Date of Award

Fall 12-15-2023

Level of Access Assigned by Author

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Forest Resources

Advisor

Mehdi Tajvidi

Second Committee Member

Islam Hafez

Third Committee Member

Aria Amirbahman

Additional Committee Members

Douglas W. Bousfield

Michael D. Mason

Abstract

The use of metal-oxide nanoparticles adsorbents is limited to fixed-bed columns in industrial-scale water treatment applications. This limitation is commonly attributed to the tendency of nanoparticles to aggregate, the use of non-sustainable and inefficient polymeric resins as supporting materials, or a lack of adsorption capacity. Foams and aerogels derived from cellulose nanomaterials have unique characteristics, such as high porosity and low density, which enables their use in a variety of environmental applications, including water treatment. However, the overall use of cellulose nanomaterial-based foams in various environmental sectors is limited due to the high cost of production associated with time- and cost-intensive manufacturing processes such as freeze-drying and supercritical CO2 drying. In addition, additive manufacturing is a prominent technology for accurately developing and controlling micro-to-macrostructures with continuous automation; however, the use of cellulose-based materials in additive manufacturing is also limited due to its complex processing route involved in different stages of manufacturing. Hence this dissertation initially assessed the feasibility of the synthesis and immobilization of magnesium-doped amorphous iron oxide nanoparticles (IONPs) on the surface of a freeze-dried and crosslinked cellulose nanofibril (CNF) aerogel for arsenic removal from water. The adsorption kinetics and isotherms were studied for both As(III) and As(V). Further work involved the use of urea as an additive to develop a microwave-assisted thawing procedure for creating CNF-based hybrid foams at a significantly shorter time and lower energy consumption than any previously reported methods. A freezing rate-dependent mechanism for foam formation was proposed, along with a new crosslinking pathway that was confirmed by FTIR and nitrogen content analyses. The foams' mechanical properties were examined in both dry and wet conditions. In addition, the dissertation provides with an investigation for the 3D-printability of a CNF paste by optimizing the solid content of CNFs with the composition of urea and carboxymethyl cellulose (CMC). The amplitude-sweep tests and zeta potential analyses demonstrated conclusively that the rheological properties of the paste are significantly influenced by the addition of urea and CMC at various concentrations. Compression and tensile strengths were evaluated, and it was discovered that a higher CMC content positively affected interlayer adhesion along the printing direction, thereby increasing the compression and tensile strengths of the structures. Using the Fourier-transform infrared spectroscopy (FTIR), a comprehensive investigation of the chemical interactions between CNF, urea, and CMC was conducted. Consequently, this method provides an economically viable alternative for promoting sustainable nanomaterials in the field of additive manufacturing, thereby creating new opportunities for increasing production scale and efficiency.

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