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Sustainable Production of Water and Energy with Osmotically-Driven Membrane Processes and Ion-Exchange Membrane Processes.

机译：渗透驱动的膜工艺和离子交换膜工艺可实现水和能源的可持续生产。

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摘要

The world population of the 21st century is facing an increasingly challenging energy landscape and declining water quality and availability, further compounded by a rapidly expanding global population against the backdrop of climate change. To meet the challenges of the water-energy nexus in a sustainable manner, existing methods need to be advanced and new technologies developed. Osmotically-driven and ion-exchange membrane processes are two classes of emerging technologies that can offer cost-effective and environmentally sensible solutions to alleviate the pressure on our water and energy demands. The objective of this thesis is to advance forward osmosis (FO), pressure retarded osmosis (PRO), and reverse electrodialysis (RED) for the sustainable production of water and energy.;A main hindrance restricting the progress of osmotically-driven membrane processes, FO and PRO, is the absence of adequate membranes. This work demonstrates the fabrication of thin-film composite polyamide FO membranes that can attain high water flux and PRO membranes capable of achieving power density of 10 W/m2, twice the benchmark of 5 W/m2 for PRO with natural salinity gradients to be cost-effective. A membrane fabrication platform based on mechanistic understanding of the influence of membrane transport and structural parameters on process performance was developed. The morphology and microstructure of the porous support layer, and hydraulic permeability and salt selectivity of the polyamide active layer were specifically tailored by thoughtful control of the fabrication and modification conditions.;The Gibbs free energy from the mixing of river water with seawater can potentially be harnessed for clean and renewable energy production. This work analyzed the thermodynamics of PRO power generation and determined that energy efficiencies of up to ∼91% can theoretically be attained. The intrinsic limitations and practical constraints in PRO were identified and discussed. Using a tenth of the annual global river water discharge of 37,000 km 3 for PRO could potentially produce electricity for over half a billion people, ascertaining natural salinity gradients to be a sizeable renewable source that can contribute to diversifying our energy portfolio.;However, fouling of the membrane support layer can diminish the PRO productivity by detrimentally increasing the hydraulic resistance. Analysis of the water flux behavior and methodical characterization of the membrane properties shed light on the fouling mechanism and revealed the active-support layer interface to play a crucial role during fouling. A brief osmotic backwash was shown to be effective in cleaning the membrane and achieving substantial performance recovery.;Reverse electrodialysis (RED) is an ion-exchange membrane process that can also extract useful work from salinity gradients. This dissertation research examined the energy efficiency and power density of RED and identified a tradeoff relation between the two performance parameters. Energy efficiency of ∼33-44% can be obtained with technologically-available membranes, but the low power densities of < 1 W/m2 is likely to be impede the realization of the process. To further advance RED as a salinity energy conversion method, ion-exchange membrane technology and stack design need to be advanced beyond their current limitations.;When analyzed with simulated existing state-of-the-art membranes, PRO exhibited greater energy efficiencies (54-56%) and significantly higher power densities (2.4-38 W/m2) than RED (18-38% and 0.77-1.2 W/m 2). The drawback of RED is especially pronounced at large salinity gradients, where the high solution concentrations overwhelm the Donnan exclusion effect and detrimentally diminish the ion exchange membrane permselectivity. Additionally, the inherent different in driving force utilization (osmotic pressure difference for PRO and Nernst potential for RED) restricts RED from exploiting larger salinity gradients to enhance performance. Overall, PRO is found to be the more favorable membrane-based technology for accessing salinity energy.;This work presents pioneering advances for forward osmosis and pressure retarded osmosis membrane development. The fundamental studies of the osmotically-driven membrane processes and ion-exchange membrane processes yielded significant findings that enhanced our mechanistic and thermodynamic understanding of the technologies. The important insights can serve to inform the realization of the emerging membrane-based technologies for the sustainable production of water and energy. The implications of the thesis are potentially far-reaching and are anticipated to shape the discussion on FO, PRO, and RED.
机译：21世纪的世界人口正面临着日益严峻的能源形势，水质和可利用性不断下降，在气候变化的背景下，全球人口的快速增长进一步加剧了这一情况。为了以可持续的方式应对水能关系的挑战，需要改进现有方法并开发新技术。渗透驱动和离子交换膜工艺是两类新兴技术，可以提供具有成本效益和对环境有益的解决方案，以减轻对我们的水和能源需求的压力。本论文的目的是为了促进水和能量的可持续生产而进行正向渗透（FO），压力延迟渗透（PRO）和反向电渗析（RED）。;主要障碍是限制渗透膜驱动过程的进展， FO和PRO是缺乏适当的膜。这项工作证明了能够获得高水通量的薄膜复合聚酰胺FO膜的制造以及能够实现10 W / m2功率密度的PRO膜的制造，这是成本为自然盐度梯度的PRO的5 W / m2基准的两倍-有效。开发了一种基于机械理解膜运输和结构参数对工艺性能影响的膜制造平台。通过精心控制制造和改性条件，可专门定制多孔支撑层的形貌和微观结构，以及聚酰胺活性层的水渗透性和盐选择性。江河水与海水混合产生的吉布斯自由能可能是用于清洁和可再生能源生产。这项工作分析了PRO发电的热力学，并确定理论上可以达到约91％的能量效率。确定并讨论了PRO中的固有局限性和实际约束。使用全球每年37,000 km 3的十分之一的水用于PRO可能会为超过10亿人口生产电力，确定自然盐度梯度是可再生的可再生资源，可有助于我们的能源组合多样化。膜支撑层的膜厚降低会不利地增加水力阻力，从而降低PRO生产率。水通量行为的分析和膜性质的方法表征揭示了结垢机理，并揭示了活性-支撑层界面在结垢过程中起着至关重要的作用。简短的渗透反冲洗被证明可有效清洁膜并实现显着的性能恢复。反向电渗析（RED）是一种离子交换膜工艺，还可以从盐度梯度中提取有用的功。本论文研究了RED的能量效率和功率密度，并确定了两个性能参数之间的折衷关系。使用技术上可行的膜可以达到约33-44％的能效，但是<1 W / m2的低功率密度很可能会阻碍该工艺的实现。为了进一步将RED作为盐度能量转换方法，离子交换膜技术和烟囱设计需要超越当前的局限性进行改进;当用模拟的现有最新膜进行分析时，PRO表现出更高的能量效率（54） -56％）和明显高于RED（18-38％和0.77-1.2 W / m 2）的功率密度（2.4-38 W / m2）。 RED的缺点在较大的盐度梯度下尤其明显，在高盐度梯度下，高溶液浓度压倒了Donnan的排斥效应，不利地降低了离子交换膜的渗透选择性。此外，驱动力利用方面的固有差异（PRO的渗透压差和RED的能斯特势能）限制了RED利用更大的盐度梯度来提高性能。总的来说，PRO被认为是获得盐分能量的更有利的基于膜的技术。这项工作为正向渗透和压力渗透膜的开发提供了开拓性的进展。对渗透膜过程和离子交换膜过程的基础研究产生了重要发现，这些发现增强了我们对技术的机械学和热力学理解。重要的见解可以为实现可持续水和能源生产的基于膜的新兴技术的实现提供信息。论文的意义可能是深远的，有望影响FO，PRO和RED的讨论。

著录项

  • 作者

    Yip, Ngai Yin.;

  • 作者单位

    Yale University.;

  • 授予单位 Yale University.;
  • 学科 Engineering Environmental.;Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 296 p.
  • 总页数 296
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:54:09

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