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

气候变化与全球范围内洪水事件发生率和严重程度的稳步增加有关，使受影响的人暴露于大量洪水及其携带的污染物中。污染物的类型变化很大，这对传统污染物屏障系统的功能提出了挑战。这项研究将开发新型复合材料，这些材料来自低成本的废料-壳聚糖和生物炭-以及膨润土，作为可持续的，适应性的和有弹性的屏障材料。壳聚糖是一种从甲壳类动物壳中提取的生物聚合物，生物炭是一种从废弃生物质中产生的含碳副产品，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在于，组合合成材料能够从洪水中去除各种不同大小和电荷的污染物分子，如重金属，营养物质和有机物，同时作为遏制屏障。这项工作将解决开发可持续工程屏障材料的需求，这些材料可以有效地减轻洪水并拦截洪水中可能发现的许多污染物类型的运输。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K-12学生和教师、本科生和研究生工程专业学生、学者和公共机构的外联活动。这项工作的目标是开发由低成本废料--壳聚糖和生物炭--合成的复合材料，使其具有可持续性、适应性、以及用于同时减轻洪水和隔离污染物的安全壳系统中的弹性屏障材料。研究目标是：（1）开发壳聚糖-膨润土复合材料、壳聚糖改性生物炭和壳聚糖-生物炭-膨润土复合材料合成的可重复方法，（2）通过表征研究如zeta电位测量来研究壳聚糖与膨润土和生物炭的物理化学和电结合机制，（3）研究合成复合材料在气候变化条件下的污染物封存/降解和化学相容性范围（4）研究壳聚糖-生物炭-膨润土复合材料在安全壳应用中用于污染物封存的潜力，并通过柱研究获得污染物传输参数。预计这项工作的贡献是：（1）开发可持续的，自适应的，低成本的安全壳屏障材料，（2）理解的基本机制，控制合成材料和选定的污染物之间的物理化学相互作用，和（3）评估合成材料的化学和环境相容性，以有效吸附选定的污染物。该合成材料有潜力适用于许多遏制应用，如内衬滞留池和垃圾填埋场liner.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.