth\u003C\/sup\u003E, 2019 at 10:00 AM\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ELocation: \u003C\/strong\u003ECapstone Building, Room338C, 828 West Peachtree St\u003C\/p\u003E\r\n\r\n\u003Cp\u003EAdvanced oxidation processes (AOPs) are effective technologies to oxidize recalcitrant organic contaminants in aqueous\u003Cbr \/\u003E\r\nphase. The UV\/free chlorine process is a promising AOP because of generating various reactive radicals at room temperature\u003Cbr \/\u003E\r\nand pressure. These electrophilic radicals eventually mineralize organic contaminants into CO2 and H2O. Understanding the\u003Cbr \/\u003E\r\ndegradation mechanisms is critical to design the UV\/free chlorine process with the lowest energy consumption and greatest\u003Cbr \/\u003E\r\ntoxicity reduction. Many researches have conducted experiments to shed the light on the degradation of some selected\u003Cbr \/\u003E\r\norganic compounds. However, these experimental studies are very time consuming and expensive. With respect to developing\u003Cbr \/\u003E\r\nkinetic models that can simulate the oxidation mechanisms, most studies invoked the simplified pseudo steady state\u003Cbr \/\u003E\r\nassumption because the mechanistically complex radicals-initiated chain reactions. Accordingly, conducting experiments and\u003Cbr \/\u003E\r\ndeveloping simplified kinetic models would be impossible to fully elucidate the oxidation mechanisms of all organic\u003Cbr \/\u003E\r\ncontaminants that may be found in aqueous phase.\u003Cbr \/\u003E\r\nTo overcome the above-mentioned challenges, we developed a first-principles based kinetic model to simulate\/predict the\u003Cbr \/\u003E\r\noxidation mechanisms of various organic compounds in the UV\/free chlorine process. First, we collected photolysis and\u003Cbr \/\u003E\r\nchemical reactions regarding the target organic compounds oxidation from literature. Second, we developed a rate constants\u003Cbr \/\u003E\r\nestimator to predict the rarely reported rate constants (e.g. organic compounds react with radicals) using group contribution\u003Cbr \/\u003E\r\nmethod or fitting experimental data through genetic algorithm. Third, we developed a stiff ordinary differential equations\u003Cbr \/\u003E\r\nsolver using Gear\u0026#39;s algorithm to predict the time-dependent concentration profiles of various target organic\u003Cbr \/\u003E\r\ncompounds. Our prediction results agreed with experimental data under various operational and water matrix conditions.\u003Cbr \/\u003E\r\nAfter verifying our kinetic model: (1) we developed quantitative structure activity relationships using Hammett constants of\u003Cbr \/\u003E\r\norganic compounds and our predicted rate constants; (2) we determined that chlorine monoxide radicals was the dominant\u003Cbr \/\u003E\r\nradicals to oxidize organic contaminants; (3) we optimized the operational conditions (i.e. UV intensity and free chlorine\u003Cbr \/\u003E\r\ndosage) that resulted in the lowest energy consumption. Furthermore, based on the predefined reaction rules, we successfully\u003Cbr \/\u003E\r\nimplemented graph theory to develop a computerized pathway generator specific for the UV\/free chlorine process. The\u003Cbr \/\u003E\r\npathway generator can automatically predict all possible reactions and byproducts\/intermediates (e.g. degradation of\u003Cbr \/\u003E\r\ntrichloroethylene generated 6,608 reactions). Therefore, our fundamental understanding about the detailed degradation\u003Cbr \/\u003E\r\nmechanisms can be significantly improved. However, we have noticed that it is difficult to estimate the rate constants of all\u003Cbr \/\u003E\r\npossible involved reactions at current stage, because we have very limited experimental data. Consequently, future work will\u003Cbr \/\u003E\r\nmainly focus on developing new methods (e.g. quantum chemistry) to estimate the rate constants of all possible involved\u003Cbr \/\u003E\r\nreactions. Then we can predict the time-dependent concentration profiles of byproducts and toxicity profiles of the system.\u003Cbr \/\u003E\r\nFinally, we investigated the disinfection byproducts formation potentials (DBPFPs) in the UV\/free chlorine process. We\u003Cbr \/\u003E\r\ndetermined the controlling factor for the design of this process was organic contaminant destruction rather than DBPFPs\u003Cbr \/\u003E\r\nreduction. Overall, our study can be used to design the most cost-effective UV\/free chlorine process for practical application\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Organic Contaminants Destruction Using UV\/Free Chlorine Process: Mechanisms and Modeling"}],"uid":"27707","created_gmt":"2019-11-25 20:06:52","changed_gmt":"2019-12-03 16:56:07","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2019-12-06T09:00:00-05:00","event_time_end":"2019-12-06T12:00:00-05:00","event_time_end_last":"2019-12-06T12:00:00-05:00","gmt_time_start":"2019-12-06 14:00:00","gmt_time_end":"2019-12-06 17:00:00","gmt_time_end_last":"2019-12-06 17:00:00","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":""}}}