Coupling Small-particle Adsorbents with Membranes for Trace-containment Removal in Water Treatment

最近的技术进步带来了有前途的纳米和微尺寸（小颗粒）材料，它们可以去除饮用水中的合成有机化学物质（soc）。这些小颗粒吸附剂，如石墨烯薄片和超细粉状活性炭（S-PAC），比较大的材料表现出更快的吸附动力学。小颗粒吸附剂在天然有机物（NOM）存在时也表现得更好，这意味着它们在实际情况下可能更好。然而，小颗粒存在一个实际问题：阻止它们进入成品饮用水。微滤（MF）和超滤（UF）膜处理是有效的，但小孔被小物质堵塞会降低水通量，增加分离所需的能量。因此，存在一个两难的问题：小颗粒对SOC的吸附效果最好，而大颗粒更容易去除。一个主要的进步将是找到SOC吸附高、NOM竞争低、去除吸附剂所需能量少的材料和条件。该项目围绕三个主要目标建立：(1)确定小颗粒吸附剂的特性，使其能够在最小的NOM干扰下吸附有机碳（SOC）。(2)确定小颗粒吸附剂对不同孔径膜的污染程度，并检查颗粒突破倾向。(3)探索以膜分离所需的最小能量实现SOC吸附的工程方法。在目标1中，将从原水和混凝/絮凝水中提取NOM，以测试soc的竞争吸附。在一些实验中，3h标记的NOM和14c标记的阿特拉津将被用于研究质量传递机制。在Aim 2中，考虑到聚集的影响，在去除小颗粒吸附剂时，将测量膜通量和颗粒突破。制备粒度控制良好的碳球，仔细研究粒度效应。在目标3中，将使用反应器/膜装置，在诱导聚合之前允许分散颗粒吸附SOC，从而减少污染和膜突破。通常研究新材料的吸附能力和动力学，但这里将同时探索竞争吸附效应和小颗粒去除要求，以了解这些现象是如何相互联系的。例如，小颗粒聚集体的结构将影响吸附动力学和膜运输。新技术将用于研究这些现象，例如放射性标记的NOM和阿特拉津，以达到以前在竞争性吸附研究中未达到的检测水平。此外，在膜系统中诱导吸附剂聚集的概念以前还没有被探索过。该项目可能导致专门设计的工程单元工艺，以有效地从饮用水源中去除令人关注的soc，如个人护理产品和内分泌干扰化合物，以保护人类健康。这项研究还将阐明理想的材料特性，为研究人员提供未来材料开发的目标。虽然去除有机碳是重点，但实际上这是一个混合系统，可以在一个过程中实现多个处理目标（即控制小分子量污染物和微生物污染物）。展望未来，可持续的水处理将需要低足迹和低能耗的过程，这是这里的双重目标。

CBET 1236070David Ladner, Tanju Karanfil, Thompson MeffordRecent technological advances have resulted in promising nano- and micro-sized (small-particle) materials that can remove synthetic organic chemicals (SOCs) from drinking water. These small-particle adsorbents, such as graphene platelets and super-fine powdered activated carbon (S-PAC), show faster adsorption kinetics than larger materials. Small-particle adsorbents also perform better in the presence of natural organic matter (NOM), which means they may be better in real-world situations. However, a practical problem exists with small particles: preventing their passage into the finished drinking water. Microfiltration (MF) and ultrafiltration (UF) membrane processes can be effective, but pore blockage by the small materials decreases water flux and increases the energy required for separations. Thus there exists a quandary: small particles are best for SOC adsorption, but large particles are easier to remove. A major advancement would be to find materials and conditions where SOC adsorption is high, NOM competition is low, and little energy is required to remove the adsorbents. This project is built around three main Aims: (1) Determine the properties of small-particle adsorbents that enable SOC adsorption with minimal interference by NOM. (2) Determine the extent to which small-particle adsorbents will foul membranes of various pore size and examine the particle breakthrough propensity. (3) Explore engineering methods to achieve SOC adsorption with minimal energy required for membrane separations. In Aim 1 NOM will be extracted from raw water and from coagulated/flocculated water to test competitive adsorption of SOCs. In some experiments 3H-labeled NOM and 14C-labeled atrazine will be used to investigate mass-transport mechanisms. In Aim 2 membrane flux and particle breakthrough will be measured when removing small-particle adsorbents, taking into account the effects of aggregation. Carbon spheres will be produced with well-controlled particle size to carefully study particle size effects. In Aim 3 a reactor/membrane setup will be used that will allow SOC adsorption by dispersed particles before inducing aggregation that is expected to decrease fouling and membrane breakthrough. Adsorption capacity and kinetics are commonly investigated for novel materials, but here both competitive adsorption effects and small-particle removal requirements will be explored simultaneously to learn how these phenomena are interconnected. For example, the structure of an aggregate of small particles will affect both adsorption kinetics and membrane transport. Novel techniques will be used to investigate the phenomena, such as the radiolabeled NOM and atrazine for detection levels that have not previously been achieved in competitive adsorption studies. Further, the concept of induced adsorbent aggregation in membrane systems has not been previously explored.This project may lead to engineered unit processes specifically designed to efficiently remove SOCs of concern, like personal care products and endocrine disrupting compounds, from drinking water sources to protect human health. The study will also elucidate desirable materials properties, giving researchers targets for which they can aim in future materials development. Although SOC removal is the focus, this is in fact a hybrid system that will allow multiple treatment objectives in a single process (i.e., the control of both small molecular weight contaminants and microbial contaminants). Moving into the future, sustainable water treatment will require low-footprint and low-energy processes, which are the dual objectives here.