GOALI: Understanding the anomolous adsorption capacity of hydrothermal char

铁姆科热液焦炭是一种廉价的碳基材料，是在液态水存在的情况下通过加热废物原料而合成的。水热焦在从土壤添加剂到电催化等各种应用领域都表现出了良好的性能，因此最近引起了人们的极大兴趣。该GALI项目的目标是了解和控制水热焦对无机和有机化合物的异常高的吸附能力。这种吸附能力可以被用来隔离构成环境风险的化合物。这项研究将与Cabot公司合作进行，该公司将提供复杂水热炭材料的全面表征。项目成果将纳入伍斯特理工学院S学生项目课程。研究小组将与总部设在伍斯特的非营利性组织有毒土壤破坏者组织合作，进行进一步的研究和指导。尽管水热焦的表面积相对较小，但它具有显著的吸附能力。有人假设，表面结合的羧酸基团自结合来调节超微孔结构，这种结构只有在氢键供体分子存在的情况下才能获得。传统的使用分子氮的气体吸附测量没有开放羧酸门控的超微孔结构，导致表观表面积较低。然而，羧酸在水中去质子化，水热焦结构膨胀，在适当的pH条件下模拟水凝胶的膨胀。因此，水热焦的吸附能力是其实际比表面积远大于测量结果的结果。为了验证这一假设，将使用两种不同的球磨技术来独立控制水热焦的表面积和表面化学：(1)有助于改善水热焦表面成分的干磨技术；(2)增加碳质材料表面积的溶剂辅助湿法磨削技术。利用这两项相关技术，PI将系统地调查水热焦的吸附能力，以确定为什么测得的水热焦的吸附容量与测得的活性碳的吸附容量相当，尽管水热焦的氮测得表面积不到活性碳测得的表面积的1%。该项目的三个目标是：(1)通过反应气体球磨来改变表面组成，了解比表面积和吸附容量之间的关系；(2)利用溶剂辅助球磨作为一种增加热解生物炭测量表面积的技术，了解测量比表面积和吸附容量之间的关系；以及(3)通过测量一系列不同特性和分子尺寸的吸附剂的吸附特性，测试水热焦超微孔面积的羧酸门控。通过解开比表面积和表面组成的相互竞争的影响，结果将使人们对水热焦显著的吸附能力有一个更深刻的理解。

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.