GOALI: Understanding the anomolous adsorption capacity of hydrothermal char

1605916 Timko水热炭是一种廉价的碳基材料，通过在液态水存在下加热废弃原料合成。 水热焦在土壤添加剂、电催化等领域具有广阔的应用前景，近年来引起了人们的极大兴趣。 该GOALI项目的目的是了解和控制热液焦对无机和有机化合物的异常高的吸附能力。这种吸附能力可用于隔离对环境构成风险的化合物。 该研究将与Cabot公司合作进行，后者将提供复杂水热炭材料的全面表征。该项目的成果将被纳入伍斯特理工学院？的学生项目课程。 该研究团队将与伍斯特的非营利组织The Toxic Soil Busters合作，进行更多的研究和指导。尽管水热焦的表面积相对较低，但它具有出色的吸附能力。据推测，表面结合的羧酸基团自缔合以介导仅在存在氢键供体分子的情况下可接近的超疏水结构。使用分子氮的传统气体吸附测量不会打开羧酸门控的超晶格结构，导致表观表面积低。 然而，羧酸在水中去质子化，并且水热炭结构溶胀，模拟水凝胶在适当pH条件下的溶胀。因此，水热炭的吸附能力是其实际表面积远大于测量的结果。为了测试该假设，将使用两种单独的球磨技术来独立地控制水热炭的表面积和表面化学：（1）可用于改性水热炭表面组成的干磨技术，和（2）增加含碳材料的表面积的溶剂辅助湿磨技术。使用这两种相关技术，PI将系统地研究水热焦的吸附能力，以确定为什么水热焦的测量吸附能力与活性炭的测量吸附能力相当，尽管水热焦的氮测量表面积小于活性炭测量表面积的1%。 该项目的三个目标是：（1）了解表面积和吸附能力之间的关系，使用反应气体研磨来改变表面组成;（2）了解测量的表面积和吸附能力之间的关系，使用溶剂辅助研磨作为增加热解生物炭测量表面积的技术;（3）通过测定一系列不同性质和分子大小的山梨酸酯的吸附特性，来检验水热焦超临界区的羧酸门控。 通过解开表面积和表面组成的竞争效应，结果将提供一个坚定的理解显着的吸附能力的水热焦。

1605916TimkoHydrothermal chars are inexpensive carbon-based materials that are synthesized by heating waste feedstock in the presence of liquid water. Hydrothermal chars have recently attracted significant interest because they exhibit promising performance in a variety of applications ranging from soil additives to electrocatalysis. The objective of this GOALI project is to understand and control the unusually high adsorption capacity of hydrothermal chars for inorganic and organic compounds. This adsorption capacity can be exploited to sequester compounds that pose environmental risks. The research will be performed in collaboration with Cabot Corporation, who will provide comprehensive characterizations of complex hydrothermal char materials. Results from the project will be incorporated into Worcester Polytechnic Institute?s student projects curriculum. The research team will partner with the Worcester-based non-profit group, The Toxic Soil Busters, for additional research and mentoring.Hydrothermal chars have remarkable adsorption capacities despite their relatively low surface areas. It has been hypothesized that surface-bound carboxylic acid groups self-associate to mediate an ultramicropore structure that is accessible only in the presence of hydrogen bond donating molecules. Traditional gas sorption measurements that use molecular nitrogen do not open the carboxylic acid gated ultramicropore structure, resulting in low apparent surface areas. However, the carboxylic acids deprotonate in water, and the hydrothermal char structure swells, mimicking the swelling of a hydrogel under appropriate pH conditions. Therefore, the sorption capacity of hydrothermal char is a result of its actual surface area being much greater than measured. To test the hypothesis, two separate ball milling techniques will be used to independently control the surface area and surface chemistry of the hydrothermal chars: (1) a dry-milling technique that is useful for modifying hydrothermal char surface composition, and (2) a solvent-assisted wet-milling technique that increases the surface area of carbonaceous materials. Using these two related techniques, the PI will investigate systematically the adsorption capacity of hydrothermal char to determine why measured adsorption capacities of hydrothermal chars are comparable to those measured for activated carbon, despite the fact that the nitrogen-measured surface areas of hydrothermal chars are less than 1% of those measured for activated carbon. The three aims of the project are: (1) to understand the relationship between surface area and sorption capacity using a reactive gas milling to modify surface composition; (2) to understand the relationship between measured surface area and sorption capacity, using solvent-assisted milling as a technique for increasing measured surface areas of pyrolysis biochar; and (3) to test the carboxylic acid gating of hydrothermal char ultramicropore area by measurement of sorption characteristics for a series of sorbates with varying characteristics and molecular sizes. By disentangling the competing effects of surface area and surface composition, the results will provide a firm understanding of the remarkable sorption capacities of hydrothermal chars.