Nanotechnology Enabled Water Treatment (NEWT) Center , 6100 Main Street , Houston , Texas 77005 , United States.
Department of Chemical and Biomolecular Engineering , Rice University , Houston , Texas 77005 , United States.
Acc Chem Res. 2019 Apr 16;52(4):906-915. doi: 10.1021/acs.accounts.8b00642. Epub 2019 Feb 22.
Fresh water demand is driven by human consumption, agricultural irrigation, and industrial usage and continues to increase along with the global population. Improved methods to inexpensively and sustainably clean water unfit for human consumption are desired, particularly at remote or rural locations. Heterogeneous catalysts offer the opportunity to directly convert toxic molecules in water to nontoxic products. Heterogeneous catalytic reaction processes may bring to mind large-scale industrial production of chemicals, but they can also be used at the small scale, like catalytic converters used in cars to break down gaseous pollutants from fuel combustion. Catalytic processes may be a competitive alternative to conventional water treatment technologies. They have much faster kinetics and are less operationally sensitive than current bioremediation-based methods. Unlike other conventional water treatment technologies (i.e., ion exchange, reverse osmosis, activated carbon filtration), they do not transfer contaminants into separate, more concentrated waste streams. In this Account, we review our efforts on the development of heterogeneous catalysts as advanced reduction technologies to treat toxic water contaminants such as chlorinated organics and nitrates. Fundamental understanding of the underlying chemistry of catalytic materials can inform the design of superior catalytic materials. We discuss the impact of the catalytic structure (i.e., the arrangement of metal atoms on the catalyst surface) on the catalyst activity and selectivity for these aqueous reactions. To explore these aspects, we used model metal-on-metal nanoparticle catalysts along with state-of-the-art in situ spectroscopic techniques and density functional theory calculations to deduce the catalyst surface structure and how it affects the reaction pathways and hence the activity and selectivity. We also discuss recent developments in photocatalysis and electrocatalysis for the treatment of nitrates, touching on fundamentals and surface reaction mechanisms. Finally, we note that despite over 20 years of growing research into heterogeneous catalytic systems for water contaminants, only a few pilot-scale studies have been conducted, with no large-scale implementation to date. We conceive of modular, on- or off-grid catalytic units that treat drinking water at the household tap, at a community well, or for larger-scale reuse of agricultural runoff. We discuss how these may be enhanced by combination with photocatalytic or electrocatalytic processes and how these reductive catalytic modules (catalytic converters for water) can be coupled with other modules for the removal of potential water contaminants.
淡水需求是由人类消费、农业灌溉和工业使用驱动的，并且随着全球人口的增长而持续增加。人们希望开发出廉价且可持续的清洁水方法，尤其在偏远或农村地区。多相催化剂提供了直接将水中有毒分子转化为无毒产物的机会。多相催化反应过程可能会让人联想到大规模的化学品工业生产，但它们也可以在小规模下使用，例如汽车中的催化转化器用于分解燃料燃烧产生的气态污染物。催化过程可能是传统水处理技术的一种有竞争力的替代方案。它们的动力学更快，操作敏感性低于当前基于生物修复的方法。与其他传统水处理技术（例如离子交换、反渗透、活性炭过滤）不同，它们不会将污染物转移到单独的、更浓缩的废物流中。在本报告中，我们回顾了我们在开发多相催化剂作为先进还原技术以处理有毒水污染物（如氯化有机物和硝酸盐）方面的努力。对催化材料基础化学的深入了解可以为更优异的催化材料设计提供信息。我们讨论了催化结构（即催化剂表面上金属原子的排列）对这些水相反应的催化剂活性和选择性的影响。为了探索这些方面，我们使用了模型金属-金属纳米颗粒催化剂以及最先进的原位光谱技术和密度泛函理论计算，以推断催化剂表面结构及其如何影响反应途径，从而影响活性和选择性。我们还讨论了光催化和电催化在硝酸盐处理方面的最新进展，涉及基本原理和表面反应机制。最后，我们注意到，尽管多相催化系统在水处理方面的研究已经有 20 多年的历史，但迄今为止，只有少数试点研究，没有大规模实施。我们设想了在家庭水龙头、社区水井或更大规模地再利用农业径流处处理饮用水的模块化、并网或离网催化单元。我们讨论了如何通过与光催化或电催化过程相结合来增强这些催化单元，以及如何将这些还原催化模块（水用催化转化器）与其他模块结合起来去除潜在的水污染物。
