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) 已成为美国和全世界人类和生态系统健康的主要威胁。传统的水处理工艺（例如商业 UV/AOP 工艺）无法有效去除许多 OMP。在美国和世界各地的先进水回收和再利用工厂中，将 UV-C 光（波长为 254 nm）与 UV-C 光（波长为 254 nm）相结合，用作最终处理屏障，以去除 OMP。氧化剂（例如过氧化氢）产生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。最近，基于硫酸根（SO4●-）的AOP由于以下原因在全世界范围内广受欢迎：与 OH● 自由基相比，SO4●- 自由基具有更高的氧化还原电位和更长的寿命，通常通过激活两种常见的自由基之一来现场生成。前体：使用催化剂或光解的过一硫酸盐（PMS）和过二硫酸盐（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，这为开发用于大规模水处理和处理的更具成本效益的AOP提供了新的机会。该项目的首要目标是加深对可见光激活 PDS 产生硫酸根的机制的基本了解，并确定这种基于硫酸根的 AOP 的功效。该项目的成功完成将产生新的基础知识，以指导基于硫酸根的 AOP 的设计和实施，以去除和破坏废水和受污染的饮用水源中的 OMP。将通过学生教育和培训来实现，包括指导德克萨斯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基于硫酸根 (SO4●) 的高级氧化工艺 (AOP) 的一名研究生。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），因此特别有吸引力。此外，过二硫酸盐中O-O键的键解离能较低（ PDS）是 SO4●- 的主要前体，表明无需催化剂即可通过可见光激活 PDS。然而，无催化剂且可见光激活的 PDS AOP 的实用性取决于。 SO4●- 的量子产率和 OMP 的特性，已被证明可以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 (1O2) 在含有阴离子（氯离子、碳酸根）的水溶液中为了应对这些挑战，该项目的主要研究人员 (PI) 提议对六 (6) 种具有独特特征的目标 OMP 的降解动力学和机制进行基础研究。使用无催化剂和可见光激活的 PDS 高级氧化过程来测量不同的分子结构 本研究的具体目标是 1) 通过可见光在三个单色波长下测量激活的 PDS 的量子产率 2) 识别和量化活性物质。广谱光以确定可见光激活 PDS 相对于紫外光激活产生 SO4●- 自由基的潜在优势；3) 确定六 (6) 个目标 OMP 在不同环境条件下的降解动力学； 4）结合和整合多种实验/工具（例如，比色法和电子分析顺磁共振波谱），以阐明和确认硫酸根基AOP中负责污染物降解的主要和次要活性物质。该项目的成功完成。通过生成新的基础知识来指导水处理和废水回收的更具成本效益和可持续的 AOP 的设计，从而产生变革性影响的潜力，以实现教育和培训目标。项目中，PI 提议利用德克萨斯农工大学 (TAMU) 和辛辛那提大学 (UC) 的现有项目来招募和指导来自代表性不足群体的本科生来从事该项目。此外，PI 还计划整合来自该项目的研究结果。这项针对 TAMU 和 UC 现有环境工程研究生/本科课程的研究。该奖项反映了 NSF 的法定使命，并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，被认为值得支持。