SEES Fellows: Sustainable Nanosilicon Production through the Electrochemical Reduction of Diatoms and Integration into Wastewater Remediation and Biofuel Industries

项目概要SEES研究员：通过硅藻的电化学还原生产可持续的纳米硅，并将其整合到废水治理和生物燃料工业中。吉拉德，威斯康星州大学麦迪逊丰富和无毒的硅纳米结构可以在各种可再生能源技术，包括太阳能电池，锂离子电池和热电材料中发挥重要作用。为了实现纳米硅在可再生能源应用中的潜力，必须以经济和可持续的方式大量生产。目前的硅生产依赖于消耗能源和材料的碳热还原过程，其中碳和砂（二氧化硅）之间的反应在非常高的温度下产生冶金硅和二氧化碳。冶金硅在多个能源和材料消耗步骤中被严格溶解、精炼和重结晶，以产生可再生能源应用的纳米硅。为了使纳米硅用于可再生能源，必须从可持续性的角度重新设计硅的大规模生产。我建议开发一种全新的方法，将纳米硅直接电化学转化为纳米硅，这将是能源和材料效率，因此廉价和可持续的。在与工业合作伙伴AlgaXperts的合作中，我们还将分析这种方法的可扩展性和可行性，通过整合到现有的废水治理和藻类生物燃料工业中，基本上回收这些过程中的纳米结构硅藻（二氧化硅）。智力Merit.A新的可持续和直接的纳米硅生产过程，通过电化学还原硅藻的纳米结构二氧化硅硅藻壳。硅藻（单细胞藻类）的天然纳米结构的二氧化硅微壳是廉价的，并且容易从开采的硅藻土沉积物或硅藻藻类培养物中获得。在主持人威斯康星大学麦迪逊分校化学系Song Jin教授的指导下，拟议的研究旨在开发新型低共熔盐电解质中纳米二氧化硅的电化学还原，这将使在非常低的温度下单步纳米硅生产成为可能，消耗的能量大大减少。如果在转化为硅后，可以保留起始的纳米形态，则该过程将代表迄今为止最可持续的纳米硅生产方法。更广泛的影响。拟议的研究将立即用于各种工业应用，并揭示SEES的新化学技术。我们还建议从工业规模的藻类培养中收获特定的硅藻属，用于废水的生物修复和生物燃料的脂质生产。获得特定的硅藻属允许控制所获得的纳米结构的类型。在与合作伙伴导师Jun Yoshitani，AlgaXperts LLC的总裁合作，我们将分析在中西部水处理设施整合这些方法的可行性。此外，这项合作研究将涉及废水流出物营养物质的化学分析，工业规模培养中特定属的选择性以及相关成本的分析。SEES研究员将更好地了解与实施大规模可持续发展技术有关的工业考虑因素。教育推广。与威斯康星大学麦迪逊分校环境研究纳尔逊研究所的Greg Nemet教授和威斯康星大学麦迪逊分校REU项目主任Andrew Greenberg博士合作，将设计和实施一个高度跨学科的夏季实习，重点是公共政策和可持续发展科学。在初级研究中吸取的经验教训将被纳入theREU夏季实习。在与格林伯格博士的合作中，SEES研究员将在与拟议研究相关的夏季研究项目中指导代表性不足的少数民族本科研究人员。SEES研究员将获得可持续发展政策，教学，课程设计，教学和研究的整合以及本科生指导方面的经验。

Project SummarySEES Fellows: Sustainable Nanosilicon Production through the Electrochemical Reductionof Diatoms and Integration into Wastewater Remediation and Biofuel IndustriesPI: Steven N. Girard, University of Wisconsin MadisonNanostructures of abundant and non-toxic silicon can serve a significant role in various renewableenergy technologies, including solar cells, Li-ion batteries, and thermoelectric materials. To realizethe potential of nanosilicon for renewable energy applications, mass quantities must be economicallyand sustainably produced. Current silicon production relies on an energy- and material- consumingcarbothermal reduction process, in which the reaction between carbon and sand (silica) at very hightemperatures yields metallurgical silicon and carbon dioxide. Metallurgical silicon is subsequentlydissolved, refined, and recrystallized in multiple energy- and material-consuming steps to generatenanosilicon for renewable energy applications. For nanosilicon to be used for renewable energy, thelarge scale production of silicon must be redesigned from a sustainability perspective. I propose todevelop an altogether new process of direct electrochemical conversion of nanosilica-to-nanosiliconthat will be energy and material efficient, and therefore inexpensive and sustainable. In collaborationwith industrial partner AlgaXperts, we will also analyze the scalability and feasibility of thisapproach through the integration into existing wastewater remediation and algae-for-biofuelindustries by essentially recycling the nanostructured diatoms (silica) from these processes.Intellectual Merit.A novel process of sustainable and direct nanosilicon production through theelectrochemical reduction of nanostructured silica frustules of diatoms will be developed. Thenaturally nanostructured silica microshells of diatoms (unicellular algae) are inexpensive and easilyobtained either from mined diatomaceous earth deposits or from diatom algal cultures. Under hostmentor Prof. Song Jin, Department of Chemistry at UW-Madison, the proposed research seeks todevelop electrochemical reduction of nanosilica within novel eutectic salt electrolytes, which willenable single-step nanosilicon production at very low temperatures, consuming considerably lessenergy. If the starting nanomorphologies can be retained following conversion to silicon, thisprocess will represent the most sustainable means of nanosilicon production to date.Broader Impact.The proposed research will be immediately useful for a variety of industrialapplications and expose the SEES fellow new chemical techniques. We further propose harvestingspecific diatom genera from industrial-scale algal cultures used for the bioremediation of wastewatereffluent and production of lipids for biofuels. Obtaining specific diatom genera allow control overthe types of nanostructures obtained. In collaboration with partner mentor Jun Yoshitani, Presidentof AlgaXperts LLC, we will analyze the feasibility of the integration of these approaches at aMidwestern water treatment facility. Furthermore, this collaborative research will involve chemicalanalysis of the wastewater effluent nutrients, selectivity of specific genera in industrial-scale cultures,and analysis of the associated costs. The SEES fellow will gain a better understanding of theindustrial considerations connected to implementing large-scale sustainability technologies.Educational Outreach.In collaboration with Prof. Greg Nemet, Nelson Institute of EnvironmentalStudies at UW-Madison, and Dr. Andrew Greenberg, Director of REU programs at UW-Madison, ahighly interdisciplinary summer practicum focusing on public policy and sustainability science willbe designed and implemented. Lessons learned in the primary research will be integrated into theREU summer practicum. In collaboration with Dr. Greenberg, underrepresented minorityundergraduate researchers will be mentored by the SEES fellow in summer research projects relatedto the proposed research. The SEES fellow will gain experience in sustainability policy, teaching,course design, integration of teaching and research, and undergraduate mentoring.