SusChEM: Customizable Separations using Oil-Coated Bubbles

矿石的加工以回收有价值的矿物，纸张的生产和循环利用以及废水的处理都需要从水浆中去除小固体颗粒的过程。让小颗粒仅靠引力沉降，将需要大得令人望而却步的沉降盆地。因此，工业标准是使空气通过浆料，使颗粒粘附在气泡上并上升到表面，在那里它们可以很容易地撇去。这种泡沫浮选工艺最适合去除疏水（亲油）颗粒，但对亲水（亲水）颗粒效果较差，因为后者离开水相并附着在气泡上的倾向较小。然而，用良性水基替代品取代油基化学品的趋势，对传统泡沫浮选方法的有效去除构成了挑战。例如，越来越多地使用环保型水性印刷油墨导致纸张回收困难。随着新的分离策略的发展，在适应现有设备和工艺方面有一个值得商榷的优势。本项目将开发一种方法，在气泡表面涂上环保、可回收的生物基油，以提高泡沫浮选去除疏水颗粒的效率。本课题的中心假设是，在气泡表面涂上一层油，会消除颗粒粘附在气泡表面的能量屏障，从而对泡沫浮选产生积极的影响，从而提高颗粒-气泡的粘附性，提高分离效率。预计油膜也会改变气泡的形状和上升动力。这些假设将在浮选柱上进行实验验证，通过光学、重力和化学分析相结合的方法，比较有涂层和无涂层的气泡。模型颗粒允许在润湿性、颗粒类型和油成分方面的系统变化，并将用于开发理论框架。该理论将扩展和验证亲水性油墨从一个实际的纸浆。该项目将导致对浮选分离性能的三相油水气泡相互作用的基本理解，允许针对特定分离任务定制浮选设备的工程设计。一名研究生和一至两名本科生将进行实验室实验。推广工作将包括使用桌面浮选柱的实际演示，目标受众是小学生和中学生。

The processing of ores to recover valuable minerals, the production and recycling of paper, and the treatment of wastewater all require processes that remove small solid particles from an aqueous slurry. Allowing the small particles to settle by gravitational forces alone would require prohibitively large settling basins. Thus, the industrial standard is to bubble air through the slurry, so that the particles adhere to the bubbles and rise to the surface where they can be easily skimmed off. This froth flotation process is best suited for removal of hydrophobic (oil-loving) particles, but is less effective for hydrophilic (water-loving) particles, as the latter have less proclivity to leave the aqueous phase and cling to the air bubble. Yet, a trend to replace oil-based chemicals with benign water-based substitutes has challenged effective removal via traditional froth flotation methods. As one example, the increasing use of environmentally friendly water-based printing inks leads to difficulty in recycling this paper. As new separation strategies are developed, there is an arguable advantage in adapting existing equipment and processes. This project will develop a method to coat the air bubble with environmentally benign and recyclable bio-based oils to increase the improve the efficiency of froth flotation in removing hydrophobic particles. The central hypothesis of this project is that an oil coating on the bubble will positively affect froth flotation by removing energy barriers for particles to adhere to the bubble surface, thereby improving particle-bubble adhesion, and increasing the separation efficiency. The oil coat is also expected to alter both the bubble shape and its rise dynamics. These hypotheses will be probed experimentally in a flotation column, comparing coated to uncoated bubbles, using a combination of optical, gravimetrical, and chemical analyses. Model particles allow for systematic variations in wettability, particle type, and the oil composition, and will be used to develop a theoretical framework. The theory will be extended and validated with hydrophilic inks from an actual paper pulp. The project will lead to a fundamental understanding of the three-phase oil-water-bubble interactions responsible for the performance of flotation separations, allowing customization of the engineering design of flotation devices for a specific separation task. One graduate student and one or two undergraduate researchers will conduct the laboratory experiments. Outreach efforts will include hands-on demonstrations using table top flotation columns, with a target audience of elementary and middle school students.