Collaborative Research: Catalyst Free Activation of Peroxydisulfate under Visible Light to Degrade Contaminants in Water: Elucidation of Kinetics and Mechanism

合作研究：可见光下无催化剂活化过二硫酸盐降解水中污染物：阐明动力学和机制

• 批准号: 2314719
• 负责人: Virender Sharma
• 金额: $ 28万
• 依托单位: The Texas A&M University System HSC
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2314719&HistoricalAwards=false
• 关键词: Collaborative; Research; Catalyst; Free; Activation

Organic micropollutants (OMPs) have become major threats to human and ecosystem health in the United States and worldwide. Many OMPs are not efficiently removed by conventional water treatment processes. Advanced oxidation processes (AOPs) such as the commercial UV/AOP process are increasingly being utilized as a final treatment barrier to remove 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. Recently, AOPs based on sulfate radicals (SO4●-) have gained worldwide popularity due to the higher redox potential and longer lifetime of SO4●- radicals compared to those of OH● radicals. Sulfate radicals are typically generated on site by activating one of two common precursors: peroxymonosulfate (PMS) and peroxydisulfate (PDS) using a catalyst or photolysis. Recent studies have shown that PDS can be activated by visible light without using catalyst thereby providing new opportunities to develop more cost-effective AOPs for large-scale water treatment and wastewater reclamation. The overarching goal of this project is to advance the fundamental understanding of the mechanisms of sulfate radical generation from PDS by visible light activation and determine the efficacy of this sulfate radical-based AOP to degrade and mineralize different classes of OMPs. The successful completion of this project will generate new fundamental knowledge to guide the design and implementation of sulfate radical-based AOPs for the removal and destruction of OMPs from wastewater and contaminated drinking water sources. Additional benefits to society will be achieved through student education and training including the mentoring of one undergraduate and two graduate students at Texas A&M University and one graduate student at the University of Cincinnati. Sulfate radical (SO4●)-based advanced oxidation processes (AOPs) are particularly attractive due to their larger redox potential and much longer half-life (30-40 microseconds) compared to those of hydroxyl radicals (OH●, 20 nanoseconds). In addition, the low bond dissociation energy of the O-O bond in peroxydisulfate (PDS), a primary precursor of SO4●-, suggests that activation of PDS is feasible by visible light without a catalyst. However, the practicality of a catalyst-free and visible light activated PDS AOP depends on the quantum yield of SO4●- and the properties of OMPs, which have been shown to promote the formation of other radical species including OH●, superoxide (O2●), and singlet oxygen (1O2) in aqueous solutions containing anions (chloride, carbonate, and phosphate) and natural organic matter. To address these challenges, the Principal Investigators (PIs) of this project propose to carry out a fundamental study of the kinetics and mechanisms of degradation of six (6) target OMPs with distinctively different molecular structures using a catalyst free and visible light activated PDS advanced oxidation process. The specific objectives of this research are to 1) measure the quantum yields of activated PDS by visible light at three monochromatic wavelengths; 2) identify and quantify reactive species in a broad spectrum of light to establish the potential advantage of visible light activation of PDS over UV light activation for the generation of SO4●- radicals ; 3) determine the degradation kinetics of six (6) target OMPs under different environmental conditions; and 4) combine and integrate multiple experimental assays/tools (e.g., colorimetry and electron paramagnetic resonance spectroscopy) to elucidate and confirm the primary and secondary reactive species responsible for contaminant degradation in sulfate radical-based AOPs. The successful completion of this project has the potential for transformative impact through the generation of new fundamental knowledge to guide the design of more cost-effective and sustainable AOPs for water treatment and wastewater reclamation. To implement the education and training goals of the project, the PIs propose to leverage existing programs at Texas A&M University (TAMU) and the University of Cincinnati (UC) to recruit and mentor undergraduate students from underrepresented groups to work on the project. In addition, the PIs plan to integrate the findings from this research into existing environmental engineering graduate/undergraduate courses at TAMU and UC.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.

有机微污染物（OMP）已成为美国和世界范围内人类和生态系统健康的主要威胁。许多OMP不能通过传统的水处理工艺有效地去除。在美国和世界范围内，高级氧化工艺（AOP）如商业UV/AOP工艺越来越多地被用作最终处理屏障，以在高级水回收和再利用工厂中去除OMP。在典型的UV/AOP工艺中，将UV-C光（波长为254 nm）与氧化剂（例如，过氧化氢）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、药物、杀虫剂、除草剂等。最近，基于硫酸根（SO 4 ●-）的AOP在世界范围内得到普及，这是由于与OH●自由基相比，SO 4 ●-自由基的氧化还原电位更高，寿命更长。硫酸根自由基通常通过使用催化剂或光解激活两种常见前体之一来现场产生：过一硫酸根（PMS）和过二硫酸根（PDS）。最近的研究表明，PDS可以在不使用催化剂的情况下被可见光激活，从而为开发用于大规模水处理和废水回收的更具成本效益的AOP提供了新的机会。该项目的总体目标是通过可见光活化促进对PDS产生硫酸根的机制的基本理解，并确定这种基于硫酸根的AOP降解和矿化不同类别的OMP的功效。该项目的成功完成将产生新的基础知识，以指导设计和实施基于硫酸根的AOP，用于从废水和受污染的饮用水源中去除和销毁OMP。通过学生教育和培训，包括指导德克萨斯州农工大学的一名本科生和两名研究生以及辛辛那提大学的一名研究生，将为社会带来更多好处。基于硫酸根（SO 4 ●）的高级氧化工艺（AOP）特别有吸引力，因为与羟基自由基（OH●，20纳秒）相比，它们具有更大的氧化还原电位和更长的半衰期（30-40微秒）。此外，过二硫酸盐（PDS）中O-O键的低键离解能，SO 4 ●-的主要前体，表明PDS的活化是可行的，可见光没有催化剂。然而，无催化剂和可见光激活的PDS AOP的实用性取决于SO 4 ●-的量子产率和OMP的性质，OMP已被证明在含有阴离子（氯化物、碳酸盐和磷酸盐）和天然有机物的水溶液中促进其他自由基物种的形成，包括OH●、超氧化物（O2●）和单线态氧（1 O2）。为了应对这些挑战，本项目的主要研究者（PI）建议使用无催化剂和可见光激活的PDS高级氧化工艺，对6种具有明显不同分子结构的目标OMP的降解动力学和机制进行基础研究。本研究的具体目标是：1）测量三个单色波长的可见光激活PDS的量子产率; 2）在宽光谱下识别和量化活性物种，以确定可见光激活PDS产生SO 4 ●-自由基相对于紫外光激活的潜在优势; 3）确定六（6）种目标OMP在不同环境条件下的降解动力学;以及4）联合收割机并整合多种实验测定/工具（例如，比色法和电子顺磁共振光谱法）来阐明和确认在基于硫酸根的AOP中负责污染物降解的初级和次级反应性物质。该项目的成功完成有可能通过产生新的基础知识来指导设计更具成本效益和可持续性的水处理和废水回收的AOP，从而产生变革性的影响。 为了实现该项目的教育和培训目标，PI建议利用德克萨斯农工大学（TAMU）和辛辛那提大学（UC）的现有项目，从代表性不足的群体中招募和指导本科生从事该项目。此外，PI计划将这项研究的结果整合到TAMU和UC的现有环境工程研究生/本科课程中。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。