Novel Biodegradable Materials for Additive Manufacturing of Complex Scaffolds for Algal Bioremediation Systems

藻类养殖在环境修复和能源生产应用方面都引起了极大的兴趣。然而，将藻类用于这些应用的经济可行性在很大程度上取决于生长特定藻类类型的效率。定制设计的材料和结构允许受控的微生物生长过程，从而提高水修复和能量收集的效率。传统上，二维合成聚合物网被用作藻类附着和生长的支架。这些传统的基质是不可生物降解的，并且不能为目标藻类生长提供最佳形状或表面特征。该奖项支持使用增材制造从纤维素纳米晶体打印可生物降解复合材料支架的基础研究，纤维素纳米晶体是从废弃的农业和林业产品中提取的天然丰富材料。研究结果将有助于推动更经济和可生物降解的途径的发展，以种植藻类来去除水中的污染物和/或生产能源。 本研究的总体目标是建立一个科学的理解的综合影响的支架组成，形状和纹理对藻类生长和支架生物降解在水修复反应器。第一个研究目标是了解材料组成和加工对长丝性能的影响。为了实现这一目标，将在三种初始混合方法之后使用挤出生产纤维素纤维/聚乳酸复合长丝：1）干混，2）喷雾干燥，和3）聚环氧乙烷/纤维素纤维母料掺入。将使用标准方法测量流变学、热学、形态学和接触角特性。第二个目标是了解长丝的流变特性（特别是弹性模量与粘性模量的比率）对通过增材制造（熔融沉积成型）打印的支架的质量（包括表面缺陷）的影响。几种类型的复合长丝将被打印到含有一系列表面结构的藻类生长支架中。将使用光学显微镜和彩色共焦轮廓术测量沉积层的特性（例如层厚度、路宽和填充空隙），并将其与表面缺陷相关联。第三个目标是了解支架形状和化学物质如何影响藻类生长和支架降解。这些支架将被放入一个实验室规模的流动反应器中，反应器中含有藻类生长介质。 以一周为增量，移除支架并通过光学显微镜检查。然后将藻类移除，并记录从不同区域收获的质量。还将使用显微镜和质量测量评估支架的变化。

Algal farming has garnered significant interest for both environmental remediation and energy production applications. However, the economic viability of using algae for these applications heavily depends on the efficiency of growing specific algae types. Custom-designed materials and structures allow for controlled microbiological growth processes that result in increased efficiency in water remediation and energy harvesting. Conventionally, two-dimensional synthetic polymer meshes are employed as the scaffolds for algal attachment and growth. These traditional substrata are not biodegradable, and do not provide the optimal shape or surface characteristics for targeted algal growth. This award supports fundamental research on using additive manufacturing to print biodegradable composite scaffolds from cellulose nanocrystals, naturally abundant materials extracted from waste agricultural and forest products. Research results will help advance the development of more economical and biodegradable routes to grow algae for removing contaminants from water and/or producing energy. The overarching goal of this research is to establish a scientific understanding of combined effects of scaffold composition, shape, and texture on algal growth and scaffold biodegradation in water remediation reactors. The first research objective is to understand the effects of the material composition and processing on the filament properties. To achieve this objective, cellulose nanocrystal/polylactic acid composite filaments will be produced using extrusion after three initial mixing methods: 1) dry mixing, 2) spray drying, and 3) polyethylene oxide/cellulose nanocrystal masterbatch incorporation. Measurement of rheological, thermal, morphological, and contact angle properties will be performed using standard methods. The second objective is to understand the effects of rheological properties (particularly the ratio of the elastic to viscous modulus) of the filaments on the quality (including surface defects) of the scaffolds printed by additive manufacturing (fused deposition modeling). Several types of composite filament will be printed into algae growth scaffolds containing a range of surface structures. The characteristics of the deposited layers (e.g. layer thickness, road width, and fill voids) will be measured using optical microscopy and chromatic confocal profilometry and correlated to surface defects. The third objective is to understand how scaffold shape and chemistry affect algal growth and scaffold degradation. The scaffolds will be put into a laboratory-scale flow reactor containing algae growth media. At one week increments, the scaffold will be removed and examined by optical microscopy. The algae will then be removed and the mass harvested from different regions recorded. Changes to the scaffold will also be assessed using microscopy and mass measurement.