CAS: Nanocellulose-Enabled Nanocomposites for Sustainable Water Remediation

PART 1: NON-TECHNICAL SUMMARY

Nanocellulose can be extracted from all lignocellulose plants (woody and non-woody) - the largest natural polymer sources on Earth. Nanocelluloses have been shown to be excellent building block materials to form low-cost and effective water purification media, such as anionic bio-adsorbents and membrane barrier layers. The incorporation of functional metal oxide nanoparticles in the nanocellulose scaffold can create new types of sustainable cationic bioadsorbents and photocatalysts for water purification while also eliminating typical adverse effects of using nanoparticles in environmental remediation.

However, there are some fundamental knowledge gaps in fully understanding the structure-property-process/synthesis relationships during the creation of hierarchically structured nanocellulose-metal oxide nanocomposites that can maintain stability and effectiveness in the aqueous environment. This project aims to investigate several fundamental issues of and provide new insights into the subject and fill those knowledge gaps.

The benefits of using such nanocomposites for water purification have only begun to be realized, demonstrating particular importance as climate change has increased the frequency and severity of clean-water shortage. In additiopn to the research, a range of educational activities will be developed to engage post-doc, graduate, undergraduate (especially minority and women scientists) and high school students, in focusing on access to safe drinking water as an issue of global sustainability while learning about the fundamental concepts of sustainability and water purification.

PART 2: TECHNICAL SUMMARY

The overall objective of this research is to understand and control the incorporation of model cationic metal oxide nanoparticles into anionic cellulose nanofiber scaffolds of different charge density and degree of fibrillation, aiming to create new functional nanocomposites from renewable and sustainable sources for water purification. The specific aims of this project are two. (1) Understand the effects of nanocellulose structure and functionality on the transport and interactions of metal oxide nanoparticles during mixing and in-situ synthesis processes in the formation of nanocomposites.

Two model nanoparticle (NP) systems are chosen: (i) aluminium oxide (Al2O3) NPs with sizes in the range of nanocellulose scaffold pore sizes to explore effective and anomalous diffusion processes through the mixing approach to form stable and homogeneous composite frameworks, and (ii) “white” and “black” (low-band gap) titanium oxide (TiO2) NPs that will be formed in-situ through synthesis, and nucleation/growth processes to understand critical factors that can control the structure and properties of nanocomposites. The NP transport and formation mechanisms, as well as the resulting dynamics behavior will be evaluated against the morphology, degree of fibrillation, and electrostatic properties of the nanocellulose scaffolds. (2) Develop advanced characterization and modeling techniques that can reveal the structure-property-processing relationships during nanocomposite formation.

The primary processing-structure characterization methods will include shear-free mixing combined with in-situ scanning small-angle X-ray scattering (SAXS), X-ray photon correlation spectroscopy (XPCS), and other spectroscopic techniques using synchrotron radiations, while the performance evaluation will be focused on adsorption of anionic contaminants (e.g., fluorides and nitrates) and photocatalytic degradation by solar radiation.

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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.