Formation of Multiscale Biopolymer Particle Structures for Novel Biosorbent Design

这项建议的目标是加深对生物聚合物凝胶微颗粒和纳米颗粒吸附金属离子的基本机理和控制过程的了解，以指导下一代生物吸附剂的设计。具体地说，这项工作将研究复杂几何形状的多相流，作为净水设备的模型，以发现在流动和后续吸附过程中驱动颗粒尺寸分离现象的机制。利用丰富和生物相容的天然生物聚合物，具有出色的吸附性能和低能量的交联路线，为有效去除工业废水中的重金属污染物提供了独特的机会，这是一个主要的环境问题。改善对水净化的多相传输方面的认识对于提高水处理的效率和速度是至关重要的。智力价值：这项研究的新颖性来自于拟议的复杂几何流动中非均质颗粒悬浮的实验研究，以及由这种流动形成的固定颗粒床在微米和纳米尺度上的质量传递。在典型的固定床充填过程中，流场与颗粒的非均匀空间分布紧密耦合。因此，目前的悬浮液模型无法预测双峰悬浮液(两种颗粒尺寸)的流动情况。此外，颗粒材料，特别是生物聚合物凝胶，已知与溶液中的金属离子具有很强的络合和静电相互作用，但包括生物聚合物纳米颗粒在内的组合多尺度结构尚未被考虑。核磁共振成像(NMRI)这一强大的实验技术将被用来收集有关粒子和物种运输的几个特征的详细信息。实验结果还将与基于单峰悬浮流连续模型的最新计算进行比较。本研究的具体目标包括：(1)合成生物聚合物纳米颗粒包裹的生物聚合物微球，并表征其对重金属离子的平衡吸附。(2)了解流经模型滤床几何形状的双峰悬浮液的粒度分离机理。(3)生物聚合物微纳米颗粒固定床流动中金属离子吸附动力学的定量研究。更广泛的影响技术：基础研究成果可以作为长期实用指南，在下一代废水净化单元中使用互补性生物聚合物微纳米结构，以提高净化效率并使用自然丰富和环境友好的材料。教育影响：教育和外展活动将侧重于将研究的概念和结果纳入多个教育级别的学生的实际、积极的实验室体验中。涉及流体力学和流变学的实验室实践经验将激励各种项目，从针对贫困高中生的学术充实计划到帮助学生为博士研究做准备的研究生实验室课程。在P.I.S实验室为高中生、本科生和研究生进行的强化研究培训也是教育活动的一个重要组成部分。这一统一的研究和教育项目将加强对多相传输问题的了解，这些问题对于实现有效地从水中去除有毒金属污染物至关重要，同时它将吸引和培训下一代科学家研究流体流动和材料特性。

0756220ShapleyThe goal of this proposal is to enhance understanding of the fundamental mechanisms of particle size separation and the processes that control metal ion species adsorption by biopolymer gel micro and nanoparticles, with the aim of guiding the next generation of biosorbent design. Specifically, the work will examine multiphase flow in complex geometries that serve as models for water purification devices in order to discover the mechanisms driving particle size separation phenomena during flow and subsequent adsorption processes. Utilization of abundant and biocompatible natural biopolymers with outstanding sorbent properties and low energy cross-linking routes offers a unique opportunity for effective heavy metal contaminant removal from industrial wastewater streams, a leading environmental concern. Improved insight into the multiphase transport aspects of water purification is essential for improving the efficacy and speed of water treatment. Intellectual Merit: The novelty of this research derives from the proposed experimental study of heterogeneous particle suspensions in complex geometry flows, and mass transfer at the micro and nanoscale in resulting fixed particle beds formed from such flows. During the filling of a typical fixed bed geometry, the flow field is tightly coupled to the nonuniform spatial distribution of particles. Hence, it is beyond the predictive power of current suspension models to anticipate the resulting flows of bimodal suspensions (two particle sizes). In addition, the particle materials, specifically biopolymer gels, are known to have strong complexation and electrostatic interactions with metal ions in solution, but a combined multiscale structure including biopolymer nanoparticles has not been considered. The powerful experimental technique of nuclear magnetic resonance imaging (NMRI) will be used to gather detailed information on several features of particle and species transport. Experimental results will also be compared with state of the art calculations based on continuum modeling of monomodal suspension flows. The specific aims of this research program include: (1) Synthesizing biopolymer microbeads coated with complementary biopolymer nanoparticles and characterizing equilibrium heavy metal ion uptake. (2) Understanding mechanisms of particle size separation in a bimodal suspension flowing through model filtration bed geometries. (3) Quantifying the kinetics of metal ion adsorption in flow through a fixed bed of biopolymer micro-nanoparticle structures. Broader Impact Technology: The fundamental research results can be implemented as long-term practical guidelines for the utilization of complementary biopolymer micro and nanoparticle structures in the next generation of wastewater purification units, in order to improve purification efficiency and employ naturally abundant and environmentally benign materials. Educational Impact: Education and outreach activities will focus on incorporating concepts and results from the research into hands-on, active laboratory experiences for students at multiple educational levels. Hands-on laboratory experiences involving fluid mechanics and rheology will energize programs ranging from an academic enrichment program for disadvantaged high school students to a graduate laboratory course helping to prepare students for doctoral research. Intensive research training in the P.I.?s laboratory, for high school, undergraduate, and graduate students, is also a key component of the educational activities. This unified research and education project will enhance the understanding of multiphase transport issues that are crucial for achieving efficient removal of toxic metal contaminants from water while simultaneously it will engage and train the next generation of scientists in the study of fluid flows and material properties.