Collaborative Research: High Surface Area Mesoporous Carbons for Facile Biofuel Recovery from Dilute Aqueous Solution

尽管在利用可再生生物质资源生产可持续液体运输燃料方面取得了重大进展，但在大多数传统生物工艺中，最终产品的毒性仍然是一个关键的、限制生产力的因素。减轻生物燃料产品毒性的一种有效方法是从培养物中进行原位回收，这需要低成本、低能耗和生物相容性分离技术，可以选择性地从稀水溶液中去除生物燃料。已经提出了低能量分离工艺，但大多数先前的研究都集中在模型，生物燃料-水解决方案；实际过程受到复杂的生物混合物的挑战，容易造成污染和材料生物相容性差，这对分离性能和整体过程可行性产生不利影响。在这里，我们建议系统地研究磁性、介孔、碳基材料，以阐明基本的物理化学性质如何影响生物燃料（乙醇和正丁醇）在理想溶液和生长培养中的吸附性能。生物燃料吸附剂相互作用的基本和机制特征，以及非理想的相互作用（污垢现象），将提供在实际系统中的结构-功能关系。最终，通过将这些材料与生产生物燃料的微生物培养物相结合，将评估通过持续的原位生物燃料回收实现的生产力提高。有序介孔材料的高比表面积和孔隙可及性使其成为生物燃料分离的理想材料。我们建议利用软模板介孔碳作为生物燃料吸附剂；孔径、表面积和孔隙形态的合成调整将提供对这些特性如何影响生物燃料吸附能力、分配系数和吸附热的基本理解。我们提出了一种单锅合成方法，在不显著影响介孔结构的情况下，将钴纳米颗粒纳入碳中，从而使吸附剂与培养物进行磁分离。回收效果将被系统地检查，以确定磁选是否是吸附剂回收的可行机制。我们将从基础研究开始，使用模型解决方案与其他常用的生物燃料分离吸附剂进行直接比较；然而，在实际应用程序中，其他考虑因素将是至关重要的。实际上，生产生物燃料的培养物是复杂的混合物，其中污垢和其他非理想的相互作用导致分离性能的改变。同时，介孔碳的微生物相容性相对未知。因此，我们将系统地检查非理想相互作用的性质和程度，以定义和纳入在现实工艺条件下促进持续性能的材料特性。将开发和检查两种不同的回收策略以进行比较分析：传统的外部循环填充床柱，以及在整个培养物中分散磁性吸附剂颗粒的新型方法（随后进行磁性收集）。我们预计后一种新方法将提供更好的效果，因为它可以使吸附剂和培养基之间持续接触，而不需要昂贵和破坏细胞的泵送。这个端到端的概念验证研究将能够评估吸附剂的物理特性对微生物培养物中乙醇和正丁醇的连续原位去除性能的影响。这些顶点实验独特地允许直接评估在理想条件下执行的基本特征是否以及如何预测真实系统的性能。对生物燃料吸附介孔材料的性质-结构关系的基本理解将使生物燃料从培养液中更有效地分离出来，并有助于减少美国对外国化石燃料的依赖。更广泛的教育影响将涉及研究生和本科生参与这一高度跨学科的研究领域。此外，这项研究的概念和结果将被纳入一个新的生物反应器和生物燃料教学实验室模块。建议向当地代表性不足的K-12学生开展外展活动，讨论生物燃料的社会重要性及其分离和生产相关的挑战；此外，这些活动将旨在纠正关于纳米技术的常见误解。将通过阿克伦全球聚合物学院向P-16进行更广泛的传播，该学院的影响力遍及全球。

1159295/1159200Vogt/NielsenDespite significant developments in producing sustainable liquid transportation fuels from renewable biomass resources, end-product toxicity remains a key, productivity-limiting factor in most conventional bioprocesses. One effective approach to relieve biofuel product toxicity is through its in situ recovery from the culture, which requires low cost, low energy, and biocompatible separation technologies that selectively remove biofuels from dilute aqueous solutions. Low energy separation processes have been proposed, but most prior studies have focused on model, biofuel-water solutions; real processes are challenged by complex biological mixtures prone to cause fouling and poor material biocompatibility, which adversely impact separation performance and overall process viability. Here, we propose to systematically examine magnetic, mesoporous, carbon-based materials to elucidate how fundamental physicochemical properties impact adsorbent performance for biofuel (ethanol and n-butanol) recovery in both idealized solutions and growing cultures. Fundamental and mechanistic characterizations of biofuel-adsorbent interactions, as well as nonideal interactions (fouling phenomena), will provide structure-function relationships in real systems. Ultimately, the productivity enhancements that can be realized through continuous, in situ biofuel recovery will be assessed by integrating these materials with biofuel-producing microbial cultures. High surface area and pore accessibility of ordered mesoporous materials make them attractive for biofuel separations. We propose to utilize soft templated mesoporous carbons as biofuel adsorbents; synthetic tuning of the pore size, surface area, and pore morphology will provide a fundamental understanding of how these properties impact biofuel adsorption capacity, partition coefficients, and heats of adsorption. We propose a single pot synthesis to include cobalt nanoparticles in the carbon without significantly impacting the mesostructure to enable magnetic separation of the adsorbent from culture. Recovery efficacy will be systematically examined to determine if magnetic separation is a viable mechanism for adsorbent recovery. We will begin with fundamental studies using model solutions for direct comparison with other commonly examined adsorbents for biofuel separations; however, additional considerations will be critical in real applications. In reality, biofuel-producing cultures are complex mixtures wherein fouling and other non-ideal interactions lead to altered separation performance. Meanwhile, the microbial biocompatibility of mesoporous carbons is relatively unknown. Accordingly, we will systematically examine the nature and degree of non-ideal interactions to define and incorporate material properties promoting sustained performance under realistic process conditions. Two different recovery strategies will be developed and examined for comparative analysis: a traditional, externally circulated packed-bed column, and the novel dispersion of magnetic adsorbent particles throughout the culture (followed by their magnetic collection). We anticipate the latter novel approach, which has never been examined in growing, biofuel-producing cultures, will provide improved efficacy as it enables continuous contact between the adsorbent and culture medium without costly and cell-damaging pumping requirements. This end-to-end, this proof-of-concept study will enable evaluation of how adsorbent physical properties impact performance as applied to continuous, in situ removal of ethanol and n-butanol from growing microbial cultures. These capstone experiments uniquely allow direct evaluation of if and how fundamental characterizations performed under idealized conditions can predict performance in real systems. A fundamental understanding of the property-structure relationships of mesoporous materials for biofuel adsorption would enable more efficient separations of biofuels from culture broths and will aid in reducing the U.S. dependence on foreign fossil fuels. The broader educational impact will involve participation of graduate and undergraduate students in this highly interdisciplinary area of inquiry. Moreover, concepts and results from this research will be incorporated into a new teaching lab module on bioreactors and biofuels. Outreach activities to local underrepresented K-12 students are proposed to discuss the societal importance biofuels and the challenges associated with their separation and production; additionally, these activities will aim to correct common misconceptions regarding nanotechnology. Broader dissemination to P-16 will be enabled through the Akron Global Polymer Academy, which has worldwide reach.