Collaborative Research: Natural Organic Matter, Capping Agents, and Nanoparticle Transport in Granular Media Filtration

CBET-1336139和1336167随着纳米技术领域的不断扩大，工程纳米颗粒（NP）进入环境的增加导致了越来越多的环境和健康问题。工程纳米颗粒的行为，其中许多作为一种途径，在环境中的污染物的快速和长距离运输/转化，是一个重要的主题，饮用水的安全和处理。由于天然有机物（NOM）在天然沃茨中普遍存在，并且已知与NP表面络合，因此对NP-NOM相互作用的机理理解将提供对颗粒介质过滤中NP的稳定性和流动性的了解。我们的研究团队采取三管齐下的方法来研究NOM影响颗粒介质过滤中"原始"和"转化"银纳米粒子（AgNPs）的水相传输的机制。我们采用过滤研究，以确定和量化NP去除效率从其预测的胶体过滤理论的偏差。在化学相互作用导致偏离理论的地方，我们使用实验工具的组合来阐明NP-NOM相互作用的动力学和机制。这项研究将最终提高我们的能力，去除工程NPs颗粒介质filtration.Intellectual优点：在形成或释放到水环境中，大多数NPs获得表面涂层通过与有机大分子相互作用。我们预计，NP表面上的涂层的性质将发挥重要作用，NP去除颗粒介质过滤。我们假设：1）"原始" AgNP（用柠檬酸盐和聚乙烯吡咯烷酮（PVP）加帽）和"转化的" AgNP（部分硫化的AgNP）将表现出与各种NOM组分的反应性，从而产生具有不同表面电荷和空间位阻程度的AgNP-NOM络合物，2）NP-的吸附动力学二氧化硅表面上的NOM络合物是由NOM的不同官能团产生的表面电荷和由NOM的物理排列产生的空间位阻的函数，和3）在AgNPs以及收集器颗粒表面上的NOM涂层导致颗粒去除效率的显著偏差。我们将使用分子光谱学、石英晶体微重力（QCM）和柱过滤实验的新组合，确定NOM与NP和二氧化硅表面相互作用的机制和动力学。更广泛的影响：作为将尖端科学融入教育的一种手段，我们提出了一个5阶段的推广计划，以加强这种交流：（1）专业教育，所有三个PI将建议在“德克萨斯水”举行一次全时段研讨会或特别会议，在为期三年的赠款的第三年，美国第三大年度水会议。(2)研究生教育，多个讲座将在四门课程中发展。这里概述的工作将用于积极招募和培训来自代表性不足群体的本科生和研究生。我们将在选择博士学位时采用多样性。学生，并另外尝试支持1 - 2个本科生的高级论文研究。(3)大学水平：我们将继续与两个主要的指导计划进行互动，这些计划旨在让代表性不足的少数民族参与工程研究计划。(4)贝勒大学有一个既定的推广计划，重点是纳米技术（物理马戏团），这是积极的工作，在韦科和拉维加初中和高中。(5)高中水平：我们将与来自圣胡安迭戈高中的学生合作，这是一所大学预科学校，位于德克萨斯大学校园附近，为经济困难的学生提供服务，主要是西班牙裔学生，以提高他们在科学和数学方面的大学准备。天然和工程纳米粒子的应用越来越多，这既是技术上的灵丹妙药，也是潜在的健康威胁。目前，关于纳米颗粒的环境迁移和归宿的信息不足。我们的工作是变革性的，为预测纳米粒子与NOM和硅砂表面的行为和相互作用提供了关键信息。目前颗粒介质过滤的实践目标是微米级颗粒;然而，NOM和其他水处理参数对颗粒介质过滤中NP命运的潜在影响在很大程度上是未知的。这项研究的结果将提供更多的知识，最终可能影响水处理设计和实践的纳米粒子的行为，从而提高公众健康的保护。

CBET - 1336139 and 1336167As the field of nanotechnology continues to expand, increased entry of engineered nanoparticles (NPs) into the environment has resulted in growing environmental and health concerns. The behavior of engineered NPs, many of which serve as an avenue for rapid and long-range transport/transformation of contaminants in the environment, is an important topic for the safety and treatment of drinking water. As natural organic matter (NOM) is ubiquitous in natural waters and known to complex with NP surfaces, a mechanistic understanding of NP-NOM interactions will provide insight to the stability and mobility of NPs in granular media filtration. Our team of investigators takes a three-pronged approach to study the mechanisms by which NOM affects the aqueous transport of "pristine" and "transformed" silver NPs (AgNPs) in granular media filtration. We employ filtration studies to identify and quantify the deviation of NP removal efficiency from its prediction by colloid filtration theory. Where chemical interactions cause deviation from theory, we use a combination of experimental tools to elucidate both the kinetics and the mechanisms of NP-NOM interactions. This research will ultimately improve our ability to removal engineered NPs by granular media filtration.Intellectual Merit :During the formation or release into the aquatic environment, most NPs acquire a surface coating by interacting with organic macromolecules. We expect that the properties of coatings on NP surfaces will play important roles in NP removal in granular media filtration. We hypothesize that: 1) "Pristine" AgNPs (capped with citrate and polyvinyl pyrrolidone (PVP)) and "transformed" AgNPs (partly sulfidized AgNPs) will exhibit reactivity with various NOM components, thereby producing AgNP-NOM complexes with different surface charge and degree of steric hindrance, 2) the kinetics of adsorption of NP-NOM complexes onto silica surfaces is a function of the surface charge produced by the different functional groups of NOM and steric hindrance resulting from the physical arrangement of NOM, and 3) NOM coating on AgNPs as well as collector grain surfaces causes significant deviation in particle removal efficiency. Using a novel combination of molecular spectroscopy, quartz crystal microgravimetry (QCM), and column filtration experiments, we will determine the mechanisms and kinetics of NOM interaction with the surfaces of NP and silica.Broader Impacts :As a means of integrating cutting-edge science into education, we present a 5-Phased Outreach Plan to enhance this exchange: (1) professional education, all three PIs will propose a full-session workshop or special session at "Texas Water", the third largest annual water conference in the U.S. in the third year of the three-year grant. (2) Graduate education, multiple lectures will be developed in four courses. The work outlined here will be used to actively recruit and train undergraduate and graduate students from underrepresented groups. We will employ diversity in choosing the Ph.D. students, and additionally try to support 1-2 undergrads for senior thesis research. (3) College level: we will continue interacting with two major mentoring programs designed to involve under-represented minorities in engineering research programs. (4) Baylor University has an established outreach program focusing on nanotechnology (ThePhysics Circus) which is actively working in the Waco and LaVega middle and high schools. (5) High school level: we will work with students from San Juan Diego High School, a college-preparatory school located near the University of Texas campus that serves economically-disadvantaged, mostly Hispanic, students to increase their college preparedness in science and mathematics. The increasing applications of both natural and engineered NPs represent both a technological panacea and potential health threat. At present, there is insufficient information regarding the environmental transport and fate of NPs. Our work is transformative in providing crucial information for predicting behavior and interactions of NPs with NOM and silica sand surface. Current practice of granular media filtration targets micron-sized particles; however, the potential influences of NOM and other water treatment parameters on the fate of NPs in granular media filtration are largely unknown. The results of this study will provide greater knowledge of the behavior of NPs that could ultimately influence water treatment design and practice, and thereby improve the protection of the public health.