Collaborative Research: Novel Materials and Reactor Design for Coupled Electrolytic Hydrogen Production and Nitrate Removal With Resource Recovery from Drinking Water

1706797/1705255 PI：Werth，Charles J./Jwahar Hussaini，Syed Mube Nitrate是世界上最普遍的地下水污染物，其管理被美国国家工程院认定为重大挑战之一。催化处理已成为从饮用水中去除硝酸盐的一种更可持续的选择，但由于缺乏科学知识和新材料方面的创新，直接应对反应堆性能和扩大规模方面的挑战，催化处理的实施受到阻碍。具体地说，可伸缩反应器中的硝酸盐处理受到向反应催化剂位置输送氢气的限制。PI提出了一种高风险/高回报的方法，该方法基于通过电活性催化剂载体原位产生吸附的原子氢。最重要的假设是，原子氢可以在发生硝酸盐还原的同一地点(或直接邻近地点)电解产生，并可以与硝酸盐还原平衡，以消除氢的传质限制，优化氢的利用，最大限度地减少能源消耗，并回收增值资源氨和氯。拟议工作的具体目标是：1)确定合成具有高导电性、金属分散性、透水性和强度的碳基催化剂载体的基本块体材料和表面化学性质。2)阐明间歇式和流通式反应器中电解制氢和硝酸盐还原耦合过程的反应机理和动力学，并确定优化这些过程的新型催化材料的基本性质。3)评价离子交换-电化学复合反应器去除饮用水中硝酸盐的经济和环境可持续性。该方法包括新的合成和电/催化实验，旨在阐明高效去除模拟饮用水中硝酸盐和回收氨的反应机理和最佳反应器条件，以及与离子交换废盐水处理和再利用相结合的技术的经济和环境生命周期分析，作为工艺优化的反馈。潜在的科学进展包括：(1)基本见解和结构-活性关系，以指导合成有效地产生氢并在催化反应部位还原硝酸盐的新型阴极材料；(2)设计一种新型的电解型反应器，将这些坚固的阴极材料整合到填充床流动系统中；(3)综合回收具有农业价值的铵以及用于减轻催化剂污染和水消毒的氯；(4)开发和传播综合模型，以便为新技术开发进行成本和环境影响评估。拟议的教育、外联和参与活动包括利用德克萨斯大学奥斯汀分校的工程开放日，让初中生和高中生接触水处理的工程设计，开发新的教学模块，并通过行业合作者向自来水公司传播。

1706797 / 1705255PIs : Werth, Charles J. / Jawahar Hussaini, Syed Mubeen Nitrate is the world's most ubiquitous groundwater pollutant, and its management is recognized as one of the Grand Challenges by the National Academy of Engineering. Catalytic treatment has emerged as a more sustainable option for nitrate removal from drinking water, but its implementation has been stymied by a lack of scientific knowledge and innovation in new materials that directly address challenges in reactor performance and scale-up. Specifically, nitrate treatment in scalable reactors is limited by hydrogen delivery to reactive catalysts sites. The PIs propose a high risk/high reward approach that is based on generating adsorbed atomic hydrogen in situ via electroactive catalyst supports. The overriding hypothesis is that atomic hydrogen can be electrolytically generated at the same (or directly adjacent to) site where nitrate reduction occurs, and this generation can be balanced with nitrate reduction to eliminate hydrogen mass transfer limitations, optimize hydrogen use, minimize energy consumption, and recover value-added resources, ammonium and chlorine. The specific objectives of the proposed work are: 1) To identify the fundamental bulk material and surface chemical properties responsible for the synthesis of carbon-based catalyst supports with high-electrical conductivity, metal dispersion, water permeability, and strength. 2) To elucidate reaction mechanisms and kinetics of coupled electrolytic hydrogen generation and nitrate reduction processes in batch and flow-through reactors, and to identify the fundamental properties of new catalytic materials that optimize these processes. 3) To evaluate the economic and environmental sustainability of a hybrid ion exchange - electrochemical reactor for nitrate removal from drinking water.The proposed approach involves novel synthesis and electro/catalytic experiments that aim to elucidate structure/property correlations, reaction mechanisms, and optimal reactor conditions for efficient nitrate removal coupled with ammonia recovery from simulated drinking water, and an economic and environmental life cycle analyses of the technology coupled to ion exchange waste brine treatment and reuse that will serve as feedback for process optimization. Potential scientific advancements include: (i) foundational insights and structure-activity relationships to guide synthesis of new cathodic materials that efficiently generate hydrogen and reduce nitrate at catalytically reactive sites; (ii) the design of a novel electrolytic- based reactor that integrates these robust cathodic materials into a packed-bed flow system; (iii) integrated resource recovery of agriculturally valuable ammonium, as well as chlorine for catalyst fouling mitigation and water disinfection; and (iv) the development and dissemination of an integrated model that allows scale up for a cost and environmental impact assessment for new technology development. Proposed educational, outreach and engagement activities include using UT Austin's engineering open houses to expose junior high and high school students to engineering design for water treatment the development of a new teaching modules and dissemination to water utilities through an industry collaborator.