Collaborative Research: Development of Novel Chitosan-Biochar-Bentonite Composite Barrier Resilient to Changing Climate: Synthesis, Characterization, and Containment Mechanisms

气候变化与世界范围内洪水事件的发生和严重程度的稳步增加有关，使那些受到影响的人暴露在大量洪水及其携带的污染物中。污染物的种类变化很大，这对传统的污染物屏障系统的功能提出了挑战。这项研究将开发由低成本废物材料-壳聚糖和生物炭-和膨润土衍生的新型复合材料，作为可持续、适应性和弹性的屏障材料。壳聚糖是一种从甲壳类动物壳中提取的生物聚合物，生物炭是一种从生物质废弃物中产生的碳质副产品，它们都可以从洪水中去除不同类型的污染物。这项工作的关键创新是，组合合成材料能够在起到遏制屏障的作用的同时，从洪水中去除各种大小和电荷的污染物分子，如重金属、营养物质和有机物。这项工作将解决开发可持续工程屏障材料的需要，这些材料可以有效地缓解洪水泛滥，并拦截洪水中可能发现的许多污染物类型的传输。该奖项将通过有组织的实地考察、研讨会和研讨会等活动，支持对K-12学生和教师、本科生和工程学研究生、学者和公共机构的推广。这项工作的目标是开发由低成本废物材料--壳聚糖和生物炭--合成的复合材料，作为围堵系统中可持续、适应性和弹性的屏障材料，用于同时缓解洪水和隔离污染物。研究目标是：(1)发展可重复使用的壳聚糖-膨润土复合材料、壳聚糖修饰生物炭和壳聚糖-生物炭-膨润土复合材料的合成方法；(2)通过Zeta电位测量等表征研究壳聚糖与膨润土和生物炭的物理化学和电学结合机理；(3)通过批量实验考察合成复合材料在不同气候条件(pH、离子强度、溶解有机物含量和污染物混合物)下的污染物隔离/降解和化学相容性范围；(4)考察壳聚糖-生物炭-膨润土复合材料在围堵应用中的污染物隔离应用潜力，并通过柱实验得出污染物迁移参数。这项工作的预期贡献是：(1)开发可持续、适应性、低成本的阻隔材料，(2)了解控制合成材料与选定污染物之间物理化学相互作用的基本机制，以及(3)评估合成材料的化学和环境兼容性，以有效吸附选定污染物。这种合成材料有潜力用于许多密封应用，如衬里保留池和垃圾填埋场衬里。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Climate change is linked to the steady increase in occurrence and severity of flooding events world-wide, exposing those impacted to large volumes of floodwaters and the contaminants they carry. Contaminant types vary widely, which challenges the functionality of traditional contaminant barrier systems. This research will develop novel composite materials derived from low-cost waste materials – chitosan and biochar – and bentonite as sustainable, adaptive, and resilient barrier materials. Chitosan, a biopolymer derived from crustacean shells, and biochar, a carbonaceous byproduct produced from waste biomass, can each remove different contaminant types from floodwater. The key innovation of this work is the ability of the combined synthesized materials to remove a wide range of contaminant molecules of varying size and charge, such as heavy metals, nutrients, and organics, from floodwater while functioning as a containment barrier. This work will address the need to develop sustainable engineered barrier materials that effectively mitigate flooding and intercept the transport of many contaminant types potentially found in floodwaters. This award will support outreach to K-12 students and teachers, undergraduate and graduate engineering students, academics, and public agencies through activities such as organized field trips, workshops, and seminars.The goal of this work is to develop composites synthesized from low-cost, waste materials – chitosan and biochar – as sustainable, adaptive, and resilient barrier materials in containment systems for simultaneous flood mitigation and contaminant sequestration. The research objectives are: (1) develop repeatable methods for chitosan-bentonite composite, chitosan-amended biochar, and chitosan-biochar-bentonite composite synthesis, (2) investigate the physico-chemical and electrical binding mechanisms of chitosan with bentonite and biochar through characterization studies such as zeta potential measurement, (3) investigate contaminant sequestration/degradation and chemical compatibility ranges of the synthesized composites under changing climate conditions (pH, ionic strength, dissolved organic content, and contaminant mixtures) through batch studies, and (4) investigate the potential of chitosan-biochar-bentonite composites for contaminant sequestration in containment applications and derive contaminant transport parameters through column studies. The contributions expected from this work are: (1) developing sustainable, adaptive, low-cost containment barrier materials, (2) understanding the fundamental mechanisms governing the physico-chemical interactions between the synthesized materials and the selected contaminants, and (3) assessing chemical and environmental compatibility of the synthesized materials for effective adsorption of the selected contaminants. The synthesized materials have potential to be adapted for many containment applications such as lined retention ponds and landfill liners.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.