Mechanisms and Kinetics of Saltwater-Driven Carbon Dioxide Capture for Environmental and Ocean Health

人类在海洋和大气中过量排放二氧化碳是对地球上所有生命的重大威胁。海洋中额外的二氧化碳导致了一种不受欢迎的过程，称为海洋酸化。此外，大气中二氧化碳的增加导致全球气温上升，显著改变了地球的气候。为了减少这些排放，许多发电厂通过燃烧后过程从烟道气中捕获二氧化碳，该过程使用淡水和含氮化学物质分离二氧化碳，这是一项前景光明的技术，不幸的是，它严重依赖淡水，并产生对环境有害的副产品。为了降低成本和能源消耗，在盐水中溶解无化学物质的二氧化碳将是替代传统淡水捕获技术的一个很好的选择。这项建议的首要目标是评估海水使用环境友好型金属纳米颗粒催化剂捕获二氧化碳的性能和环境影响。该项目的成功完成将提供一项战略，通过利用丰富的自然资源消除有害二氧化碳来改变大气和海洋环境的长期健康。除了对环境的直接影响，该项目还将推进农业、环境和能源行业的净化技术。健康的海洋对全球气候至关重要，吸收大约40%的二氧化碳排放。开发一种新的二氧化碳催化分离方法对于应对快速的全球变暖和海洋酸化至关重要。这项研究的目的是了解聚合物稳定的纳米镍催化剂用于天然海水中基于吸附的气体分离的基本机理。这一目标将通过使用纳米显微镜和光谱学在海水中反应期间对纳米颗粒的尺寸、形态和表面化学进行全面的非原位和原位检查来实现。这项研究将研究镍纳米颗粒表面和周围溶液之间界面上的随时间变化的表面化学，从而更好地了解纳米颗粒的渐进反应状态。对纳米颗粒参与的二氧化碳在盐水中溶解反应机理的基本见解将解释在传统不利条件下前所未有的溶解效率。为了进一步了解纳米颗粒驱动的二氧化碳在盐水中的溶解，将研究溶解动力学作为载体流体、反应条件和催化剂性能的函数。最后的任务将是评估促进碳酸盐矿物沉淀的主要元素，确定主要矿物类型，确定所产生的矿物的特征，并研究以碳酸盐为基础减缓海洋酸化的可行性。这项研究将为在不同流体、反应和催化剂性质条件下的催化二氧化碳分离提供一个基本的理解，推动能源和化学工业中有效气体分离的科学发展。此外，了解非均质咸水环境中碳酸盐的形成将有助于确定对海洋生物有价值的主要副产品以及碳酸盐矿物对海洋钙化的影响。所学到的知识将是变革性的，在许多环境能源过程中促进海水的使用，同时节省日益有限的淡水供应。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Human-caused excessive carbon dioxide emissions in the ocean and the atmosphere are a significant threat to all life on Earth. This extra carbon dioxide in the ocean leads to an undesirable process called ocean acidification. In addition, the increased carbon dioxide in the atmosphere causes the global temperature to rise, significantly altering the Earth's climate. To mitigate these emissions, many power plants capture carbon dioxide from flue gas through a post-combustion process that separates the carbon dioxide using freshwater and nitrogen-containing chemicals, a promising technology that, unfortunately, relies heavily on freshwater and produces environmentally harmful byproducts. To reduce costs and energy consumption, chemical-free carbon dioxide dissolution in saltwater would be a good alternative to conventional freshwater capture techniques. The overarching objective of this proposal is to evaluate the performance and environmental impact of seawater to capture carbon dioxide using environmentally friendly metal nanoparticle catalysts. Successful completion of the project will provide a strategy to transform the long-term health of atmospheric and ocean environments by removing harmful carbon dioxide using ample natural resources. Beyond the direct impact on the environment, the project will advance decontamination technologies for the agricultural, environmental, and energy industries.A healthy ocean is essential for the global climate, absorbing roughly 40% of carbon dioxide emissions. The development of a novel catalytic carbon dioxide separation approach is critical for addressing rapid global warming and ocean acidification. The goal of this research is to understand the fundamental mechanisms of absorption-based gas separation in natural seawater using polymer-stabilized nickel nanoparticle catalysts. This goal will be accomplished by a comprehensive ex-situ and in-situ examination of the nanoparticle size, morphology, and surface chemistry during reactions in seawater using nanoscale microscopy and spectroscopy. The research will investigate the time-dependent surface chemistry at the interface between the nickel nanoparticle surface and the surrounding solution, enabling a better understanding of the progressive reaction states of the nanoparticles. Fundamental insights into the reaction mechanism of nanoparticle-involved carbon dioxide dissolution in saltwater will explain the unprecedented dissolution efficiency under conventionally unfavorable conditions. To further understand nanoparticle-driven carbon dioxide dissolution in saltwater, the dissolution kinetics will be investigated as a function of carrier fluids, reaction conditions, and catalyst properties. The final tasks will be to evaluate the dominant elements that promote precipitation of carbonate minerals, identify the leading type of minerals, characterize the resultant minerals, and study the feasibility of carbonate-based mitigation for ocean acidification. This research will provide a fundamental understanding of catalytic carbon dioxide separation under variable fluid, reaction, and catalyst property conditions, advancing science towards effective gas separation in the energy and chemical industry. In addition, an understanding of carbonate formation in the heterogeneous saltwater environment will enable the identification of dominant byproducts valuable to marine organisms as well as the impacts of carbonate minerals on marine calcification. The learned knowledge will be transformative by promoting the use of saltwater in many environmental energy processes while saving the increasingly limited freshwater supply.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.