Collaborative Research: Enhanced Photolysis and Advanced Oxidation Processes by Novel KrCl* (222 nm) Irradiation

高级氧化工艺（AOPs），如商业UV/AOP工艺，越来越多地被用作去除有机微污染物（OMPs）的最终处理屏障，在美国和世界各地的高级水回收和再利用工厂。在典型的UV/AOP工艺中，UV- c光（波长254 nm）与氧化剂（例如过氧化氢）结合产生OH自由基，OH自由基可以破坏和矿化omp，包括个人护理产品，药品，杀虫剂，除草剂等。氯化氪准分子灯（KrCl* excilamps）是一种新型的、有前途的无汞紫外线光源，其辐射波长为222nm。与商用UV/AOPs中使用的低压汞灯相比，对KrCl* excilamps光化学性质和性能的表征研究有限。此外，还需要更多的研究来评估和基准KrCl* excillamp与商用UV/AOP系统中使用的低压UV- c灯的性能，以降解和矿化受污染的饮用水水源和废水中的omp。这个项目的首要目标是解决这些知识差距。为了推进这一目标，首席研究员（pi）提议利用紫外光解和紫外/AOP技术，利用发射222 nm紫外辐射的KrCl* excilamp，对水溶液和环境相关水/废水样品中OMPs的降解和矿化进行基础研究。该项目的成功完成将通过产生基础知识来促进基于KrCl* exilamp的UV工艺的设计和实施，从而在水处理和废水回收过程中去除omp，从而造福社会。通过学生教育和培训，包括佐治亚理工学院的一名研究生和一名本科生以及北达科他州立大学的一名研究生的指导，将为社会带来额外的好处。氯化氪准分子灯（KrCl* excilamp）是一种很有前途的水处理紫外光源。由于在222 nm的高能光子，KrCl* excilamps表现出有效的消毒性能，并有可能在光解和基于UV的高级氧化过程（UV/AOPs）中增强有机微污染物（OMPs）的去除。然而，关于KrCl* excilamp下OMPs的光解和UV/AOP的基础知识有限。为了解决这一关键的知识空白，主要研究者（pi）提出系统地研究基于KrCl* excilamp的光解和UV/AOP在222 nm降解水溶液中的OMPs，目的是阐明相关的反应机制和水基质组成对性能的影响。本研究的具体目标是：1)测量KrCl* excilamps在222 nm处的直接光解速率常数、摩尔消光系数和量子产率，并将测量的性能与254 nm处的性能进行比较；2)利用过氧化氢、过氧二硫酸钠和过氧乙酸在222 nm的UV/AOP中量化和模拟反应物质的产生，并在222 nm的UV/AOP中确定所选OMPs的降解效率；3)利用UV/AOP评价水基质组成对222 nm下OMPs光解降解的影响，重点研究了在222 nm下强吸收紫外光且反应性强的硝酸盐；4)鉴定有机微污染物转化产物，阐明222 nm光解和AOP的机理，包括消毒副产物前体的产生。为了实现该项目的教育和培训目标，项目负责人建议利用佐治亚理工学院和北达科他州立大学（NDSU）现有的项目，从代表性不足的群体中招募和指导本科生参与该项目。此外，pi计划将研究成果整合到乔治亚理工学院和NDSU现有的环境工程研究生/本科生课程和外展活动（例如，STEM科学博览会和K-12学生夏令营）中。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Advanced oxidation processes (AOPs) such as the commercial UV/AOP process are increasingly being utilized as a final treatment barrier to remove organic micropollutants (OMPs) in advanced water reclamation and reuse plants in the United States and worldwide. In a typical UV/AOP process, UV-C light (254 nm in wavelength) is combined with an oxidant (e.g., hydrogen peroxide) to generate OH free radicals that can destroy and mineralize OMPs including personal care products, pharmaceuticals, pesticides, herbicides, etc. Krypton chloride excimer lamps (KrCl* excilamps) are novel and promising mercury-free UV sources that emit radiation with a wavelength of 222 nm. Compared to low-pressure mercury lamps that are utilized in commercial UV/AOPs, only limited research has been devoted to the characterization of the photochemical properties and performance of KrCl* excilamps. In addition, more research is needed to assess and benchmark the performance of KrCl* excilamps against those of low-pressure UV-C lamps used in commercial UV/AOP systems to degrade and mineralize OMPs from contaminated drinking water sources and wastewater. The overarching goal of this project is to address these knowledge gaps. To advance this goal, the Principal Investigators (PIs) propose to carry out a fundamental investigation of the degradation and mineralization of OMPs in aqueous solutions and environmentally relevant water/wastewater samples using UV photolysis and UV/AOP with a KrCl* excilamp that emits UV radiation at 222 nm. The successful completion of this project will benefit society through the generation of the foundational knowledge required to advance the design and implementation of KrCl* exilamp-based UV processes for the removal of OMPs during water treatment and wastewater reclamation. Additional benefits to society will be achieved through student education and training including the mentoring of one graduate student and one undergraduate at Georgia Tech and one graduate student at North Dakota State University.Krypton chloride excimer lamp (KrCl* excilamp) emitting light at 222 nm is a promising ultraviolet (UV) source for water treatment. Because of the high-energy photons at 222 nm, KrCl* excilamps exhibit effective disinfection performance and have the potential to enhance removal of organic micropollutants (OMPs) in photolysis and UV-based advanced oxidation processes (UV/AOPs). However, limited fundamental knowledge is available on the photolysis and UV/AOP of OMPs under a KrCl* excilamp. To address this critical knowledge gap, the Principal Investigators (PIs) propose to systematically investigate the KrCl* excilamp based photolysis and UV/AOP at 222 nm to degrade OMPs in aqueous solutions with the goal of elucidating the relevant reaction mechanisms and the impact of water matrix composition on performance. The specific objectives of the research are to 1) measure the direct photolysis rate constants, molar extinction coefficients, and quantum yields of KrCl* excilamps at 222 nm for a wide range of structurally-diverse OMPs, and compare the measured properties with those at 254 nm; 2) quantify and model the generation of reactive species in a UV/AOP at 222 nm using hydrogen peroxide, peroxydisulfate, and peracetic acid, and determine the degradation efficiency of selected OMPs using UV/AOP at 222 nm; 3) evaluate the effect of water matrix composition on the photolysis and degradation of OMPs using UV/AOP at 222 nm, with a focus on nitrate which strongly absorbs UV light and is highly reactive at 222 nm; and 4) identify organic micropollutant transformation products and elucidate the mechanisms of photolysis and AOP at 222 nm including the generation of disinfection byproduct precursors. To implement the education and training goals of the project, the PIs propose to leverage existing programs at Georgia Tech and North Dakota State University (NDSU) to recruit and mentor undergraduate students from underrepresented groups to work on the project. In addition, the PIs plan to integrate the research findings into existing environmental engineering graduate/undergraduate courses and outreach activities (e.g., STEM science fairs and summer camps for K-12 students) at Georgia Tech and NDSU.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.